Application of Austempered Ductile Iron in Hydraulic Components with Dynamic Loads

等温淬火球墨铸铁在动载荷液压元件中的应用

• 批准号: 289765656
• 负责人: Professor Dr. Winfried Petry
• 金额: --
• 依托单位: Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II)
• 依托单位国家: 德国
• 项目类别: Research Grants (Transfer Project)
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/289765656?language=en
• 关键词: Application; Austempered; Ductile; Iron; Hydraulic

Austempered ductile iron (ADI) and isothermed ductile iron (IDI) are heat treated ductile irons (GJS). The heat treatment of ADI consist of the steps austenitising, quenching and isothermal austempering. During the austenitisation the austenite enriches with carbon. As the austenite partially transforms into ferrite during the isothermal austempering, the carbon enrichment of the remaining austenite increases making it stable at room temperature. IDI on the other side is intercritically austenitised followed by a controlled cooling. The cooling rate is selected in a way that pearlite forms. The microstructure of IDI therefore consist of proeutectoid ferrite and pearlite.Compared to the base material (GJS) the tensile strength or elongation of ADI can be increased by factor two or more. IDI shows mechanical properties between those of ADI and ductile iron. These materials are therefore interesting for components with hydraulic loads such as valve control clocks. As increasing hydraulic pressures along with constant design spaces are required for these components, the increase of fatigue properties is limited with standard ductile irons.The principle aim of the research project therefore is to increase the fatigue properties of components, which are exposed to dynamic oil pressures by the application of ADI. As a possible cost-effective alternative IDI will also be tested for this application.On the basis of extensive preliminary work, the heat treatment of the used materials will be characterised by neutron diffraction. The combination of preliminary work and new data allows a sound alloy decision with respect to the requirements of the demonstrator. An appropriate heat treatment strategy will be developed using static and dynamic tests. On the basis of these results ADI and IDI samples will be produced, which will be tested under hydrodynamic loads.The samples of the numerous dynamic tests will be used for the analysis of transformation of austenite to martensite under dynamic loads. The fractured samples will be analysed using metallography and diffraction in order to investigate the supposed correlation of transformation and crack propagation.

奥贝球铁（ADI）和等温球铁（IDI）都是热处理球铁（GJS）。奥贝球铁的热处理包括等温淬火、等温淬火和等温淬火三个步骤。在奥氏体化过程中，奥氏体富含碳。随着奥氏体在等温等温淬火过程中部分转变为铁素体，剩余奥氏体的碳富集增加，使其在室温下稳定。在另一侧的IDI被临界间结晶化，随后进行受控冷却。冷却速率以珠光体形成的方式选择。因此，ADI的显微组织由先共析铁素体和珠光体组成，其抗拉强度或伸长率比基体（GJS）提高两倍或两倍以上。IDI的力学性能介于ADI和球墨铸铁之间。因此，这些材料对于具有液压负载的部件（例如阀控制时钟）是有意义的。由于这些部件需要沿着增加的液压和恒定的设计空间，因此标准球墨铸铁的疲劳性能的提高受到限制。因此，研究项目的主要目的是通过应用ADI来提高承受动态油压的部件的疲劳性能。作为一种可能的成本效益替代方案，IDI也将在此应用中进行测试。在广泛的前期工作的基础上，所用材料的热处理将通过中子衍射进行表征。初步工作和新数据的结合允许根据验证机的要求做出合理的合金决定。将使用静态和动态测试开发适当的热处理策略。在这些结果的基础上，将生产ADI和IDI样品，并在水动载荷下进行试验。大量动态试验的样品将用于分析动态载荷下奥氏体向马氏体的转变。将使用金相学和衍射分析断裂样品，以研究相变和裂纹扩展的假定相关性。

项目成果

Carbon Redistribution Process in Austempered Ductile Iron (ADI) During Heat Treatment—APT and Synchrotron Diffraction Study

• DOI: 10.3390/met9070789
• 发表时间: 2019-07
• 期刊: Metals
• 影响因子: 2.9
• 作者: Xiaohu Li;J. N. Wagner;A. Stark;R. Koos;M. Landesberger;M. Hofmann;G. Fan;W. Gan;W. Petry