自升式平台桩腿焊接变形和应力控制技术研究

Research on Welding Distortion and Stress Control of Jack-up Platform Leg

自升式平台的桩腿由多段大厚度高强钢圆筒拼接而成,所需的大量的多层多道焊工艺,以及导致复杂的焊接变形与残余应力,是桩腿加工精度和安全性检验中需格外关注的问题。焊接变形、应力与焊接工艺参数和工艺措施有关,因此文章选取了4项对焊接变形及应力有重要影响的工艺参数,即预热温度、保温缓冷措施、焊接速度和约束条件,通过热弹塑性有限元计算,分析这4项工艺参数对圆筒圆度和应力极值的影响,并基于对焊接变形与应力的综合控制,提出了工艺优化建议。

The jack-up platform leg is made of dozens of big-thickness high strength steel cylinders, and a mass of multi-pass weldings are involved, which lead to welding distortions and residual stresses complicatedly distributed, so it need to pay extra attention to the above problems for the manufacturing accuracy and construction security of leg. Because the welding distortions and residual stresses have strong relationships with the welding technological parameters, four technological parameters were selected which have significant influences on welding distortions and residual stresses： preheating temperature, slow cooling measures, welding speed and restraint. Via the thermal elastic-plastic FEM analysis, the influences of the four technological parameters on cylinder roundness and maximum stress were studied, and the suggestions for process optimization were presented, based on the combination control of welding distortions and residual stresses.