Oxidation phenomena of medium-Mn steels

中锰钢的氧化现象

• 批准号: 516364140
• 负责人: Professor Dr.-Ing. Ulrich Krupp
• 金额: --
• 依托单位: Institut für Werkstoffwissenschaft und Werkstofftechnik
• 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/516364140?language=en
• 关键词: Oxidation; phenomena; medium; Mn; steels

Medium Mn-steels, also referred to as 3rd generation Advanced High Strength Steels, have an extraordinary potential for an application-oriented adjustment of their properties via thermomechanical treatment. Martensite, which form during air cooling due to the high content of manganese, is transformed into austenite during intercritical annealing, the stability of which is increased by elemental redistribution (partitioning). During the final cooling, a microstructure is formed which, in addition to high ductility, also exhibits a pronounced strain hardening potential. However, the comparatively high manganese concentration is both a beneficial and detrimental. Manganese has a high affinity for oxygen, which leads to the formation of an oxide layer during heat treatment, even at low oxygen partial pressures, which in turn severly impairs the adhesion of anti-corrosion coatings. Knowledge of the oxidation behavior of these steels during such thermomechanical treatment with comparably short annealing times of a few minutes is largely based on industrial experience, whereas the long-term oxidation behavior, especially of power plant steels, has already been quantitatively investigated and is widely understood. Within the scope of this project, the early stage of oxidation of medium manganese steels at temperatures between 400°C and 900°C is to be experimentally quantified and described with regard to the relevant transport and phase formation processes. To clarify the importance of Mn, Si and Al for oxidation and phase formation, high-purity laboratory melts with a precisely controlled composition are produced and the microstructure is specifically adjusted. The analysis of the oxidation kinetics, the local identification of formed oxide phases and their morphology as well as the local and integral determination of the concentration distribution in the oxide and metal form the basis for a numerical model based on finite differences and the CALPHAD method, with which the oxidation behavior of these Steels should become predictable. Based on the results of the high-purity laboratory melts, a limited number of industrial melts are selected and produced with the usual accompanying elements in order to test the transferability of identified mechanisms. On the basis of industrial melts, the extent to which medium-Mn steels can be annealed with a surface suitable for hot-dip galvanization is determined using suitable process control. The results of the project are expected provide access to cost-effectively controlling the formation of different oxide phases through the microstructure of a medium-Mn steel and by controlling the temperature and the ambient atmosphere. In addition, preferential formation of suitable oxide phases in the early stages of oxidation, the formation of oxide is to be minimized, which reduces material loss and improves the CO2 balance.

中等MN阶梯，也称为第三代高强度钢，具有通过热力学处理对其性质进行调整的非凡潜力。在锰含量较高的空气冷却过程中形成的马氏体在中间批判性退火过程中被转化为奥斯丁岩，其稳定性通过元素再分配（分区）提高。在最终冷却过程中，形成了微观结构，除高延展性外，还表现出明显的应变硬势。但是，锰浓度相对较高既有益又有害。锰对氧气具有很高的亲和力，这在热处理过程中导致氧化物层的形成，即使在低氧部分压力下，这又又损害了抗腐蚀涂层的粘合剂。在这种热机械处理过程中，这些钢的氧化行为的了解在很大程度上基于工业经验，而短期退火时间相对短，而长期氧化行为，尤其是发电厂钢的长期氧化行为，已经进行了定量研究，并且已广泛理解。在该项目的范围内，在400°C和900°C之间的温度下，中型锰钢的氧化早期应在实验中进行实验量化和描述。阐明了Mn，Si和al对于氧化和相形成的重要性，产生了具有精确控制组成的高纯度实验室熔体，并特别调整了微观结构。氧化动力学的分析，形成的氧化物相及其形态的局部鉴定以及氧化物和金属中浓度分布的局部和积分确定，构成了基于有限差异和Calphad方法的数值模型的基础，这些方法应与这些钢的氧化行为相比可以预测。根据高纯度实验室熔体的结果，选择并生产有限数量的工业融化，并使用通常的参与元素来测试确定的机制的可传递性。根据工业熔体，使用适当的过程控制确定适合热浸镀锌的表面可以将中MN钢的退火程度。预计该项目的结果可以通过中等MN钢的微观结构以及控制温度和环境气氛来获得成本效益控制不同氧化物相的形成。另外，在氧化物的早期阶段，首选形成合适的氧化物阶段，应最小化氧化物的形成，从而减少材料损失并改善二氧化碳的平衡。