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Ein Verfahren zur Bemessung elektronenstrahlgehärteter Randschichten unter Wälzbeanspruchung
A method for the dimensioning of electron beam-hardened surface layers under rolling contact
Due to its various process advantages electron beam hardening is a competitive heat treatment method. Based on the example of rails for linear guidance systems a dimensioning method for electron beam welded surface layers under rolling contact was developed. The properties of these surface layers vary with the distance to the surface. Therefore, the dimensioning process requires knowledge of the local stresses due to service loads, information on local endurable stresses of the hardened layer, the transition zone and the base material, and, finally, methods to compare and evaluate these quantities. The report provides a description of the stresses due to service loads, of the superimposed residual stresses and explains their interpretation as fatigue relevant stress quantities. Numerical modelling and simulation methods are demonstrated to be an effective tool to determine residual stress fields from the hardening process and to investigate the stability of the calculatedresidual stre sses under cyclic rolling contact. Several hypotheses are utilized to evaluate the stress states. The concept of the local endurance limit is used to determine locally endurable stresses (Woodwine analysis). The results predicted with the dimensioning procedure are compared to experimental data from the literature and from own experiments.