Study on Evaluation of Tearing Instability of Welded Joints.

The establishment of analytic condition of tearing instability of structural component containing weld defects is required. However, because of the mechanical heterogeneity in welds, it is complex to evaluate the resistance of crack extension and tearing instability in the welded joints.In this paper, the applicability of various tearing instability criteria to welded joints was experimentally investigated. The results obtained are as follows ;(1) Tearing instability criterion described by fracture mechanical parameter should be applied to homogeneous material like base metal in principle.(2) However, the prediction of instability on the even-matched weld joints was not almost affected by the estimation error on fracture mechanics parameter caused by the heterogeneity.(3) Tearing instability criteria without fracture mechanical parameter were suitable for the prediction of instability on the welded joints. But the application criterion should be selected by the aim of instability assessment.(4) Behavior of tearing instability was affected by CM, (=material compliance) as well as CMZ (= loading compliance). It was clear that material having large CM1 value was not easy to instabilize.