Reliability assessment of creep rupture life for Gr. 91 steel

摘要

This paper presents reliability assessment of the long-term creep life of Gr. 91 steel, which is a major structural material for high temperature structural components of Generation-Ⅳ reactor systems. A number of creep rupture data for Gr. 91 steel were collected through literature surveys, and the long-term creep life was predicted by Larson-Miller parameter. A "Z parameter" method was used to describe the magnitude of the deviation of the creep rupture data to a master curve. A "Service Condition-creep Rupture property Interference (SCRI) model" based on the Z parameter was used to simultaneously consider the scattering of the creep rupture data of materials and the fluctuations of service conditions in reliability assessment. A statistical analysis of the creep rupture data was conducted by the Z parameter. To carry out the SCRI model, a number of random variables for Z_s describing service conditions and Z_(cr) describing the dispersion of the creep rupture data were generated using a Monte-Carlo simulation technique. As examples for application, the creep rupture life under a certain service conditions of Gr. 91 steel was reasonably drawn from the viewpoints of reliability.