Effect of welding on creep damage evolution in P91B steel

Abstract

Study of creep behavior of base metal (without weld) and welded specimens of P91B steel over a range of temperatures (600-650 C-omicron) and stresses (50-180 MPa) showed similar values of minimum creep-rates for both specimens at higher stress regime (>100 MPa) whilst, significantly higher creep rates in the case of welded specimens at lower stress regime. Considering that welded specimen is comprised of two distinct structural regimes, i.e. weld affected zone and base metal, a method has been proposed for estimating the material parameters describing creep behavior of those regimes. Stress strain distribution across welded specimen predicted from finite element analysis based on material parameters revealed preferential accumulation of stress and creep strain at the interface between weld zone and base metal. This is in-line with the experimental finding that creep rupture preferentially occurs at inter critical heat affected zone in welded specimens owing to ferrite-martensite structure with coarse Cr23C6 particles. (C) 2017 Elsevier B.V. All rights reserved.