Effect of Process Parameters on Microstructure and Properties of Fe-Cr-Mo-B Flux Cored Wire Argon arc welding Cladding Layer

The Fe-Cr-Mo-B flux cored wire cladding layers was fabricated on the Q235 steel substrate by argon arc welding. The effects of cladding current （120, 180, 240 A） and cladding pass （one-pass, two-pass, three-pass） on the morphology, dilution rate, phase composition, microstructure, hardness and wear resistance of the cladding layer were studied. The optimal argon arc welding parameters were determined. The results show that the coating layer had a smooth surface under different process parameters, and there were no defects such as holes and cracks at the interface with the substrate. The coating layer was composed of phases such as Mo₂FeB₂, （Mo, Fe, Cr）₃B₂, α-Fe, M₂₃（C, B）₆, etc. With the increase of cladding current, the dilution rate increased, and the number of Mo₂FeB₂ hard phases first increased and then decreased, changing from large-volume irregular shapes to small-volume regular square shapes. The M₂₃（C, B）₆ hard phase changed from continuous network to intermittent network or daisy-shaped. The hardness first increased and then decreased, and the wear quality loss first decreased and then increased. With the increase of cladding pass, the dilution rate decreased, the number of Mo₂FeB₂ hard phases increased, changing from block-like to rod-like, and the M₂₃（C, B）₆ changed from intermittent network to continuous network. The hardness increased, and the wear quality loss decreased. The optimal argon arc welding parameters were a welding current of 180 A and cladding pass of three. Under these conditions, the cladding layer had a smooth surface, a moderate dilution rate （19.4%）, the maximum hardness （1 144.2 HV）, the minimum wear quality loss （4.7 mg）, and the best wear resistance.