Abstract:

In order to study the structural damage and mechanical property of Super304H steel in high temperature condition, two kinds of the Super304H heat-resistant steel were taken as research object: one was serviced at 863 K for 20 000 h as the reheater in an ultra-supercritical unit and the other was aged at 923 K for 1 100 h with the same P function value. The structure aging of the Super304H reheater was investigated after running for a long term, and the microstructure aging and mechanical properties degradation were studied on serviced and aging super304H steel tubes with same P function value. The results show that microstructures of the inner/outer side of the steel tube are heterogeneous due to their different running environments. The microstructure and mechanical properties of the inner side of the serviced Super304H steel tube are approximately equal to those of the aging super304H steel tube with the same P function value, however, the structural damage of the outer side of the serviced steel tube is more severe than that of aging one. Therefore, the artificial aging method in lab is conditionally accepted to simulate the structural damage of serviced steel tube, based on Larson-Miller parameter.

Key words: Super304H heat-resistant steel, isothermal aging, Larson-Miller parameter (LMP), structural damage, mechanical property