Microstructure and mechanical properties of wire-powder hybrid additive manufacturing for high nitrogen steel

Abstract

A novel wire-powder hybrid arc additive manufacturing (WPHAAM) was applied for melting zone nitridizing to avoid the deterioration effect caused by the loss of nitrogen in high nitrogen steel. A designed Cr-Mn-N wire with 0.79 wt% of nitrogen (HNS6) was used to build a high nitrogen wall body by introducing WPHAAM method. The influence of nitrogen content on solidification behavior, microstructure, and tensile properties were studied in the as-built conditions. With the increase of amount of feeding powder, the solidification mode of the deposited wall changes from primary ferrite with second-phase austenite (FA mode) to primary austenite with second-phase ferrite (AF mode), and the mechanical properties are enhanced. When the powder feeding rate reaches 0.33 g/min, the solidification changes to A mode, and the deposited metal is austenite. The ultimate tensile strength and elongation of the deposited metal are 1014 MPa and 50.8% respectively.