산화손상을 고려한 오스테나이트계 스테인리스강의 저주기 피로수명 연구

초록

Austenitic stainless steel is widely used in high-Temperature environments as the core material in various industrial applications. This work analyzes the characteristics of oxidation damage via microscopic observations after low-cycle fatigue testing based on the temperature in relation to the fatigue life, which is based on the oxidation damage of austenitic stainless steel containing niobium. In addition, a unified low-cycle fatigue life model based on the Riedel model coupled with the Neu Sehitoglu oxidation damage life model is proposed by considering the fatigue, creep, or fatigue creep interactions as well as oxidation damage. Low-cycle fatigue tests were conducted for temperatures of 200~800°C as well as 0.4% and 0.5% strain amplitude conditions, and the validity of the proposed model was confirmed by comparing the experimental results with the analytical values. Thus, oxide thickness and depth could be predicted with average errors of 2.8% and 6.7%, respectively, and low-cycle fatigue life could be predicted with a 2 factor of accuracy at the measured temperatures and strain amplitude conditions. From the results, low-cycle fatigue life could also be predicted for oxidation damage as well as fatigue, creep, or fatigue creep interactions, which account for 60~75% of the total fatigue failure of austenitic stainless steel at high temperatures and with periodic loading.

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