Effect of forming angle on microstructure and properties of 4Cr5MoSiV1 steel formed by selective laser melting

Abstract

Selective laser melting(SLM) 4Cr5MoSiV1 steel has good strength/hardness and wear resistance, which is the important guarantee to improve its service life. In order to optimize the structure and properties of 4Cr5MoSiV1 steel formed by selective laser melting, the microstructure, microhardness, tensile properties and wear resistance of 4Cr5MoSiV1 steel samples were studied under the different forming angles. The results show that with the increase of forming angle, the heat accumulation between the melt channels of sample is decreased, the grain size is decreased, and the fine grain strengthening is enhanced, so the microhardness of the sample is increased. With the increase of forming angle, the number of slip lap surfaces and the degree of slip of tensile sample are increased, and the normal stress at the melt boundary is decreased, so the tensile strength and elongation after fracture of the sample are increased. The wear mechanisms of the wear sample are mainly adhesive wear and oxidation wear, and the wear resistance of the sample is increased with the increase of forming angle. At the same forming angle, after repeated heat accumulation on the surface of the sample bottom layer, the fine grain strengthening and solid solution strengthening are weakened, and the microhardness and wear resistance are reduced, so the microhardness and wear resistance of the sample are decreased. The microhardness, wear resistance and tensile properties of 4Cr5MoSiV1 steel sample formed by SLM are positively correlated. The mechanical properties of sample are the highest at 45° forming angle, the highest tensile strength is 1576.5 MPa, the highest elongation is 17%, the highest micro-hardness of upper surface is 608.4HV, and the lowest wear resistance of the upper surface is 4.95×10-9 kg·N-1·m-1.

Keywords

• selective laser melting
• 4cr5mosiv1 steel
• forming angle
• microstructure
• mechanical pro-perty