The Numerical Research On Welding Residual Stress And Deformation Of Thick Wall Pressure Vessel

Based on the welded residual stress and deformation of saddleback weld which.on big pipe of high temperature gas cooled reactor thick wall nuclear pressure vessel, through numerical analysis of finite element, to use "Element Birth and Death" analogies the residual stress and deformation on welded splice of multi-pass welding procedure, in order to provide guidance for decreasing the residual stress and welded deformation in the manufacture of the welded thick-wall nuclear pressure vessel.Firstly, in the way of numerical calculation, analytical study on residual stress and deformation of different welding parameter which on same groove type's welded splice. Result state clearly, each of the temperature soared to 1300℃,1400℃and 1460℃on welding line, after welding completed, no matter stress on which way, all focus on nearby welding, moreover, the stress get smaller and smaller as removed from welding center. Although some node's stress to exceed the yield limit of materials, have little meaning to whole welded construction. The MAX deformation lie to left side of big pipe, and the deformation get smaller removed from left side to container bottom, as close to the bottom, the deformation began to harder. By comparison, the 1300℃post weld stress and deformation are less than other two kinds of welding parameter.Secondly, in the process of welding manufacture, enormous implications of the post weld stress and deformation due to weld groove type and size. Under same welding parameter of the text, numerical analysis to three different groove type of welded splice. Result state clearly, between the I-form groove width of 30mm and 38mm, the stress is relatively minor of 30mm post weld, but the deformation relatively larger. The 30mm of I-form groove and double U-groove width, the stress is relatively minor of double U-groove poet weld, but the deformation relatively larger. At the same time, in order to analysis the influence to the residual stress and deformation of different number of weld passes and boundary constraint, to analog computation on different number of weld passes and boundary constraint of 30mm wide I-form groove and double U-groove. The results showed, to increase the number of weld passes and throw the reins to vessel have little meaning to the residual stress, but relatively big influence to deformation.Finally, in order to make sure the security and reliability of the welded structure, the paper studies the elimination of the welding residual stress with high heat processing. All the result to compared, the stress and deformation are relatively minor after heat treatment of 610℃×3h. So in the selected techniques, heat treatment of three hours is best reasonable. Welding residual deformations is the key factor affecting the structure design integration,manufacturing technique rationality and structure applied reliability. For the purpose of preventing the adverse effection of the welding deformation on the manufacture, assembly and so on, an anti-deforming method is suggested to do the deal.