Probabilistic Analysis of Fracture Toughness of Weld HAZ with LBZ

概要

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Significance of local brittle zone has been investigated in the fracture toughness evaluation of the weld HAZ produced by multi-pass welding. Microstructures in the HAZ of multi-pass welds have an appreciable variation due to multiple thermal cycles. Brittle fracture initiation in the multi-passed HAZ is mainly controlled by the most embrittled microstructure, the coarse grained HAZ (C.G. HAZ), irrespective of the presence of tougher region, e.g. the fine grained HAZ. Critical CTOD of HAZ-notched specimen with respect to brittle fracture initiation is determined by both the toughness of the C.G. HAZ itself and the entire size of the C.G. HAZ sampled at the crack front. As the C.G. HAZ size along the crack front increases, failure probability at a lower CTOD value increases. The C.G. HAZ size dependence of failure probability in the HAZ-notched specimen can be analyzed on the basis of the weakest link model. That is, by utilizing the weakest link model the toughness results for specimens containing a relatively small size of the C.G. HAZ can be converted into those for a larger size of the C.G. HAZ.
社団法人溶接学会の論文
1988-10-01