High Temperature Creep Rupture Characteristics of Ni-Based Alloy718

J. Ocean Eng. Technol. 2008;22(6):52-57.

Kwon Sang-Woo,Kong Yu-Sik,Kim Seon-Jin

Department of Mechanical Design Engineering Pukyong National University,School of Mechanical Engineering Pukyong National University,School of Mechanical Engineering Pukyong National University

니켈기 초내열합금 Alloy718의 고온 크리프 파단 특성

권상우,공유식,김선진

부경대학교 기계설계공학과 대학원,부경대학교 기계공학부,부경대학교 기계공학부

Keywords: Creepcharacteristics, Steady state creep rate, Creep rupture time, Larson-Miller parameter LMP, Initial strain

핵심용어: 크르프 특성, 정상상태 크리프 속도, 크리프 파단시간, 초기연신율

Abstract

The short-term high temperature creep rupture behavior of Ni-based Alloy718 steel was investigated at the elevated temperatures range of 550 to $700^{circ}C$ under constant stress conditions. The creep rupture characteristics such as creep stress, rupture time, steady state creep rate, and initial strain were evaluated. Creep stress has a quantitative correlation between creep rupture tim and steady state creep rate. The stress exponents (n, m) of the experimental data at 550, 600, 650 and $700^{circ}C$ were derived as 33.5, -24.9, 26.1, -21.2, 16.8, -12.8 and 10, -8.2, respectively. The stress exponent decreased with increasing creep temperature. The creep lift prediction was derived by the Larson-Miller parameter (LMP) method and the resultant equation was obtained as follows: T($logt_r$+20)=-0.00252 ${sigma}^2$-1.377${sigma}$+-22718.