Study On Fracture Performance For Welded Joint Containing Unsymmetrical Strain-stress Field And On Engineering Treatment

It is a difficult thing that the integrity of welded joint is assessed because it is the more complex construct for its asymmetry and changing crack location. This paper will consider the welded joint containing a crack on fusion line for the right method of assessing the fracture toughness of welded structures, and prefer to an engineering treatment method adapting to this state.Firstly, based on two welding experiments by electron-beam welding and brazing, the case of welded joint beside the fusion line are investigated to see the components, organization and property and the fine element method and program are set up for the typical structure of welded joint with a crack on fusion line. Secondly, the strain - stress field of this kind of welded joint is seriously analyzed and it is found that this fracture field is different from those of all-base material and symmetrical structure of welded joint. It is the unsymmetrical strain - stress field. So, the proper fracture parameter must be found to study the fracture properties of this typical welding structure. Furthermore, the fracture parameters of the J-integrity are used to research the fracture driving force for a crack on three different locations on the middle welding seam, fusion line and hot-effect zone in welded joint. The results show that there are different calculating values. After those, the fracture field of the welded joint with a crack on fusion line is analyzed to get the formula of the parameter of the crack open displacement(COD) suited to the nature of fractureproperty.Finally, considering the engineering appliance, the fracture driving forces of the mismatched welded joints are carefully researched and the engineering treatment is gained accurately to assess the integrity of welded structures containing defects on fusion line. For the more, considering the mixed fracture field, the fracture parameter of mixed angle, which can explain the nature of welded joint with a crack on fusion line, is fit to research the fracture properties of the different mismatches of welded joints.