Effect of Solution Temperature on Microstructure and Mechanical Properties of Selective Laser Melted Fe-22cr-5ni-0.26n Duplex Stainless Steel

Abstract

Selective Laser Melting (SLM) technology is effective for fabricating complex shape parts with superior strength and ductility. However, the high-temperature gradient and rapid solidification rate induce residual stress, leading to unstable material microstructures. In this study, the influences of different solution temperatures (1000 °C, 1100 °C, and 1200 °C) on the evolution of crystal phase and microstructure of Fe-22Cr-5Ni-0.26N duplex stainless steel (DSS) fabricated by SLM were investigated. The resulting changes were then used to clarify the corresponding variations in mechanical properties of the specimens under tensile loading. The results revealed that AS-SLM sample showed high yield strength and poor elongation which was 1162.52MPa and 4.97%. Solution treatment at 1000 °C can increased the elongation from 4.97% to 29.21% due to the two-phase structures recovered, texture weaken, grains refined, as well as eliminate dislocation and residual stress through recrystallization. As the temperature rose, the yield strength declined, while elongation remained almost unchanged. Except for elongation, the tensile strength, yield strength, and hardness were all higher than those of forged specimens. Therefore, proper heat treatment is an efficient strategy to improve the mechanical properties of the SLM Fe-22Cr-5Ni-0.26N DSS with excellent yield strength and ductility.

Keywords: Selective laser melting, Duplex stainless steel, Solution temperature, Grain size, Misorientation, Mechanical properties