Correlation between the weld residual stresses and it’s tensile and impact strength

The tensile strength, impact strength and the hardness of the weld were determined. A criteria was proposed for describing the effect of residual stress on the weld mechanical properties. Dimensionless parameters Rya (the average of residual stress over the material yield strength), Rym (the maximum residual stress over the material yield strength), Ru2 (the difference of residual stress over the material ultimate strength) and Ru3 (the difference ratio between the maximum and minimum of three-dimensional residual stresses over the material ultimate strength) were presented to describe the influence of residual stresses on the actual mechanical behavior of the welded pipe. Maximum Rya criterion and lowest strength were obtained at the weld gap center on the external surface of the pipe. The sharp decline in Ru2 criteria is in consistent with the sever reduction in impact strength perpendicular to the weld gap.