Evaluation of various effects on bend straightening properties of case hardened notched shafts

拟议项目的目的是将已完成的基础研究项目中获得的知识转移到工业矫直工艺的设计中。对于驱动部件的制造来说典型的相对小的矫直路径导致塑性（对于矫直操作所需的）局部化到这样的区域，在该区域中，由相同符号表征的过大的载荷应力和初始残余应力与低流动极限一致。在这方面，局部塑性通常足以实现期望的矫直效果。局部应力状态受缺口和台肩以及整个部件尺寸的显著影响，所有几何特征都是应用真实的部件所需的。初始表面层的性质，如残余应力状态，残余奥氏体的分布和表面损伤的存在，分别是不可避免的热处理的结果。关于表面硬化和缺口部件的矫直行为已经有了一些发现。然而，根据目前的最新技术水平，直接合理化基于单个影响因素的影响的综合评估是不可行的，因此，将在本项目中详细说明。第一个目标是分析单个影响因素对弯曲矫直行为的影响，以了解局部塑性、残余奥氏体转变以及最终局部残余应力演变之间的相互关系。然后，将获得的知识传递给项目合作伙伴，以实现弯曲矫直工艺的稳健设计。

The aim of the proposed project is to transfer the knowledge gained within a completed, basic research project to the design of industrial straightening processes. The comparatively small straightening paths that are typical for manufacturing of drive components lead to a localization of plasticity (required for the straightening operation) to areas, in which excessive load stresses and initial residual stresses being characterized by the same sign coincide with low flow limits. In this regard, localized plasticity is often sufficient to achieve the desired straightening effect. Local stress states are significantly affected by notches and shoulders as well as the overall part dimensions, all geometrical features being required for application of the real components. The initial surface layer properties such as the residual stress state, the distribution of retained austenite and the presence of surface damage, respectively, are inevitably a result of the heat treatment. Some findings regarding the straightening behavior of case-hardened and notched components are already available. However, a comprehensive assessment, directly rationalizing effects seen based on individual influencing factors, is not feasible based on current state-of-the-art and, thus, will be elaborated in this project. The first goal is to analyze the impact of individual influence factors on the bend straightening behavior in order to gain an understanding of interrelationships between localized plasticity, transformation of retained austenite and, finally, evolution of local residual stresses. The knowledge gained is then transferred to the project partner to allow for robust design of the bend straightening process.