Investigation on interactions between topography, friction and wear in the tribological system tool-component in hot forging

在本研究项目的范围内，将研究热锻造工具的微观组织和工具与锻件之间的摩擦之间的复杂相互作用的基本知识以及工具的性能。首先，将研究热锻造条件下摩擦系数和成形力与随机组织、工具和零件温度以及润滑条件的关系。在此基础上，结合金相组织和工艺参数，从长寿命磨损性能的角度出发，设计和研究了适合于系列锻造试验的工具。在假设加载情况对研究参数有显著影响的前提下，将实现两种不同载荷情况(热、力学、摩擦学)明显变化的锻模。除了与地形有关的摩擦力和成形力之外，本项目的另一个重点是成形过程中微观组织与工作载荷的一致性。根据IFUM进行的其他调查，已知有某些类型的显微组织不会因成形操作而直接被压扁或粗化破坏。根据以往的知识，不能准确地定义这些结构的必要特征。合适和一致的显微组织对锻模磨损行为的影响也是未知的。此外，通过适当的比值来表征三维情况下锻模的微观组织变化也是本项目的研究内容。这将基于雅培-费尔斯通曲线图，该曲线图允许分析不同的表面值，例如DIN EN ISO 25178(SPK、SK、SVK)的值。到目前为止，还没有系统地研究这些值来表征微观结构表面变化，特别是在模具磨损增加的情况下。通过获得这一知识，将为理解摩擦学系统工具锻造中的相互作用并将这些知识应用于不同的应用开辟新的可能性。

Within the scope of this research project basic knowledge of the complex interactions between the microstructure of hot forging tools and friction between tools and forgings as well as the performance of the tools are to be investigated.At first, friction coefficients and forming forces in dependence of stochastic microstructures, tool- and part-temperatures as well as lubrication conditions will be investigated under conditions of hot forging. On that basis, suitable tools for serial forging test will be designed and investigated in terms of long life wear-performance under consideration of microstructure and the named process parameters. Acting on the assumption, that the investigation parameters are significantly influenced by the loading situation, two different kinds of forging dies with clearly varying load situations (thermal, mechanical, tribological) will be realized.Another focus of this project beside the topography-depending friction and forming force is the consistency of the microstructure against the working loads during the forming process. Based on other investigations, carried out at the IFUM, it is known that there are certain kinds of microstructures that are not directly destroyed by the forming operation in terms of flattening or roughening. Based on previous knowledge the necessary characteristics of these structures could not be defined exactly. The effect of an adequate and consistent microstructure on the wear behavior of forging dies is also not known.Furthermore, the characterization of microstructural changes of forging dies in the threedimensional case by appropriate specific values are to be investigated within this project. This will be based on the Abbott-Firestone-Graph which allows the analyses of different surface values like for example the values of DIN EN ISO 25178 (spk, sk, svk). A systematical investigation of these values for the characterization of microstructural surface changes especially in the case of increasing die wear is not existent so far. By achieving this knowledge new possibilities will be opened up to understand the interactions in the tribological system tool-forging and to apply this knowledge for different applications.