Determination of forming limits of the martensitic chromium steels in hot forming processes

马氏体铬钢热成形过程成形极限的测定

• 批准号: 385989694
• 负责人: Professor Dr.-Ing. Bernd-Arno Behrens
• 金额: --
• 依托单位: Institut für Umformtechnik und Umformmaschinen (IFUM)
• 依托单位国家: 德国
• 项目类别: Research Grants (Transfer Project)
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/385989694?language=en
• 关键词: Determination; forming; limits; martensitic; chromium; Determination; forming; limits; martensitic; chromium

The aim of the planned research project is numerical simulation of the hot forming of a martensitic chromium steel taking into account the forming limit at elevated temperatures, the resulting microstructure and their effects on the product properties. In the sheet metal forming, hot forming of martensitic chromium steels has various advantages over hot stamping of manganese-boron steels, such as a lower critical cooling rate, a higher elongation at break (fracture strain) along with higher strengths and a better corrosion resistance of the material. During the hot forming processes, complex interactions between the workpiece temperature, the tool temperature and the process time exist which significantly influence the microstructure, the final component properties and the residual stresses as well as the component distortion thus numerical modelling and prediction of the process limits is of particular importance for this process. In particular, the higher material costs of martensitic chromium steels compared to the manganese-boron steels make a simulative process design vital in order to save resources, tests and thus reduce the costs. The planned development of a material model for the numerical simulation of hot forming of martensitic chromium steels will be carried out based on a material model which was developed in the DFG funded preceding research projects for hot stamping of the manganese-boron steel (22MnB5). A comprehensive material characterization is required in order to adapt the material model to the martensitic chromium steels and their microstructural behavior.For the determination of the forming limits of sheet metals, the use of forming limit diagrams is state of the art. As the flow behavior and the deformability of a material are dependent on the temperature, conventional forming limit diagrams obtained at room temperature cannot be used for hot forming processes. In order to predict the deformability of martensitic chromium steels as well as the influence of the forming temperature on the deformability in the hot forming process, the further objective of this project lies in the determination of temperature-dependent forming limit diagrams and their implementation in the numerical simulation. This allows a realistic evaluation of the forming limit and the resulting component properties after cooling. The numerical model is validated with the help of hot formed demonstrator components.

计划研究项目的目的是考虑到高温下的形成极限，由此产生的微观结构及其对产品性能的影响，对马氏体铬钢的热模拟进行了数值模拟。 在金属形成中，马氏体铬钢的热形成与锰 - 孔钢的热冲压相比，具有各种优势，例如较低的临界冷却速率，较高的休息时伸长率（断裂菌株）以及较高的强度以及材料耐腐蚀性的较高的强度。在热形成过程中，工件温度，刀具温度和过程时间之间存在复杂的相互作用，从而显着影响微观结构，最终组件特性和残留应力以及组件失真，因此对过程限制的数值建模和预测对于此过程至关重要。特别是，与锰钢相比，马氏体铬钢的材料成本较高，这使得为了节省资源，测试并降低成本至关重要。计划开发一种材料模型，用于基于在DFG资助的先前研究的研究项目中开发的材料模型来进行马氏体铬钢的热形成，以进行锰 - 波龙钢的热冲压（22mnb5）。为了使材料模型适应马氏体铬钢及其微观结构行为，需要进行全面的材料表征。确定板金属的形成极限，使用形成极限图的使用是艺术的状态。由于材料的流动行为和可变形性取决于温度，因此在室温下获得的常规形成极限图不能用于热形成过程。为了预测马氏体铬钢的可变形性以及形成温度对热形成过程中变形性的影响，该项目的进一步目的在于确定温度依赖性形成极限图及其在数值模拟中的实现。这允许对形成极限和冷却后产生的组件属性进行现实评估。借助热的演示器组件验证了数值模型。