Author : Masnaji Rajaram Nukulwar, Vidyadhar Sudarshan Dixit, Sunil Tukaram Shinde and S.S. Pimpale

This paper summarizes fatigue test on high strength steel specimens in the as-welded condition and specimens treated by Shot peening. Results indicate that material strength has effect, to a certain extent, on the fatigue performance of Shot peening welded joints. High tensile weld residual stress is one important factor contributing to fatigue crack development even under reversal or compressive cyclic loadings. A compressive stress induced by Shot peening is beneficial by eliminating the tensile residual stresses and generating compressive residual stresses, which improves fatigue strength of welded structures. Internal stresses were investigated on five base metal samples treated by shot peening. The induced compressive residual stresses benefit to increase the threshold value of stress intensity factor range, for fatigue crack initiation and early propagation. Shot peening was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. Shot peening could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. It is shown that Shot peening is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength.

Keywords: Fatigue analysis, shot peening, welded joint analysis, Residual Stresses, Fatigue Failure, Axial Loading.