Effect of Heat Treatment on Microstructure and Mechanical Properties of GHS785L Alloy Steel Fabricated by Laser and Wire Additive Manufacturing

Laser and wire additive manufacturing (LWAM) is a novel technology widely used in several industries owing to its low cost and high depositional efficiency. Because of the complicated thermal history of the process, microstructures obtained by LWAM differ considerably from those obtained by traditional methods. In this study, GHS785L alloy steel walls were fabricated using LWAM, and the microstructures and tensile properties were investigated under different heat treatment conditions. After quenching, a large amount of lath martensite formed in the deposition layer, and the microhardness, yield strength, and tensile strength increased by 5%, 18%, and 16%, respectively, whereas the elongation ability decreased by 18%. Tempered sorbite formed after tempering at 575 degrees C for 30 min. The microhardness distribution of the deposition layer was highly uniform, and the elongation of the tempered-state sample increased by 33% compared to that in the quenched-state sample. The results indicate that the tempered GHS785L alloy steel walls have better mechanical properties than those of the deposition-state sample.