The Study On Effects Of Welded Joint Geometry Parpmeters On Fracture Position

Pipeline is one of the current transportation systems. In terms of steel pipeproduction and pipeline construction, welding as one of the key working procedure is keyto affecting the quality of pipeline steel pipe and the safe operation of pipeline. However,welding is a complex heating process, the HAZ (heat affected zone) of welded jointssubjected to high temperature leads to a serious deterioration in the organization andperformance, thereby affecting the fracture behavior of the joint and this effect is relatedto the geometry parameters of welded joints. So in this paper, considering theperformance of HAZ, the yield behavior of joint was investigated and then to speculatethe rule of welded joint fracture position. The results would provide theoretical basis foroptimizing welding process and improving quality of weld seam of high strength steelpipe.In this paper, welded joints of X90high strength thick walled double submergedpipeline steel as the object of study,different microstructure and properties in the HAZwas simulated by using Gleeble-3500thermal simulation testing machine, and thedifferent mechanical properties of HAZ was obtained by tensile test. The model of tensiledeformation for weld seam of double side submerged arc weld was constructed and thefracture location of the welded joint was simulated by using ANSYS finite elementnumerical simulation software. The rationality of the model was validated by experiment.Based on this model, variation of stresses and fracture position was analyzed in theprocess of the welded joint tensile test with the change of welded joints geometryparameters.The results showed that the geometry parameters of welded joints affected thevariation of the welded joint fracture position. The fracture position occurred in the basemetal because of the deformation of HAZ restrained. In other geometry size under certainconditions, there were three critical value of outside weld seam width which had animportant influence on the welded joint fracture position and the size of the critical valueaffected the rule of welded joint fracture position. Meanwhile, the diagram of the strength mismatch factor of HAZ and base metal, inside weld length and the critical values ofoutside weld length was obtained.