한국주조공학회

The effect of various types of heat-treatment on the mechanical properties of cast Alloy 718 has been investigated. Cast Alloy 718 bars were subjected to ‘standard heat-treatment treatment treatment treatment’_(SHT), ‘HIP (Hot Isostatic Pressing) heat-treatment’_(HHT), and ‘HIP-simulated heat simulated heat simulated heat simulated heat-treatment’_(HS). In the absence of long time high temperature heat-treatment, a small amount of Laves phase remained in the treatment, a small amount of Laves phase remained in the treatment, a small amount of Laves phase remained in the treatment, a small amount of Laves phase remained in the ‘SHT’ specimen, and needle shaped δ precipitated in the vicinity of the Laves phase. Due to the formation of the Laves and δ phases in the ‘SHT’ specimen, it exhibited lower tensile properties than those of the others_specimens. On the other hand, the Laves phase was completely dissolved into the matrix after ‘HHT’ and ‘HS’ treatments. It is known that isostatic pressure reduces the self-diffusion coefficient, because of the lower self-diffusivity under HIP conditions in the interdendritic region, Nb segregation and the high amount of γ” precipitation that occurs. Due to the higher fraction of coarse γ” phases, the ‘HHT’ treated Alloy 718 treated Alloy 718 showed excellent tensile strength. treated Alloy 718 treated Alloy 718 showed excellent tensile strength.

Cast Alloy 718, Segregation, γ” strengthening, HIP, Heat-treatment