Effect of Current Mode on Anisotropy of 316L Stainless Steel Wire Arc Additive Manufacturing.

In order to study the anisotropy mechanism and the effect of current mode on the anisotropy, the arc additive manufacturing experiment of 316L stainless steel was completed by using direct current and pulse current, respectively. The results of microstructure analysis show that each layer of the additive wall can be divided in the longitudinal direction into a heat-affected zone, a central zone and a remelting zone. The grain growth direction of each zone was basically the same, and the microstructure, alloying element content and hardness of the three zones were obviously different. The crystallographic texture and inhomogeneity of the layer were the main reasons for the anisotropy. Compared with the use of direct current, the difference in tensile strength between horizontal and vertical specimens was reduced by 23.5% when using pulse current. Additionally, the wall has high forming accuracy, small grain size and good plasticity. And the δ-ferrite content inside the layer is lower, the hardness of each zone is higher, and the hardness difference between the three zones is smaller. [ABSTRACT FROM AUTHOR]