High Temperature Performance Evaluation of As-serviced 25Cr35Ni Type Heat-resistant Steel Based on Stress Relaxation Tests

Abstract

Based on an as-serviced 25Cr35Ni type steel, the high temperature property evaluation using stress relaxation test(SRT) method and residual life prediction were studied. The results show that creep rupture property decreases because of the formation of network carbides along grain boundaries and coarsening of secondary carbides in the austenitic matrix. Based on the relationship of stress relaxation strain rate curves obtained at different temperatures, and the extrapolation equation of stress relaxation rate-rupture time, it is capable to perform residual life evaluation by combining SRT data and a small amount of creep rupture test(CRT). Good agreement is observed for predicting results performed by current method and traditional method.

Keywords

• 25Cr35Ni type heat-resistant steel
• stress relaxation
• life prediction
• TTP parameter method