Effect of prestraining and strain-aging on toughness of MnMoNi steel weld metal

Specimens of both as-deposited and reheated submerged arc weld MnMoNi weld metal have been subjected to plastic deformation and static strain-aging treatments. These treatments were carried out in an attempt to simulate some aspects of the thermomechanical conditions occurring in pressurised water reactor components such as the ferritic pressure vessel. Ductile to brittle transition curves were investigated using Charpy impact tests. The influence of such treatments on the tensile properties was also studied. The strain-aging treatment is found to have a more pronounced effect on the impact toughness of the as-deposited (AD) weld-metal region than of the reheated microstructure (RH).