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

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.