Microstructure and properties of hybrid additive manufacturing 316L component by directed energy deposition and laser remelting

Arc additive manufacturing is a high-productivity and low-cost technology for directly fabricating fully dense metallic components. However, this technology with high deposit rate would cause degradation of dimensional accuracy and surface quality of the metallic component. A novel hybrid additive manufacturing technology by combining the benefit of directed energy deposition and laser remelting is developed. This hybrid technology is successfully utilized to fabricate 316L component with excellent surface quality. Results show that laser remelting can largely increase the amount of delta phases and eliminate sigma phases in additive manufacturing 316L component surface due to the rapid cooling. This leads to the formation of remelting layer with higher microhardness and excellent corrosion resistance when compared to the steel made by directed energy deposition only. Increasing laser remelting power can improve surface quality as well as corrosion resistance, but degrade microhardness of remelting layer owing to the decrease in delta phases.