High pressure rolling of low carbon steel weld seams: Part 2 – Roller geometry and residual stress

Large residual stresses are an undesirable but inevitable side effect of fusion welding operations, and localised high pressure rolling of the weld seam is a proposed method for eliminating them. In this study, neutron diffraction has been used to map the residual stresses within low carbon steel weld seams treated with high pressure rolling. The effect on the residual stress distribution of using different roller types was determined, along with the influence of these different rollers on final weld seam geometry. Rolling was found to completely change the residual stress state in the weld, creating large compressive longitudinal residual stresses. It was effective for this purpose regardless of whether it was applied directly to the weld seam or to regions either side of it. The fatigue life of welded specimens was shown to be reduced by rolling; however, it is suggested that this is due to geometric and metallurgical effects.