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基于有限元分析软件ANSYS,对SA335 P91炉管全位置对接打底焊温度场和应力一应变场进行了三维数值模拟。建立了焊接瞬态温度场和应力一应变场三维移动热源模型,得到了全位置焊时左右焊道交汇处(90°)的瞬态轴向应力和环向应力分布以及应力-应变随时间变化的规律:在闭合小孔区内表面的轴向和环向应力均为拉伸应力,且环向应力比轴向应力大,并有明显的边缘应力效应;该处在高温凝固阶段的瞬态应力随小孔停留时间的延长和焊接电流的增大而减小。与之相反,其等效应变的变化则随之增大,这是造成打底焊时在小孔闭合区容易产生凝固裂纹的主要原因之一。
Based on the finite element analysis software ANSYS, the three-dimensional numerical simulation of the temperature field and the stress-strain field of SA335 P91 full-position butt-welding of backing-up tube was carried out. The three-dimensional heat source model of welding transient temperature field and stress-strain field was established. The transient axial stress and hoop stress distribution and the stress-strain change with the time of the welding place (90 °) : The axial and circumferential stresses on the surface of the closed orifice area are tensile stress, and the hoop stress is larger than the axial stress, and there is obvious edge stress effect; the transient state in the high temperature solidification stage The stress decreases with the extension of the hole residence time and the increase of the welding current. In contrast, the equivalent strain increases with the increase, which is one of the main reasons that lead to solidification cracks in the closed area of the hole during the backing welding.