On repair weld residual stresses and significance to structural integrity

Abstract

This paper starts with a brief state of the art assessment on what has been learned over the last few decades in understanding residual stress development mechanisms, particularly those uniquely associated with weld repairs. A special emphasis will be given to how some of the residual stress features contribute to structural integrity of a component containing weld repairs. In contrast to initial fabrication welds, residual stresses associated with finite length repair welds tend to exhibit important invariant features, regardless of component configurations, materials, and to some degree, welding procedures. Such invariant features are associated with the severe restraint conditions present in typical repair situations. A number of weld repair cases are examined in this paper. In addition to highlighting important residual stress distribution features, fracture mechanics calculations are performed to examine how repair weld residual stresses quantitatively contribute to crack driving force as a function of crack location and size. One simple and effective technique for mitigating detrimental residual stress effects on structural integrity is also demonstrated by considering overall weld repair dimensions.