Microstructure and properties of 316L stainless steel parts fabricated by double wire CMT + P additive manufacturing

The cold metal transition plus pulsed (CMT + P) double wire double arc process was used to add 60 layers of 316L stainless steel deposits, and the effects of different deposition current on the microstructure and mechanical properties of the deposits are comparatively analysed. With the increase of the deposition current, the forming width increases gradually, the height increases first and then decreases, and the forming surface is good without obvious defects, which is a feasible double wire double arc additive manufacturing process. Metallographic analysis shows that the microstructure consists of γ-Fe and δ-ferrites, and the bottom up was dominated by continuously growing columnar dendrites. When the current changes, there are obvious changes in the size and shape of the ferrite, and the ferrite is negatively correlated with the deposition current; The mechanical property analysis shows that the overall performance was optimal when the deposition current is 100 A. The average impact absorption work is 31.15 ± 0.85 J, the overall tensile strength reaches 521.9 ± 5.18 MPa, the overall yield strength reaches 214.45 ± 5.87 MPa, and the elongation at break reaches 47.6 ± 2.1 %, and the fracture is a toughness fracture; The highest average hardness of 209.1HV0.3 is achieved at a deposition current of 83A, but the hardness is more uniform at a deposition current of 100 A.