Microstructure and mechanical properties of high chromium nickel-based superalloy fabricated by laser metal deposition

摘要

A high chromium (Cr) superalloy, K648, has been additively fabricated by using laser metal deposition (LMD) for the first time, and the microstructure and mechanical properties of the deposits are investigated. The results show that the main phases of the K648 superalloy are γ-Ni, γ', α-Cr and M_(23)C_6. The microstructure from the bottom to the middle region is mainly composed of epitaxially grown columnar dendrites, and the microstructure in the top region is mainly equiaxed grains. Element segregation exists in the LMD K648 superalloy. The average microhardness of the LMD K648 superalloy is about 220.5HV. The tensile strengths of LMD K648 superalloy show obvious anisotropic characteristics and the maximum ultimate tensile strength is about 833 MPa.