Residual Stress Analysis in Weldments-Theoretical Approach

Residual stresses are self equilibrating stresses existing in materials or components under uniform temperature conditions. When two pieces of plates/pipes are joined together by welding, localised residual stresses coupled with shrinkage are generated in the vicinity of the weld. The presence of these residual stresses can be detrimental to the strength of the joint. Tensile residual stresses are generally detrimental, increasing the susceptibility of a weld to fatigue damage, stress corrosion and fracture. During welding, temperature conditions range from melting point of the material to room temperature. Mechanical and thermal properties of the material are temperature dependent and this change with temperature during the welding process. The material stress-strain behaviour is elastic-plastic and temperature dependent. Thermal stresses are produced in the material during the process of heating and cooling. When the material is cooled to room temperature, the locked up stresses present in the material are retained residual tresses.