Synthesis and Characterization of Innovative Fe–Cr–Mn Ferritic Stainless Steel by Laser Powder Bed Fusion

Abstract

Crack development for laser‐fused metallic materials is one major challenge for laser‐based powder bed fusion (LPBF). The cracks are manifested in two forms, i.e., macrocracks along building layers due to spalling and microcracks along the high‐angle grain boundaries. To mitigate the crack formation, a new type of ferritic stainless steel Fe–Cr–Mn are synthesized by LPBF. The well‐developed columnar ferrite grains with an enhanced fine acicular austenite precipitation, which possess Nishiyama–Wassermann (N–W) orientation relationship with the ferrite matrix, can be readily produced when the laser energy density is beyond 100 J mm−3. Porosity can be further reduced below 0.5% by optimizing the laser power and scanning speed. It is found that laser rescanning may eliminate the cracks without modifying the grain morphology, crystallographic texture, and phase distribution.