Effects of notch position and weld metal matching on CTOD of HAZ

In order to investigate the effect of weld metal yield strength on the fracture toughness behaviour of the coarse grained heat affected zone (CGHAZ), the CTOD and Charpy-V toughness of CGHAZ in three mismatched weldments were measured. The base plate was StE 460; bead-on-plate welds were produced by submerged arc welding with three different filler metals. A variety of notch orientations and depths have been studied. The main conclusion is that the 'apparent toughness' of the CGHAZ depends not only on the CGHAZ microstructure itself, but also on the mechanical properties of the adjacent materials. The 'apparent CGHAZ toughness', decreased with increasing weld metal strength and increased with decreasing crack depth in the under- and normal matched welds. (orig.)