The Research On The Influence Weld Geometry Size And Haz Softenting Degree To Loading Capacity Of Piepeline Steel Pipe

Submerged arc welding(SAW) with the particularities of automated, efficient and high quality has become the essential welding method to the process of pipe manufacturing. Therefore, the longitudinal submerged arc welded pipe forming by the method of double-sided straight-seam submerged arc is also widely used in oil and gas pipeline industries. Based on the complexity micro-structure and mechanical properties of the welded joints, as well as non-uniformity stress distribution under the condition of the pressure-bearing, the bearing capacity of the welded pipe line ignoring the welding residual stress on the welded joints was analyzed in this paper. Meanwhile, the simulate of the entire pipeline adopts the finite element software ANSYS. This process not only saves the test costs but it also has combined with the actual situation. In addition, the simulation method makes it possible for the performance analysis of the entire pipe under different forming conditions possible and provides a more accurate engineering practice theoretical basis.Firstly, a reasonable welded joints size was found under the condition that the impact of the pipe bearing capacity and yield position by penetration and weld width size is considered, but the impact of reinforcement and the weld toe angle size is ignored. As the result the size of the default model of welded joints received by adjusting the size and submerged arc welding groove welding process.Secondly, the optimal ratio of joint strength and the size of welded joints was made by analyses the impact of the heat affected zone(HAZ) softening and the strength of the weld joint performance. At the same time, the loss strength could be compensated which caused by the changing joint size, combined with the changed welded joint sizes.Finally, the situation is more realistic of the actual pressure in the pipeline under the bearing condition through the establishment of three-dimensional finite element model. Compared with the two-dimensional model, the accuracy of the simplified model was verified.After a series of simulation, reasonable welding technology to achieve optimal pipeline weld penetration and weld width was concluded. The weld joint has optimum carrying capacity, and the position of the first occurrence of the failure can be predicted. Furthermore, the analysis of the impact of different strength and the degree of softening of the heat affected zone for the welded joints on the carrying capacity can play a guiding role on welding material selection and groove shapes selection options. At the same time, the application of three-dimensional model has verified the accuracy of the two-dimensional model under low pressure.