Creep Behavior of High Temperature Prestrain in Austenitic 25Cr-20Ni Stainless Steels

J. Ocean Eng. Technol. 2002;16(3):59-64.

오스테나이트계 25Cr-20Ni 스테인리스강의 고온 예변형에 의한 크리프 거동

박인덕,남기우,안석환

요코하마국립대학 공학연구원,부경대학교 재료공학부,부경대학교 기계공학부

Keywords: Prestrain, Strain Rate, Rupture Strain, Precipitates, Subgrain Size

핵심용어: 예변형, 변형속도, 파단 변형률, 석출물, 아결정립크기

Abstract

In the present study, we examined the influence of prestrain on creep strength of Class M alloy(STS310S) and Class A(STS310J1TB) alloys containing precipitates. Prestrain was given by prior creep at a higher stress than the following creep stresses. Creep behaviour before and after stress change and creep rate of pre-strained specimens were compared with that of virgin specimens. Pre-straining produced the strain region where the strain rate was lower than that of a virgin specimen both for STS310J1TB and STS310S steels. The reason for this phenomenon was ascribable to the viscous motion of dislocations, the interaction between dislocations and precipitates in a STS310J1TB steel, and the interaction of dislocations with sub-boundaries in a STS310S steen which has the higher dislocation density and smaller subgrain size resulted from pre-straining at higher stress.