连续油管钢带斜焊温度场及残余应力场数值模拟

Numerical simulation of temperature and residual stress field of steel welding for coiled tubing

采用有限单元法,模拟连续油管钢带斜焊及形变热处理过程中温度场和残余应力场的分布情况。结果表明:在焊接过程中焊缝附近温度梯度很大,远离焊缝的地方温度梯度渐渐趋于平缓;随着焊接热源的移动,温度中心也随之移动,最高温度可达母材的熔点,能量集中在很小的范围内,造成高度集中的瞬时热输入。焊后残余应力主要集中在焊缝附近,最大应力值为432 MPa;形变热处理之后残余应力集中分布在热处理区域的边界,最大应力值为431 MPa。对比发现形变热处理并不能减小或消除焊接残余应力,只能使残余应力重新分配,远离焊缝附近,使该位置的材料趋于安全。

The temperature field and residual stress distribution of coiled tubing during steel welding and thermomechanical treatment process were simulated initially with the method of finite element.The results show that temperature gradient is high near the weld and becomes flat away from the weld.With the movement of welding thermal source,the temperature center also moves and the maximum temperature is up to the melting point of the base metal.Energy concentrates in a small range,resulting in transient high concentration of heat input.Post welding residual stress concentrates in the vicinity of the weld and the maximum residual stress value is 432 MPa.Residual stress is mainly distributed in the border region after thermomechanical treatment process and the maximum residual stress value is 431 MPa.By comparison,it is found that thermomechanical treatment process can not reduce or eliminate the welding residual stress,but it can only lead to the redistribution of residual stress,makes residual stress away from the weld,so that the material in this location tends to be safe.