Investigation of laser-powder bed fusion driven controllable heterogeneous microstructure and its mechanical properties of martensitic stainless steel

Martensitic stainless steels, fabricated by laser-powder bed fusion (L-PBF) technology, have recently garnered considerable attention owing to their high strength and favorable corrosion resistance for automotive and aerospace applications. However, intricate and inhomogeneous temperature history during the L-PBF process makes it challenging to understand the microstructure evolution and the corresponding mechanical properties. This study aims to explore the potential of this technology in enhancing the mechanical properties of martensitic stainless steels. It specifically focuses on the microstructure resulting from the inherent quenching and tempering heat treatment that occurs during the process. The distinctive microstructure of AISI 410 stainless steel included alternating high-temperature tempered, coarsened grain, and low-temperature tempered zones. Consequently, the as-built stainless steel exhibited the exceptional mechanical properties: an ultimate tensile strength of 1350 ± 55 MPa and an elongation at fracture of 14.3 % ± 1.2 %. Remarkably, these mechanical properties are comparable to those of AISI 410 stainless steel treated with a conventional quenching and partitioning heat treatment. These findings support for the effectiveness of in-situ quenching and tempering during L-PBF, demonstrating its potential to yield high-performance heterogeneous alloys.