Effect of δ-Ferrite Formation and Self-Tempering Behavior on Mechanical Properties of Type 410 Martensitic Stainless Steel Fabricated via Laser Powder Bed Fusion.

Abstract

This study explores the formation of δ-ferrite and its self-tempering behavior in the microstructure of Type 410 martensitic stainless steel produced via laser powder bed fusion (L-PBF). The study investigates the correlation between varying energy densities applied during the L-PBF process and the resultant mechanical properties of the as-built specimens. A microstructural analysis shows that with an increase in energy density, the δ-ferrite fraction decreases, while the martensite content increases, leading to changes in tensile strength and elongation. Higher energy densities reduce tensile strength but significantly enhance ductility. The self-tempering effect of martensite in reheated zones, caused by the complex thermal cycling during the L-PBF process, plays a critical role in determining mechanical behavior. These findings provide valuable insights for optimizing the additive manufacturing of martensitic stainless steels to achieve the desired mechanical properties.