Study on the Slope Change in the Larson-Miller Plot of 23Cr-26Ni-W Austenitic Heat-Resistant Steel

摘要

Tendency of creep-rupture life changes with stress variables in 23Cr-26Ni-W austenitic heat-resistant steel is studied in 175～300 MPa range. It is found that the slope of Larson-Miller (LM) curve is suddenly changed in the applied stresses of 175～200 MPa range at 700 °C. It is impossible to explain the complex response of creep-rupture lives to the applied stress with the conventional changing fracture-mode mechanism. In this research, the mechanism of the slope change in LM plot of 23Cr-26Ni-W austenitic heat-resistant steel is elucidated by comparing and analyzing the microstructural changes before and after the stress insensitive phenomena.