Investigation on the Surface Modification of High-Mn Lightweight Steel Through 3D Printing

Due to their excellent mechanical properties and low mass density, high-Mn austenitic lightweight steels have received much attention as a candidate material for reducing the weight of structural components. Generally, the austenitic lightweight steels can achieve excellent balance of high tensile strength (TS>700MPa) and tensile ductility (El.>50%) by forming fine κ-carbides during aging treatment. However, further increase in tensile strength by excessive aging treatment results in a sharp drop in tensile ductility due to the formation of intergranular secondary phases such as intergranular κ-carbide, D03 phase, and β-Mn. This trade-off dilemma limits the application of the lightweight steels. In this work, we investigate the surface modification of High-Mn austenitic lightweights through 3D printing; i.e., a metal powder containing a composition of different lightweight steel grade was built on the surface of High-Mn austenitic lightweight steels through 3D printing. After 3D printing, the solution and aging treatments were performed. Microstructure analyses and hardness testing were carried out, showing that the hardness profiles across the interface change depending on the formation of κ-carbide and β-Mn.