不同焊接参数下CT70连续钢管高频电阻焊残余应力分布的数值模拟

目的研究CT70连续油管高频电阻焊接后的残余应力值和分布规律,以及焊接速度和挤压量等焊接参数对残余应力的影响。方法通过有限元计算的方法施加移动面热源和移动挤压辊,来模拟高频电阻焊的加热和加压过程,并用小孔法测量了高频电阻焊后连续钢管的残余应力值。结果对比计算的和实际的焊缝尺寸,均是内壁处为0.2 mm,壁厚中间部位为0.1 mm,内壁凸起高度为1.0 mm,宽度为2.1 mm,验证了有限元模型的准确性。计算得到的高频电阻焊后在焊缝处的轴向残余应力较大,在400～500MPa之间;环向残余应力较小,在-100～200MPa之间,与小孔法测量的残余应力一致。结论焊缝附近的残余应力主要由不均匀加热引起,远离焊缝处的残余应力主要由挤压引起。热源与挤压辊间距离和焊接速度增加会导致焊缝附近的残余应力增加;挤压量增加和焊接功率增加会导致焊缝附近的残余应力降低。

Numerical Simulation of Residual Stress Distribution of CT70 Coiled Tubing Welded by High Frequency Resistance Welding under Different Welding Parameters

The object of this study is to analyze the residual stress and its distribution of CT70 coiled tubing caused by high frequency resistance welding (HFRW) and the influences of welding parameters such as welding speed and extrusion amount on the residual stress. The moving surface heat source and the moving squeeze roller were applied by the finite element method to simulate the heating and pressurizing process of high-frequency resistance welding, and the residual stress of the coiled tubing after high-frequency resistance welding was measured by the blind-hole method. The accuracy of the finite element model was verified by comparing the calculated and actual weld size and residual stress. The weld width of inner surface was 0.2 mm and the weld width in the middle of the thickness was 0.1 mm. And the height and width of the hump of inner surface were 1.0 mm and 2.1 mm separately. The axial residual stress of coiled tubing welded by HFRW was large, which was in the range of 400 to 500 MPa; and the circumferential residual stress was small, which was in the range of -100 to 200 MPa. It was consistent with that measured through the orifice method. The residual stress near the weld is mainly caused by uneven heating, and the residual stress away from the weld is mainly caused by the pressurization. Increase of the distance between the heat source and the squeezing roller and increase of welding speed will result in increase of residual stress near the weld; increase of extrusion amount and welding power will result in decrease of residual stress near the weld.