Determining high temperature properties of weld materials

Abstract

Welds form an integral part of most power and chemical plant structures. At elevated temperature, the service life of these structures are often governed by the creep behaviour of welds. Efforts have been made to understand creep stress distributions in and deformation behaviour of welds and to predict the failure life. In this context, the determination of the high temperature properties of welds is essential. However, due to the complex nature of the material inhomogeneity in the weld regions, accurate determination of material properties of welds is not a straight forward task. This paper describes some aspects related to the determination of high temperature material properties of welds. Experimental creep testing methods involved and the procedures for generating the material constants in creep and damage constitutive equations for the parent, HAZ and weld material zones of welds are introduced. Practical applications of these techniques are discussed and the results obtained from typical high temperature CrMoV welds in main steam pipe lines are presented.