Effect of stress relieving on fracture properties of submerged-arc vvelds of C–Mn steels

AbstractA series of multipass submerged-arc welds in C–Mn steels produced at interpass temperatures of 60° and 250°C have been studied in the as-welded and stress-relieved conditions. For those welds containing 0·08%C and less than 1·0%Mn stress relieving at 625°C causes an increase in the critical crack-opening displacement (COD) transition temperature, owing to the formation of brittle grain-boundary carbide networks. To explain this carbide development a carbon-concentration profile model, which depends on the extent of the transformation of austenite to pro-eutectoid ferrite is proposed. The results are compared with earlier work on steels containing 0·08%C and more than 1·0%Mn in which stress relieving produced a decrease in the critical COD transition temperature.