Distribution of residual stresses in reinforcing steel bars

The paper describes investigations about residual stress distributions in reinforcing steel bars (rebars) which were manufactured by a thermo-mechanical process, e.g. Tempcore®. In respect to the fatigue resistance it was aimed at to measure the longitudinal (axial) residual stresses. Different known methods have been discussed. Here the slitting of long samples by high–pressure–water–jet (HPWJ) and electrical–discharge–machining (EDM) was applied on samples with diameters of 16 and 28 mm of two manufacturers. The stresses were assessed by deformation measurements during and after the slitting processes. Additional investigations of chemical composition, structural texture, hardness, density and strength were carried out. The main result was that contrary to the former assumption compression stresses exist in the inner cross-section part and tensile stresses near or even at the surface.