Alloy 282 초내열합금 모재 및 용접부의 기계적 특성과 미세조직에 미치는 시효열처리 조건의 영향

The effect of aging heat treatment conditions on the mechanical properties and microstructure of the base and weld metal of Alloy 282 superalloy was investigated. The aging heat treatment conditions employed in this study were as follows: two-steps (1010 °C for 2 hours plus 788 °C for 8 hours) and one-step at 788 °C, 738 °C, and 688 °C for 4 hours. The base metal with the one-step aged condition exhibited lower hardness but longer creep life than that treated with the two-step aged condition. The base metal subjected to the two-step aging exhibited the highest hardness and the shortest creep life, mainly due to the precipitation of Mo-rich M6C-type carbides and coarse γ'' (Ni3(Al,Ti)) phase. For the weld metal, regardless of aging heat treatment conditions, creep elongation and life decreased significantly compared to the base metal, due to the coarse effective grain size and inhomogeneous distribution of γ'' precipitates. (Received May 27, 2020; Accepted July 01, 2020)