적층제조 공정으로 제조한 Co-Cr-Mo 합금의 미세조직과 기계적 물성에 대한 연구

Abstract

This work investigated the effect of line energy on microstructures and mechanical properties of Co-Cr-Mo alloy single-track fabricated by the directed energy deposition (DED) method was investigated. As the line energy increased, the Co-Cr-Mo alloy single-track became wide and thick, and the thickness of the fusion zone at the interface increased because of the enthusiastic reaction with the substrate material. The Co-Cr-Mo alloy single-track with low line energy has a columnar grain microstructure with a strong (0 0 1)γ texture parallel to the build direction. In contrast, the single-tracks with high line energy have mixed microstructure, including fine columnar grains and coarse equiaxed grains, with random texture. In addition, the SDAS of the single-track depends on the line energy due to the rapid cooling rate. The diffusion of alloying elements from the substrate material throughout the fusion zone occurred and influenced the chemical composition and mechanical properties of the Co-Cr-Mo alloy single-track. The single-track with high line energy has poor hardness and low elastic modulus because the line energy determines the diffusion of alloying elements. The rapid cooling rate induces residual stress, which promotes the strain-induced ε-Co phase in the Co-Cr-Mo alloy single-track. The effect of the ε-Co phase on the mechanical properties of the single-track is insignificant.