Variability of Short Term Creep Rupture Time and Life Prediction in Stainless Steels

J. Ocean Eng. Technol. 2010;24(6):97-102.

Jung Won-Taek,Kong Yu-Sik,Kim Seon-Jin

Department of Mechanical Design Engineering Pukyong National University,Department of Mechanical & Automotive Engineering Pukyong National University,Department of Mechanical & Automotive Engineering Pukyong National University

스테인리스 강의 단시간 크리프 파단시간의 변동성과 수명예측

정원택,공유식,김선진

부경대학교 대학원 기계설계공학과,부경대학교 기계자동차공학과,부경대학교 기계자동차공학과

Keywords: Creep rupture time, Weibull distribution, Variability, Creep life prediction, Lason-miller parameter

핵심용어: 크리프 파단 시간, 와이블 분포, 변동성, 크리프 수명예측, 라슨-밀러 파라메터

Abstract

This paper deals with the variability of short term creep rupture time based on previous creep rupture tests and the statistical methodology of the creep life prediction. The results of creep tests performed using constant uniaxial stresses at 600, 650, and $700^{circ}C$ elevated temperatures were used for a statistical analysis of the inter-specimen variability of the short term creep rupture time. Even under carefully controlled identical testing conditions, the observed short-term creep rupture time showed obvious inter-specimen variability. The statistical aspect of the short term creep rupture time was analyzed using a Weibull statistical analysis. The effect of creep stress on the variability of the creep rupture time was decreased with an increase in the stress level. The effect of the temperature on the variability also decreased with increasing temperature. A long term creep life prediction method that considers this statistical variability is presented. The presented method is in good agreement with the Lason-Miller Parameter (LMP) life prediction method.