Research progress on the influence of microstructure characteristics of metal additive manufacturing on its corrosion resistance

Additive manufacturing technology is a method of manufacturing parts that are stacked layer by layer through the principle of discrete stacking, which is different from traditional subtractive manufacturing. It has been widely concerned due to its advantages of short process flow, high material-utilization rate, and highly flexible manufacturing. Additive metal manufacturing is the most important branch of additive manufacturing technology. Its forming parts have high complexity, showing excellent mechanical properties than ordinary castings. After more than 20 years of development, it has been widely used in aerospace, medical, energy, and other related fields. In the current mainstream metal material in the manufacturing process, the main use of high-energy beam-melting metal powders results in extremely high overcooling, whereas cold fine grains exhibit special precipitation and increase the mechanical properties of the material. However, there are still doubts about the corrosion performance of metal additive manufacturing parts in the service process. The mechanism of the corrosion effect of special microstructures and precipitation relative to materials in the service process is still unclear. Therefore, it is urgent to review the systematic research of the corrosion resistance of high-energy beam metal additive manufacturing parts. Corrosion resistance is also one of the key factors for metal additive manufacturing products to occupy a place in the market and should be paid attention to. Therefore, this article summarized the current research progress on the corrosion performance of metal additive manufacturing workpieces on three commonly used metal additive manufacturing technologies: laser melting, electron beam melting, and directional metal deposition. The residual stress, grain size, precipitated phase, and anisotropy affect the corrosion resistance behavior. The influence mechanism of the parameter optimization and heat-treatment process on the corrosion resistance of the material was analyzed. Finally, the prospects of improving the corrosion resistance of metal additive manufacturing products were discussed.