The effect of post weld heat treatment (PWHT) temperature on laser beam welds in high-entropy alloys (HEAs) using a cold-rolled cantor system (CoCrFeMnNi) was investigated. Laser welding of low heat input was applied to reduce thermal distortion. The cold-rolled HEA welds indicated larger grain size and inferior tensile/hardness properties as compared to the base metal (BM). By applying PWHT, the welds showed superior hardness to the BM with no variation in the face-centred cubic phase and a decrease in the size and fraction of CrMn oxide inclusions. As the PWHT temperature increased (800–1000°C), the variation in the grain size decreased between the weld metal and heat-affected zone, thus resulting in approximately the same tensile strength and elongation of the transverse welds as compared to the BM.

This study investigates the effects of welding velocity on weldability of dissimilar cast/rolled high-entropy alloys and the applicability of cryogenic temperatures. Cast HEA side of dissimilar weld metal (WM) indicates a larger dendrite packet and dendrite arm spacing (DAS) than rolled WM. Size difference is associated with epitaxial growth from each base metal (BM). As the welding velocity increases (6–10 m min⁻¹), shrinkage voids and DASs decreases. Dissimilar welds show tensile properties comparable to cast BM, where there are tensile fractures of dissimilar welds. Cryogenic properties of dissimilar welds are superior to those of room-temperature welds, because deformation twins and dislocation densities are significantly formed at 77 K. Therefore, dissimilar welds can be applied to the production of cryogenic products.

This study investigates the gas tungsten arc (GTA) weldability of austenitic stainless steel (STS) 304 using STS 308L and high-entropy alloy (HEA) fillers and its applicability in cryogenic environments. Because the grain sizes of both weld metals (WMs) were coarser than those of base metal (BM), and all WMs have a few phase transformations, the tensile properties of all WMs were worse than that of the BM. However, the tensile strength and elongation of HEA weld at 77 K increased simultaneously than those at 298 K, whereas the elongation of STS 308L weld decreased at 77 K than that at 298 K. All WMs exhibited excellent tensile strengths at 77 K, attributable to martensite transformations and deformation twins, respectively.

The effect of martensite–austenite (M–A) constituents and simulated microstructure on low-temperature toughness was investigated in YS 500 MPa grade structural steel welds. The specimens were fabricated using a direct quenching and tempering process. After simulated weld thermal cycles, the coarse-grained heat-affected zone (CGHAZ) and intercritically reheated coarse-grained heat-affected zone (IRCGHAZ) were produced using a Gleeble tester and real welded joint to support the simulation results. The largest low-temperature toughness was observed in the fine-grained heat-affected zone (FGHAZ) owing to the fine-ferrite microstructure. However, the toughness decreased in the IRCGHAZ because of the slender morphology of the M–A constituents that formed primarily along the prior austenite grain boundaries in the IRCGHAZ.