Effects of geometry, location, and direction on microstructure and mechanical properties of 15–5PH stainless steel fabricated by directed energy deposition

Abstract

Laser-based directed energy deposition (DED) additive manufacturing (AM) was used to fabricate 15–5 precipitation-hardening (PH) stainless steel, and the geometry-dependent, location-dependent and direction-dependent microstructure as well as the mechanical properties of the resulting materials were investigated. Two different geometric components, deposition cuboid (DC) and deposition wall (DW) were fabricated, and the microstructure and mechanical properties of the samples were measured at different locations and in different directions. Finite element simulation was employed to interpret the thermal history of DED processing. The experimental and simulation results indicated that DED components presented different microstructure and mechanical properties in different geometries, directions, and locations, due to complex thermal history during DED processing. The use of post-heat treatment significantly decreased the amount of retained austenite, eliminated texture and resulted in homogeneous grain structure, leading to uniform mechanical properties. This study increases understanding of the microstructure characteristics and properties of AM PH steel.