engleski

Experimental and Numerical Analysis of Strength Overmatched Weld Root Passes on the Heat Affected Zone Fracture Behaviour

In the last decade the extensive fracture toughness testing of welded joints with the crack located in the heat-affected zone of structural steels was performed. Many investigations of fracture behaviour show that unpredictable fracture behaviour of specimen with crack tip located in HAZ can occur. The reason for such behaviour may lie in the HAZ microstructure heterogeneity and existing of local brittle zones (coarse-grained heat affected zone - CGHAZ). The spreading of stress and strain fields in the vicinity of crack tip, which is located in the HAZ, may be analysed very effective by finite element calculation. The aim of this paper is to determine the effect of different crack tip position in HAZ on crack driving force and consequently on fracture behaviour of strength mismatch fracture toughness specimen. The results for principal stresses distribution shown that highest maximum principal stress is reached just under the HAZ crack tip in direction of BM. Numerical analysis shows that changing of crack tip position has a significant effect on fracture behavior in elastic and plastic loading range. Significantly low effect on fracture behaviour has changing of amount of overmatching weld metal in root layer. Obtained results give principles for idealization of finite elements modelling of fracture behavior of welded joints.

Fracture toughness testing; weld joint; heat affected zone; finite element analysis

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