Influence of cooling of forging dies on the process-related microstructural changes in the surface zone and their effect on wear behaviour

由于高载荷作用，热锻工具表面区发生了局部组织变化。这对磨损行为有显著影响。因此，分析模锻过程中的这些操纵表面区及其对磨损行为的影响具有重要意义。微观组织的变化主要取决于模具内的位置和时间相关的温度行为，而模具冷却系统对温度行为有很大的影响。该研究项目旨在从根本上检查模具冷却系统对表面区与工艺相关的组织变化的影响。主要目的是研究不同冷却条件下的组织变化，并确定组织变化与磨损行为之间的关系。另一个次要目标是确定摩擦学和机械联合载荷对热锻模具表面区显微组织的影响。研究目标将通过改变冷却和润滑的概念来实现，通过不同的喷涂参数和不同的固定模具温度来调整冷却梯度。在功能上隔离冷却和润滑，通过定时调节每一区域的冷却剂数量，允许对冷却过程进行特定配置。模具将通过合适的表面喷水冷却系统进行冷却。将制定不同的冷却策略，以配置冷却过程。润滑和冷却功能的分离，取消了传统的水-石墨悬浮液润滑，从而通过静电粉末涂层对模具进行润滑。根据所用粉末的不同，模具和工件之间可能会产生不同的摩擦条件，摩擦学应力也会有所不同。锻造不同强度的钢可以改变模具的机械应力。本课题的研究成果将有助于优化模具冷却过程中的微观组织变化，从而有效地提高模具的磨损性能和使用寿命。

The surface zones of hot forging tools undergo local microstructural changes due to high loads. This affects the wear behavior significantly. Therefore, the analysis of these manipulated surface zones in die forging and their effect on wear behavior is of great importance. The microstructural changes mainly depend on the location and time dependent temperature behavior in a die which is highly influenced by the tool cooling system. The research project aims at fundamentally examining the influence of the die cooling system on the process-related microstructural changes in the surface zones. The main objective is to investigate the microstructural changes under varying cooling conditions and determine the correlation between the microstructural changes and the wear behavior. Another minor objective is to determine the influence of the combined tribological and mechanical loads on the microstructure in the surface zones of hot forging dies. The research objectives will be achieved by varying the cooling and lubrication concepts by adapting the cooling gradient through different spraying parameters and different stationary die temperatures. Functionally isolating cooling and lubrication allows a specific configuration of the cooling process through a timed regulation of the amount of coolant per area. The die will be cooled by an appropriate surface water spray cooling system. Different cooling strategies will be developed in order to configure the cooling process. The separation of the lubrication and cooling functions eliminates the conventional lubrication with water-graphite suspension, thus the die will be lubricated through electrostatic powder coating. Depending on the powder used, different friction conditions between the die and the workpiece can be generated and the tribological stresses can be varied. The mechanical stress of the die can be altered by forging steels of different strengths. The gained results of the research project should help to optimize the die cooling regarding the microstructural changes to improve wear behavior and service life efficiently.