Microstructure and mechanical properties of 304 stainless steel produced by interpass milling hybrid direct energy deposition-arc

Abstract

Good surface forming accuracy is an important indicator for evaluating the quality of the additive components, especially for complex components that require high surface forming accuracy, and the regulation of microstructure and properties has a very important impact on metal processing and manufacturing. In this study, an experimental device for interpass milling hybrid direct energy deposition-arc was developed. Combined with the simulation method, the effect of interpass milling on the forming accuracy was deeply studied from the liquid metal's force and flow behavior. The changes in microstructure and properties were also studied in depth from the evolution mechanism of residual stress and the solidification of liquid metal, thereby enhancing the controllability of the forming and properties of stainless steel additive components. The results showed that the addition of interpass milling refined the grains, weakened the orientation texture of the crystal plane, and significantly improved the uniformity of the microstructure. Finally, the additive component with the best mechanical properties was obtained at a milling depth of 200 μm, with a 31.8 % increase in microhardness, 14.9 %, and 59.2 % increase in tensile strength and elongation, respectively. The anisotropy to isotropy of the deposited sample was transformed.

Keywords

• Direct energy deposition-arc
• Interpass milling
• Macro forming accuracy
• Microstructure
• Mechanical properties