The stress distribution in
multi pass welding was generated by FEM with an axisymmetric model.The distribution of stress
components under different local
Post Weld Heat Treatment(Pwht) conditions,with different types of
multi pass welding,was studied using visco elastic plastic FEM.The results show that the welding residual stress on the outer surface and on the inner surface behave quite differently with heated band width.The residual stress on the outer surface decreases slowly with the increase of the heated band width.On the contrary,the residual stress on the inner surface can be removed effectively with relatively small heated band width.The relation between the residual stress and heated band width can be divided into two types:monotonical type and local minimum type.The relation between the residual stress and heated band width in multi pass welding behaves in the latter type.The heated band width of 5 Rt is reasonable.Excessive wide heated band width appears ineffective to further reduce the residual stress.Finally,the stress after local PWHT was measured by X ray method.