Effect of solution temperature on the microstructure evolution and mechanical properties of laser powder bed melting GH3536 alloy

GH3536 nickel-based superalloy was fabricated by laser powder bed melting (LPBF). The effect of different laser power and scanning speed on the number of defects was studied, and the process parameters were optimized. In order to alleviate the anisotropy of the deposited microstructure and eliminate the residual stress, LPBF alloy was treated with solution heat-treatment, and the effect of solution temperature on microstructure and mechanical properties was investigated. Through the characterization of grain size, carbide distribution and grain boundary type, it was found that with the increase of solution heat-treatment temperature, the deposited microstructure disappeared, carbide dissolved, and the number of small angle grain boundary decreased. According to the mechanical properties test, the tensile yield strength at room temperature of solution heat-treated sample with 1100 ℃ was 450 MPa. With the increase of solution heat-treatment temperature, the resistance of small angle grain boundary to dislocation movement weakened and the yield strength decreased. The yield strength of 1220 ℃ solution sample was 315 MPa. The high temperature tensile strength of 1100 ℃ solution sample was 220 MPa, and the carbides precipitated along grain boundaries at high temperature. With the increase of solution heat-treatment temperature, the quantity of carbides distributed along grain boundaries decreased, and the tensile strength increased gradually.