当前期刊: Journal of Materials Engineering and Performance Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Boro-Austempering Treatment of High-Strength Bainitic Steels
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-24
    Pedro Gabriel Bonella de Oliveira, Fábio Edson Mariani, Luiz Carlos Casteletti, André Itman Filho, Amadeu Lombardi Neto, George Edward Totten

    Abstract High-strength bainitic steels are considered potential candidates for the 3rd generation of advanced high-strength steels (AHSS). The main characteristic of silicon-alloyed steels is the presence of carbide-free bainite, obtained by low-temperature austempering. Salt bath boriding is an effective method for increasing wear resistance and provides high corrosion resistance. The combination of these two treatments is called boro-austempering and is a promising alternative to increase the wear resistance of AHSS. In the present work, samples were borided at 900 °C for 2 h, direct-cooled from that temperature and isothermally held in a salt bath at 360 °C for 1 and 3 h. The substrate and the layers produced were characterized by optical microscopy (OM), scanning electron microscopy (SEM), x-ray diffraction (XRD), Vickers microhardness (HRV) and microadhesive wear tests. The tribological characteristics of the layers were compared with those of the substrate. The microscopic analysis showed the effectiveness of boro-austempering treatment in the production of carbide-free bainite microstructure and the surface borided layers. As a result, there were increases in surface wear resistance up to 115% when compared to the substrate.

    更新日期:2020-01-24
  • Microstructure Evolution and Compressive Properties of Multilayered Al/Ni Energetic Structural Materials under Different Strain Rates
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-24
    Mingzhi Wang, Jingli Li, Jingzhe Zhang, Xiang Liu, Zhifu Mao, Zixuan Weng, Hongyi Wang, Jie Tao

    Abstract Multilayered Al/Ni energetic structural materials integrating exothermic properties and mechanical properties were prepared by the method of electrodeposition and hot pressing in this research. Then, the uniaxial quasi-static compression and split Hopkinson pressure bar experiments were conducted at strain rates from 10−4 to 6.5 × 103 s−1 at room temperature. The effects of compression strain rate on the microstructure evolution and the compressive properties of multilayered Al/Ni energetic structural materials were systematically investigated. With increasing quasi-static compression strain rate, the compression strength increased slightly for two kinds of Al/Ni multilayers prepared under different hot pressing time. With the hot pressing process extending to 4 h, the dynamic compression strength of multilayered Al/Ni composites monotonically increased from 494.7 to 564.2 MPa with increasing strain rate. It was shown that Al/Ni energetic structural materials exhibited evident strain hardening and strain rate strengthening. However, when the compression strain rate reached 6500 s−1, the Al/Ni composite prepared with the hot pressing time of 1 h showed prominent thermal softening. Notwithstanding, it was found that the compression strength of Al/Ni composite prepared at 4 h was evidently higher than that at 1 h, since the second phase reinforcement counteracted the thermal softening. In addition, the critical failure strain presented obviously increasing tendency with the increased compression strain rates.

    更新日期:2020-01-24
  • Ductile–Brittle Variation Phenomenon and a Special Transformation-Induced Plasticity Effect in NbTi-NiTi Composite
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-24
    Jiang Jiang, Daqiang Jiang, Shijie Hao, Fangmin Guo, Xiaohua Jiang, Lishan Cui

    Abstract In order to study the transformation-induced plasticity (TRIP) effect in a NiTi shape-memory alloy composite, an in situ NbTi-NiTi composite was prepared by vacuum arc melting, hot forging and wire drawing. An unusual ductile–brittle variation phenomenon was observed by means of a series of tensile tests. The composite was brittle in the absence of transformation at 200 °C, and the fracture strain was about 2%. With lowering the tensile temperature, the composite became ductile when stress-induced martensitic transformation occurred, and the elongation increased to about 18% (a ninefold increase) during tensile test at room temperature. This ductile–brittle variation phenomenon indicates that the stress-induced martensitic transformation of NiTi alloy helps to improve the ductility of the composite, which is just the exhibition of TRIP effect in the NbTi-NiTi composite. Different from conventional TRIP steels, the TRIP behavior in NiTi induces only an increase in the elongation, but not any increase in fracture strength.

    更新日期:2020-01-24
  • Manufacture of Tungsten Heavy Alloy Tube by Diffusion Bonding of Semicircular Tubes
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-22
    Zu Seong Park, Sang Wook Han, Ji Hoon Kim, Songkil Kim, Young Hoon Moon

    Abstract An innovative manufacturing method to fabricate tubular parts made of tungsten heavy alloy (THA) by diffusion bonding of sintered semicircular tubes is proposed and characterized in this study. THAs are produced by blending tungsten grains with a lower-melting-point Ni-Fe binder metal. During the liquid phase sintering (LPS) process of THA, the Ni-Fe liquid wets the tungsten and provides a soluble diffusion network for rapid sintering. Multi-phase THAs are usually very difficult to produce as a tubular piece. During the LPS of the powder compact, a gravity-induced slumping leads to some distortion in the bottom of the tubular parts. One possible alternative to handle this problem is to combine the segmented THA pieces by solid-state diffusion bonding to build up tubular piece. Thus, this study proposes combining the semicircular THA tubes using the diffusion bonding technique to manufacture the tubular THA parts. To provide uniform contact pressures along the joining surfaces, horizontal diffusion bonding is performed using a specially constructed supporting apparatus to reduce the gravity effect. An industry-applicable tube manufacturing process has been well characterized, and its feasibility has been demonstrated by bond quality that was assessed by optical metallography and mechanical testing.

    更新日期:2020-01-23
  • Effect of Photoelectrochemical Activity of ZnO-Graphene Thin Film on the Corrosion of Carbon Steel and 304 Stainless Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Omid Razavizadeh, Behrouz Bahadormanesh, Mohammad Ghorbani, Abdolreza Simchi

    Abstract In this research, the ZnOG hybrid thin film was produced via solgel method. The surface morphology, band gap and photoactive properties of the films were studied by means of SEM, UV–Vis and photoluminescence analysis. In addition, the ability of the thin film in photocathodic protection of carbon steel (CS) and 304 stainless steel in 3.5 wt.% NaCl and Na2S solutions under dark and UV illumination was investigated by polarization test as well as OCP and current measurements during coupling of steels with ZnOG photoanode. The mix band gap is reduced to the orders of 1.17 eV through hybridization of ZnO with graphene oxide. In both NaCl and Na2S solutions, the ZnOG thin film could effectively protect the SS304 in dark condition. Moreover, UV illumination improved the level of protection via photoinduced electrons. The ZnOG film slightly accelerates the corrosion of CS in dark condition in NaCl solution. Nevertheless, UV illumination leads to photocathodic protection of CS in mentioned environment. In Na2S solution, while coupling to ZnOG photoanode had not much effect on the surface electrochemical activity of CS, UV illumination caused photocathodic protection.

    更新日期:2020-01-22
  • Microstructure and Properties of AlCoCrFeNiSi High-Entropy Alloy Coating on AISI 304 Stainless Steel by Laser Cladding
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Guozhong Zhang, Hao Liu, Xianhua Tian, Peijian Chen, Haifeng Yang, Jingbin Hao

    Abstract In this paper, to improve the hardness and wear resistance, AlCoCrFeNiSi HEA coatings were synthesized on AISI 304 stainless steel by laser cladding. The microstructure, chemical composition, constituent phases, microhardness, wear resistance and corrosion resistance of the coating were analyzed by scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), x-ray diffraction (XRD), Vickers microhardness tester, pin-on-disk tribological tester and electrochemical workstation, respectively. The experimental results showed that the coating possessed a single body-centered cubic (BCC) phase structure (Fe-Cr). Si element was dissolved into Fe-Cr solid solution, resulting in severe lattice distortion. The dislocation density of the coating was as high as 1.07 × 1014 m−2. Therefore, the microhardness (630.36 HV0.3) of the HEA coating was significantly improved by the effect of solid solution strengthening and dislocation strengthening. The coating exhibited excellent wear resistance, and abrasive wear was effectively avoided. The wear mechanism of the coating involved mainly oxidation wear and slight adhesion wear. The corrosion resistance of the coating was better than that of AISI 304 stainless steel in 3.5% NaCl solution. In conclusion, the AlCoCrFeNiSi HEA coating prepared by laser cladding can provide excellent wear protection to stainless steel at no expense to its own corrosion resistance.

    更新日期:2020-01-22
  • Effects of Yttrium and Heat Treatment on the Microstructure and Mechanical Properties of CLAM Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Guoxing Qiu, Dongping Zhan, Changsheng Li, Yongkun Yang, Min Qi, Zhouhua Jiang, Huishu Zhang

    Abstract The effects of normalizing and tempering temperatures on the microstructures and mechanical properties of China Low Activation Martensitic (CLAM) steel with and without yttrium were studied. Based on the optimized traditional heat treatment, two special intermediate heat treatments were studied to improve the mechanical properties of the steels. The AC3 temperature of the CLAM steel was increased by adding yttrium. The optimized traditional heat treatments were 1000 °C × 30 min + 755 °C × 90 min and 1050 °C × 30 min + 755 °C × 90 min for the C1 and C2 alloys, respectively. The intermediate heat treatment results indicated that the precipitation behavior of carbides was effectively controlled. The size of the M23C6 carbides was refined during the two intermediate heat treatments due to the priority precipitation of MX particles. However, coarsening of grains and martensite laths occurred during heat treatment with furnace cooling. The twice-quenched tempering samples had a smaller grain size and martensite lath width than the other samples. The ductile–brittle transition temperature was − 69 and − 103 °C for the C1 and C2 alloys with twice quenching, and the yield strengths were 745 and 760 MPa, respectively. An excellent balance of strength and impact toughness was obtained with the twice-quenching and once tempering heat treatment process.

    更新日期:2020-01-22
  • Effect of Ultrasonic Impact Treatment on the Fatigue Performance of Cold Expanded AA6061-T6 Hole
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Yan-li Wang, You-li Zhu, Zhi-hai Cai

    Abstract Cold expansion is widely used to improve the fatigue life of fastener holes. However, fatigue crack often initiates at the entrance edge of the hole due to lower compressive or tensile residual stress as a result of cold expansion. In the current study, the entrance edge of the cold expanded hole has been ultrasonically impacted with a specially designed pin, and comparative fatigue tests are performed to evaluate the influence of the ultrasonic impact treatment on the fatigue performance of the cold expanded holes. The findings show that the ultrasonic impact treatment imparted a larger compressive residual stress and created a fillet arc at the entrance edge, which resulted in an obvious reduction in the fatigue crack propagation rate in the earlier stage of the fatigue crack growth and extended the fatigue life of the cold expanded holes further.

    更新日期:2020-01-22
  • Synthesis and Characterization of CoFe 2 O 4 /MWCNTs Nanocomposites and High-Frequency Analysis of Their Dielectric Properties
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Latif Ullah Khan, Muhammad Younas, Shafi Ullah Khan, Muhammad Zia Ur Rehman

    Abstract Nanoparticles of CoFe2O4 were synthesized by chemical co-precipitation method. The CoFe2O4/MWCNT nanocomposites were synthesized with increasing contents of MWCNTs, i.e., 0.0, 2.0, 3.0, and 5.0% by weight via ultrasonication method in a dispersive medium using ortho-xylene. The synthesized cobalt ferrite nanoparticles and their nanocomposites were characterized by impedance analyzer, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and x-ray diffraction (XRD) techniques. The XRD indexed patterns confirmed the face-centered cubic structure of CoFe2O4/MWCNT nanocomposites. The average crystallite size in all the samples was in the range of 15 to 35 nm. The decorations of CoFe2O4 on MWCNTs were confirmed by SEM images. The FTIR results showed two vibrational bands. With the increasing contents of multi-walled carbon nanotubes in the cobalt ferrite/MWCNT nanocomposites, the dielectric properties were also enhanced. At 1 MHz, dielectric constant, dielectric loss, and tangent loss factor were increased from 26, 15.1, and 0.580 for pure cobalt ferrite to 47, 28.9, and 0.614 for loading of 5% MWCNTs, respectively. At 1 GHz, dielectric constant, dielectric loss, and tangent loss factor were increased from 11.6, 0.33, and 0.028 for pure cobalt ferrite to 19.4, 0.61, and 0.031 for loading of 5% MWCNTs, respectively. Such a huge increase in the dielectric properties of cobalt ferrite and multi-walled carbon nanocomposites exploited their applications at high frequency.

    更新日期:2020-01-22
  • Manufacturing of Single-Polymer Composite Materials Based on Ultra-High Molecular Weight Polyethylene Fibers by Hot Compaction
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Dmitry Zherebtsov, Dilyus Chukov, Valerii Torokhov, Eugene Statnik

    Abstract This paper describes the manufacturing process and properties of single-polymer composites based on ultra-high molecular weight polyethylene fibers produced by hot compaction. The hot compaction results in partial surface melting of the initial fibers, and melted part after cooling forms a matrix of the self-reinforced composites. Using high pressure during hot compaction allows to increase the fibers’ melting point and allows to avoid relaxation processes. Moreover, the fiber-to-matrix ratio may be changed using this approach by varying pressure and temperature. The flexural test was carried out to determine the mechanical properties. Samples obtained at 160 °C and 50 MPa have optimum properties (flexural strength and Young’s modulus were equal to 116.5 MPa and 15.3 GPa, respectively). It was found that mechanical properties of the obtained composites depend on both matrix amount and preservation of oriented fibers structure. The small amount of melted fibers does not allow to form matrix for load transferring. But the excessive melting of the fibers can result in a significant decrease in the fibers’ mechanical properties.

    更新日期:2020-01-22
  • Homogenization and Multiscale Analysis of 3D Carbon–Carbon Composites Using Eigendeformation Technique
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Atul Ramesh Bhagat, Puneet Mahajan

    Abstract This paper presents the application of eigendeformation technique for multiscale analysis of 3D carbon–carbon (C/C) composite. Methodology for eigendeformation technique has been taken from the work of Oskay and Fish. It involves the determination of influence functions for the elastic case and damage conditions from the representative volume element (RVE). The constitutive law for 3D C/C composite in the presence of damage has been determined. Damage in the carbon fiber bundle, matrix and interface has been modeled. The methodology has been extended using VUMAT subroutine for carrying out a multiscale analysis of 3D C/C composite. The multiscale simulation was carried out for an open hole test on 3D C/C composite, and the results were compared with experiment. Strain distribution and failure loads obtained using multiscale simulation and experiments were found to be in good agreement.

    更新日期:2020-01-22
  • Synthesis and Properties of Mg-Based Foams by Infiltration Casting Without Protective Cover Gas
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Viviana M. Posada, Juan Ramírez, Jean Paul Allain, Akshath R. Shetty, Patricia Fernández-Morales

    Abstract Fabrication and characterization of Mg-based scaffolds by infiltration casting, without protective cover gas, are presented. Distinctive results were observed among the foams depending on the precise selection of casting variables. Foams with pore sizes ranging from 590 to 1040 µm, porosities ranging from 60.01 to 79.35%, and measured Young’s moduli ranging from 0.8 to 1.9 GPa, were obtained. These architected parameters for this cellular material were found to match the structural properties of cancellous bone while satisfying the mechanical requirements to support the bone healing process (0.3-3 GPa). Casting temperature and melting time were set at 680 °C and 10 min for infiltrating 590 µm salt particles. A salt flux combination containing MgCl2, MgO, CaF2, and KCl, is used to protect the molten metal, and its effect on ignition and oxidation of the Mg alloy is evaluated. The results of the crystalline phase and chemical analysis indicate a safe production process since there is no evidence of high contamination or new-formed phases.

    更新日期:2020-01-22
  • Mechanical and Tribological Properties of NbTi-N X and NbTi-N 12 -CH Coatings Prepared Using Radio Frequency Magnetron Sputtering and Their Application for Micro-drills
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Y. L. Su, W. H. Kao, Y. H. Mao

    Abstract In this study, NbTi-NX and NbTi-N12-CH coatings were prepared using radio frequency magnetron sputtering on high-speed steel substrates, where X represents the flow rate of nitrogen and CH represents a coating containing carbon and hydrogen integrated with acetylene. The crystalline phases were characterized using x-ray diffraction, and the surface and cross-sectional structures were analyzed using scanning electron microscopy. The x-ray diffractometry results revealed that except for the NbTi-N8 and NbTi-N12-CH coatings, all other coatings exhibited a crystalline phase. Five peaks were observed for the NbTi-N12 coating as follows: TiN (111), (200), and (222) and Nb2N (110) and (112). Thus, this structure had the most diversified orientations. The x-ray photoelectron spectroscopy results revealed that only the NbTi-N4 coating had pure niobium- and titanium-binding energies. For the other coatings, some Nb-N and Ti-N bonds were oxidized to form Nb-ON and Ti-ON, respectively. Regarding the mechanical properties, the NbTi-N12 coating had the highest hardness value (26.6 GPa). A wear test was conducted with a load of 5 N, and the NbTi-N12 coating exhibited the lowest wear rate in the NbTi-NX coating series. Conversely, the NbTi-N12-CH coating had the best tribological properties, such as the lowest friction coefficient (0.137), wear depth (0.203 μm), and wear rate (0.85 × 10−6 mm3/Nm). For the substrate wear performance, the wear depth and wear rate were approximately 13.7 and 13.2 times higher than those of the substrate with the NbTi-N12-CH coating, respectively. We applied the NbTi-N12-CH coating to a micro-drill and tested it by high-speed drilling 2000, 4000, and 6000 holes. The results revealed that when this coating was applied to micro-drills, their drill life could be increased to 4000 holes, which is twice that of an uncoated micro-drill.

    更新日期:2020-01-22
  • Microstructure, Mechanical and Corrosion Properties of Mg-1.61Al-1.76Ca Alloy under Different Extrusion Temperatures
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Zhuo Fu, Zhifeng Wang, Guofeng Li, Yu Yao, Hui Yu, Yu Liu, Tianhao Zheng, Hanqing Xiong

    Abstract Extrusion temperature can significantly influence grain size, the shape of second phase particles and the dislocation distribution of Mg alloys. In this study, the effects of extrusion temperatures ranging from 250 to 400 °C on the microstructure, mechanical properties and corrosion resistance of a Mg-Al-Ca alloy with 1.61 wt.% Al and 1.76 wt.% Ca (Mg-1.61Al-1.76Ca) were investigated. The results showed that the size of grains and phases increased with an increase in extrusion temperature; the yield strength and ultimate tensile strength values decreased with an increase in temperature, while the fracture elongation increased initially (up to 300 °C) and decreased thereafter with an increase in temperature. Under test, the extruded alloy exhibited some evidence of corrosion at 250 °C, while extrusion at 300 °C demonstrated better corrosion resistance. Thus, the 300 °C extruded alloy possessed the optimum comprehensive performance because of the relatively small grains, fine second phase particles and fewer dislocations.

    更新日期:2020-01-22
  • Etching of Carbon Fiber-Reinforced Plastics to Increase Their Joint Strength
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Stefano De La Pierre, Valentin Giglia, Marco Sangermano, Laurence Cornillon, Olivier Damiano, Monica Ferraris

    Abstract An original method to increase the mechanical strength of adhesively joined carbon fiber-reinforced plastics (CFRPs) and honeycomb CFRP sandwich structures by etching is proposed, based on sulfuric acid etching of the CFRP surface. Etched composites are joined by a novel phenolic resin-based adhesive and are cured, and their cross section is observed by FESEM. Etching of CFRP was aimed to obtain a “brush”-like composite to be infiltrated by the adhesive, giving a fiber-reinforced, stronger composite joint. This method gave a 100% increase in the lap shear strength for the adhesively joined etched CFRP, compared to the non-etched ones.

    更新日期:2020-01-22
  • Carburizing Heat Treatment of Selective-Laser-Melted 20MnCr5 Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-21
    Mei Yang, Richard D. Sisson

    Abstract As a novel manufacturing technology, additive manufacturing (AM) has many advantages such as energy saving, reduced material waste, faster design-to-build time, design optimization, reduction in manufacturing steps, and product customization compared to conventional manufacturing processes. Heat treatment is widely used to improve the properties of conventional manufactured steel parts. The response of additively manufactured steel parts to heat treatment may be different from conventionally manufactured steel parts due to variations in the as-deposited alloy microstructure. An understanding of heat treatment processes for additively manufactured steel parts is necessary to develop their heat treatment process parameters. In the present work, 20MnCr5 steel was selected to investigate the carburizing heat treatment of additively manufactured parts. These parts were fabricated by selective laser melting (SLM) for the carburizing study. It was found that the AM parts fabricated by the SLM process show the microstructure of tempered martensite, while the microstructure of as-received wrought part is ferrite and pearlite. It was also experimentally found that the SLM process decarburizes the entire SLM part. Before carburizing, a normalization process was conducted on both SLM and wrought 20MnCr5 parts to reduce the effect of the pre-carburizing microstructure. The objective of this project is to determine the carburizing performance of additively manufactured steel parts. The results for the SLM parts in terms of carbon concentration and microhardness profiles are compared with the results for the wrought steel. It was found that the carburized SLM part in the present work has higher carbon concentration near the surface, deeper case depth, and higher total carbon flux than the carburized wrought part.

    更新日期:2020-01-22
  • Correlating Effect of Temperature on Cyclic Plastic Deformation Behavior with Substructural Developments for Austenitic Stainless Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-16
    Rima Dey, Soumitra Tarafder, Himadri Bar, S. Sivaprasad

    Abstract Low-cycle fatigue experiments have been carried out at elevated and sub-zero temperatures. Corresponding effect on cyclic plasticity characterizing parameters such as cyclic hardening/softening and Masing behavior is compared for different loading conditions. Disparities in the fatigue life as well as the cyclic plastic behavior have been attributed to the phase transformations that largely obstruct the dislocation motion. Further, the changes in strains in the materials matrix have been quantified through misorientation studies, wherein clear demarcation in strain distributions due to fatigue loading at different temperatures was obtained and further correlated with the substructural alterations observed through transmission electron microscopy.

    更新日期:2020-01-17
  • Effect of Carbide Density on Fatigue Limit of H21 Die Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-16
    D. N. Korade, K. V. Ramana, K. R. Jagtap

    In the present work, the effect of carbide density on microstructure, hardness, wear rate, and fatigue limit of AISI H21 die steel has been studied. The specimens of H21 die steel have been employed hardening at 1195 °C, double tempering at 540 °C, cryotreatment at − 185 °C for 24 h, and soft tempering at 100 °C. The microstructure, hardness, wear rate, and fatigue limit of the conventionally treated and cryotreated specimens have been examined. The pin-on-disk machine has been used for the dry sliding wear test. The fatigue test has been carried out using constant amplitude rotating bending fatigue test machine which indicates enhanced fatigue limit for cryotreated specimens. The improvement in hardness, wear behavior, and fatigue limit of cryotreated specimens as a result of increased carbide density with reduced carbide size and retained austenite has been observed. The carbides Fe6W6C, Cr23C6 and Cr7C3 played an important role in increasing the hardness, wear behavior, and fatigue limit of the material. The Basquin’s equation was used for the analysis of the fatigue test. The minimum value of the fatigue strength exponent of Basquin’s equation shows the enhanced fatigue limit of cryotreated specimens.

    更新日期:2020-01-16
  • Effect of Aging on Structure and Properties of a Transformation-Induced Plasticity-Aided High-Manganese Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-16
    Mukesh Kr. Chowrasia, Akshay Kumar, M. K. Banerjee, U. Pandel

    This paper reports the results of investigation on 0.1C-17Mn-5.5Ni-1.8Al-2.7W-4.6Mo-2.3Cu-0.002B steel designed to assume excellent combination of strength and toughness. The air induction melted steel was subjected to hot forging at 1200 °C followed by hot rolling in six passes from 1100 °C. The rolled samples were reheat-quenched from 1050 °C in iced water. The quenched samples were isochronally aged at temperatures within 500-650 °C at interval of 50 °C. The mechanical properties were determined by hardness measurement and tensile testing. Structural characterization was accomplished by x-ray diffraction, optical and electron microscopy. Differential scanning calorimetric study was conducted to understand the precipitation kinetics. A typical age-hardening behavior was noted in the aged samples due to the precipitation of M2C and Ni3Al. Strain hardening of martensite, precipitation hardening due to the presence of nanosized precipitates and Orowan hardening were found to be instrumental in attaining a maximum hardness of 723 HV. The microstructure of aged samples consists of retained austenite, ε-martensite, α′-martensite and uniformly distributed nanosized precipitates of Ni3Al and M2C, lying broadly within two different size regimes. The sample peak aged at 550 °C attained a strength of 1.4 GPa at a total elongation value of 25%. The combination of high strength and high ductility has resulted from precipitation strengthening, TRIP phenomenon and high degree of structural fineness.

    更新日期:2020-01-16
  • Process Optimization of Plane Strain Compression for 06Cr19Ni9NbN Steel Based on Processing Maps
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-16
    Yongxing Jiao, Cunlong Zhou, Jiansheng Liu, Wenwu He, Yue Xu

    Abstract Hot compression tests of 06Cr19Ni9NbN steel were conducted at strain rates of 0.005-5 s−1 and temperatures of 900-1200 °C on a Gleeble 1500 thermo-mechanical simulation tester. Based on the true stress-true strain data, processing maps of the steel were established. The influences of the temperature and strain rate on the processing map were analyzed in detail. The optimal process parameters for hot compression were determined to be in the temperature and strain rate ranges of 1000-1200 °C and 0.005-0.1 s−1, respectively. Plane strain compression experiments were conducted using the recommended process parameters. A temperature of 1200 °C and reduction ratio of 38% are the recommended compression parameters, yielding a grain size of 74 µm. The mechanical properties of the material after compression were obtained by tensile tests at room temperature. The mechanical properties were optimal at 1200 °C and a reduction ratio of 38%. The elongation, area reduction, yield strength, and tensile strength were 63.69%, 76.12%, 281 MPa, and 703 MPa, respectively. The results of the plane strain compression experiments and tensile tests were consistent with the processing map results, indicating that the processing maps were accurate for optimizing the compression process parameters.

    更新日期:2020-01-16
  • Investigation of Stress Corrosion Cracking Initiation in Machined 304 Austenitic Stainless Steel in Magnesium Chloride Environment
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-14
    Wenqian Zhang, Huanchun Wu, Siyang Wang, Yujin Hu, Kewei Fang, Xuelin Wang

    The effect of the machining-induced residual stresses and microstructural changes on the stress corrosion cracking (SCC) initiation in 304 austenitic stainless steel was investigated. The residual stress was measured with an x-ray diffractometer, and the microstructural changes were characterized by the electron backscatter diffraction. Through a load-free testing in the boiling magnesium chloride solution, the subsurface zone of high SCC sensitivity was identified by detecting the depth of the micro-cracks. The development of the SCC micro-crack was related to the machining-induced residual stresses and microstructural changes. The results showed that the SCC micro-crack was prone to propagate in the subsurface where the residual stress was larger than 200 MPa, along with high-density grain boundary. Additionally, the SCC micro-crack initiation was observed to develop along the machining-induced slip bands.

    更新日期:2020-01-15
  • Electrochemical Behavior and Passive Property of 13Cr Martensitic Stainless Steel in Nitric Acid Solution
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-14
    Sunil Kumar Bonagani, Vivekanand Kain, Vishwanadh Bathula, Rumu H. Banerjee, Sharma Tenneti

    Intergranular corrosion behavior of a 13Cr martensitic stainless steel (MSS) in tempered condition was studied. Tempering was done in the temperature range of 300-700 °C after austenitization, and microstructure was established using scanning and transmission electron microscopy. Electrochemical characterizations to establish localized corrosion susceptibility were performed in 5% HNO3 solution. The MSS tempered at 550 °C showed sensitization and significant localized attack during tests in HNO3. Characterization of surface film on this condition revealed an oxide with a higher defect density (through electrochemical impedance spectroscopy–Mott–Schottky analysis) and Fe content (x-ray photoelectron spectroscopy) as compared to that for the austenitized condition. The inability of sensitized MSS tempered at 550 °C to form a protective surface film was attributed to the formation of considerable nano-sized Cr-rich carbide precipitates associated with narrow Cr depletion zones. On the other hand, the MSS tempered at 300 and 700 °C did not show any localized attack in HNO3 and this was attributed to lack of sensitization at 300 °C and de-sensitization at 700 °C.

    更新日期:2020-01-15
  • Recovery Stress and Storage Modulus of Microwave-Induced Graphene-Reinforced Thermoresponsive Shape Memory Polyurethane Nanocomposites
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-14
    Ritesh Kumar Gupta, S. A. R. Hashmi, Sarika Verma, Ajay Naik, Prasanth Nair

    A special class of smart material was developed using shape memory polyurethane (SMPU) elastomer and graphene nanoplatelets (GNPs) via melt-blending process using micro-compounder. The shape recovery of the developed composites was studied under microwave irradiation. The nanocomposites were developed having 0.2, 0.4, 0.6, and 0.8 phr GNPs in the SMPU matrix. The effects of GNP reinforcement on morphology, shape memory effects, and viscoelastic properties of the composites were investigated. The recovery stress of virgin SMPU increased with reinforcement and maximized on the incorporation of 0.6 phr GNPs. The deformation-induced shape memory creation process influenced significantly the recovery stress of composites as compared to virgin SMPU. The recovery stresses of SMPU at 50, 75, and 100% strain were 1.5, 1.7, and 1.9 MPa, whereas the values of GNP-SMPU composites were 3.2, 3.4, and 4.1 MPa corresponding to 0.6 phr GNP reinforcement. The value of storage modulus above the glass transition temperature of SMPU increased from 9.2 to 15.1 MPa on the addition of 0.6 phr GNPs. The peak of the damping factor, tan δ shifted toward higher temperatures with the increased GNP content. The morphological study confirms the uniform dispersion of GNPs in the SMPU matrix. The microwave-induced heating of 0.8 phr GNP composite shows 80% shape recovery in 60 s, which is faster than convectional heating.

    更新日期:2020-01-14
  • Effect of Al-Si Coating on Weldability of Press-Hardened Steels
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    RuiMing Chen, ChaoQun Zhang, Ming Lou, YongBing Li, Blair E. Carlson

    Resistance spot welding (RSW) of Al-Si-coated PHS was undertaken, and the effect of Al-Si coating on nugget formation and mechanical properties was investigated. Press-hardened steel (PHS) has long been applied to automotive body structure construction to support mass and corresponding greenhouse gas emission reductions. PHS materials are often combined with an Al-Si coating applied as an oxidation barrier though unfortunately, the Al-Si coating poses a challenge to the resistance spot welding (RSW) of PHS containing stack-ups. As a newly developed coating for the hot stamping process, the property of Al-Si coating is different from base metal and traditional coatings, and the influence mechanism of Al-Si coating on the welding process is not clear. It would remain at nugget edge and might cause severe stress concentration. To investigate this problem, RSW of 1.5-mm Al-Si-coated PHS was undertaken, and the results indicate that a large portion of the Al-Si coating is extruded and forms a sharp notch close to the nugget edge during the welding process. During the post-weld cooling stage, a thin layer of residual coating is formed between the nugget and notch root. The mechanical performance of the welded joints is limited by the thin residual Al-Si layer which acts as a preexisting crack and supports the interfacial fracture. The presence of the Al-Si coating at the faying interface also significantly delays nugget formation, though it contributes to a larger nugget size by inhibiting expulsion events at the faying interface.

    更新日期:2020-01-14
  • Bonding Performance of Fiber-Reinforced Polymer-to-Concrete Joints under the Effect of Corrosion Cracking
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    Xu Yang, Ze-Jie Pan, Wei-Wen Li, Feng Xing

    Externally bonded (EB) carbon fiber-reinforced polymers (CFRPs) have been progressively considered for application in concrete structures. However, the corrosion of reinforcing steel bars (rebars) in reinforced concrete (RC), which is more common in coastal environments than in inland environments, can degrade structural performance. The bonding performance of FRP-to-concrete joints can be further deteriorated by the degradation of the interfacial bonding behavior between the rebar (or rebars) and concrete cross-sectional area reduction at the steel bar plane induced by rust expansion. In this study, the effect of rebar corrosion on the FRP bonding performance of RC components was experimentally investigated for the first time. Single shear tests assisted by a 3D optical displacement measurement system were used to obtain the full-field distribution of specimen displacements. The test results show that, although the corrosion level and diameter of the steel bar slightly affected the bonding strength of FRP-to-concrete, the corrosion crack width increased as the steel bar corrosion level increased, which affected the failure mode. Hence, as the corrosion level of the steel bars increased, the likelihood of concrete cover separation increased. Finally, a modified strength design model accounting for the rebar corrosion level was proposed in this paper.

    更新日期:2020-01-14
  • Evaluation of Mechanical Behavior and Surface Morphology of Shot-Peened Ti-6Al-4V Alloy
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    Yan Wen, Pu Liu, Lechun Xie, Zhou Wang, Liqiang Wang, Weijie Lu, Chuanhai Jiang, Vincent Ji

    Abstract The effects of shot peening (SP) on mechanical behavior and surface morphology of Ti-6Al-4V were investigated in detail. After SP, the uniformity of compressive residual stress (CRS) was analyzed. The CRS decreased as SP intensity increased because of the severe impact of shots. The CRS was enhanced from − 762.7 to − 795.5 MPa with an increase in SP intensity. The fatigue life was increased from 0.46 × 106 cycles to 8.10 × 106 cycles after SP when the loading amplitude was 610 MPa. This increase was mainly attributed to the enhancement of the crack initiation hindering and propagation by the high CRS and refined domain sizes. The results of surface morphology showed that the convexity and concave regions were generated after SP and the improvement in SP intensity aggravated the increase in roughness. Although the roughness increased after SP, it did not hinder the enhancement of fatigue lives, indicating that CRS played a leading role in the improvement in fatigue lives. Thus, the analysis and discussion revealed that SP was beneficial for the improvement of the surface mechanical behavior of titanium alloys.

    更新日期:2020-01-14
  • Influence of Processing Conditions on Properties of AISI 316LN Steel Grade
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    Tibor Kvackaj, Alica Rozsypalova, Robert Kocisko, Jana Bidulska, Patrik Petrousek, Martin Vlado, Imrich Pokorny, Jan Sas, Klaus-Peter Weiss, Michal Duchek, Robert Bidulsky, Jan Duchon, Dusan Simcak

    The influence of rolling temperatures performed at ambient and cryogenic conditions in the interval of deformations ε = <10; 50> (%) on structural development and mechanical properties of steel grade AISI 316LN was studied. The evaluations of microstructures were studied by optical and transmission electron microscopy. The initial strength properties of the material after solution annealing tested at 293 K were: RP0,2 = 325 MPa, Rm = 640 MPa, and A5 = 49%. The biggest values of strength properties were obtained by material processing at cryorolling conditions with thickness reduction of 50% and tested at 77 K as follows: RP0,2 = 1571 MPa, Rm = 1880 MPa, and A5 = 4%. From the analysis, it is resulted that the dislocation slip is the main mechanism of plastic deformation realized by rolling at ambient temperatures; at cryogenic temperatures, it is possible to observe a combination of dislocation slip accompanied with deformation twinning.

    更新日期:2020-01-14
  • Residual Stress Field of High-Strength Steel After Shot Peening by Numerical Simulation
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    Chunmei Zhao, Changjun Shi, Qiang Wang, Changchun Zhao, Yukui Gao, Qingxiang Yang

    The high-strength steel (40CrMnsiMoVA) used in aviation industry was taken in this work. The residual stress field of the steel after shot peening was determined by x-ray stress instrument. Meanwhile, the finite element model of the shot peening was established, and the residual stress field of the steel after shot peening was numerically simulated by ANSYS software. Then, the simulated result was compared with the measured one to verify the validity of the model. Based on this model, the residual stress fields of the steel with different shot velocities and shot diameters were simulated. The results show that, with the increase in the shot velocity, maximum residual stress (σmrs), maximum residual stress depth (ξ0) and strengthen depth (ξm) are increased gradually. When the shot velocity is 280 m/s, the σmrs reaches − 696 MPa, and the ξ0 and ξm increase to 0.43 and 0.70 mm, respectively. With the increase in the shot diameter, the σmrs, ξ0 and ξm are increased gradually. When the shot diameter is 1.5 mm, the σmrs, ξ0 and ξm increase to − 800 MPa, 0.56 and 0.78 mm, respectively.

    更新日期:2020-01-13
  • Effect of Process Parameters on Microstructure and Dynamic Compressive Property of Ti-6Al-4V Plates Fabricated via Friction Stir Welding
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    Bao Jiawei, Yang Ting, Yang Suyuan

    Abstract The microstructure and mechanical properties of Ti-6Al-4V plates (thickness: 5 mm) welded via friction stir welding (rotation speed: 150-300 rpm, welding speed: 70-100 mm/min) were investigated. The microstructural investigation revealed that the nugget obtained at 150 rpm and 70 mm/min was composed of a mixed structure, whereas the other weld joints were composed of a fully lamellar structure. Transmission electron microscopy analysis revealed that fine recrystallized α-grains and dislocations occurred in the lamellar structure. The tensile tests showed that the tensile strength of all joints reached 96% of the tensile strength characterizing the base material. Moreover, the failure strain of each joint during tensile testing was > 13%. The weld joints with fully lamellar nuggets exhibited better dynamic compressive properties than the joints with mixed-structure nuggets. The results demonstrated that the recrystallized α-grains and dislocations are beneficial for enhancing the dynamic mechanical properties. The optimum dynamic mechanical response was obtained when a rotation speed and welding speed of 300 rpm and 100 mm/min, respectively, were employed as the welding parameters.

    更新日期:2020-01-13
  • Impact of pH on the Corrosion of Novel Metal-Metal Glassy Alloys in Artificial Seawater: An Electrochemical and Morphology Study
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-13
    Khadijah M. Emran, Albandaree K. Al-Harbi

    Two novel Fe78Co9Cr10Mo2Al1 and Fe49Co49V2 (at.%) metal-metal glassy alloys were studied in artificial seawater at 27 °C with pH values in the 7.5-8.5 range. The corrosion behavior of both alloys was investigated by using electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP) measurements as well as physical techniques such as x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Good agreement between the resistance of both alloys with rising pH values was observed. The high corrosion rate for the VX50 alloy is related to the absence of passivation behavior on the alloy surface. The VX9 alloy shows a low corrosion current density and a low corrosion rate due to the alloying element such as Cr, which enables the formation of a protective film.

    更新日期:2020-01-13
  • High-Temperature Tribological Performance of Vacuum Hot-Pressed NiCr Matrix Composite Containing SrAl 12 O 19
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-10
    Feng Liu, Le Feng, Hongdou Liu, Wenwen Zhao

    Abstract The tribological properties of NiCr-30 wt.% Al2O3 (denoted by NC30A) composite with 4 wt.% SrCO3 were investigated at different testing temperatures. The results indicated that the formation of SrAl12O19, which was derived from the solid-state reaction between SrO and Al2O3 in the sintering process had an impact on the friction coefficient and wear rate of NC30A composite. In the temperature range from 200 to 800 °C, the tribofilm containing SrAl12O19 and oxides (NiO, Cr2O3 and NiCr2O4) led to a decrease in the friction coefficient, while the detachment of Al2O3 grains and the oxidation of Ni on the worn surface endowed the sintered composite with a slightly higher wear rate.

    更新日期:2020-01-11
  • Modeling of High-Temperature Flow Stress of VN and Nb-Ti Microalloyed Steels during Hot Compressive Deformation
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-09
    S. A. J. Chalimba, R. J. Mostert, W. E. Stumpf, C. W. Siyasiya, K. M. Banks

    Abstract A simple mathematical model has been developed which describes the flow curve behavior up to the peak true stress or a true strain of 0.6 in unstable austenite. The hot working behavior was analyzed by compression tests over a temperature range of 750–1000 °C and at strain rates of 0.1–50 s−1. The constitutive behavior focused on the interaction between work hardening and dynamic softening attributed to recovery, recrystallization and dynamic austenite to ferrite transformation. This model extends the application of the well-established Estrin and Mecking (EM) work-hardening model in the unstable austenite region. The work hardening is countered by softening kinetics, represented in this model by JMAK-type expressions for both dynamic transformation and recrystallization. The predicted results correlate well with experimental results in VN and Nb-Ti microalloyed steels.

    更新日期:2020-01-09
  • Improved Mechanical Properties of a Quenched and Partitioned Medium-Carbon Bainitic Steel by Control of Bainitic Isothermal Transformation
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-08
    Qiangguo Li, Yanan Zhang, Wandong Li, Xuefei Huang, Weigang Huang

    A triplex microstructure of bainite, martensite and retained austenite in the 0.3C-1.4Si-1.8Mn (wt.%) steel was obtained by the bainitic isothermal transformation combined with Q&P process (B-QP process). The effects of bainite morphology and content on the mechanical properties have been studied by controlling the isothermal holding temperature and time. Results show that with isothermal holding temperature increasing from 320 to 400 °C, the bainite changes from lower bainite to upper bainite and the ultimate tensile strength and toughness decrease. Compared to the Q&T, 360 °C B-QP and 400 °C B-QP processes, the microstructure of the 320 °C B-QP-treated sample consists of lower bainite, martensite and retained austenite, and it exhibits the best combination of strength (1617 MPa), elongation (18.6%), the product of strength and elongation (PSE, 30.1 GPa%) and maximum impact toughness (103 J) when the lower bainite content is about 50%. In addition, the work hardening behaviors indicate that both the 400 °C B-QP sample with upper bainite morphology and the 320 °C B-QP sample containing 75% lower bainite exhibit the higher work hardening rate at the high strain level and larger uniform elongation.

    更新日期:2020-01-09
  • Grain Size Effects on Static and Dynamic Strength of Ultrafine-Grained Al-Mg-Mn Alloy Produced by High-Pressure Torsion
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-08
    A. N. Petrova, I. G. Brodova, S. V. Razorenov, E. V. Bobruk

    In the paper, the structure and static and dynamic mechanical properties of ultrafine-grained A5083 alloy (Al-Mg-Mn) produced by high-pressure torsion (HPT) are reported. The static yield stress and tensile strength were determined in tensile tests at a strain rate of ~ 10−3 s−1, and the dynamic yield stress and spall strength were calculated from free-surface velocity histories obtained during shock-wave loading at a strain rate of 105 s−1. The HPT technique provides strong grain refinement. The average grain size of the alloy after HPT is 100-180 nm and depends on the accumulated true strain. HPT significantly improves the static strength properties of the alloy. The static yield stress is increased by 360-390% and the static ultimate tensile strength by 166-182%. It is shown that the dynamic yield stress improved by 168-181%, while the dynamic spall strength was not improved by HPT. Moreover, the nanostructured alloy with a grain size of ~ 100 nm demonstrates the lowest spall strength.

    更新日期:2020-01-08
  • The Effect of Acid Pickling on the Corrosion Behavior of a Cerium Conversion-Coated AA2198-T851 Al-Cu-Li Alloy
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-08
    Rafael Emil Klumpp, Uyime Donatus, João Victor S. Araujo, Marcelo Myada Redígolo, Caruline de S. C. Machado, Isolda Costa

    Abstract The effect of acid pickling pretreatments prior to cerium conversion coating process on the corrosion behavior of AA2198-T851 alloy substrates was investigated. Three acid pretreatments were employed: nitric acid (HNO3), phosphoric acid (H3PO4) and sulfuric acid (H2SO4). The cerium conversion coating process was performed using a batch solution composed of cerium nitrate and hydrogen peroxide. Microscopic techniques, electrochemical impedance spectroscopy, polarization resistance and open-circuit potential measurements were employed to investigate the effect of each acid pretreatment. The untreated and nitric acid pretreated substrates presented more defective cerium conversion layers than the substrates treated with phosphoric and sulfuric acids. Accordingly, the corrosion resistance of the untreated and nitric acid-treated substrates was very low, while that of the substrates treated with phosphoric acid and sulfuric acids were greatly improved. The sulfuric acid pickling treatment was the best pretreatment before cerium conversion coating among the investigated pretreatments on the AA2198-T851 Al-Cu-Li alloy.

    更新日期:2020-01-08
  • Synergistic Effect of O 2 and H 2 S on the Corrosion Behavior of N80 Steel in a Simulated High-Pressure Flue Gas Injection System
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-08
    Kexi Liao, Feilong Zhou, Xiaoqin Song, Yanran Wang, Shuai Zhao, Jianjun Liang, Long Chen, Guoxi He

    Abstract The aim of this work was to understand the synergistic effect of O2 and H2S on the corrosion behavior of N80 steel in a simulated high-pressure flue gas injection system. Weight loss measurements show that the presence of O2 and an increase in temperature significantly accelerated the general corrosion rate of the N80 steel. We calculated a gray relational grade between different impact factors and the general corrosion rate from the results of an orthogonal experimental corrosion rate. The grade ranking of impact factors was: O2 concentration (0.817) > temperature (0.706) > total pressure (0.689) > H2S concentration (0.665) > CO2 concentration (0.517). Surface characterization of corrosion scales was done using scanning electron microscopy, energy-dispersive spectroscopy, x-ray powder diffraction, and 3D optical microscope analysis. The results show that in the O2-H2S-CO2-H2O coexistence system the products were composed mainly of FeCO3, FeS, Fe2O3, Fe3O4, and elemental sulfur. The results of the corrosion rate test and the characterization show that the presence of O2 greatly accelerated the corrosion process and changed the corrosion mechanism. Elemental sulfur, which was generated by the reaction between the H2S and the O2, participated in the corrosion process of the N80 steel. It could be considered that the synergistic effect of O2 and H2S accelerated the corrosion of the N80 steel. In addition, the porous structures of the corrosion scales and the severe local pits show that the high content of O2 inhibited the formation of FeCO3 and aggravated the corrosion of N80 steel.

    更新日期:2020-01-08
  • The Pitting Behavior of Newly Modified 17-4 Precipitation Hardened Stainless Steel with Different Nb, N, and Mo Contents
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-06
    Yunlong Wu, Qi Guo, Wangyan Lv, Feng Huang

    Abstract The effect of the addition of Nb, N, and Mo to 17-4 precipitate hardening stainless steel (17-4 PH steel) on its pitting behavior in a simulated geothermal environment was investigated using a cyclic polarization test, and the pitting potentials and the repassivation potentials of the materials were acquired to evaluate their pitting resistance. Nb and N were found to lower the pitting potential of 17-4 PH steel, while Mo increased it. In the case of repassivation potential, the addition of all these elements seemed to have a slightly negative impact. Cr-rich oxide, Nb carbonitride (Nb (C, N)), and reversed austenite were found in the materials. The element distribution of/around the Cr-rich oxide inclusion and the Nb (C, N) precipitate of the material were studied. A Cr-depleted zone was found around the inclusion/precipitate, which rendered the surrounding area to be more susceptible to pitting corrosion. Pit embryos and well-developed pits were observed after the cyclic polarization tests. Pits tended to initiate in the vicinity of the inclusion/precipitate, and the dissolution of the oxide around the pit embryo was seen, which was believed to cause the local deterioration of the electrochemical environment. Lacy cover with narrow strip-shaped holes was found above the well-developed pit, and the forming mechanism of these holes was believed to be the dissolution of martensitic.

    更新日期:2020-01-06
  • Microstructure and Thermal Stability of Icosahedral Quasicrystals in Suction Casting Al-6 at.%Mn(-2 at.%Be) Alloys
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-06
    Zhongwei Chen, Qi Zhang, Bolong Dong, Zhiqiang Liu

    Formation and microstructure of icosahedral quasicrystals in suction casting Al-6 at.%Mn(-2 at.%Be) alloys have been investigated by scanning electron microscopy, energy-dispersive spectrometer (EDS), x-ray diffraction (XRD), transmission electron microscopy, and differential scanning calorimetry (DSC). Based on the DSC analysis, isothermal annealing was designed, and XRD was performed to analyze the phase composition after heat treatment. The quasicrystalline microstructure of Al-6 at.%Mn(-2 at.%Be) alloys was obtained by suction casting. Be element addition in Al-Mn alloy modified the appearance of the quasicrystalline phases from hexagons to petals; meanwhile, the primary phase transformed from the Al6Mn compound to quasicrystalline approximant phase. Combined with XRD and scanning results show Be suppressed the formation of Al6Mn and promoted the formation of a quasicrystalline approximant phase. The thermal stability of the icosahedral phases contributes to a better performance of alloys at higher temperature. EDS analysis shows that the quasicrystalline phase is not a stoichiometric compound but a range of compositions.

    更新日期:2020-01-06
  • Correction to: Constitutive Modeling for Hot Working Behavior of SP-700 Titanium Alloy
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-03
    Amir Hossein Sheikhali, Maryam Morakkabati

    The three original authors have agreed that Seyed Mahdi Abbasi’s name should be removed from the article. The byline should read Amir Hossein Sheikhali, Maryam Morakkabati.

    更新日期:2020-01-04
  • In Vitro Degradation and Cytocompatibility of As-Cast Mg-5Zn- x Sr Alloys
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-03
    Gong Xiaole, Chen Jihua, Yan Hongge, Xia Weijun, Su Bin, Cheng Meixin, Yin Hui

    The biodegradation behaviors and cytocompatibility of the as-cast Mg-5Zn-xSr alloys (≤ 1.0%) are carefully characterized by immersion testing, electrochemical measurement and cell proliferation and adhesion testing. The biodegradation rates increase in the order of Mg-5Zn-0.2Sr, Mg-5Zn-1Sr, Mg-5Zn-0.6Sr and Mg-5Zn in both 0.9%NaCl and Hank’s solution. The as-cast Mg-5Zn-0.2Sr alloy is the most corrosion resistant, which can be attributed to the finest grain size, the lower volume fraction of secondary phases and the higher stability of corrosion layer. Filiform corrosion along grain boundaries is dominant in the Mg-5Zn-0.2Sr alloy at the initial stage, and the cyclic polarization scans show that it has the highest pitting corrosion resistance. Grain size effect on corrosion is not as obvious as that of the secondary phases for the as-cast Mg-Zn-Sr alloys. The 0.2%Sr addition can reduce the biodegradation rate, promote the cell growth and improve the cell adhesion ability of the as-cast Mg-5Zn alloy, which is attractive for biomedical applications.

    更新日期:2020-01-04
  • Effect of Ni on Surface Energy and Diffusion Creep of Solid Ag
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    S. N. Zhevnenko, I. O. Dmitrieva, V. E. Antonova

    The effect of nickel on surface energy of the solid/gas interface of silver was studied. The measurements were taken using foils according to the previously developed in situ method in an atmosphere of Ar + 10% H2 at high temperatures. This method simultaneously allows one to determine the surface energy and diffusion creep rate. The solubility of nickel in silver is very low, so the measurements were taken for the alloys in the two-phase region with 0.45 at.% Ni and 1.5 at.% Ni, as well as for pure nickel. Nickel is shown to significantly increase the surface energy of silver and slow down the diffusion creep rate.

    更新日期:2020-01-04
  • Characterization of Corrosion Within Friction Stir Weld Zones of an API X-70 Steel Using a Novel Microcell Setup
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Juliane Ribeiro da Cruz, Rodnei Bertazzoli

    The susceptibility of API-X70 friction stir weld zones to corrosion in a Na2SO4 acid medium is successfully investigated using an innovative microcell setup. Microstructures were characterized by optical and electron microscopy, Vickers microhardness mapping and linear potential scan voltammetry, at micro- and macroscales. Potential galvanic couples between the weld zones were identified. The most anodic zone was base metal, which, with a banded microstructure of ferrite and perlite, developed a potential difference of up to 45 mV in comparison with the adjacent heat-affected zone. Friction stir welding promoted solute redistribution and the formation of martensite/retained austenite constituent, which contributed to reduced galvanic corrosion between ferrite and cementite. The thermo-mechanically affected zone was the most cathodic region, composed of acicular ferrite, coarse bainite and martensite/retained austenite constituent. Polarization resistance progressively increased, and corrosion current density progressively decreased, from base metal toward stir zone. In addition to the reduction in galvanic corrosion, a more uniform distribution of corrosion products in the stir zone also accounted for this behavior.

    更新日期:2020-01-04
  • Structure and Mechanical Properties of AISI1045 in the Helical Rolling–Pressing Process
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Abdrakhman Naizabekov, Irina Volokitina, Sergey Lezhnev, Alexandr Arbuz, Evgeniy Panin, Andrey Volokitin

    The structure and mechanical properties of steel AISI 1045 subjected to three passes of the combined process “helical rolling–pressing” at a temperature of 500 °C were investigated. During the helical rolling–pressing process, the structure was substantially crushed to ultrafine-grained state, as the structure of steel AISI 1045 with an average grain size of 25 µm after deformation was decreased by 25 times, the average grain size was 1 µm. The values of tensile strength and yield strength increase in three passes from 619 to 925 MPa and from 545 to 867 MPa, respectively. The relative contraction after rupture varies from 42 to 35%; but the change is not as significant as in usual helical rolling. The combined helical rolling–pressing process is an effective way to form an ultrafine-grained structure and improve the mechanical properties of AISI 1045 steel.

    更新日期:2020-01-04
  • Microstructure and Mechanical Properties of Carbon Nanohorns Reinforced Aluminum Composites Prepared by Ball Milling and Spark Plasma Sintering
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    M. Jagannatham, S. Sankaran, Prathap Haridoss

    Abstract Commercial purity aluminum was reinforced with different percentages of carbon nanohorns (CNH) using ball milling (1 h) followed by spark plasma sintering (SPS) at 550 °C for 5 min under 50 MPa pressure with heating rate 100 °C/min. The microstructure, hardness and compression properties of the spark-plasma-sintered carbon-nanohorns-reinforced aluminum (Al-CNH) composites were evaluated. Transmission electron microscopy revealed a uniform distribution of 0.3% CNH in Al, but above 0.3% CNH, agglomeration occurred. The compression strength of Al-0.3%CNH composites increased by 44% compared to the milled Al sample without CNH.

    更新日期:2020-01-04
  • Investigation of the Microstructure and Mechanical Characteristics of Disk Laser-Welded Ti-6Al-4V Alloy Joints
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Pavel Kovačócy, Beáta Šimeková, Ingrid Kovaříková, Erika Hodúlová, Mária Dománková, Jana Ptačinová, Peter Jurči

    Laser beam welding of 2-mm-thick sheets of the Ti-6Al-4V alloy is reported in this paper. Different combinations of processing parameters (shielding gas, laser beam power, focal position, welding speed) were used. The laser welding parameters have been correlated with macrostructure and microstructure of welded joints, their microhardness, and to tensile properties of the welded material as well as the weld joints themselves. It has been determined that argon as a shielding gas is more preferable than helium. For the manufacturing of the weld joints with good penetration and geometry, at least a 42.75 J/mm of heat input into the material should be introduced. In this case, the weld joint has fine microstructure containing acicular martensite and small amount of remaining β-phase, and both the weld joint and the base material manifest good mechanical properties. Undesirable microstructural coarsening and deterioration of mechanical properties of welded material occur when that optimal heat input to the material is too much exceeded.

    更新日期:2020-01-04
  • Effect of Alternating Current on Passive Film and Corrosion Behavior of Pipeline Steel with Different Microstructures in Carbonate/Bicarbonate Solution
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    M. Zhu, J. L. Yang, Y. B. Chen, Y. F. Yuan, S. Y. Guo

    The relationship between microstructure and alternating current (AC) corrosion behavior of X80 pipeline steel was systematically studied in CO32−/HCO3− solution using corrosion tests and surface analysis technology. The results show that AC prevents the formation of passive film and decreases its stability. AC generates a different damage effect to the passive film on steels with various microstructures. The passive film of normalized microstructure steel has a relatively high stability, followed by the hot-rolled steel, and that of the annealed sample is the most unstable. The influence of AC on passive film of steels with various microstructures causes a difference in the corrosion resistance. The corrosion form of steels with different microstructures applied with AC displays the obvious characteristic of localized corrosion. The normalized microstructure has the optimum corrosion resistance, followed by the hot-rolled steel, and the annealed steel possesses the worst corrosion resistance. The difference in the AC corrosion behavior of X80 steels may be related to the microstructure.

    更新日期:2020-01-04
  • Effects of Ti and High Cooling Rate on the Phase Equilibria and Properties of Ni 3 (Al,V) Alloys
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Tomasz Czeppe, Anna Wierzbicka-Miernik, Anna Sypien, Grzegorz Garzel, Anna Goral, Lidia Litynska-Dobrzynska, Marek Kopyto, Witold Przybyło

    Abstract Investigations of the Ni3(Al,V,Ti) alloys with 5 at.% Ti addition show that high quenching rates from the liquid state allow for the preservation of the metastable Ni(Al,V,Ti) solid solution at low temperatures as well as for the limitation of the eutectoid decomposition range. Annealing at the temperatures close to the eutectoid decomposition causes an increase in the amount of the Ni3Al and Ni3V equilibrium phases, as well as the precipitation of the Ni3Ti phase. The V addition reveals the ability to stabilize Ni solid solution, while Ti retards Ni3V phase precipitation but also supports the precipitation of the Ni3Ti phase, in spite of the higher than 5 at.% range of Ti solubility in the Ni3V phase. The increase in V and Ti content at the cost of a decrease in Al content strongly increases micro-hardness of the alloys crystallized at high rates. For the alloys containing predominantly V, increased ductility was noticed in the temperature range of the dissolution of Ni3V precipitates.

    更新日期:2020-01-04
  • Forming and Warm Die Quenching Process for AA7075 Aluminum Alloy and Its Application
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Zhiqiang Zhang, Xiaokai Zhang, Dongye He

    In order to investigate the effect of die temperature on the microstructure and mechanical properties of formed components, the forming and quenching experiments on U-shaped components of 7075 aluminum alloys at different die temperatures ranging from 25 to 350 °C were carried out. Mechanical properties of formed components were measured by Vickers hardness measurement, tensile test and electrical conductivity test. Microstructure evolution was observed by optical microscopy and scanning electron microscopy. In order to evaluate the effect of die temperature on the shape accuracy of formed components, the springback of U-shaped component was analyzed. The results showed that the Vickers hardness and tensile strength (TS) of formed components decreased with the increase in die temperature. The reduction in strength of the formed component was not obvious until die temperature reached 250 °C. The Vickers hardness and TS were 180 HV and 585 MPa, which were similar to those in T6 temper. When die temperature increased to 350 °C, the Vickers hardness and TS dropped to 93 HV and 445 MPa, respectively. As die temperature increased, the grain size increased gradually and the precipitated phase became larger. Springback angle of formed components decreased with the increase in die temperature. The die temperature should be 200 °C for forming and warm die quenching process of 7075 aluminum alloys to obtain enough strength effect and shape accuracy.

    更新日期:2020-01-04
  • Improved Elevated Temperature Properties in Al-13%Si Piston Alloys by Mo Addition
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    L. Jin, K. Liu, X.-G. Chen

    Eutectic Al-13%Si alloys are widely used in the automotive industry for manufacturing components, such as pistons and cylinder heads. To reduce greenhouse gas emissions and enhance the engine efficiency, their service temperature keeps increasing to 250-350 °C, leading to the deterioration of their mechanical properties and the creep resistance. In the present work, Mo was further added to Mn-containing Al-13%Si piston alloys aiming at improving the overall properties at elevated temperatures. Compared with the Mn-containing base alloy, Mo further enhanced the precipitation of dispersoids by expanding the dispersoid zone and restricting the dispersoid-free zone after the proper precipitation treatment (520 °C/12 h), resulting in a remarkable improvement in the yield strength at both room temperature and 300 °C, as well as the creep resistance at 300 °C. Furthermore, the beneficial effect of Mo addition on the improved yield strength and creep resistance was especially prominent during long-term thermal exposure (up to 1000 h at 300 °C) due to the synergistic effect of thermally stable dispersoids and the retardation of the gradual fragmentation and spheroidization of Si particles.

    更新日期:2020-01-02
  • Influence of Deep Cryogenic Treatment and Secondary Tempering on Microstructure and Mechanical Properties of Medium-Carbon Low-Alloy Steels
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Wanglin Chen, Weikai Wu, Cong Li, Xianna Meng

    Deep cryogenic treatment (DCT) and secondary tempering for 40CrNiMoA steel were carried out to obtain the desirable microstructures corresponding to excellent mechanical properties suiting for the preparation of flex spline of harmonic drive reducer. The effects of DCT and secondary tempering on microstructural characteristics and mechanical properties were investigated by x-ray diffraction, scanning electron microscopy, electron backscattered diffraction and transmission electron microscopy, in association with property measurements. The results show that the DCT promotes the transformation of retained austenite to martensite, the precipitation and homogeneous distribution of carbides as well as the refinement of martensitic substructures. The structural and morphological changes significantly improve the hardness, yield and tensile strength of steels, but slightly lower the elongation of them. Further secondary tempering at special temperatures can successively increase the elongation and fracture toughness of the DCT-treated 40CrNiMoA steels at the cost of slight decrease in hardness and strength due to the reduction in dislocation density. Therefore, the DCT in combination with secondary tempering can improve the comprehensive mechanical properties of 40CrNiMoA steels to produce the flex spline with a higher lifetime.

    更新日期:2020-01-02
  • Stress Corrosion Cracking Behavior of 2024 and 7075 High-Strength Aluminum Alloys in a Simulated Marine Atmosphere Contaminated with SO 2
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Feng Ge, Luo Zhang, Huiyun Tian, Mingdong Yu, Jianming Liang, Xin Wang

    Abstract The stress corrosion cracking (SCC) of high-strength 2024-T351 and 7075-T651 aluminum alloys in simulated marine atmospheric medium containing HSO3− was investigated. The results showed that the presence of HSO3− could significantly accelerate the corrosion process of 2024-T351 and 7075-T651 high-strength aluminum alloy. This process was attributed to the enhanced anodic dissolution and hydrogen embrittlement caused by the HSO3−. The SCC susceptibility showed an increasing trend in both of aluminum alloys with increasing HSO3− concentration. Meanwhile, the hydrogen generated by HSO3− was shown to change the failure mode of these two aluminum alloys.

    更新日期:2020-01-02
  • Constitutive Equations, Processing Maps, and Microstructures of Pb-Mg-Al-B-0.4Y Alloy under Hot Compression
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Weizong Bao, Longke Bao, Dan Liu, Deyi Qu, Zhuangzhuang Kong, Mingjun Peng, Yonghua Duan

    Abstract Hot compression behaviors of Pb-Mg-Al-B-0.4Y alloy under strain rate of 0.001-1 s−1 and temperature of 493-613 K were performed by employing hot compressing tests. According to the experimental stress–strain curves, as the strain increases, the flow stress increases firstly, then reaches the peak stress, and finally decreases to a steady state. Constitutive equations in traditional Arrhenius model and improved Arrhenius model in multi-linear regression were used to predict the flow stress of Pb-Mg-Al-B-0.4Y alloy. The values of MARE and RMSE in the traditional Arrhenius model are 11.780 and 21.169%, respectively, which are larger than 7.227 and 7.447% of the improved Arrhenius model, indicating that the predicted accuracy of the improved Arrhenius model is more accurate. The hot processing maps under the experimental conditions were established. Based on processing maps and microstructure observation, the optimum processing parameters are 0.001 s−1 ≤ \(\dot{\varepsilon }\) ≤ 0.01 s−1 and 587 K ≤ T ≤ 613 K.

    更新日期:2020-01-02
  • In Situ Synthesized (Cr, Fe) 7 C 3 -Reinforced Composite Coatings via Laser Cladding Deposition of Fe-Based Alloys and Carbon Fibers
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Jianfeng Li, Zhencai Zhu, Yuxing Peng, Gang Shen

    A (Cr, Fe)7C3 carbide-reinforced composite coating is fabricated via laser-irradiating cladding deposition of a Fe60 alloy powder and carbon fibers (CFs) mixture onto a 16Mn steel substrate surface. The microstructure, microhardness and wear resistance of the composite coating are investigated. High-hardness (Cr, Fe)7C3 carbides are uniformly embedded in the ductile γ-Fe/(Cr, Fe)23C6 lamellar eutectics matrix, with some B4C nanoparticles and unmelted CFs also present in the matrix. The composite coating possesses much higher microhardness, anti-friction and wear resistance properties than the steel substrate due to the combined action of the (Cr, Fe)7C3 carbides and γ-Fe/(Cr, Fe)23C6 lamellar eutectics. Micro-cutting and severe plastic deformation are the main wear mechanisms of the substrate, whereas micro-scratching is the predominant wear mechanism of the composite coating, with the formation of a lubricating film mitigating wear on the coating surface.

    更新日期:2020-01-02
  • Influence of Guillotine Clearance on Cut-Edge Damage to Nonoriented Electrical Steel
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Canming Wang, Qiusheng Yan, Jiabin Lu, Xiaowei Zhang

    Abstract Nonoriented electrical steel of 0.65 mm thickness was sheared to investigate the influence of guillotine clearance on cut-edge damage. The result shows that all the burr, work hardening, and magnetic property damage present an increasing trend initially, then a decrease, followed by an increase with increasing guillotine clearance. In particular, when the relative guillotine clearance (c/t) is within 4.6-6.2%, the burr is small and the cut edge is only slightly damaged. Damage to the burr, work hardening, and magnetic properties are influenced and inter-correlated. The plastic deformation of the microstructure at different c/t ratios is the decisive factor affecting burr forms and cut-edge damage. On the one hand, it leads to different degrees of work hardening and then results in a diversity of crack propagation patterns, forming burr and cross-sectional morphologies with different shapes. On the other hand, the stress distribution and grain orientation also change, which further influences the magnetic properties. Moreover, the relationship between microstructure deformation and grain orientation was established by analyzing texture occupancy and orientation distribution function diagrams. It is clarified that both nucleation position evolution and edge stresses generated by different clearances contribute to the evolution of grain orientation and texture.

    更新日期:2020-01-02
  • Effect of the Diffusion Annealing Process on the Sliding Wear Resistance of Cobalt Boride Layer
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    A. M. Delgado-Brito, A. D. Contla-Pacheco, V. H. Castrejón-Sánchez, D. López-Suero, J. Oseguera-Peña, I. Campos-Silva

    New results about the sliding wear resistance under dry and wet conditions of cobalt boride layer exposed to a diffusion annealing process (DAP) were estimated in this study. Firstly, the cobalt boride layer (CoB-Co2B) was developed at the surface of the ASTM F1537 alloy using the powder-pack boriding process (PPBP) at 1273 K with 6 h of exposure. Then, the borided ASTM F1537 alloy was exposed to the DAP at 1273 K with 2 h of exposure in an argon atmosphere. The cobalt boride layers, obtained by the PPBP and PPBP + DAP, were characterized by different physicochemical techniques and depth-sensing Vickers microindentation to determine the nature of phases formed on the surface, the chemical composition along the depth of the cobalt boride layers, and the indentation properties, respectively. The wear sliding tests on the PPBP, PPBP + DAP, and the reference material (ASTM F1537 alloy) were performed using a ball-on-flat configuration comprised with an WC–Co ball as a counterpart using a constant normal force; particularly, for the wet (lubricated) sliding tests, the materials were immersed in a Hanks’ balanced salt solution. The failure mechanisms on the worn tracks were analyzed and correlated with the behavior of the friction coefficient (CoF) and wear resistance of the tested materials. Finally, and according to the entire set of experimental conditions, the results showed that after DAP, the CoB layer was dissolved completely on the surface of the borided ASTM F1537 alloy, with a change of the magnitude of residual stresses (compressive) on the cobalt boride layer. In addition, under dry and wet conditions, the presence of a stiff and hard (CoB) layer formed by the PPBP on the surface of the ASTM F1537 alloy increased the wear resistance compared with the values estimated on the PPBP + DAP and reference material.

    更新日期:2020-01-02
  • Microstructures, Mechanical Properties, and Corrosion Behaviors of Refractory High-Entropy ReTaWNbMo Alloys
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2020-01-02
    Delong Yan, Kaikai Song, Honggang Sun, Shuang Wu, Kang Zhao, Hezhi Zhang, Shengzhong Yuan, Jeong Tae Kim, Niraj Chawake, Oliver Renk, Anton Hohenwarter, Li Wang, Jürgen Eckert

    Abstract A refractory ReTaWNbMo high-entropy alloy (HEA) with an equal atomic ratio prepared by rapid solidification displays a BCC crystal structure. After annealing the as-quenched samples at 673, 873, 1073, and 1273 K for 12 h, respectively, the crystalline phase still keeps its BCC structure, but the crystalline morphology transforms from coarse dendrites to fine equiaxed crystals together with gradual grain refinement. The intragranular regions are enriched in W and Ta, while the crystals in the intergranular regions are enriched in Nb, Mo, and Re. With the increase in annealing temperature, the yield strength increases, and the compressive plasticity and fracture strength are obviously enhanced. The failure mode gradually changes from transgranular to intergranular fracture. Furthermore, the corrosion behaviors of the as-cast ReTaWNbMo HEA and the annealed states in a 3.5 wt.% NaCl solution were also studied. The samples annealed at 1273 K exhibit the best corrosion resistance due to the elemental re-distributions within grains.

    更新日期:2020-01-02
  • High Temperature Tensile Behavior of a Nickel-Based Superalloy 55Ni-17Cr-12Fe-9Mo-2Nb-1.5Al Used in Launch Vehicle Applications
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2019-12-20
    P. Manikandan, G. Sudarshan Rao, K. Saravanan, V. S. K. Chakravadhanula, M. Amruth, S. V. S. Narayana Murty, V. M. J. Sharma, P. Ramesh Narayanan

    55Ni-17Cr-12Fe-9Mo-2Nb-1.5Al alloy is a nickel-based superalloy (Russian designation is XH55MбЮ or KhN55MBYu, XH55) without any equivalent in American/European alloy designation. It is used in cryogenic engine of satellite launch vehicles application in two different heat-treated conditions: (1) standard aged (STA) at 730 °C/15 h + 650 °C/10 h and (2) STA + BC (brazing cycle) treatment carried out in vacuum at 1030 °C with holding time of 30 min. Due to the braze cycle adopted for manufacturing, it is essential to study the deterioration in mechanical properties, if any. Hence, the present work is carried out to understand the material behavior in tensile mode (25, 425, 575, 700 and 900 °C) for XH55 alloy in STA condition and STA + BC conditions, compared with corresponding microstructural analysis, morphology and composition using microscopy at various length scales. The tensile stress–strain curve shows characteristic sudden drops in stress with respect to strain, attributed to dynamic strain aging at different temperatures for both STA and STA + BC conditions. In STA condition, the yield strength of the material decreased with increase in temperature. In STA + BC condition, the yield strength decreased up to 425 °C, increased up to 700 °C as the material was subjected to artificial aging during testing and finally decreased at 900 °C. Marginal deterioration in mechanical properties have been observed due to the braze cycle adopted against STA condition.

    更新日期:2019-12-21
  • Increasing Wear Resistance of Low-Carbon Steel by Anodic Plasma-Electrolytic Nitroboriding
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2019-12-20
    V. S. Belkin, P. N. Belkin, B. L. Krit, N. V. Morozova, S. A. Silkin

    The article describes the research for improvement of properties of low-carbon steel 20 by anodic nitroboriding in the electrolyte containing boric acid in the quantity necessary for ensuring sufficient boron potential in the saturating medium—vapor-gaseous envelope. Current–voltage and temperature–voltage characteristics of plasma-electrolytic treatment in the suggested electrolyte; the influence of oxidation and anodic dissolution processes on weight balance, structure and phase composition of the modified layer, its microhardness, roughness and wear resistance were considered. There was a significant (up to 1180 HV) increase in microhardness and a fivefold decrease in wear and corrosion. The data of tests showed that the operational resource increases more than 45 times for threaded fastening pair subjected to nitroboriding.

    更新日期:2019-12-21
  • Innovatively Joining Thin Al Alloy Sheets Using the Synergistic Effect of Rotating and Stationary Shoulders and Joint Mechanical Properties
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2019-12-19
    Zhen Yang, Kuo Zhang, Wei Hu, Shude Ji, Xin Li

    In this work, thin Al alloy sheets were first joined by the synergistic effect of rotating and stationary shoulders. A tool system combined with an inner rotating shoulder and an outer stationary shoulder was designed. The inner rotating shoulder is mainly used to produce essential heat input, and the outer stationary shoulder is mainly used to enhance the metallurgical bonding and eliminate arc corrugation and flash. The results show that sound joints without flash and arc corrugation are obtained by this newly proposed method. Hooks and cold laps are very small inside the joints, and their heights gradually decrease with an increase in the rotating speed from 400 to 1000 rpm. The hardness and lap shear failure loads of the joints welded by the tool with rotating and stationary shoulder are higher than that welded by a traditional tool because of less heat input during welding. The lap shear failure load of the joint first increases and then decreases by increasing the rotating speed. The maximum failure load of 5364 N is obtained at 600 rpm, and the joint shows tensile fracture mode.

    更新日期:2019-12-19
  • Microstructure Evolution and Recrystallization of D36 Steel during Ultrasonic Impact Assisted with Electropulsing and Heat
    J. Mater. Eng. Perform. (IF 1.476) Pub Date : 2019-12-17
    Tao Liu, Xiaopei Li, Guoyi Tang, Guolin Song

    Ultrasonic impact treatment (UIT) combined with high-energy electropulsing (EP) was applied to D36 low-carbon steel with three different electrical regimes. Submicron crystalline was obtained on the superficial region after the treatment due to continuous dynamic recrystallization. The cementite experienced strain-induced decomposition and precipitation. The microstructure is significantly determined by the current density and temperature. A strengthened layer with a maximum hardness of 285 HV was obtained in EP-UIT, in comparison with the hardness of 227 HV resulted from UIT solely. Alongside with high hardness, the strengthened layer extended to a remarkable depth of nearly 2 mm due to acoustic softening, electroplasticity and thermal softening engaged simultaneously. A 3-μm oxide layer in average consisting of magnetite and hematite formed on the treated surface. Joule heat and athermal effect of EP are the factors inducing these phenomena.

    更新日期:2019-12-18
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
加州大学洛杉矶分校
上海纽约大学William Glover
南开大学化学院周其林
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug