High Temperature Creep Rupture Characteristics of Ni-Based Alloy718 Jointed by Friction Welding

J. Ocean Eng. Technol. 2008;22(6):58-63.

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

마찰용접된 니켈기 초내열합금 Alloy718의 고온 크리프 파단 특성

권상우,공유식,김선진

부경대학교 기계설계공학과 대학원,부경대학교 기계공학부,부경대학교 기계공학부

Keywords: Creep characteristics, Friction welding, Creep rupture time, Larson-Miller parameter LMP, Steady state creep rate(SSCR), Stress exponent

핵심용어: 크리프 특성, 마찰용접, 크리프 파단시간, 정상상태 크리프 속도, 응력지수

Abstract

The short-term high temperature creep rupture behavior of Ni-based Alloy718 steels jointed by friction welding wasinvestigated at the elevated temperatures 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 time 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 26.1, -22.4, 22.5, -18.5, 17.4, -14.3 and 6.9, -8.1, respectively. The stress exponents decreased with increasing creep temperature. The creep life prediction was derived by the Larson-Miller parameter (LMP) method and the result equation obtained is as follows: T(logtr+20)=-0.00148${sigma}^2$-3.089${sigma}$+23232. Finally, the results were compared with those of the base metal for Alloy718.