Influence of post weld treatment on the fracture toughness in welding procedure qualification- and component welds

Standard fracture toughness tests were done using full thickness (60mm) single edge notched bend and compact specimens extracted from identically fabricated SA-tandem plate- and tube-weldments on a C-Mn steel. Critical values of CTOD were determined at -10 degrees C for the weld metal of double V- and K-joints and for the HAZ of K-joints both in the as welded and post weld heat treated condition. To enable valid fracture toughness testing of specimens in the as welded condition mechanical precompression treatment was applied. Fracture toughness results obtained for weld metal and HAZ of the mechanically- and thermally-stress relieved qualification- and component-welds are compared. Whereas in the aw-condition fracture toughness results from WPQ-tests can be directly applied for tube welds there is some risk of overestimating the tube weld metal fracture toughness from WPQ-tests after p w h t. (IWM)