随焊冲击碾压减小应力变形防止热裂纹应变场分析
Strain field analysis of weld with trailing impact rolling to control residual stress and distortion and prevent hot cracking
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摘要: 随焊冲击碾压法(Weld with Trailing Impact Rolling,WTIR)是一种降低应力、减小变形防止热裂纹的新方法。文中分析了在前后冲击碾压轮作用下,焊缝金属塑性流动和应变场的变化规律,揭示了这种方法的机理。前轮周面内凹,迫使焊缝金属由焊趾处向焊缝中心流动,对处于脆性温度区间的焊缝金属施加一个横向挤压塑性应变,减小甚至抵消致裂的拉伸应变,防止了焊接热裂纹的产生。后轮缘稍向外凸,将焊缝金属冷却产生的压缩塑性变形充分碾开,减小了工件的应力和变形。试验结果表明,随焊冲击碾压能有效地防止焊接热裂纹的产生,将试件的纵向挠曲变形与横向收缩变形量控制到常规焊接状态的1/10和1/5左右,同时能将薄壁构件焊接残余应力控制到非常低的水平,甚至由拉应力状态转变为压应力状态,验证了应变场分析的正确性。Abstract: Weld with trailing impactive rolling (WTIR) is a new technology to reduce the weld residual stress and distortion. The front impact roller exerts transverse compression plastic strain on the weld which is in the brittle temperature range, this will counteract the tensile strain which leads to hot cracking. The rear impact roller stretches longitudinal and transverse compressive plastic deformation of the weld adequately, thus reduces the residual deformation and stress of the weldment. The experimental results show there is no hot cracking in the WTIR weld. The longitudinal deflection deformation and the transverse contraction deformation of the weld with WTIR are reduced to 1/10 and 1/5 of the ordinary weld respectively, and the residual stress in the weld also decreases greatly.