MEASUREMENT OF 3-DIMENSIONAL RESIDUAL-STR ESSES AT ROLLED BARS WITH HIGH HARDNESS

Bars out of 56 Ni Cr Mo V7, a diameter of 63 mm and a length of 100 mm were rolled with a force of 12 kN and 27 kN. The hardness of the bars was 2150 N/mm(2). In 8 different direction along the surface the resi dual stresses were determined with the help of x-ray diffraction. This was done several times after electrolytic reduction of the material a t the measuring zone to get a stress profile in dependence of the dept h. Afterwards in two dimensions along the surface and perpendicular to the surface the residual stresses inclusive the shear stresses were d etermined. High compressive residual stresses were along the surface, but therefore tensile residual sires ses were perpendicular to the sur face at a zone of around 1.5 mm depth. A comparison of the residual st resses with stresses induced by shot peening is done.