Application of small punch creep testing for evaluation of creep properties of as-received and artificially aged 5Cr-0.5Mo steel

The small punch creep testing method was applied to evaluate the creep properties for the as-received and artificially aged 5Cr-0.5Mo steel. The small punch creep test was conducted at 600 °C using loads between 67 and 100 N and specimen size of 3 mm diameter and 0.25 mm thickness under an argon gas atmosphere. In order to study the effect of aging on creep properties, steel specimens were aged at 600 °C for up to 6000 h. The small punch creep curves indicated that the time to rupture decreased and minimum creep rate increased with testing load. The aging process of steel specimens caused the decrease in time to rupture with increasing aging time, which can be attributed to the increase in size and the decrease in number density of precipitates with aging time. The load-equivalent stress ratio was determined to be about 0.49 by finite element method for the as-received steel. In contrast, the load-stress ratio was found to be 0.63 for the experimental SP creep and uniaxial creep test results. However, the best relationship between stress and time to rupture was obtained for the experimental ratio of 0.63.