A generalisation of the Wilshire–Scharning methodology to creep life prediction with application to 1Cr–1Mo–0.25 V rotor steel

摘要

Wilshire–Scharning have recently developed a new methodology that has been demonstrated to deliver accurate longer term creep life predictions, and so offers the prospect of cost-effective acquisition of long-term creep design data. This methodology differs from existing approaches to creep life prediction by normalising the applied stress through the appropriate tensile strength. This article develops a generalisation of this Wilshire–Scharning model that has the potential to increase the predictive accuracy of this methodology—which will be so essential if it is to be adopted as a way of economising on the acquisition of creep design data. When applied to 1Cr–1Mo–0.25 V steel, it was found that this generalisation reduced the average error in prediction from 2.5 under the Wilshire–Scharning specification to 1.8 years when extrapolating from 5,000 out to over 100,000 h. Further, over this time scale the generalised model produces a mean absolute percentage error of 28%. This compares to 47% obtained using the traditional 4Θ projection technique and 26% using a modification of this methodology as recently proposed by Evans.