Processing properties of gradient material fabricated by double wire arc additive manufacturing

Double wire welding arc additive manufacturing（ Double-wire WAAM） technology is a kind of new technology that can fabricate materials by using arc heat to melt two different welding wires. MG70 S-6 and QD266 wires were used in the experiment. The gradient materials with different properties in vertical direction were fabricated by adjusting the feeding speed of two wires,and then microstructures and mechanical properties of additive material were analyzed. The result showed that the forming effect could be improved by adjusting the feeding speed of two wires. In addition,microstructures of the optimized additive material mainly consisted of cellular grains and dendritic grains and its growth direction changed along the height direction. The components of the microstructure were ferrite and a small amount of pearlite,and few bainite appeared on top. Finally,with deposition ratio of wear-resisting welding wire layer by layer increasing,more quenched microstructures formed and its hardness values increased layer by layer. The hardness of top layer reached 451. 9 HV.