J-integral analysis of heterogeneous mismatched girth welds in clamped single-edge notched tension specimens

•We present a crack driving force estimation procedure for heterogeneous welds.•The procedure is based on a ‘homogenized’ version of the EPRI equation.•Complex welds are translated into equivalent idealized mismatched welds.•The procedure is validated for clamped SE(T) specimens.•A mismatch limit load for clamped SE(T) specimens is developed.

Flaw assessment procedures require a quantification of crack driving force, and such procedures are generally based on the assumption of weld homogeneity. However, welds generally have a heterogeneous microstructure, which will influence the crack driving force. This paper describes a stress-based methodology to assess complex heterogeneous welds using a J-based approach. Clamped single-edge notched tension specimens, representative of girth weld flaws, are analyzed and the influence of weld heterogeneity on crack driving force has been determined. The use of a modified limit load for heterogeneous welds is proposed, suitable for implementation in a ‘homogenized’ J-integral estimation scheme. It follows from an explicit modification of an existing solution for centre cracked tension specimens. The proposed solution provides a good estimate of crack driving force and any errors in the approximation may be accounted for by means of a small safety factor on load bearing capacity.