Layer thickness dependence of performance in high-power selective laser melting of 1Cr18Ni9Ti stainless steel

Abstract

High-power selective laser melting (HP SLM) technology has been used to build 1Cr18Ni9Ti stainless steel samples with 60–150μm thick powder layers. The relative density, metallurgical bonding mechanisms, microstructure and mechanical properties of the samples are presented. It is found that full density cannot be obtained at thicker powder layers due to the residual micropores. With increasing layer thickness from 60μm to 150μm, the primary dendrite spacing first increases from about 0.5μm to 1.5μm and then stabilizes around 2.0μm. The microhardness of the fabricated samples by HP SLM shows directional dependent due to the anisotropy of microstructure and grain coarsening in the bonding area. Tensile strengths of the HP SLMed 1Cr18Ni9Ti samples are much higher than those of wrought 1Cr18Ni9Ti regardless of layer thickness and building direction. Importantly, the powder layer thickness cannot be increased without limit to ensure the comprehensive performance of the HP SLMed samples.