焊缝层数对特厚度管板焊接残余应力与变形影响的有限元分析

Finite Element Analysis of Effect of Layers on Residual Stress and Deformation in Butt-Welded Ultra-Thick Tube-Sheet

基于ABAQUS软件,建立了顺序耦合的焊接残余应力与变形有限元计算程序,对大型环氧乙烷(EO)反应器国产化中采用的390mm厚20MnMoNb特厚板拼焊反应器管板的焊接过程进行了残余应力与变形计算,并讨论采用不同焊缝层数对管板焊后残余应力与变形的影响.焊接采用双U形坡口,通过翻转管板进行两面坡口的交替焊接,为防止管板发生过度变形,焊接时始终在管板两端压有重量为4.5MN配重.计算结果表明:焊后管板发生了一端翘起的角变形,在靠近表层的焊缝及热影响区存在较大残余拉应力,在焊缝内部为较大的残余压应力;由于配重对变形的限制导致先焊面的应力大于后焊面;增加焊缝层数,使变形增加,残余应力降低,但并不显著.对如此大型特厚板约束焊,增加焊缝层数不是降低其焊接残余应力的有效手段.

Butt-welding residual stress and deformation of 390mm 20MnMoNb ultra-thick plates for manufacturing the tube sheet of a large scale EO （Ethylene Oxide） reactor were simulated by using finite element program ABAQUS. The effect of layers on the residual stress and deformation was discussed. The welding grove was double U-shaped which were welded alternatively by flipping over the tube sheet. Moreover, in order to avoid the excessive deformation of the tube-sheet, two 4 500 kN loads were applied on both ends of the tube-sheet. The results showd that angular deformation occurred in the tube-sheet. A large tensile residual stress was generated in the weld seam, the heat affected the zone near the surfaces of the tube-sheet, and compressive residual stress was generated in the weld root. As the layers increased, the deformation increased, however the stress decreased（which wass not significant）. The result proves that it is nol an effeclive method to decrease the residual stress by increasing the layer number for such ultra thick plates.