Residual Stress Management in Welding: Residual Stress Measurement and Improvement Treatments

Abstract

Residual stress (RS) can significantly affect engineering properties of materials and structural components, notably fatigue life, distortion, dimensional stability, corrosion resistance etc. Residual stresses play an exceptionally significant role in fatigue of welded elements. The influence of residual stresses on the multi-cycle fatigue life of butt and fillet welds can be compared with the effects of stress concentration. Even more significant are the effects of residual stresses on the fatigue life of welded elements in the case of relieving harmful tensile residual stresses and introducing beneficial compressive residual stresses in the weld toe zones. Residual stress management is a concept that addresses major aspects of residual stresses in welds and welded structures. According to the concept three major stages, i.e. RS determination, RS analysis and RS redistribution are considered and evaluated, either experimentally or theoretically to achieve the optimum performance of welded structures. All three stages as well as a number of new engineering tools such as ultrasonic computerized complex for residual stress measurement, UltraMARS, software for analysis of the effect of residual stresses on the fatigue life of welded elements and new technology and, based on it, compact system for beneficial redistribution of residual stresses by ultrasonic peening, UltraPeen will be discussed. Examples of industrial applications of the developed engineering tools for residual stress analysis and fatigue life improvement of welded elements and structures will be given.