Influence of hydrogen on the Phase Transformation behaviour of Low Transformation Temperature (LTT) alloys investigated using ED-XRD

使用 ED-XRD 研究氢对低相变温度 (LTT) 合金相变行为的影响

• 批准号: 393558612
• 负责人: Professor Dr.-Ing. Thomas Kannengießer
• 金额: --
• 依托单位: Bundesanstalt für Materialforschung und -prüfung (BAM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 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/393558612?language=en
• 关键词: Influence; hydrogen; Phase; Transformation; behaviour

Hydrogen uptake in steels can take place during manufacturing, processing and during service. This can cause a dramatic decrease of the steel's mechanical properties. Especially newly developed and high strength steels are prone to hydrogen-assisted cracking. Several models describe the mechanisms behind hydrogen-assisted cracking phenomenologically. Yet, these models are inconsistent and due to the lack of suitable measurement techniques its experimental validation is often poor. Furthermore, materials consisting of more than one phase are not considered within the established models. The planned research project focuses on two two-phase high strength steels of industrial relevance (Low Transformation Temperature Steel and Supermartensitic High Grade Steel). With help of time- and space-resolved energy-dispersive X-ray diffraction experiments, the influence of hydrogen on the phase transformation from austenite to martensite under load and the hydrogen diffusion in the two phase microstructure will be investigated in tensile tests. The varied parameters are the hydrogen concentration and the strain rate. The data analysis allows identifying the correlation between the applied load and phase-specific properties like grain size distribution, crystal structure and micro stresses. These findings allow identifying the hydrogen diffusion paths under mechanical load in the two-phase microstructure and the role of hydrogen during strain-induced phase transformation and crack initiation. The results will be compared with the existing models from literature and the models will be extended regarding the applicability for multiphase microstructures.

钢中的氢吸收可以发生在制造、加工和使用过程中。这会导致钢的机械性能急剧下降。特别是新开发的高强度钢容易发生氢致开裂。有几种模型描述了氢辅助裂化现象背后的机制。然而，这些模型是不一致的，由于缺乏合适的测量技术，其实验验证往往是穷人。此外，在已建立的模型中不考虑由多于一个相组成的材料。计划中的研究项目侧重于两种工业相关的两相高强度钢（低相变温度钢和超级马氏体高等级钢）。借助时间和空间分辨的能量色散X射线衍射实验，在拉伸试验中，氢对在载荷下从奥氏体到马氏体的相变以及氢在两相组织中的扩散的影响将被研究。变化的参数是氢浓度和应变速率。数据分析允许识别所施加的载荷与相特定性质（如晶粒尺寸分布、晶体结构和微应力）之间的相关性。这些研究结果允许识别氢的扩散路径下的机械载荷在两相微观结构和氢的作用，在应变诱导相变和裂纹萌生。结果将与现有的模型从文献中进行比较，模型将扩展多相微观结构的适用性。