Finite element simulation and experimental study of selective laser melted 40Cr steel forming process

Selective Laser Melting (SLM) is a novel manufacturing method of complex metal parts. 40Cr is a traditional steel with low cost and high strength, and has wide application. However, the process parameters for the selective laser melted 40Cr steel have not yet been developed. In this paper, based on ANSYS finite element analysis results of the molten pool size and experiments, the optimal parameter of selective laser melted 40Cr was developed and maximum relative density of the fabricated samples was up to 99.34%, when the laser power was 285 W and the scanning speed was 960 mm/s. It was found that the sample consisted of alpha-Fe phase and a small quantity of gamma-Fe retained austenite phase. The microstructure of the specimen was mainly composed of lath martensite, granular bainite and lower bainite. The microstructure of the specimen was mainly composed of lath martensite, granular bainite and lower bainite. Hardness, tensile strength, yield strength and elongation of the sample with maximum relative density reached to 430HV, 1467.75 MPa and 1298.82 MPa and 25.26% respectively. The mechanical properties of SLMed 40Cr steel is superior to that of 40Cr specimens made by other manufacturing methods, such as casting, electropulsing quenching, etc.