Characterization of Microstructural Anisotropy in 17-4 PH Stainless Steel Fabricated by DMLS Additive Manufacturing and Laser Shot Peening

The present study aims to produce the additive manufacturing of precipitation-hardened 17-4 PH stainless steel with isotropic microstructure using direct metal laser sintering (DMLS). The deposits' microstructure and surface properties were modified to improve their physical properties. The required surface modification has been obtained by applying shot peening strain-hardening effect on the deposited layers. Microstructure and mechanical properties were enhanced by using shot peening. Results revealed that the microstructure of the DMLS deposits was strain hardened and modified with the presence of a fine grain structure. The grain size analyses by electron backscattered diffraction (EBSD) indicated the nearly isotropic microstructure in the deposits along with the build-up direction (Z-axis) and transverse direction (XY directions) with the presence of equi-axed microstructure. The mechanical properties of the DMLS deposits were evaluated to determine the hardness, tensile strength, yield strength, and elongation. The results revealed that the properties obtained for both directions are nearly the same. The strength of the deposits was further improved by applying heat treatment techniques.