• Dong, J.; Epp, J.; da Silva Rocha, A.; Nunes, R. M.; Zoch, H.-W.; Wimpory, R.: Zerstörungsfreie Eigenspannungsanalyse von Stahlwellen nach unterschiedlichen Prozessschritten vom Drahtziehen zum Induktionshärten. HTM Journal of Heat Treatment and Materials 69 (2014), p. 348-359

10.3139/105.110244

Abstract:
A process chain for manufacturing of machine parts in general consists of several process steps, e. g. continuous casting, hot rolling, annealing, pre-straightening, cold drawing, straightening and polishing, machining, induction hardening, and grinding. Distortion is frequently observed after the final heat-treatment process. However not only the hardening process, but also the history of the manufacturing chain is responsible. In the present work several essential manufacturing steps of a process chain were investigated experimentally and the distribution of the residual stresses as an important carrier of distortion potential was analyzed by means of non-destructive neutron diffraction over the whole cross section of the shafts. The results showed nonsymmetrical residual-stress distribution along the cross section after the pre-straightening of the uncoiled wire. The cold drawing created high-tensile residual stresses at the surface in radial and tangential directions, while much higher compressive stresses were found, particularly in axial direction, in the core. The residual stresses of the drawn shaft were reduced largely by a following cross-roll straightening. The final induction hardening changed the residual-stress state again largely in dependence on the process parameters. The influences of the investigated manufacturing steps on the residual-stress states are finally discussed in connection with the resulting distortion.