Measurement and calculation of residual stresses after die forging

For die forgings, fabricated from steels Ck 45, 42 CrMo 4 and 38 MnSiV S 6 3, TTT and CCT diagrams were determined, and after different heat treatments, measurements of mechanical properties, fatigue strength and residual stresses were carried out. The diameter of the specimens after the forging process was 32 and 45mm. The residual stresses after quenching between -450 and +160N/mm 2 could be reduced to about 60N/mm 2 by tempering up to 620°C. The fatigue strength in the range of 300N/mm 2 depends more on the strength than on the residual stresses. Calculations with the program Antras-Thepla correlate well with the measured microstructures and residual stresses. This shows that the materials and processing data used for the calculation are conform to real processes.