Prediction of Residual Stresses in Welded Joint under Mechanical Vibration

Welded joints are used for construction of many structures.In this investigation vibratory stress was applied to mild steel specimens while they were being welded to observe its effect on the residual stress microstructure and hardness of the material. Residual stresses were found to decrease in response to vibration whether it was applied during welding or after weldingWelding is a joining or repair process which induces high residual stress field which combines with stresses resulting from in-service loads strongly influencing in-service behavior of welded components. When compared with stresses due to service loads tensile residual stress reduces crack initiation life accelerates growth rate of pre-existing or service-induced defects and increases the susceptibility of structure to failure by fracture. Also welding residual stresses are formed in a structure as a result of differential contractions which occur as the weld metal solidifies and cools to ambient temperature. Previously some of the methods like heat treatment and peening kind techniques were used for reduction of residual stress. However those methods need special equipment and are time consuming. In this we are proposing a new method for reduction of residual stress using vibration during welding. For this Mechanical vibrations will be used as vibration load for Mild steel butt welded joints