Creep behavior and cavitation evolution of 15CrMoG steel at high temperatures

Abstract

15CrMoG steel is a type of heat-resistant steel frequently used in boiler and piping systems. Creep properties of the 15CrMoG steel at service temperatures are not much documented due to the difficulties in obtaining long-term creep data. Herein, the creep behavior and the cavity evolution of 15CrMoG steel were investigated based on 20,000 h of creep tests at varied temperatures. Creep curves were analyzed to elucidate the creep behavior and creep rupture mechanism of the 15CrMoG steel. A continuum damage model was adopted to fit the rupture stress versus creep time data, and the results showed the reliability of this model in describing the creep behavior and predicting the creep life. The creep rupture stress at 20,000 h decreased significantly with the increase in the temperature in the tested temperature range. The cavitation in the 15CrMoG steel samples occurring during the creep tests was also examined by microscopic analysis, the results of which confirmed that the cavitation evolution is responsible for the reduced mechanical performance and finally creep rupture of the steel. This work provides valuable high-temperature creep data of the 15CrMoG heat-resistant steel and insights into evaluation and prediction of long-term creep behavior at high temperatures.