Temperature field simulation and microstructure study of WAAM fabricated Mg-Gd-Y-Zn-Zr alloy

Abstract

A new combined heat source model was established to more accurately simulate the shape and temperature distribution of the molten pool in additive manufacturing. The model was verified by comparing experimental and simulated results. Experimental and simulation studies have ascertained that the cooling rate of the liquid phase directly impacts the microstructure, thereby significantly affecting the performance of the fabricated parts. When the inter-layer cooling time is controlled at 400 seconds to maintain a thermal accumulation temperature below 246°C, the liquid phase cooling rate is between 2295 °C/s and 1395 °C/s. Under these manufacturing conditions, a profusion of networked secondary phases precipitate along the grain boundaries, primarily composed of rod-like LPSO structures and Mg5(Gd,Y,Zn). Employing this process can notably enhance the performance across different regions of the formed parts, with the hardness reaching up to 110.4 HV, yield strength up to 223 MPa, and compressive strength up to 498 MPa.