Establishing the intrinsic connection between microstructure, 3D defects, and the corrosion behavior of selective laser melted WE43 alloys
摘要
To elucidate the underlying corrosion mechanism of selective laser melting (SLM) WE43 alloys, a detailed comparative analysis was conducted on the microstructure and corrosion behavior of WE43 Mg alloy in extruded, SLM, and solution-treated states. The SLM WE43 alloy exhibits a mixed grain microstructure composed of columnar and equiaxed grains, with an average grain size of 3.64 μm. Secondary phases are continuously distributed along melt track boundaries, and the dislocation density reaches up to 2.55 × 1014 m−2. SLM WE43 alloy, with a relative density of 99.47%, demonstrates the highest corrosion rate of 59.26 mm year−1, which decreases to 24.33 mm year−1 after solution treatment. In contrast, the extruded WE43 alloy exhibits the lowest corrosion rate of 6.26 mm year−1. While the extruded and solution-treated WE43 alloys primarily undergo pitting corrosion, the SLM WE43 alloy experiences 3D spatial corrosion due to micro-galvanic corrosion of the secondary phases, high dislocation density, and rapid Cl− propagation in 3D defects, characterized by the corrosion products peeling off in successive layers. The study of the 3D spatial corrosion behavior of SLM WE43 alloy offers key insights into the rapid corrosion mechanisms of SLM-produced magnesium alloys.
Graphical abstract