Influence of powder particle size distribution on microstructure and mechanical properties of 17-4 PH stainless steel fabricated by selective laser melting

Abstract

This study explores the influence of particle size distribution (PSD) and heat treatment on 17-4 PH stainless steel fabricated by selective laser melting, which greatly improved the elongation of the material on the basis of ensuring the strength. Scanning electron microscope and electron backscattering diffraction were used to characterize the microstructure of 17-4 PH stainless steel. 17-4 PH stainless steel PSD+ and PSD− samples have obtained equiaxed grain, and the internal tissue distribution in PSD+ sample crystals is uneven. By reason of the gas in the large partials of PSD+ powder falling into the size distribution of 49 μm–58.9 μm, it was difficult to escape during the SLM process, which reduced the material density and mechanical properties. Compared with the PSD+ specimens, the tensile strength, hardness and elongation of the PSD− specimens are increase to 345.2 HV, 938.7 MPa, and 22%, respectively. This trend is retained after heat treatment, and the surface hardness, tensile strength and elongation rate of PSD− HT specimens, which are 5.3%, 5.4% and 12.9% higher compared with the PSD+ HT specimens, respectively.