A Novel Approach to the Prediction of Long-Term Creep Fracture, with Application to 18Cr-12Ni-Mo Steel (Bar, Plate, and Tube)

Designers of new power-generation plants are looking to make use of new and existing high-strength austenitic steels so that these plants can operate with much higher steam and, therefore, metal temperatures. However, this article shows that the Wilshire–Scharning methodology is incapable of producing accurate long-term-life predictions of these materials from short-term data. This article puts forward a modification of this approach that should enable existing and newly developed austenitic stainless steels to be brought into safe operation more cost effectively and over a shorter time span. The estimation of this model showed that the activation energy for creep was dependent on whether the test stress was above or below the yield stress. Analysis of the results from tests lasting only up to 5000 hours accurately predict the creep lives for stress-temperature conditions, causing failure in 100,000 hours or more.