Welding Dissimilar Alloys of CoCrFeMnNi High-Entropy Alloy and 304 Stainless Steel Using Gas Tungsten Arc Welding

The weldability of a CoCrFeMnNi high-entropy alloy (HEA) and 304 stainless steel (304 SS) was investigated to determine their potential for application in the nuclear and aerospace fields. Autogenous dissimilar butt welding was performed using gas tungsten arc welding, and the resulting joint was complete with no defects. SEM/XRD analysis showed that the fusion zone microstructure consisted of a single fcc phase without the formation of intermetallic compounds. However, there is an unmixed zone near the 304 SS side, which can be attributed to subcooling of the composition caused by the lower liquidus temperature of the bulk weld metal than that of the base metal. Furthermore, a small increase in the hardness of the fusion zone compared with that of the CoCrFeMnNi HEA was observed. These results can be attributed to the grain refinement of the weld and the strengthening effect owing to the incorporation of carbon. The joints exhibited a tensile strength of similar to 465 MPa and ductility of 38%, where the strength was comparable to that of the CoCrFeMnNi HEA, and a joint fracture was found at the side of the CoCrFeMnNi HEA. This indicates that the weldments are suitable for room temperature structural applications.