ADIMEW Project: Ductile Tearing Prediction of a Cracked 16" Dissimilar Metal Weld Junction

Abstract

ADIMEW (Assessment of aged piping DIssimilar MEtal Weld integrity) EC project aimed to quantify the accuracy of structural integrity procedures used in the European nuclear industry to ensure the safety of defect-containing dissimilar metal welds in aged PWR Class 1 piping. A 16 inch diameter DMW weld junction containing a large machined crack has been tested successfully under bending at 300°C to determine the actual behaviour of cracks close to the interface. The 16” Dissimilar Metal Weld mock-up (Pressurizer DMW type) has been manufactured according to nuclear industry specifications by FRAMATOME-ANP and the four point bending test has been performed by EDF. The fracture behaviour of the cracked pipe test is rather complex since the crack is not located where large yielding develops in the pipe, the crack surface is conical but its front is straight, the crack is loaded under mixed mode and is parallel to the interface between ferritic and austentic weld metal where strain concentration develops. Furthermore the welding process induces residual stresses only partially released by the post weld heat treatment. This paper presents ductile fracture analyses of the test and comparisons to experimental measurements. Framatome-ANP and ESI performed a J based analysis up to initiation and a ductile crack growth simulation using the Rice and Tracey criterion.