Effects of process parameters on the microstructure and mechanical properties of AISI 1045 steel prepared by selective laser melting

AISI 1045 steel is medium carbon low alloy steel, characterized by low cost and high comprehensive properties, and it is one of the most widely used steel materials. In this study, AISI 1045 steel was successfully prepared by selective laser melting (SLM) with optimized process parameters. The influence of powder layer thickness, scanning speed, and volume energy density (VED) on the relative density, microstructure, and mechanical properties of AISI 1045 steel has been systematically investigated. The results show that the phase composition of powder and SLMed-AISI 1045 steel is mainly α-Fe, the microstructure of sample is mainly fine martensite, and the grain size is mainly in the range of 0.3–1.7 µm. The sample prepared by SLM has a crystal orientation of < 101 > direction. At the same time, twin martensite and nano-precipitate were found. The Vickers hardness and compressive strength of AISI 1045 steel prepared by SLM are 541 ± 9 HV0.1 and 2055.85 MPa, respectively. The excellent mechanical properties are mainly attributed to fine grain strengthening and precipitation strengthening. Finally, the tensile properties and friction resistance of commercial AISI 1045 steel were measured and compared with SLMed-AISI 1045 steel. The results show that SLMed-AISI 1045 steel has high strength and wear resistance, the yield strength is 3.6 times that of commercial AISI 1045 steel, while maintaining high ductility.