Deposition characterization of high-manganese (13Mn) steel built via directed energy deposition and its wear behavior

High-manganese steel (HMS) has high work-hardening and impact toughness as well as excellent wear resistance. In this study, directed energy deposition (DED) was employed to deposit HMS onto the surface of Inconel 718. The deposition characteristics were analyzed according to laser power and powder feed rate. From the results, the lowest amount of pores and lack of fusion were observed when the laser power was 1050 W and the powder feed rate was 4 g/min. In the first layer of the deposited HMS, the Laves phase was formed due to fusion with Inconel 718, while the hardness rapidly decreased to 250 HV because of the low hardness of the Fe–Ni phase. A wear test was conducted according to different loads and RPMs using the ball-on-disc method, with the results indicating that a higher load led to a lower wear rate. When the wear load was high, the surface hardness increased after the wear test, and surface severe plastic deformation (SSPD) thickened. Such phenomena occurred because the grains near the surface underwent refinement and the dislocation density increased as the load increased. An oxide layer was generated on the surface at 300 RPM, but no oxide layer was formed at 100 RPM. As an oxide layer was not formed, the wear rate was the highest at 100 RPM due to direct contact between the ball and matrix. This study demonstrates the industrial applicability of surface coating using HMS as a powder for maximizing wear resistance.