Microstructure and texture characterization in friction stir lap welded TIMETAL 21S

International audienceThe evolution of microstructure and texture during friction stir lap welding (FSLW) of TIMETAL 21S (β-type Ti-15Mo-3Nb-3Al-0.2Si, wt.%) sheets were investigated through electron backscatter diffraction (EBSD). Excellent grain refinement is obtained through stir zone (SZ) thickness (1.2-1.8 µm). The microstructure of the thermomechanically affected zone (TMAZ) is characterized by elongated deformed grains surrounded by small recrystallized grains indicating the occurrence of discontinuous dynamic recrystallization (DDRX). The microstructure of heat affected zone (HAZ) is quite similar to the base metal (BM). The texture transformed from weak rolling-recrystallization texture in BM and HAZ to a typical shear texture with the domination of D1 or D2 components in the SZ and TMAZ area. A net shear texture gradient is formed across the SZ thickness which is connected with the heterogeneity of deformation. It is believed that the concomitant occurrence of grain size, dislocation and texture strengthening is responsible for the mechanical property distribution in different parts of FSLW joint

Development of the PC-GMAW welding technology for TMCP steel in accordance with welding thermal cycle, welding technique, structure, and properties of welded joints

In this paper, the effect of the welding thermal cycle (WTC) on the structure and properties of the S460M steel heat affected zone (HAZ) metal has been studied. In particular, the changes in the mechanical properties vs the HAZ metal cooling rate in the 600÷500 °C temperature range was studied for S460M model samples, heat-treated in accordance with WTCs. The results from the experimental data refers to the static strength, ductility, and impact toughness values at the level of the base metal, as well as to structural changes in the seam. The weld metal and HAZ welded joints of S460M steel, made by pulsed arc welding, have shown adequately high resistance to brittle fracture, and at 20% greater strength. Thus, based on the obtained results, it is recommended to apply pulse-current gas metal welding of the thermo-mechanical cold processingsteel instead of conventional welding.11Nothe

Optimization of the pulsed arc welding parameters for wire arc additive manufacturing in austenitic steel applications

© 2022, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.Industrial development continues to present challenges for manufacturers. One of them is additive manufacturing (AM) with metallic materials. One promising solution is wire arc additive manufacturing (WAAM). Currently, WAAM is a more promising tool for developers, firstly due to the simplicity of its realization and secondly for its cost-effectiveness. Building materials are represented by welding wires, so the deposition rate is favorable. A pulse power source is commonly used in this scheme of realization. Much less attention has been paid to the optimization of the power source working regime, i.e., welding mode. Indeed, the power determines the whole process of WAAM. Therefore, in the present work, an attempt has been made to perform a scientifically based design for the optimal welding mode. The austenitic welding wire was chosen to eliminate phase-transition effects in the solid state of the deposited metal. As a result of the investigation, the advantages of the designed welding mode for WAAM application are made clear. It was shown that the predominant effect on penetration depth possesses pulse current and its input is 49%, while other parameters, i.e., pause current, pulse on time, and frequency, have a less valuable impact. The Taguchi optimization algorithm allowed the development of a specific welding mode for providing better formation of the welds, more grain fined microstructure, and thus improved properties of the modeled wall. Successful efforts have been made to optimize welding modes for WAAM applications. This study is important for manufacturers as well as engineers and scientists.11Nsciescopu

Non-equimolar Cantor high entropy alloy fabrication using metal powder cored wire arc additive manufacturing

In the current contribution, the wire arc additive manufacturing of non-equimolar Co-Cr-Fe-Mn-Ni high-entropy alloy using gas metal arc welding (GMAW) with metal powder-cored wire (MPCW) is proposed. The powder's filler of designed wire feedstock contains Co-Cr-Mn-Ni components in equal atomic amounts relative to each other with Fe metal stripe as a shield. The proposed method provides the possibility to build bulk high-entropy alloy samples with the desired characteristics. The current work approach is superior in a number of indicators to such alternative methods of obtaining bulk HEAs as melting in vacuum, plasma arc melting, selective laser melting, or electron beam melting