Microstructure evolution and corrosion behavior of TC11 laser melt deposition additive components after post-heat treatment

Abstract

The TC11 components were produced using a high-power, high-speed laser metal deposition (LMD) process. Subsequent post-heat treatment significantly improved the microstructures and corrosion resistance of the components. The results showed that the microstructure of the as-deposited component primarily comprised α Widmanstatten microstructure and mesh basket-weave microstructure. After post-heat treatment, the original interlayer zone disappeared in the deposition direction, and the microstructures were transformed from α’ to α phase. The aspect ratio of the α phase decreased, and the α grain boundary (αGB) became spheroidized. The tensile strength decreased but plasticity increased significantly. Overall, the corrosion resistance was improved in both directions, with greater improvements observed in the deposition direction. Phase ratio, grain size and KAM value are all factors affecting the corrosion resistance, but for the deposited direction, the significant improvement of the corrosion resistance is mainly due to the weakening of the charged galvanic corrosion effect between the non-interlayer zone and interlayer zone.