This study investigates the dynamic temperature behaviour around a melt pool in metal-based powder bed fusion using a laser beam (PBF-LB/M) to clarify the influence of the associated morphological changes of the metal powder experimentally. Gas-atomized 18Ni (300-grade) maraging steel powders were processed by PBF-LB/M while high-speed photography with a two-colour radiometric thermal imaging system

Cold spraying (CS) is one of the most recently used additive manufacturing (AM) processes that allow forming large 3D objects efficiently without severe thermal effects. However, due to some limitations of the CSAM process, it is difficult to achieve the desired geometry with high precision. As a potential solution to this issue, CSAM process coupled machining, that is, hybrid addition and subtraction

Sheared edge cracking phenomenon is a key problem limiting the application of high-strength steels. Therefore, it is very necessary to explore the cracking causes to promote the solution of this problem. In this paper, the damage in the sheared edge of DP780 steel is investigated by microstructure characterization, micro/macro mechanical property evaluation, and numerical simulation. Microvoids, microcracks

Challenges in developing novel alloys, specifically for use in laser powder bed fusion, may be overcome by in situ alloying of elemental powders during laser melting. This process could expedite prototyping of various alloy compositions and alleviate the restrictions and cost barriers of creating custom made alloy powder. In this research, the efficacy of in situ alloying is studied with respect to

Laser texturing of cutting tool is a promising surface modification method for improving the machinability and form accuracy of the machined workpieces in the precision machining of difficult-to-machine material. However, the blocking of micro-textures by the cutting chips, i.e., derivative cutting, usually occurs because of the severe friction between the tool and chip, which can hinder the effectiveness

Wire - arc additive manufacture (WAAM) is suitable for Inconel 718 components due to its high deposition efficiency. However, large columnar dendrites decrease the mechanical properties and can cause severe mechanical anisotropy. Cold rolling and warm rolling through flame heating have been investigated to analyze their effects on microstructure and tensile properties compared to as-deposited WAAM

High-efficient welding technology with rotating arc assisted by laser under shielding gases with different He content was investigated for the application of 9% Ni steel in LNG storage. High-speed image and electrical signal acquisition were adopted to investigate arc stability and metal transfer behavior during hybrid laser arc welding. The results indicated that with increasing content of He, the

Ultrasonic vibration has been applied in the incremental sheet forming process and shows the potential to reduce the forming force and increase the formability, but the constitutive behavior and deformation behaviors of material under the high-frequency vibration are still not completely explained. In the present work, a hybrid constitutive model which combines the phenomenological, thermal activation

To further understand metadynamic recrystallization, various measurement techniques were performed with two materials: SUS316 austenitic steel and A5083 aluminum alloy, which were selected to represent materials with low to medium and high stacking fault energies, respectively. Microstructure characterization using electron backscatter diffraction with the grain orientation spread approach was utilized

Conventionally, the main goal of process optimization in selective laser melting is to achieve the highest relative density. However, for Inconel 718, this study has demonstrated that the highest relative density does not correspond to the best mechanical properties. Moreover, similar relative densities can result in significant differences in mechanical properties. This phenomenon arises from the

In this work, experimental and numerical approaches are performed to explore the influence of scanning strategies on the microstructure, crystallographic texture as well as the mechanical behavior of Ti-6Al-4V alloy manufactured by Laser Powder Bed Fusion (LPBF). In-situ monitored data of the energy intensity show that different scanning strategies result in variations of energy intensity distribution

Plastic flow of hollow cylinders under combining axial compression with torsion was examined in upsetting and in lateral extrusion. The hollow cylinders with initial height/outer diameter of 0.5–2.5 and initial inner/outer diameter of 0.3–0.9 were compressed/extruded and simultaneously twisted with respect to the axisymmetric forging axis in one-way or cyclic alternating. Due to superposition of torsional

The continuous galvanizing process (CGP) under high dew point temperature has been recognized as a viable technique for improving the coating quality of advanced high-strength steels (AHSS). However, the effect of this surface modification technique on resistance spot welding (RSW) process is not clear. The aim of this study is to investigate the role of different surface conditions and initial microstructures

Compound forging is a promising approach for the manufacturing of bimetal parts. However, reliable material interlock is difficult to be obtained in compound forged bimetal parts due to the asynchronous material flow. To overcome this problem, in this work, the previous proposed thixotropic-core compound forging (TCF1) method was applied in the precision forming of a bimetal cylinder spur gear. This

Low-frequency vibration-assisted metal plastic forming is a novel promising technology, adopting a high-pressure-capability device compared to the ultrasonic vibration system. This work focuses on the low-frequency vibration assisted upsetting (LFVAU) process of Ti45Nb, to reduce the flow stress and crack initialization in the cold deformation of titanium alloy. The results show that the flow stress

The content of intermetallic compounds (IMCs) in friction stir lap welded (FSLW) dissimilar joints of Mg and Al alloys could be reduced by the addition of interlayer metal to improve the mechanical properties of the joints, while the underlying mechanism is still unclear. In this study, Cu and Ni powders are added as the interlayer materials into the FSLW joints of AZ31 Mg alloy and Al–Zn–Cu–Mg alloy

Electron beam welding of Nb/GH3128 dissimilar alloys was conducted in this research. Microstructure characterization and finite element simulation were utilized to uncover the cracking mechanism of the joint. The obtained results revealed that a brittle reaction layer, composed of Ni6Nb7/Laves phase beside the Nb substrate, was a critical cracking factor triggering the cracking along the reaction layer

More and more experiments have shown that particle-reinforced metal matrix composites (PMMC) exhibit obvious size effects. The aclassic plasticity theory does not contain internal length scale and cannot explain this size effect. In this paper, based on the Taylor relationship, the concept of "geometrically necessary dislocations" and the mechanism of dislocation multiplication, slippage and extinguishing

In this paper, a novel method of electromagnetic partitioning forming with elastic cushion is proposed. Its main principle is based on that the parts vibrate at high speed under the action of the electromagnetic force and the rebound force of the elastic pad. The state of the elastic parts inside the workpiece is changed into plastic state, and then, springback is eliminated through vibration. A common

Electrohydraulic sheet forming is a high-velocity manufacturing process, which utilizes a pressure pulse induced by underwater electrical discharge to plastically shape metals. It has attracted wide interest for its potential to shape metal materials with poor formability. Such advantages can be exploited by combining this process with the conventional stamping process or by using it solely. In both

The present study addresses a thin-walled investment casting methodology of AZ91D-1 wt% CaO magnesium alloy for stent manufacturing. Additive manufacturing and Yttria-based coating were applied to optimize the process. An induction melting furnace assisted by vacuum was used to cast magnesium alloy stents with 0.4 mm and 0.8 mm wall thickness under an argon-protective atmosphere. According to the proposed

Heat straightening of welding-induced distortion, which has mostly relied on shipyard experience, was systemized for computation. The process of geometrically flattening a curved surface with fixed edges was formulated step by step based on thermal forming mechanisms. The proposed algorithm divides the measured surface into patches, connects them with virtual springs, and optimally arranges the patches

The traditional metal smith has the remarkable capability to form a variety of part shapes from flat sheets using only a few universal tools. Such versatility is increasingly appealing to manufacturers who now seek to diversify part catalogues and reduce tooling costs. Despite this utility, the laborious, manual nature of these traditional techniques preclude them from meeting modern-day, high-volume

The high optical reflectance of Cu at near-infrared wavelengths narrows the process window to fabricate Cu parts by laser powder bed fusion (LPBF). Coating powders with optically absorptive materials has been investigated to improve processability and enhance part properties. However, given the intense heat localization and thin coating layers relative to the powder, the mechanisms of thin film coating

The performance of the selective laser melting (SLM) parts was critically affected by the surface quality and internal defects that are closely related to process parameters. An in-depth understanding of the relationship between the formation and evolution of surface and internal defects and process parameters is needed to achieve defect-free and high-performance SLM parts. In this study, the influencing

Electrical discharge-assisted milling (EDAM) is an efficient machining process for titanium alloys according to previous studies. However, a complete understanding of the surface integrity of titanium alloy machined with EDAM is not yet sufficient. Therefore, in this paper, surface defects such as chip layer adhesion, debris, feed marks, and burrs were investigated and identified. Among them, the adhesion

Laser texturing of zirconia-alumina ceramics is a promising surface modification method for many applications, such as enhancing osseointegration of alumina toughened zirconia (ATZ) dental implants or improving friction behavior of zirconia toughened alumina (ZTA) hip replacement bearing components. The common problems in laser texturing of ATZ/ZTA ceramics are thermal cracking, low material removal

To broaden the applications of Hastelloy X superalloy manufactured by laser directed energy deposition (DED-L), ultrasonic micro-forge treatment (UMT) assisted DED-L was developed to print Hastelloy X components with improved mechanical properties. In this study, the residual stress and mechanical properties of the non-UMT- and UMT-treated samples are compared, and the microstructure was examined to

In near-isothermal local loading forming (NLLF) of large-size Ti-alloy parts, one of the challenging issues is to achieve accurately prediction of complex microstructural development. In this work, a thermo-mechanical-microstructural FE model considering complicated phase transformation and morphology transformation of the whole forming process is developed and experimentally verified. The simulated

An alternating magnetic field was designed to increase weld depth of laser-MIG hybrid welded 316 stainless steel joint. The influencing mechanism of alternating magnetic field on improving penetration ability of hybrid heat source of laser-MIG hybrid welding was revealed. The results suggested that the difference of weld depth under different magnetic flux density was attributed to the change of characteristics

The melting process during laser powder bed fusion (LPBF) is accompanied by complex physical phenomena, which can rarely be scaled with acceptable effort to utilize the melting process in component design to obtain tailored mechanical properties with adequate machine productivity. A constitutive law relating melt pool geometry to the process parameters thereby plays an essential role in practically

The application of additively manufactured high strength aluminium base alloys is, among others limited due to either a lack in processability or economic feasibility with the alloys currently available. Within this work, the mechanical properties of additively manufactured eutectic Al-Ni alloys are investigated for the first time. With an average ultimate tensile strength of 545 MPa at an elongation