Bend-Straightening of Case-hardened Shafts - Scientific Basis and Modeling

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Bend-straightening of case hardened shafts scientific basis and modelingBend-straightening of case hardened shafts is an important process step during manufacturing processes of components for drive technology. From the viewpoint of materials engineering it is an elasto-plastic bending operation. As a consequence, inhomogeneous plastic deformations occur leading to complex multiaxial residual stress states. In this context, inhomogeneous microstructure and strength in the cross section, a possible transformation of retained austenite and a potentially occurring strength-differential-effect are of importance. Existing investigations in this context are targeted towards shortening of process times and avoiding damage. Basic information about the materials states after bend-straightening operations and their consequences are lacking. During the first part of the project, an understanding of the basic processes, e. g. of local plastic deformations and retained austenite transformations will be gained to understand the formation of residual stress distributions. Then the consequences of these materials states on the mechanical behavior under further loading in the straightening direction as well as opposite to it will be studied. In this way, important aspects of the consequences of straightening operations on the mechanical behavior of shafts will be analyzed. Experiments will be complemented by numerical simulations and will finally enable optimized straightening strategies.