Influence of Preparation Procedures on Residual Stresses in Welded Joint Specimen for Toughness Test Available to Purchase

Electrogas welding is an essential technique for joining thick plates which are frequently used in shipbuilding. As the heat input is very large, the grain size tend to be coarse and the fracture toughness property is deteriorated. On the other hand, the welding induced residual stress is believed to have significant effect on crack initiation especially for brittle fracture behavior. Wide plate specimen with deep notch can be employed in the toughness test to consider the residual stress field. To investigate the influence of preparation procedures on residual stresses in welded specimen for toughness test, numerical simulation based on thermal elastic-plastic FEM was carried out. Firstly, transient welding temperature and stress-strain was simulated; secondly, cutting to separate specimens and pre-cracks were virtually introduced in the finite element model. The dynamic mesh refining method proposed by the author was used to accelerate the computation. Attention was paid on welding length and the end effect on residual stresses which are altered by cutting. The simulation result shows that, the stress distribution has significant difference near the tip of crack between specimens prepared with and without welding ends.