Comparison Study of Low-Heat-Input Wire Arc-Fabricated Nickel-Based Alloy by Cold Metal Transfer and Plasma Arc

A comparative study of Inconel 625 surfacing on low-carbon steel produced by cold metal transfer (CMT) welding and plasma arc welding (PAW) was carried out. CMT surfacing weld with large reinforcement was produced as compared with PAW, and PAW generated smaller contact angle and larger dilution rate. Regression analysis based on weld forming features indicated that the main factor affecting dilution rate and weld width was welding speed, and dilution ratio decreased with increasing welding speed. Good surfacing forming was produced by plasma arc welding, and CMT surfacing process was more suitable for wire arc deposition. The characteristic of fast solidification and epitaxial growth was presented on the microstructure of surfacing layer of CMT and PAW, and that mainly consisted of γ-Ni columnar dendrites. Shear strength of PAW surfacing layer was 53% higher than that of CMT. Fracture morphology of CMT shear specimens was quasi-cleavage brittle fracture and that of PAW showed ductile fracture characteristics.