Cold bending effect on residual stress, microstructure and mechanical properties of Type 316L stainless steel welded joint

Abstract

The cold bending process is often applied to the welded structures during manufacturing, but how it influences the properties of the welded joint is still poorly understood. Therefore, in this paper, four samples were cut from the as-welded plate and bent to 0° (i.e. without bending), 30°, 60° and 90° to study the effects of cold bending on welding residual stress, microstructure and mechanical properties of Type 316L stainless steel welded joint. The results showed that large tensile transverse residual stresses were generated at about 25 mm from the welding centreline (WCL) on the outer surface. When the welded joint was bent to 90°, no shear bands or deformation induced α' martensite was formed due to the high stability of the austenitic phase, indicating that the microstructure has not been changed significantly. Although the hardness values in the welded joint were all increased with the increasing bending angle, the hardness variation around the mid-thickness was not as significant as the other regions.