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热影响区软化焊接接头应力分布特征及强度预测

Characteristics of stress distribution and prediction of strength inheat-affected zone softened welded joints

  • 摘要: 细晶粒钢焊接接头热影响区晶粒粗化引起强度的局部下降,对接头承载能力的影响需要做出定量评价。有限元分析发现,在热影响区软化焊接接头的拉伸试样上,Mises等效应力分布具有确定的特征:在软化的热影响区减小,在与之相邻的焊缝区和母材区相应升高,分布规律符合指数函数规律,在热影响区与焊缝及母材的交界面上发生突变,突变的幅度与交界面两侧材料的屈服应力差值及外加载荷有一定相关性;在焊缝及母材区Mises等效应力增加量的积分等于热影响区减少量的积分。在此基础上提出了预测热影响区软化焊接接头强度的方法,其预测结果与有限元分析有很好的一致性,可用于热影响区软化焊接接头强度的预测和高匹配接头的强度设计。

     

    Abstract: The effects of yield stress decrease due to coarsening grain in the HAZ (heat-affected zone) of fine-grained steels welded joint son the load capacities of the joint are required to be evaluated.The finite element analyses are carried out on tensile plate specimen of butt-weldedjoint with softened HAZ.The stress distribution in such joints shows the characteristics as follows:the Mises equivalent stress increase with the exponential law in the welds and base metal adjacent to softened HAZ,and that in softened HAZ decrease correspondingly.At the boundaries between HAZ and weld metal and base metal Mises equivalent stressesrapidly changes,amplitudes of which are related to the differences of yield stresses in the both sides around the boundary,and applied stress.The integration of the decrease in the Mises equivalent stress in the softest zone equals to that of the increase over the weld metal and base metal zones.Based on above results,an approach to predict the tensile strength of such joint is suggested.The prediction results using this method areconsistent with the results calculated with finite element analysis method.This approach is suitable for prediction of strength of the HAZ-softened welded joints,and design for tensile strength in overmatched welded joints.

     

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