AN APPROACH TO ESTIMATE ROOM TEMPERATURE CREEP OF STRUCTURAL STEELS

Room temperature creep (RTC) behaviors of the as-rolled (AR) and normalized (Nor) X70 pipeline steel as well as the AISI304 stainless steel were investigated. At different stress levels, their RTCs mainly showed the feature of logarithmic creep with continuously falling rate. By comparing RTC with tensile tests, it was found that the loading process of RTC test was the same as the tensile test, and the strain rate at the start of RTC was equal to that at the end of loading process. Based on these results and by combining the constitutive equations of RTC with the Ramberg-Osgood equation, which is generally used to describe the stress-strain relationship in tensile tests, an approach to estimate RTC strain was presented as a function of the applied stress. On applying it to the X70 pipeline steel and AISI304 stainless steel, it was indicated that the estimated results of RTC were well consistent with the experimental data and that all the errors were within a factor of 2.