Effects of Dissolution Amount of Base Metal Fe on Microstructure and Properties of Welding Seam with CoCrFeMnNi High Entropy Alloy Filler

High entropy alloy is used as filler, transition layer and surfacing material to improve the microstructure and properties of weld or cladding layer because of its excellent microstructure and properties. 20 steel plate was welded by CoCrFeMnNi manual argon arc welding with high entropy alloy welding wire. By changing the groove type and angle, the dissolution amount of base metal Fe was controlled, and its phase, microstructure and properties were explored. The results show that the weld grain morphology is coarse columnar crystal morphology. When the Fe content is less than 35.7%, the phase structure of the weld keeps the FCC face-centered cubic structure. With the further increase of Fe dissolution, the phase structure of the weld changes from FCC to FCC+BCC (body-centered cube) and BCC. The performance test of the weld shows that the hardness and toughness of the weld with a single FCC structure remain basically unchanged, but with the appearance of BCC in the weld, the hardness of the weld increases and the toughness decreases. Compared with the analysis of CoCrFeMnNi, it is found that the hardness mainly depends on its phase structure, while the toughness is related to the grain shape and size of the structure besides the phase structure.