Effect of laser power on microstructure and mechanical properties of K418 nickel-based alloy prepared by selective laser melting

Abstract

K418 alloy was prepared by selective laser melting (SLM) at different laser powers (160∼240 W) in this paper. The influence of laser power on the densification behavior, microstructure, microhardness, and tensile properties was studied systematically. The results showed that the densities of the material increased rapidly first and then decreased slowly with the increase of laser power. When the laser power increased from 160 W to 240 W, the surface defects of the specimen decreased, the microstructure changed from columnar dendrites to cellular, and the grains grew in the direction preferentially. When the laser power is 200 W, the grain size is the smallest, the content of small-angle grain boundaries is more, the Schmidt factor is less, and then the best mechanical properties are achieved, at which the microhardness reaches 362.89 ± 5.01 HV, the tensile strength reaches 1244.35 ± 70.1 MPa, the yield strength reaches 863.89 ± 23.1 MPa, and the elongation of the material reaches a maximum of 12.53 ± 0.71 %. In addition, the fracture mode of the material is a mixed tough-brittle fracture mechanism.

Keywords

• Laser power
• Selective laser melting
• Nickel-based superalloy
• Microstructure
• Mechanical property