显示样式:     当前期刊: Journal of Materials Processing Technology    加入关注       排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Influence of Rotation Speed and Axial Force on the Friction Stir Welding of AISI 410S Ferritic Stainless Steel
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    Gerbson de Queiroz Caetano, Cleiton Carvalho Silva, Marcelo Ferreira Motta, Hélio Cordeiro Miranda, Jesualdo Pereira Farias, Luciano Andrei Bergmann, Jorge F. dos Santos

    The Friction Stir Welding process parameters were varied to provide a combination of an acceptable surface finish, absence of cracks, and full tool penetration. Two levels of rotation speed and axial forces from 10 to 30 kN were applied, whilst keeping the welding speed constant at 1 mm/s. One of the defects analyzed was the production of flashes. This can occur due to an increase in axial force and because of the instability in its applications, which implies directly on the formation of volumetric defects along the stir zone. FSW joints without root flaws can be achieved through a correct balance between the axial force and rotation speed, which also allows a greater immersion of the tool probe in the joint. Both rotation speeds using an axial force of around 20 kN proved to be good welding parameters for the FSW process. The welding of the AISI 410S steel (under these conditions) resulted in joints without internal defects and with a good surface finish.

    更新日期:2018-07-18
  • Substructure of deformation zones in austempered ductile iron finish-turning chips
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    Kambuyi Katuku

    A series of dry finish-turning tests of a structural austempered ductile iron with PcBN cutting-inserts were run with a depth of cut of 200 µm, a feed-rate of 50 µm rev-1 and a cutting length of ~100 m, and using machining speeds stretching from 50 to 800 m min-1. Substructure developed within chips’ deformation zones was studied by transmission electron microscopy. At machining speeds equal or beyond 150 m min-1, shear-induced unlocking of incomplete austempering transformation and continuous-cooling austempering of residual and retained austenite would plausibly stand as phase transformations behind the overwhelming volume fraction of ferrite within the chips’ deformation zones and related regions. Formation (and coalescence) of ferrite sub-grains within these zones, possibly concurrently with their parent shear-platelets, would be the result of rotational dynamic recrystallization. Substructure refinement in the deformation zones of chips formed under machining speeds equal or beyond 150 m min-1 could heighten the diffusion rates of cutting-insert components therein.

    更新日期:2018-07-18
  • Development and validation of a meshless 3D material point method for simulating the micro-milling process
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    S. Leroch, S.J. Eder, G. Ganzenmüller, L.J.S. Murillo, M. Rodríguez Ripoll

    A meshless Generalized Interpolation Material Point Method for simulating the micro-milling process was developed. This method has several advantages over well-established approaches (such as finite elements) when it comes to large plastic strains and deformations, since it inherently does not suffer from tensile instability problems. The feasibility of the developed material point model for simulating micro-milling is verified against finite element simulations and experimental data. The model is able to successfully predict experimentally measured cutting forces and determine chip temperatures in agreement with conventional finite element simulations. After having verified the approach, the model was applied to perform extensive numerical 3D simulations of the micro-milling process. The goal is to evaluate the response of the micro-milling cutting forces as function of the hardening behavior of the micro-milled material. The meshless 3D simulations reveal a dependency of tool force slopes (with respect to the uncut chip thickness) on the hardening parameters. Based on these findings, a new approach is outlined to determine hardening parameters directly from two micro-milling experiments with distinct, sufficiently large uncut chip thicknesses.

    更新日期:2018-07-18
  • A new approach to control and optimize the laser surface heat treatment of materials
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    Sagar V. Telrandhe, J. Bhagyaraj, Sushil Mishra, S. Karagadde

    Laser heating is often used to perform the surface treatment by modifying local microstructural and mechanical properties of components having complex geometries. In this study, the laser surface heat treatment of a rotating cylindrical work-piece was investigated using both experimental and numerical modeling approaches, with an aim to correlate and predict the temperature distribution during the process. The depth of the laser affected zone was predicted by solving the transient heat transfer with a moving laser heat source, using finite element analysis. The temperatures derived from the microstructural examination of the experimental specimen were found to closely agree with the predicted results from the numerical simulations. The numerical and experimental results have also led to a new observation, indicating a linear variation of the absorptivity with the laser scan speed. The prediction of the cooling curves from simulation suggested the β → α " phase transformation and the recovery of the β phase, and the existence of new phases were confirmed through electron microscopy. The rapid cooling during the laser surface treatment was found to induce a flake-structure that consisted of both martensite ( α " ) and regained bcc ( β ) phase. A new polynomial input power function has been proposed to achieve uniform distribution of the heat penetration along the cylinder axis, saving about 10% of the material wastage.

    更新日期:2018-07-18
  • Controlling the sensor properties of smart structures produced by metal forming
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    Martin Krech, Andreas Trunk, Peter Groche

    A rotary swaging process is presented which allows the manufacturing of smart structures by forming hollow shafts and joining sensor elements simultaneously. A reasonable form- and force-fit of the sensor element is required to ensure the desired sensory properties of the structure, such as linearity, long-term stability and repeatability. However, the conjoint forming process is subjected to uncertainty which leads to fluctuations of the remaining pre-tension forces. In order to increase the adjustability and accuracy of the process, the utilization of the sensor signals for a control approach is investigated. A prediction model is established on the base of a correlation analysis. It was found that the sensor forces occurring during the integration process can be used as a measure to predict the resulting pre-tension with sufficient accuracy. In order to manipulate the process in a beneficial way a control variable has to be identified. Therefore, several test series are conducted to investigate the suitability of infeed speed and mandrel force as possible control variables. A prerequisite is that the joining process can be manipulated, while the resulting geometry of the part remains unchanged. A possible time slot for an intervention is determined and a first control approach is implemented. Two different target values of the pre-tension force are tested. Compared to open loop controlled processes the accuracy of the targeted pre-tension condition could be improved significantly.

    更新日期:2018-07-18
  • Effects of ambient pressure on single-pulse laser processing of austenite stainless steel
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    Jiangzhou Su, Zhijing Zhang, Muzheng Xiao, Zhipeng Ye, Yichong Yang

    The effects of ambient pressure on single-pulse laser processing of austenite stainless steel were investigated in this study. The ambient pressure environments were created by Ar gas and ranged from 0.001 bar to 45 bar. It is observed that the ejection and expansion of the metal vapor are severe under a low pressure and gradually become limited with the increase of ambient pressure. Numerous oxides remain on the molten-pool surface under a low pressure, and a shiny solidified molten-pool surface without oxides can be obtained when the pressure is higher than 10 bar. Furthermore, the ripples induced by the ejection of the metal vapor were detected on the solidified molten-pool surface, and it significantly reduced with the increase in ambient pressure. Larger aspect ratios of molten pools were obtained under higher pressures, and a tendency wherein the primary dendrite arm spacing and grain size decrease with the increase of ambient pressure was observed. When the ambient pressure changed from 0.001 bar to 45 bar, the aspect ratio increased by approximately 12%, the dendrite arm spacing decreased approximately 12% and 4% on the side and center positions, respectively, and the grain size decreased approximately 37%.

    更新日期:2018-07-18
  • Arc weldability of Incoloy 825 to AISI 321 stainless steel welds
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-17
    Navid Sayyar, Morteza Shamanian, Behzad Niroumand

    Composition effect of Inconel 625, Incoloy 65 and ER347 fillers on microstructural evolution and solidification crack (SC) sensitivity of gas tungsten arc welded Incoloy 825 to AISI 321 SS was investigated. The structure of welds had been mostly austenitic, and solute segregation caused formation of eutectic-nature secondary phases in inter-dendritic / cellular spaces of three weld alloys. The dilution effect led to a transition from FA to AF mode of solidification in ER347 weld and decreased its ferrite content. Inconel 625 and ER347 welds had the highest and lowest resistance to SC during Longitudinal Varestraint Test, respectively. Fine dendritic structure of Inconel 625 weld resulted in easier strain accommodation and better weldability properties of this alloy. Severe cracking and high sensitivity of ER347 weld to SC were characterized because of low ferrite content and easier wettability of solidification grain boundaries due to formation of low-melting Nb and Ti-rich phases. Inconel 625 filler could play an effective role in establishing an appropriate bridge in terms of thermal expansion coefficient between dissimilar parent metals.

    更新日期:2018-07-18
  • GMAW-based additive manufacturing of inclined multi-layer multi-bead parts with flat-position deposition
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-10
    Yongzhe Li, Xing Huang, Imre Horváth, Guangjun Zhang

    The objective of this paper is to propose a mathematical description of the shape-forming process of multi-layer multi-bead parts with inclined structures. Related conceptual fundamentals were clarified, including (i) the basic model of a single layer, (ii) the inclination angle and (iii) various types of slops. In the layers-overlapping model, material shortage areas are generated at the edges of layers. To solve the problem, the deposition amount of beads at the edges of the second and above layers should be modified, in association with the parameters applied to fabricate the slope. Various basic inclined components were deposited to validate the proposed mathematical formulation. Findings from the basic experiments were: (i) depositing additional material to compensate for the material shortage areas is necessary for realizing the designed geometries of the layers, (ii) depositing the bead at the layer edges alongside an already-deposited neighboring bead enables a better shape-forming in the case of negative slopes and (iii) the deposition order of beads in a layer has little influence on the shape formation of positive slopes. A complex part was also fabricated as a case study to validate the model and findings in the real-life context. Practical issues with regard to using the model and the solutions to the issues were discussed.

    更新日期:2018-07-12
  • Combined hot stamping and Q&P processing with a hot air partitioning device
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-11
    Bin Zhu, Jia Zhu, Yanan Wang, Bernard Rolfe, Zijian Wang, Yisheng Zhang

    Combining the hot stamping process and a Quench and Partition (Q&P) heat treatment can improve the mechanical properties of hot stamped automotive parts. This paper investigates using a new heating device to heat or cool a part to a given temperature. Instead of performing the partitioning heat treatment in a furnace, this work proposes using a new hot air process that performs the partitioning treatment. The new device obtains a fast heating rate and a uniform temperature distribution, necessary for Q&P. The effect of partitioning time and temperature on the mechanical properties of parts were analyzed by the new processing method, which is suitable for use in the area of industrial hot stamping. The results show that the hot air partitioning device provides more control over the partitioning temperature because convection is more efficient than radiation. Control over the quench temperature and partition is critical for the Q&P process to enable the carbon diffusion to stabilize the austenite. Furthermore, the highest product of strength and elongation (1380 MPa × 13%) using the hot air process under the authors’ set-up condition is obtained when the partitioning time is 60 s and the temperature is 425 °C, thanks to the optimum ratio between martensite and austenite, which was observed through scanning electron microscopy.

    更新日期:2018-07-12
  • Theoretical and experimental research on the law of flexible roll profile electromagnetic control
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-06
    Wenwen Liu, Yanfeng Feng, Tingsong Yang, Fengshan Du, Jingna Sun

    To obtain a better strip shape, this paper proposes a new micro-scale roll profile control technology. According to the principle of the technology, it can be called roll profile electromagnetic control technology (RPECT). To achieve multi-point and real-time measurement the profile of electromagnetic control roll, the new roll profile test technology is proposed. Relying on the RPECT and new roll profile test technology, a φ270 mm×300 mm roll profile electromagnetic control experimental platform (RPECEP) is designed and built. An electromagnetic-thermal- mechanical coupled axisymmetric simulation model with the same size is established. Through experiments and simulations, RPECT is confirmed to achieve micro-scale flexible roll profile adjustment. An all-around comparison of experimental results and calculated results confirms that the new roll profile test technology is feasible and the calculatde results agree well with the experimental results. Based on the model, the variation of the roll profile is analysed for different electromagnetic parameters; the structures and positions of the electromagnetic stick, reasonable electromagnetic parameters and optimal time period for the roll profile control are determined, and methods for changing the number of roll profile curves are given.

    更新日期:2018-07-08
  • Two-step forming for improvement of forming limit in rotary nosing with relieved die for fabrication of axisymmetric and eccentric nosed tubes
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-07
    Wataru Oba, Yusuke Imaizumi, Shohei Kajikawa, Takashi Kuboki

    This paper presents application of two-step forming for improving the forming limit in rotary nosing with a relieved die. Nosing is one method which is used for reducing the diameter of a tube tip. “Two-step nosing” is composed of two stages and different dies are applied for the two stages. The die shapes are determined based on the occurrence tendency of defects in “one-step nosing”, where only one die is used through the whole process. In this research, a series of experiments and numerical analyses of one-step nosing was carried out for investigating the mechanism of the occurrence of defects. As a result, it is revealed that the occurrence of defects was highly relevant with the contact area between the die and tube. Based on the result of one-step nosing, the optimum die shapes were determined for the two stages, and then “two-step nosing” improved the forming limit 9% higher than one-step nosing under the optimum condition. Furthermore, “two-step nosing” was experimentally applied for forming eccentric nosed tubes, and its superiority was verified.

    更新日期:2018-07-08
  • Enhancing efficiency of field assisted sintering by advanced thermal insulation
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-07
    Alexander M. Laptev, Martin Bram, Kim Vanmeensel, Jesus Gonzalez-Julian, Olivier Guillon

    The influence of advanced thermal insulation on energy consumption and temperature distribution during electric field assisted sintering of conductive stainless steel powder and non-conductive zirconia powder was investigated. Four types of tool setup were considered: i) without insulation, ii) with die wall insulation, iii) with additional insulation of die faces and iv) with spacers manufactured from carbon fiber reinforced carbon composite (CFRC). The influence of thermal insulation on energy consumption was experimentally studied for samples with diameter of 17 mm. The temperature distribution in samples with diameters of 17 mm, 50 mm and 150 mm was modeled using the Finite Element Method. The power consumed during dwell was almost half the value when die wall insulation was used. The additional insulation of die faces and the application of CFRC spacers provide a threefold decrease in power during sintering of steel powder and a fivefold reduction during sintering of zirconia powder. The advanced thermal insulation significantly homogenizes the temperature distribution within samples of small and medium size. The advanced thermal insulation provides a strong decrease in the temperature gradient inside large conductive sample with a diameter of 150 mm. However, insulation apparently cannot ensure acceptable temperature homogeneity within non-conductive parts of such diameter. The reason for this is the specific current path and related heat concentration near the sample edge.

    更新日期:2018-07-08
  • Influence of non-consumable electrode configuration on arc welding characteristics
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-07
    A.V. Savinov, O.A. Polesskiy, I.E. Lapin, V.I. Lysak, P.P. Krasikov, A.A. Chudin

    The proposed configurations of non-consumable electrodes allow arcing with a diffuse cathode spot in a wide range of the welding current and exhibit longer service lives as compared to those of cone electrodes, which significantly enhance the arc welding characteristics in inert atmosphere. The effect of the geometric parameters of the electrode working area on the weld penetration depth, width, and geometric factor was investigated. It was found that the maximum value of penetration depth was achieved using the electrode with a slot in the working area and a cut along the welding direction, which enabled welding at relatively high speed and heat input leading to the formation of high-quality seams. The electrode with a cut across the welding direction exhibits the minimum penetration depth and maximum geometry factor and thus is most suitable for high-performance surfacing.

    更新日期:2018-07-08
  • Microstructural evolution and mechanical property development with nickel addition in low-carbon weld butt joints
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-08
    Gaojun Mao, Rui Cao, Cyril Cayron, Roland Logé, Xili Guo, Yong Jiang, Jianhong Chen

    Four metal powder flux-cored wires with added nickel (Ni) were designed to systematically investigate how Ni influences the microstructure and toughness in low-carbon bainitic weld metals (WMs). The microstructure was safely predicted by utilizing reasonable welding craft parameters (i.e., appropriate heat input and proper interpass temperature). Microstructural characterization, crystallographic analysis, microhardness mapping, fracture microparameter measurement, and finite element method calculations were all taken into account. This work showed that more martensite transformation occurs with increasing Ni and that the ductile-brittle transition temperature drops with added Ni. The boundaries with low-angle misorientation (i.e., less than 4°) enhance microhardness and the optimal inclusion size is in the range of 0.3–0.45 μm, thus revealing the reasons for the resulting microhardness and toughness variations. In addition, the high-angle grain boundaries in close-packed plane packets effectually prevent cracks. From a practical perspective, 4 wt.% Ni could be the best design for welding wires in the present work. This work confirmed many of the results found in recently published literature. These results provide a reference for the composition design of welding wires and the processing method of WMs.

    更新日期:2018-07-08
  • Effect of shielding gas on the metal transfer and weld morphology in pulsed current MAG welding of carbon steel
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-04
    Yong Zhao, Xiaojian Shi, Keng Yan, Guoqiang Wang, Zhanjun Jia, Yuxiang He

    A high-speed camera system has been used to observe the metal transfer with bead-on-plate welding. A stable pulsed streaming spray transfer was accompanied by arc jumping when the shielding gas of Ar+4%CO2+3%O2 was used, but the change of metal transfer mode had a tight relationship with the bell-shaped arc rather than critical current when a mixture of Ar+13%CO2+3%O2 was as shielding gas. With increasing CO2 concentration in the shielding gas, the bright arc area and arc length decreased due to the compression effect of carbon dioxide. Weld penetration and weld width increased slightly due to the higher arc force. The ferrite content in the weld metal increased slightly with increasing CO2 concentration in the shielding gas.

    更新日期:2018-07-05
  • Laser sintering and laser parameters optimization for porous foam microchannel reactor
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-04
    Minqiang Pan, Guanping Dong, Pingnan Huang, Hongqing Wang

    Porous foam microchannel reactor can effectively improve the reaction efficiency of Methanol reforming hydrogen production. Currently, porous foam microchannel reactors are primarily formed by the solid phase and liquid phase sintering techniques which generally require the metal fiber sheet of semi-finished products sinter at 800-1000℃ temperature conditions for 30-60 minutes. In this paper, a method of laser-sintered porous metal fiber sintering plate is proposed. Compared with the traditional methods, laser sintering technology has the advantages of shorter sintering time and retaining the surface microstructure which is more conducive to the adhesion of the catalyst. The effects of laser power, scanning rate, scanning distance, and scanning path on the sintering effect were also studied and analyzed. The results show that the porosity of copper fiber laser sintering sheets can reach 80% by laser sintering. When the laser sintering parameters for I=60A, f=20Hz, h=6.5ms, v=15mm/s, under the condition of variable speed sintering can achieve the best mechanical properties.

    更新日期:2018-07-05
  • Low-temperature diffusion bonding of W/Mo joints with a thin Cu interlayer
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-07-02
    Mei Rao, Jian Zhang, Jiahui Ding, Guoqiang Luo, Qiang Shen, Lianmeng Zhang

    By adding a thin Cu interlayer, refractory metals 93W and Mo1 can be reliably bonded by plasma activated sintering at low temperature. High resolution observations and an analysis of the joints indicate that the elements are sufficiently diffused at the interface of the W/Mo joints with a thin Cu interlayer without the formation of any intermetallic compounds. The maximum average shear strength of the W/Mo joint bonded at 700 °C for 20 min is greater than 210 MPa. Fe and Ni atoms in the 93W alloy can diffuse into the thin Cu layer and form a Cu solid solution. The presence of Fe and Ni in the Cu solid solution promotes diffusion bonding at both the W/ thin Cu and thin Cu /Mo interfaces, which contributes to the high bonding strength of the W/Mo joint bonded at low bonding temperatures. The fracture model of the W/Mo joint bonded at 700°C is a mixture of brittle fracture in the W base metal, ductile fracture in the thin Cu layer and brittle fracture in the Mo base material.

    更新日期:2018-07-03
  • 更新日期:2018-07-03
  • EXPLOSIVE WELDING OF ALUMINIUM TO STAINLESS STEEL
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-30
    G.H.S.F.L. Carvalho, I. Galvão, R. Mendes, R.M. Leal, A. Loureiro
    更新日期:2018-07-01
  • Microstructures and properties of roll-bonded stainless /medium carbon steel clad plates
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-28
    Yu Tao, Jing Yu-an, Yan Xiaolin, Li Wenbin, Pang Qihang, Jing Guo

    A 304 stainless steel/medium carbon steel clad plate was fabricated by hot-rolling in an argon atmosphere. The interfacial microstructures of the clad plates were observed by SEM, and the carbide phases were identified by XRD and TEM. The effect of the rolling parameters on the shear strength and composition diffusion was analyzed. The results show that a sensitization region appears in the stainless steel side and a decarburization region is present in the carbon steel side. The sensitization region is composed of a dual structure, ditch and full-depletion of chromium zones. The precipitates in the stainless steel side are Chromium-rich M23C6 carbides.

    更新日期:2018-06-30
  • Flow behaviors and microstructural evolutions of a novel high-Co powder metallurgy superalloy during hot working
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-28
    Liming Tan, Guoai He, Yunping Li, Feng Liu, Yan Nie, Liang Jiang
    更新日期:2018-06-30
  • Gradual-Cooling Solidification Approach to Alleviate Macrosegregation in Large Steel Ingots
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-28
    Honghao Ge, Fengli Ren, Duanxin Cai, Jing Hao, Jun Li, Jianguo Li

    Based on the mechanisms of macrosegregation evolution in large steel ingots, an approach named as gradual-cooling solidification (GCS) was proposed to alleviate the macrosegregation of large steel ingots. A three-phase mixed columnar dendritic-equiaxed solidification model was employed to investigate the approach. The solidification model considered the dendritic structure of equiaxed grains, nucleation and growth of equiaxed crystals, growth of columnar trunks, thermal-solutal buoyancy, sedimentation of equiaxed crystals, and columnar-to-equiaxed transition (CET). After the verification of model accuracy by a reported experiment results of a 55-ton steel ingot, this model has been used to study the GCS approach. The simulation results showed that the GCS approach has significant potential to alleviate the macrosegregation of the large steel ingot; e.g., for a 55-ton steel ingot, the variation range of segregation value decreased from 0.854 in the conventional casting case to 0.077 in the GCS case.

    更新日期:2018-06-28
  • Fabrication of graded surfacing layer for the repair of failed H13 mandrel using submerged arc welding technology
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-28
    Xinyue Wang, Jihui Wang, Zhiming Gao, Da-Hai Xia, Wenbin Hu
    更新日期:2018-06-28
  • Novel drill bit based on the step-control scheme for reducing the CFRP delamination
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-25
    Fei Su, Lei Zheng, Fujian Sun, Zhenhua Wang, Zhaohui Deng, Xinyi Qiu

    Exit damages such as burrs and delamination frequently occur during the CFRP drilling. Tool geometry strongly influences drilling performance. In this paper, the advantages of dagger drill and brad-spur drill are analyzed and a pulling-shearing effect is proposed. According to the pulling-shearing and the cut-push effects, a step-control scheme for reducing the CFRP delamination is proposed to design a novel drill bit. Theoretical and geometrical analyses of the drilling process and drilling tests have been carried out on CFRP composites. The results indicate that the pulling-shearing and the cut-push effects can be successfully implemented by the novel drill with V-shaped cutting edge. Due to the pulling-shearing and the cut-push effects, the fibbers along the hole edge can be cut off cleanly when the novel drill penetrates the last ply. Then the damages can be reduced significantly. The changing trend reflected from the tests is basic anastomotic with the step-control scheme. Compared with the dagger drill and the brad-spur drill, the novel drill has a good performance on reducing the thrust force as well as the damages. However, some defects such as the tearing are easy to generate when the feed per revolution is high.

    更新日期:2018-06-27
  • Improvement of S355G10+N steel weldability in water environment by Temper Bead Welding
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-25
    J. Tomków, D. Fydrych, G. Rogalski, J. Łabanowski

    The normalized S355G10 + N steel was chosen for testing, it is used in a variety of applications including the building of offshore structures, which may require repairs in water environment. The main aim of the work was to check susceptibility to cold cracking for fillet welds – Controlled Thermal Severity (CTS) tests and butt welds – Tekken tests and in next step evaluation effectiveness of Temper Bead Welding (TBW) application in wet welding conditions for joints welded by covered electrodes. The TBW effectiveness was experimentally verified as a method that may reduce the susceptibility to cold cracking in water environment. An application of the TBW technique caused the maximum hardness of the heat affected zone to fulfill the criterion of PN-EN ISO 15614-1 standard in level of 380HV10. It was determined that for S355G10 + N steel the beneficial range of the pitch value between beads is 75%-100%.

    更新日期:2018-06-27
  • Metallurgical and mechanical properties of underwater friction stir welds of Al7075 aluminum alloy
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-25
    R. Ruzbehani, A.H. Koukabi, H. Sabet, M. Paidar, O.O. Ojo
    更新日期:2018-06-27
  • Uphill filling system for a bar-like casting
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-26
    Lintao Zhang, Kenny W.Q. Low, Fawzi Belblidia, Johann Sienz

    Bar-like sand mould tilted angle reduced free surface fluctuations. The primary and secondary reflected wave heights decreased with the scaling of Re0.8 and Re0.55, respectively. These heights were reduced by 54% and 51% when θ was increased from 0° to 5°. A larger tilted angle was found to generate an air cavity in the cast, the size of which was observed to vary with Reynolds number (Re). An optimised range of tilted angle (2° to 3°) was proposed as a compromise to reduce the free surface fluctuations and maintain a perfect casting shape at the end of the filling stage.

    更新日期:2018-06-27
  • Fabrication of micro-textured surfaces using ball-end micromilling for wettability enhancement of Ti-6Al-4V
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-24
    Tej Pratap, Karali Patra

    The present work applied a high speed ball-end micromilling process for fabrication of micro-textured surfaces with different configurations such as parallel micro-dimple, staggered micro-dimple and micro grid, in order to enhance the wettability of Ti-6Al-4V. Advancing and receding angles of both untextured and micro-textured surfaces were measured using nano-scale ultrapure deionized water droplet. These angles were further utilized to predict Young's equilibrium contact angles to compare the wettability among different surfaces. Effects of different configurations, geometry variations (pitch, depth and diameter) and machining zone overlapping on equilibrium contact angle were investigated. Results indicate that all configurations of micro-textures enhance the wettability due to increase of roughness factor and area surface roughness. Further, machining zone overlapping influences the surface topography of micro-textures and plays a vital role in wettability enhancement. Among different configurations, micro grid texture with low pitch and high depth produces best wettability due to higher overlapping of the machining zone which produces unique pyramidal surface configuration. The pyramidal structure provides ease in droplet flow by providing larger interface area to occupy same drop volume that has also been confirmed by the drop shape analysis (drop radius and height). Further, stable contact angles were observed over time as chemical composition remained unchanged before and after micro-texture fabrication using ball-end micromilling.

    更新日期:2018-06-25
  • Self-adjusting EDM/ECM high speed drilling of film cooling holes
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-19
    Chaojiang Li, Bowei Zhang, Yong Li, Hao Tong, Songlin Ding, Zhiqiang Wang, Lei Zhao

    In order to reduce the thickness of recast layer and improve the surface quality of film cooling holes, a novel high speed self-adjusting electrical discharge machining (EDM)/ electrochemical machining (ECM) approach was developed by applying two independent flushing systems that were able to switch automatically in the machining process. The new flushing systems used different work-liquids and online dynamically changing discharge parameters. With the change in gap distance and the depth of the hole drilled, the dominant machining mechanism is graduated changed from EDM to electrochemical discharge machining (ECDM) and ECM. The formation mechanism of the recast layer on nickel alloy was investigated by comparing the surface characters of the bulk material and those of the recast layer using transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDS). The results from comparison experiments, in which different discharge parameters and sustaining time were applied, show that this new flushing systems would ensure much better flushing continuity of the working fluid and improve the discharge gap status. In addition, low voltage and current would benefit the ECM process and the removal of recast layer.

    更新日期:2018-06-22
  • Influence of pulse energy on machining characteristics in laser induced plasma micro-machining
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-20
    Xingsheng Wang, Chenbing Ma, Chengyu Li, Min Kang, Kornel Ehmann

    This work investigates the influence of pulse energy on machining characteristics using a 10 picosecond laser during Laser induced plasma micromachining (LIPMM) process. An axisymmetric model combining the effects of cascade, multiphoton ionization, and recombination and diffusion losses was developed to simulate the spatial and temporal plasma profiles at various pulse energies in distilled water. Thereafter, micro-channels with the corresponding pulse energies were created on stainless steel using LIPMM, and the plasma focusing process, depth and width of the machined channels were investigated. It was found that pulse energy had a negligible effect on the variation of the focusing distance during the LIPMM focusing process. The simulations and experimental geometric features showed similar qualitative trends with the increasing pulse energy at the plasma’s focal plane. However, the pulse energy had a significant influence on the machined depth, but a much lesser influence on the machined width.

    更新日期:2018-06-22
  • Process parameters optimization and mechanical properties of forming parts by direct laser fabrication of YCF101 alloy
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-20
    Tianbiao Yu, Yu Zhao, Jiayu Sun, Ying Chen, Wanrui Qu

    In this paper, the process parameters optimization and performance testing in direction laser fabrication were studied. Some critical parameters that affect the part properties and process stability were researched and discussed in detail. The results show that the parameters (power, scan speed, and powder feed rate) affect the track geometry, and then influence the quality of the cladding specimens. The z-axis increase quantity plays an essential role in fabricating stability. The defects caused by laser opening and closing can only weaken to a certain extent by uniformly distributing the position of laser power on. Crack and pore inside the forming, surface defects, and non-uniform microstructure must be avoided during the parameters optimize and process control, because these defects can cause the failure of the process. The surface morphology, crack and pore in cross-section, micro-hardness, wear resistance and strength were measured and analyzed to select or optimize the optimal process parameters. With optimizing process parameters, the stability of laser cladding process and mechanical properties of the part can be significantly improved.

    更新日期:2018-06-22
  • Design of the laser dieless drawing process of tubes from magnesium alloy using FEM model
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-21
    Andrij Milenin, Piotr Kustra, Tsuyoshi Furushima, P. Du, Jiří Němeček

    This paper is dedicated to a computer aided design of the laser dieless drawing process used for production of magnesium alloy tubes. Using laser as a heat source allows quick control of the heating and helps to regulate the temperature during sample deformation. One of important problems related to the development of this technology is a prediction of diameters of final product. The problem is caused by the character of the process in which elongation of tubes not predetermined by the tool but takes place due to pulling and free forming of the material. To design of technology a code based on finite element method (FEM) dedicated to the laser dieless drawing process and related method of design was developed. A numerical experiment was carried out by performing calculations with varied tension and heating parameters. The calculation results (in form of technological diagrams) allow determination of the process parameters needed for reaching specific final dimensions of the tube and for explanation of limitations of this process related to low ductility of the tubes. Examples of a fracture observed in experiments were related to a neck formation during elongation of the tubes. Two reasons for the neck formation were observed in modeling. The first was related to overheating of a tube and high gradient of temperatures along a centerline of the tube. The second corresponds to a high value of deformation and material hardening. To validation of the FEM model, measured values of temperature, load, tube diameter and fracture monitoring were used. Further, the model allowed to identify a window of permissible process parameters. It was shown that using out-of-the-window parameters leads to non-homogeneous distribution of the tube diameter or fracture. Based on the model results a set of selected design parameters from the processing window were used for a practical production of tubes from AZ31 alloy with a preset external diameter. Analyses of microstructure of initial tubes and tubes after the laser dieless drawing show that the process allows to obtain tubes with homogeneous distribution of grains and to improve initial inhomogeneity of the microstructure.

    更新日期:2018-06-22
  • Effect of bypass coupling on droplet transfer in twin-wire indirect arc welding
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-21
    Zhihao Zhang, Dongting Wu, Yong Zou

    The bypass coupling technique was employed on twin-wire indirect arc welding (TWIAW) to improve its penetration. In bypass coupling twin-wire indirect arc welding, the cathode current can be adjusted by changing the cathode-wire feeding speed. The melting efficiency increases with the cathode-wire current. At the same total current, the deposition and dilution rates of twin-wire indirect arc welding with bypass coupling is twice and a third those of conventional gas metal arc welding, respectively, which are good for low-heat input welding, such as surfacing. High-speed camera observation indicated that the cathode droplet transfer mode changes from free transfer to contact transfer with the increase of the cathode-wire current. The repulsion force of the anode droplet to the cathode wire increases with the increase of the cathode-wire current.

    更新日期:2018-06-22
  • Design and cracking susceptibility of additively manufactured Al-Cu-Mg alloys with tandem wires and pulsed arc
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-19
    Jianglong Gu, Jing Bai, Jialuo Ding, Stewart Williams, Limin Wang, Kun Liu
    更新日期:2018-06-20
  • Direct writing of metal film via sputtering of micromachined electrodes
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-19
    Ahmed M. Abdul-Wahed, Anindya L. Roy, Zhiming Xiao, Kenichi Takahata

    This paper presents the first micro-scale process for local deposition and direct writing of metal films through sputtering of a micromachined target electrode. The deposition process is achieved via a highly confined micro DC glow plasma generated between the electrode’s tip and the substrate at atmospheric pressure. Using cylindrical microelectrodes with diameters down to 40 µm, a micro glow plasma is stably established to show local deposition of the material on silicon substrates. The controlled manipulation of microplasma enables direct film writing of arbitrary patterns, for thicknesses ranging from the 100-nm order up to several microns variable with the discharge and scanning conditions. The process and drawn films are characterized for copper, copper-tungsten alloy, and nickel-200 alloy to reveal its potential applicability for a wide range of target materials. The spectroscopic analysis indicates the films’ elemental compositions to match well with those of the target materials. The direct drawing over non-planar substrates is also demonstrated to show the feasibility of 3D film printing using the developed process.

    更新日期:2018-06-20
  • sEffect of activated flux on penetration depth, microstructure and mechanical properties of Ti-6Al-4V TIG Welds
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-19
    K. Devendranath Ramkumar, Vinayak Varma, Madhukar Prasad, N. Deva Rajan, N. Siva Shanmugam
    更新日期:2018-06-19
  • Fabrication of metallic bipolar plate for proton exchange membrane fuel cells by using polymer powder medium based flexible forming
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-18
    Canbin Zhang, Jiang Ma, Xiong Liang, Feng Luo, Rong Cheng, Feng Gong

    Flexible forming process-polymer powder medium based flexible forming (PPFF) is presented in this research. The metallic bipolar plate (BPP) for a proton exchange membrane (PEM) fuel cell, with a micro-scale flow channel on its surface, is formed using rigid die forming and PPFF process, respectively. Pure copper C1100 (with a thickness of 0.1 mm), annealed at 450 °C for 1 h in vacuum condition, is selected as blank material. The forming experiments are carried out at room temperature in dry friction condition. By comparing the limit forming depth, fracture topography, section wall thickness distribution and surface forming quality of micro-scale flow channels between rigid die forming and PPFF process, it reveals that PPFF process could be developed as a feasible technique to fabricate the bipolar plates of PEM fuel cells. The PPFF process has the following advantages: greater forming depth, more uniform wall thickness distribution, and low cost of the die.

    更新日期:2018-06-19
  • Laser polishing of additive manufactured CoCr alloy components with complex surface geometry
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-18
    K.C. Yung, T.Y. Xiao, H.S. Choy, W.J. Wang, Z.X. Cai

    Laser polishing, capable of polishing selective nonplanar areas, is exploited to improve the surface roughness of additive manufactured metal components. It offers a highly repeatable, higher speed polishing process as well as low labor costs compared with traditional mechanical abrasive polishing. In spite of the fact that many studies can be found on laser polishing processes, few have reported that focus on metal components, manufactured additively by selective laser melting (SLM) technology, with geometrically different complex surfaces. This paper presents a novel method to reduce the surface roughness of Cobalt Chromium (CoCr) components with complex surface geometry by using a layered polishing method which can constantly adjust the defocusing distance of the laser along with the surface shape of the components. The optimized laser polishing parameters used were firstly obtained from the test results on planar surfaces of CoCr alloy samples and samples with complex surface geometry were then polished based on the laser parameters. Characterizations for the laser polished samples were conducted using optical profiling and scanning electron microscopy, showing that the surface roughness was reduced significantly in comparison with the as-received samples. A reduction of up to 93% in surface roughness was achieved. The mechanical hardness was also characterized by testing for Vickers hardness, which indicated the surface hardness of the laser polished samples was enhanced by 8%. Moreover, a simple and effective model was developed to illustrate the method of laser polishing on the complex surface geometry of additive manufactured CoCr alloy components. The analytical model is helpful in understanding and evaluating the underlying mechanisms of laser polishing.

    更新日期:2018-06-19
  • Numerical study of the effect of the oscillation frequency in buttonhole welding
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-15
    Won-Ik Cho, Villads Schultz, Peer Woizeschke

    A three-dimensional transient simulation was conducted with comprehensive models of the laser welding process with a combination of wire feeding and one-dimensional sinusoidal beam oscillation. Both a realistic filler wire feeding and simultaneous melting by oscillating laser beam were considered. The buttonhole formation, which was shown in the simulations, was affected by the shape of the molten filler wire, e.g. the length and angle. The buttonholes formed at higher oscillation frequencies and became clearer with increasing oscillation frequency. The so-called chopping frequency of the wire, found in the frequency domain through Fourier analysis, became more dominant with increasing oscillation frequency. The wire chopping process seems to affect the number of multiple reflections, the power absorption, and the buttonhole behavior.

    更新日期:2018-06-15
  • Influence of the Flyer Kinetics on Magnetic Pulse Welding of Tubes
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-15
    Joern Lueg-Althoff, Joerg Bellmann, Soeren Gies, Sebastian Schulze, A. Erman Tekkaya, Eckhard Beyer

    In this paper, the influence of different pulse generators with their characteristic discharge frequencies on the process parameters of magnetic pulse welding (MPW) of aluminum EN AW-6060 tubes on steel C45 cylinders is analyzed. Experimental, numerical, and analytical investigations focus on the radial impact velocity vi,r v i , r , the time dependent collision angle β(t) β t and the impact pressure pi p i . The influence of the temporal course of the magnetic pressure pm(t) p m t is discussed. It is shown that the minimum radial impact velocity required for welding with the same geometrical setup can be reduced significantly at low discharge frequencies compared to high ones. This is attributed to a different deformation behavior of the tubular flyer part and consequently more favorable collision angles. Geometric changes to the joining setup enable a targeted modification of β(t) β t and allow for a reduction of vi,r v i , r even at high-frequency systems. During the design of an MPW process, it is essential to consider the pulse characteristics. The advanced analysis methods presented in this paper contribute to the targeted establishment of favorable collision conditions for MPW, taking the distinctive features of the applied equipment into account.

    更新日期:2018-06-15
  • Study on the mechanism and key technique of ultrasonic vibration and magnetic field complex assisted WEDM-LS thick shape memory alloy workpiece
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-15
    Yan Wang, Qiang Wang, Zijun Ding, Duxing He, Wei Xiong, Siyu Chen, Zongxue Li

    In this study, a novel complex technique of ultrasonic vibration (USV) and magnetic field (MF) assisted WEDM-LS (USV-MF complex assisted WEDM-LS) is proposed to enhance the machine characteristics and then to investigate the effects of the main process parameters on the MRR and surface quality including surface roughness (SR) in machining thick shape memory alloy TiNi-01. The principle and schematic diagram of the USV-MF complex assisted WEDM-LS machining setup are analyzed firstly. The vibration state simulation analysis of wire electrode in USV assisted WEDM-LS and USV-MF complex assisted WEDM-LS under different machining parameters were carried out in the paper. Then the simulation analysis of distribution of the discharge points on wire electrode in USV-MF complex assisted WEDM-LS shows the distributions of discharging points become more uniform reducing the broken electrode wire caused by the concentration of the discharge point of the electrode wire. The establishment of process parameters (MRR and Ra) models is finished and verified by experiments. Comparison of the experimental results of only MF assisted, USV-MF complex assisted and conventional WEDM-LS reveals that when process parameters are selected in the appropriate range, USV-MF complex assisted can significantly improve the ratio of normal pulse discharge states, increase the machining efficiency and improve surface quality simultaneously, reducing Ra. The proposed USV-MF complex assisted WEDM-LS process presents enormous advantages and potential for applications in the practical machining and manufacturing field.

    更新日期:2018-06-15
  • Structural design and bonding strength evaluation of Al/epoxy resin joint via interpenetrating phase layer
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-15
    Asuka Suzuki, Yuta Arai, Naoki Takata, Makoto Kobashi
    更新日期:2018-06-15
  • Investigation of impeller design and flow structures in mechanical stirring of molten aluminum
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-15
    Takuya Yamamoto, Aire Suzuki, Sergey V. Komarov, Yasuo Ishiwata

    This study investigated the flow characteristics of aluminum melt agitated by differently shaped impellers. A typical impeller used in the aluminum industry has twisted blades. The present study examined the effect of twisting angle on the flow pattern through PIV experiments and numerical simulation using water model. The results revealed that the twisting angle affects the strength and direction of discharge flow. The strength of discharge flow became weaker with increasing the twisting angle while the flow direction was influenced by both the front blade surface of impeller and space interval between the adjacent blades. The structure of trailing vortices was found to be also varied depending on the impeller twisting angle.

    更新日期:2018-06-15
  • Effect of stirring rate on microstructure and properties of microporous mullite ceramics
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-14
    Wenfeng Li, Huishi Guo, Qingfei Huang, Ping Han, Yonggai Hou, Wenjun Zou
    更新日期:2018-06-14
  • Borosilicate nozzles manufactured by reproducible fire shaping
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-13
    B.N. Mu noz-Sánchez, M.G. Cabezas

    Borosilicate glass nozzles are used by researchers in many fields. They are mainly manufactured by two methods: (i) heating and drawing (or pulling), and (ii) fire shaping (or fire polishing). The latter produces the nozzle by heating one capillary end with a flame, and nozzles are typically much shorter than those obtained by pulling, what may be necessary for some applications. In this work, we built an experimental setup and we evaluated the performance and reproducibility of two different approaches to fire shaping. The first approach heats the tip of a horizontal capillary on the side of the flame. The resulting nozzles are very short and have very good symmetry at the neck. However, there is a small but significant misalignment angle between the nozzle neck and the capillary axes that may be unacceptable for its use in some experimental setups. The second fire shaping approach heats a vertical capillary at the top of the flame. The resulting nozzles show very good symmetry and a very low, and acceptable, misalignment angle between the nozzle neck and the capillary axes. As the phenomena involved in the process are complex, the diameter variability for the same experimental conditions (heating position and time) is high. Results show that using the nozzle shortening to control the neck diameter may be an alternative to produce nozzles of a desired size. However, the shape reproducibility is very good, as nozzles of the same diameter have the same shape, even when they have been produced in different conditions.

    更新日期:2018-06-14
  • A combined experimental and numerical examination of welding residual stresses
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-06
    Maarten Rikken, Richard Pijpers, Henk Slot, Johan Maljaars
    更新日期:2018-06-07
  • Experimental and FEM study of Ti-containing TWIP steel weldability
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-05
    V. García-García, I. Mejía, F. Reyes-Calderón
    更新日期:2018-06-06
  • Tube hydro-forging − a method to manufacture hollow component with varied cross-section perimeters
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2017-11-06
    Guan-Nan Chu, Gang Chen, Yan-Li Lin, Shi-Jian Yuan

    To overcome the problems in high pressure tube hydroforming (HPTH), such as too high forming pressure, thickness thinning and low productivity, a new forming technology was put forward, named as tube hydro-forging(THFG). In THFG, hollow components were formed by cross-section compression, overturned the traditional idea about conventional tube hydroforming in which the tube was expanded into the desired shape. Compared with HPTH, the role of the internal pressure was translated into the function of supporting and the tube sidewall was subjected to compression deformation throughout the process. These changes permit the THFG process with lots of advantages, such as low required internal pressure, avoiding thickness thinning or crack defect, no need for axial feeding, and so on. In this study, an analytical model based on a rigid, perfectly plastic material model was developed to investigate the possibility and the main influencing factors of the THFG. The analytical solution developed was compared with the experimental results. Experimental results validate that the tube can be formed into the desired shape by cross-section compression under a certain internal pressure supporting. Through the analytical model combining FEM simulation, the critical support pressure was given. The critical support pressure increases gradually as the deformation going on and has great dependence on the materials properties, however has no dependence on the tube thickness. It is also validated that the required pressure in the THFG is much lower than that needed in the traditional tube hydroforming.

    更新日期:2018-06-03
  • Numerical Simulation of the Formation of Hourglass Welds during Laser Welding
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2017-12-14
    Bon Seung Koo, Pornsak Thasanaraphan, Herman F. Nied

    The purpose of this study is to understand the effect of laser welding parameters on the formation of hourglass shaped welds in low carbon steel. Transient laser welding is modeled in ANSYS to simulate the coupled heat-transfer/fluid-flow behavior that produces corresponding hourglass shaped melt pool geometry. Characteristics of the hourglass mode are full narrow penetration and wide surface of molten pool. Recoil pressure induced by rapid metal vaporization strikes the melt pool to form a deep and narrow key hole. Simultaneously, surface tension minimizing its surface free energy primarily acts to widen the melt pool. Comparison of the weld geometries show that welding parameters associated with changes in the melt fluid dynamics are of great importance in the formation of the hourglass shaped melt pool during laser welding.

    更新日期:2018-06-03
  • Effects of tool geometry on friction stir welding of AA6061 to TRIP steel
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-02
    Sheng Zhao, Jun Ni, Guoqing Wang, Yuhan Wang, Qingzhen Bi, Yanhua Zhao, Xun Liu

    With the appropriate process parameters, both large and small tools can produce sound joints with tensile strengths (TS) 80% higher than those fabricated with Al base metal. As a large tool moves into the steel, it can peel off and embed steel fragments into the Al matrix, causing critical defects around the embedded fragments. Using small tools and lower rotational speed (RS) will significantly reduce the welding heat, resulting in an unwelded Al/steel interface at the bottom of the weld. Since the tool size and process parameters determine the amount of generated heat, they also determine the thickness of the intermetallic compound (IMC) layer that forms at the Al/steel interface. The welding forces in the weld plane are primarily affected by the tool offset.

    更新日期:2018-06-02
  • Reaction-assisted diffusion bonding of Ti6Al4V alloys with Ti/Ni nanostructured multilayers
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-06-01
    Ying Ma, Hong Li, Linpai Yang, Anming Hu

    The Ti and Ni alternating layers were deposited onto the base materials by magnetron sputtering. Ti/Ni multilayers with different stoichiometries of Ti and Ni were investigated. The joining processes were performed at 800 °C for 60 min under pressure of 5-15 MPa. The microstructures of the interface and the mechanical performances were assessed. Reliable joints can be obtained successfully with all three multilayers with different Ti/Ni ratios. A higher pressure and higher Ni content in the multilayers contributed to a higher shear strength. The highest shear strength of 160 MPa was achieved for the joint under 15 MPa using Ti/Ni multilayers with the stoichiometry ratio of Ti/Ni of 1:3, the hardness of the joint was 6.9 GPa. The intermediate phases appeared to be combinations of hard intermetallics frequently occurred in the Ti-Ni binary system.

    更新日期:2018-06-02
  • Influence of the electric pulse on springback during stretch U-bending of Ti6Al4V titanium alloy sheets
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-31
    Yixi Zhao, Linfa Peng, Xinmin Lai

    Electrically assisted stretch U-bending tests have been conducted in this research to analyze the influence of electrical parameter duty cycle cycle on the springback of Ti6Al4V sheets. It is found 30% duty cycle brings about 50% increase in residual height of split angle of U-bending specimen compared with that obtained in room temperature. Meanwhile, 30% duty cycle causes additional 13% effect on springback relief than that treated in 10% duty cycle at the same temperature, which indicates elevated temperature alone is insufficient to account for overall decrease on springback during the treatment of electric current. Subsequent electrically assisted stress relaxation test under the same condition gives further explanation on the decrease of springback in short period numerically. Microstructure evolution observed in both tests illustrates grain growth along with dislocation motion activated by thermal expansion results in stress softening in the duty cycle less than 20%. As for the duty cycle of 30%, the precipitated αʹ phase reveals that the accelerated phase transformation α→β can provide additional stress drop and such observation is also certified by hardness investigation conducted in this research.

    更新日期:2018-05-31
  • Microstructure and Mechanical Properties of Underwater Hyperbaric FCA-Welded Duplex Stainless Steel Joints
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-31
    Yu Hu, Yonghua Shi, Kun Sun, Xiaoqin Shen, Zhongmin Wang
    更新日期:2018-05-31
  • On productivity of laser additive manufacturing
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-31
    Andrey V. Gusarov, Sergey N. Grigoriev, Marina A. Volosova, Yuriy A. Melnik, Alexander Laskin, Dmitriy V. Kotoban, Anna A. Okunkova
    更新日期:2018-05-31
  • 更新日期:2018-05-31
  • Influence of dimple and spot-texturing of HSS cutting tool on machining of Ti-6Al-4V
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-30
    Mayur S. Sawant, N.K. Jain, I.A. Palani
    更新日期:2018-05-31
  • Interfacial evolution of explosively welded titanium/steel joint under subsequent EBW process
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-30
    Ting Wang, Feng Zhang, Xiaopeng Li, Siyuan Jiang, Jicai Feng

    Electron beam welding of titanium alloy to mild steel with a transition joint prepared by explosively welding method was carried out. The interfacial structure of explosive weld and tensile strength of the joint were affected significantly by the distance between electron beam weld and explosive weld. When the electron beam weld was 1.5 mm away from the explosive weld, the explosive interface layer was liquefied during electron beam welding process, which was consisted of Fess, Fe + Fe2Ti eutectic, FeTi + Fe2Ti peritectic and Ti + Fe2Ti eutectic from the Fe side to the Ti side. When this distance increased to more than 3 mm, the thickness of interfacial intermetallic compounds in explosive weld decreased sharply from 40 µm to lower than 3 µm. The interface layer kept in solid state and diffusion of Ti and Fe atoms occurred across the interface. When the electron beam weld was located 6 mm away from the explosive weld, the maximum tensile strength of 418 MPa was obtained. In this case, the residual stress across the explosive interface induced by electron beam welding reached to the lowest value in this experiment.

    更新日期:2018-05-31
  • Feature extraction and physical interpretation of melt pressure during injection molding process
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-30
    Xundao Zhou, Yun Zhang, Ting Mao, Yufei Ruan, Huang Gao, Huamin Zhou

    Melt pressure is crucial in injection molding. A variety of pressure sensors have been installed in injection molding machines and molds to collect melt-pressure information. Many methods have been developed to extract the features of melt pressure. However, challenges exist for these feature extraction methods because they are, inevitably, extremely dependent on manual operation. In this study, an unsupervised feature extraction method using a sparse autoencoder is proposed to extract the features of melt pressure during injection molding. An injection molding model was applied to reinterpret the network structure of a sparse autoencoder to better understand the network structure. The feature curve, which is defined as the curve of weights between input and hidden units, was proved to be a significant indicator to measure how melt compression causes variations in injection pressure. Over 10,000 shots were conducted to verify the proposed feature extraction method. The experimental and simulation results show that the feature curve effectively extracts switching points (gate and velocity-pressure switchover), important indicators (viscosity index, holding pressure, and peak pressure) in the injection molding process and shows how the geometric features of a part affect the melt flow.

    更新日期:2018-05-31
  • Yb: YAG laser welding of dual phase steel to aluminium alloy
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-29
    R. Indhu, S. Soundarapandian, L. Vijayaraghavan

    In this work, laser welding of dual phase steel (DP 600) to aluminium alloy (AA 6061) was studied both experimentally and by computational modeling. Three different laser energy densities (640 J/mm2, 850 J/mm2 and 1250 J/mm2) were chosen to study the effect of heat input on microstructural changes and strength of the joint. It was inferred from the results that the laser energy density had a direct influence on the formation of intermetallic phases such as Fe2Al5 and FeAl3. At relatively high laser energy density (1250 J/mm2), thick intermetallic layer and crack propagations were observed at the interface of the weld, which deteriorated the strength of joint. Whereas, maintaining the laser energy density at 850 J/mm2 enhanced the weld quality by lowering the intermetallic thickness in the range of 6 – 10 µm and defects such as cracks were also lowest at the weld interface. The formation of the cracks in the interfacial region was largely influenced by the hard and brittle intermetallics, which was evident from the microhardness results. The microhardness value along the interface exhibited a maximum of 836 H V at 1250 J/mm2, which was much higher than the base metal hardness (AA 6061 – 65 H V, DP 600 - 255 H V). A two-dimensional computational model was used to predict the temperature histories at different laser energy densities during welding. The results of the computational model (penetration depth and material ablation) correlated well with the experimental results.

    更新日期:2018-05-30
  • Micro Friction Stir Welding of Multilayer Aluminum Alloy Sheets
    J. Mater. Process. Tech. (IF 3.647) Pub Date : 2018-05-29
    Kaifeng Wang, Haris Khan, Zhiyi Li, Sinuo Lyu, Jingjing Li
    更新日期:2018-05-30
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
化学 • 材料 期刊列表