Research on microstructure and mechanical properties of 316 stainless steel fabricated by arc additive manufacturing in different paths

Using 316 stainless steel as the material, the differences in the microstructure and mechanical properties of additive manufacturing specimens by three paths of parallel reciprocating, cross shaped and insert stacking were discussed. The results indicated that there were obvious differences in the microstructure in middle areas of the three specimens. The dendrites of the parallel reciprocating specimen were coarse and developed, and the growth direction was uniform. The cross shaped specimen, with disordered dendrites, not only had many dendrite growth directions but also had a large interlayer transition zone. The secondary dendrite of the insert stacking specimen was not developed and the microstructure was fine. In terms of microhardness, the Vickers hardness of the three specimens decreased first and then increased from the bottom to the top. The microhardness of the parallel reciprocating specimens was the largest. In terms of tensile properties, the longitudinal tensile strength of the parallel reciprocating specimen was the highest, and this path could be used when subjected to longitudinal force. Insert stacking specimen had the highest transverse tensile strength, and this path could be used when subjected to transverse forces. The mechanical properties of the cross shaped specimen showed isotropy, which was beneficial to be used in the case of multi-directional stress and high plastic requirements.