对接接头横向残余应力调控技术
Investigation on New Technique of Adjusting Welding Residual Stresses in Butt Joint
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摘要: 分析了现有消除和调控焊接残余应力的常用措施所依据的原理,认为在不考虑材料相变的前提下,减轻对焊缝金属冷却收缩的制约可以有效地调控实际焊接接头上的残余应力。分析了纵向残余应力和横向残余应力之间的内在关系,在遵循虎克定律和考虑到金属形变时保持体积不变的前提下得出了纵、横向残余应力密切相关的推论,即横向残余应力也会影响纵向残余应力的值。在此基础上提出了减轻焊件自重引起的与焊接平台间的摩擦拘束以调控焊件中的横向残余应力的构想,并以Q235钢板为对象研究了采用该措施后平板对接接头纵、横向焊接残余应力的变化情况。试验结果表明,采取了减轻焊件自重引起的横向拘束的工艺措施后,板厚为8mm的试件上即获得焊接构件上的横向残余应力显著降低的结果。该措施对纵向残余应力亦有较大的影响,即减小横向残余应力的同时,接头上的纵向残余应力亦随之有所下降。Abstract: The principles of the common techniques for adjusting or relieving of residual stress in welded joints are analyzed in the paper.The authors believe that if the technical measure to reduce the restrained contraction of weld during cooling is taken the extent of the residual stress could be adjusted effectively in actual joint under the condition of no phase transition in base metal taking place.The relation between the longitudinal and transverse residual stress based on the Hook's Law and the principle of volume keeping constant during metal deformation is established (i.e.the value of transverse residual stress may affect that of longitudinal residual stress) and the new explanation for the low temperature stress relieving method is given.The authors have suggested and investigated a new method to adjust and control the transverse residual stress in butt joint based on the viewpoint of reducing the friction between the welding platform and work piece.The results obtained from the experiments showed that both transverse and longitudinal residual stress in butt joint could be decreased evidently after the measure to reduce the friction resistance being taken for Q235 mild carbon steel butt joints with 8 mm thickness.