Session: MF-16-01 Creep and Creep-Fatigue Interaction
Paper Number: 61795
Start Time: Tuesday, July 13, 2021, 05:00 PM
61795 - Error Estimates in Extrapolation of Creep Rupture Data: Applied to an Austenitic Stainless Steel
Time extrapolation of creep rupture data is technical important since high temperature plants have typically a much longer design life and actual life than the testing times that are possible to reach in laboratories. The time extrapolation is practically always performed using statistical methods. Time-temperature parameters (TTPs) such as Larson-Miller or algebraic expressions are fitted the measured creep rupture data and then the results are generalised to longer times. Practically all these methods are empirical in the sense that they are not derived from basic physical principles, which means that the error in the predicted results is unknown, and this is quite unsatisfactory. For this reason the authors have developed procedures that can give an accurate estimate of the errors involved. This has been established by performing systematic analysis of fitting expressions to a single data curve or to a family of curves. In this way an upper bound to the error can be derived. This is a much safer method in comparison to estimating the error by comparing the results from different TPPs or analysing the results with post assessment tests (PATs). The procedures are illustrated for creep resistant austenitic stainless steels. The procedures are illustrated for creep resistant austenitic stainless steels. Both alloys with low alloy content such as 316H (17Cr12Ni2Mo) and with high content for example Sanicro 25 (22Cr25Ni4W1.5Co3CuNbN) are considered.
Presenting Author: Rolf Sandstrom KTH Royal Institute of Technology
Authors:
Rolf Sandstrom KTH Royal Institute of TechnologyJunjing He Hangzhou Dianzi University
Error Estimates in Extrapolation of Creep Rupture Data: Applied to an Austenitic Stainless Steel
Category
Technical Paper Publication