A Simplified Approach to the Effect of Specimen Size on the Creep Rupture of Cross Weld Samples

Abstract

Various methods are available to assess the performance of welded joints under creep conditions. One approach uses the creep rupture testing of cross weld geometries in uniaxial tension. This paper examines an idealized model of a cross weld specimen where the weld metal is weaker than the parent material. The analysis, which is developed from published work on brazed and soldered joints, characterizes the limit load of the specimen as a function of the weld thickness:specimen diameter ratio and the yield strengths of both materials. The limit load is then used to define a creep reference stress which may be applied to uniaxial data. The predictions of the failure location and failure time are compared with cross weld creep data generated within the CEGB as no suitable data were found in the general literature. Finally, the model is used to postulate a size or weld thickness:specimen diameter effect on stress rupture testing of cross weld geometries.