Application of Fracture Mechanics to a Delayed Cracking in a Weldments of HT80 Steel (Report 2)
Transition Behaviour from Stable Delayed Cracking to Unstable Brittle Fracture
1979 Volume 48 Issue 2 Pages 128-133
Details
1979 Volume 48 Issue 2 Pages 128-133
Delayed crack behaviour from a notch of poor penetration, in a we ldments of HT80 steel of 31 mm thickness has been investgated. Three points bend specimens of 70 nim width with weld defect of poor penetration were welded. In these specimens, the tip of thenotch was located on a fusion line in modified-Vee joints. J integral has been applied to evaluate the delayed fracture toughness in coarse grained HAZ, Results can be summarrized as follows:
1) Fracture mode of the pressure vessel at proof loading, that is the transition from stable delayed cracking to unstable cleavage fracture, can be easily reappeared by the laboratory test proposed in this report.
2) The susceptibility to delayed cracking in the weldments of HT80 steel can be iuccessfully evaluated as a function of J integral.
3) A new method to evaluate delayed fracture toughness has been proposed. This method is based on three parameters method proposed by, S.J. Garwood et al.
4) Delayed fracture toughness's transition curve is shifted to higher temperature side than fracture toughness's transition curve by 25°C.
