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.

中锰钢，也称为第三代先进高强度钢，具有通过热机械处理以应用为导向调整其性能的巨大潜力，马氏体是在空气冷却过程中由于锰含量高而形成的。在临界退火过程中转变为奥氏体，其稳定性通过元素重新分布（分配）而增加。在最终冷却过程中，形成的微观结构除了具有高延展性外，还具有良好的韧性。然而，相对较高的锰浓度既有利又有害。锰对氧具有高亲和力，即使在低氧分压下也会导致在热处理过程中形成氧化层。在这种几分钟退火时间相对较短的热机械处理过程中，对这些钢的氧化行为的了解主要基于工业经验，而在该项目范围内，中锰钢在 400°C 至 900°C 温度下的早期氧化行为已得到定量研究，尤其是电厂钢的长期氧化行为。需要对相关传输和相形成过程进行实验量化和描述 为了阐明 Mn、Si 和 Al 对于氧化和相形成的重要性，需要精确控制高纯度实验室熔体。氧化动力学分析、形成的氧化物相及其形态的局部识别以及氧化物和金属中浓度分布的局部和整体测定构成了数值分析的基础。基于有限差分和 CALPHAD 方法的模型，根据高纯度实验室熔体的结果，选择有限数量的工业熔体并使用通常的伴随元素生产这些钢的氧化行为。为了测试已确定机制的可转移性，在工业熔体的基础上，使用适当的过程控制来确定中锰钢可以退火并具有适合热浸镀锌的表面的程度。预期可以通过中锰钢的微观结构以及控制温度和环境气氛来经济有效地控制不同氧化物相的形成。此外，在氧化的早期阶段优先形成合适的氧化物相。最大限度地减少氧化物的形成，从而减少材料损失并改善二氧化碳平衡。