Failure mechanisms in solid solution strengthened ductile cast iron

固溶强化球墨铸铁的失效机制

• 批准号: 459577017
• 负责人: Professor Dr.-Ing. Christoph Broeckmann
• 金额: --
• 依托单位: Institut für Anwendungstechnik Pulvermetallurgie und Keramik (IAPK)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/459577017?language=en
• 关键词: Failure; mechanisms; solid; solution; strengthened

Nodular cast iron is a well-established material that stands out due to its excellent casting properties, high recycling rate and low costs, while at the same time offering the best mechanical properties, which is why it is used in numerous applications. In addition to the conventional grades, the newly developed grades, which are solid solution strengthened with silicon, have a high potential to further increase the strength while maintaining high elongation at break. Forged components can be substituted and can be produced more resource-efficiently with solid solution-strengthened cast iron. However, designers have so far been reluctant to use this material because it can exhibit unpredictable brittle fracture behaviour depending on temperature and load case. Our own preparatory work for this project has shown that this is particularly related to the formation of a B2-superstructure, which can be observed increasingly in the ferritic matrix structure at elevated silicon contents. In this research project, the local distribution of the superstructure in the ferritic matrix structure as well as its influence on failure mechanisms and fracture behaviour will be fundamentally investigated and explained. For this purpose, the silicon content is to be varied in steps, since the formation of the superstructure depends essentially on the silicon gradient, which forms around a graphite nodule during solidification in the austenitic matrix. In addition, the influence of the reduction of the silicon gradient by adding alloying elements, such as aluminium, on the formation of the superstructure is to be investigated. In order to make the experimentally gained knowledge usable for further development, numerical simulation methods are used to create a microstructure model in which the influence of the metallurgical gradients in the microstructure on the failure mechanisms under mechanical stress can be mapped and predicted. The aim of the integrative simulation approach is to be able to simulate the whole process and mechanical properties for cast iron for the first time, taking into account local metallurgical gradients, and to make it usable for future developments. By combining the expertise of the two research departments in this project, a milestone in the further development of cast iron materials will be reached, which promises a clear methodological advantage over the current state of the art and allows future application-oriented high-strength cast iron developments with high fracture toughness.

球墨铸铁是一种久负盛名的材料，它因其优异的铸造性能、高回收利用率和低成本而脱颖而出，同时还提供了最佳的机械性能，这就是为什么它在许多应用中被使用。除了传统牌号外，新开发的牌号是用硅强化的固溶体，在保持高断裂伸长率的同时，具有进一步提高强度的巨大潜力。锻造零件可以用固溶强化铸铁替代，并且可以更节约资源地生产。然而，到目前为止，设计者一直不愿使用这种材料，因为它可能会表现出不可预测的脆性断裂行为，这取决于温度和载荷情况。我们自己为这个项目所做的准备工作表明，这特别与B2超结构的形成有关，随着硅含量的增加，这种超结构在铁素体基质结构中越来越多地被观察到。在本研究项目中，将从根本上研究和解释超结构在铁素体基组织中的局部分布及其对失效机制和断裂行为的影响。为此，硅含量要逐步变化，因为超结构的形成主要取决于在奥氏体基中凝固过程中围绕石墨球体形成的硅梯度。此外，通过添加合金元素，如铝，降低硅梯度对超结构形成的影响还有待研究。为了使实验所获得的知识可用于进一步的开发，利用数值模拟方法建立了一个微观组织模型，在该模型中可以映射和预测组织中的冶金梯度对机械应力下的失效机制的影响。综合模拟方法的目的是首次模拟铸铁的整个过程和力学性能，并考虑局部冶金梯度，使其适用于未来的发展。通过将两个研究部门在该项目中的专业知识结合起来，将达到铸铁材料进一步发展的里程碑，这承诺了相对于当前技术水平的明显方法优势，并允许未来开发具有高断裂韧性的面向应用的高强度铸铁。