Simulation Analysis of the Strain Behaviour of X80 Girth Weld Joint
As the service environment of the pipeline is becoming worse and worse, large plastic deformation may occur at any time when the pipeline through the poor geological area. The load of the pipeline consists of the tension load and the internal pressure load while the main failure mode of the high-grade steel is ductile fracture. In order to study the influence of the tension load and the internal pressure load on the strain capacity of the X80 high deformation steel with circumferential cracks, the GTN (Gurson–Tvergaard–Needleman) model was adopted for analysis with both X80 high deformation steel wide plate and pipe. The results showed that the crack propagation could be divided into the blunting stage, the unstable flaw growth stage and the stable flaw growth stage. CTOD increased with the crack propagation in the process, the softening of weld heat affected zone could lead to the weak of the strain capacity. The toughness of the X80 high deformation steel under a certain crack size became worse gradually with the increase of softening degree.
KeywordsX80 high deformation steel Ductile fracture Strain capacity
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