Strategies for the Minimization of Residual Stresses in Welds

The great majority of joining processes for metals and alloys involves some degree of local heating.  This often leads to very significant residual stresses in the welded joint.  Furthermore these stresses are often tensile in the weld and heat affected zones: regions where the microstructure may be sub-optimal and thus the mechanical properties inferior to the structure as a whole.

There are an increasing number of strategies emerging for reducing levels of tensile stresses in welded joints which will be compared and contrasted in this presentation.  There are methods which aim to reduce the creation of misfit between weld zone and parent during welding.  These include using thermal gradients, applied loads or phase transformations.  Other methods involve post weld treatments of which post weld heat treatment is the most commonly used, but mechanical methods are also available.  Some are more appropriate to flat welded plates;  others are particularly useful for thick welds or those for which post weld heat treatment might be impractical.   In each case the mechanisms by which the misfit is reduced will be explained and an example highlighting the degree to which the residual stresses (and in some cases distortion) may be controlled.