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

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.