Fracture Toughness Evaluation of Welas with Mechanical Heterogeneity

Abstract

Effects of fracture toughness distributions in the vicinity of pre-existing notches on fracture performance have been studied with reference to fracture toughness evaluation of welds. Fracture toughness tests and fracture performance tests are carried out using the specimens made from HT 80 steel welded joints and stainless explosive clad steels. In the present paper, effect of local embrittlement on toughness evaluation is paid major attention. In the case which notch tip exists in the local embrittlement zone, fracture initiation is dominated mainly by fracture toughness of local embrittlement zone. When the embrittlement is much remarkable, it may be reasonable that short crack arrest toughness of base metal is adopted as fracture toughness for evaluating joint performance because multi-stage fracture occurs inevitably. In the case which local embrittlement zone exists at a short distance from notch tip, fracture behaviors are dependent on the plastic deformation in the vicinity of notch tip under loading. Fracture toughness of local embrittlement zone has become dominated fracture behaviors when plastic zone front occured in the vicinity of notch tip reaches the embrittlement zone.