Study ot the stress corrosion cracking in the weld seam of low alloyed steels with particular regard to the steel T24

低合金钢焊缝应力腐蚀开裂研究，特别是T24钢

• 批准号: 257480435
• 负责人: Professor Dr.-Ing. Wolfgang Tillmann
• 金额: --
• 依托单位: Lehrstuhl für Werkstofftechnologie (LWT)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/257480435?language=en
• 关键词: Study; ot; stress; corrosion; cracking

Under certain operational conditions (combination of mechanical and corrosive loading at temperatures in the range from 120 to 250°C), an unwanted stress corrosion cracking (SCC) in the region of the weld seams is observed in the steel 7CrMoVTiB10-10 (T24). Within the frame of this project, the mechanisms of this crack initiation and crack propagation process and the possibility to influence using pretreatments [welding, thermal treatment, preoxidation) and the loading conditions (strain rate at monotonic deformation, parameters of superimposed cyclic loading, temperature, O2 content and pH value of the aqueous medium) are studied thoroughly. The aim of the project is the identification of microstructural, environmental and loading factors and criteria that effect the susceptibility to SCC of the material in the region of the weld seam, significantly. After the evaluation of the results, the proposers will determine suitable measures to improve the resistance of the material to SCC. Various commercial measuring as well as analytical procedures will be used for these studies (SEM, SEM-EDX analysis, nanoindentation, optical profile analysis with an infinite focus microscope, residual stress measurements using X-rays and neutrons). Additionally, test methods developed by the proposers will be adapted to the requirements of this project and employd for the studies (slow strain rate tests in high temperature water with controlled water chemistry and a simultaneous analysis of surface strain fields and acoustic signals emitted form the volume). The expected contributions to the existing knowledge and understanding of the SCC phenomena in the weld seam of the steel T24 are also of significance for other ferritic and bainitic, low alloyed and heat-resistant steels.

在某些操作条件下（在120至250°C的温度范围内的机械和腐蚀载荷的组合），在7 CrMoVTiB 10 -10（T24）钢的焊缝区域中观察到不必要的应力腐蚀开裂（SCC）。在该项目的框架内，这种裂纹萌生和裂纹扩展过程的机制和使用预处理（焊接，热处理，预氧化）和加载条件（单调变形时的应变速率，叠加循环加载的参数，温度，O2含量和水介质的pH值）的影响的可能性进行了深入研究。该项目的目的是识别影响焊缝区域材料SCC敏感性的微观结构、环境和载荷因素以及标准。评估结果后，建议者将确定适当的措施，以提高材料对SCC的抵抗力。各种商业测量以及分析程序将用于这些研究（SEM，SEM-EDX分析，纳米压痕，无限聚焦显微镜的光学轮廓分析，使用X射线和中子的残余应力测量）。此外，提案人开发的测试方法将适应本项目的要求，并用于研究（在高温水中进行慢应变率测试，控制水化学，同时分析表面应变场和声学信号）。对T24钢焊缝中SCC现象的现有知识和理解的预期贡献对于其他铁素体和贝氏体、低合金和耐热钢也具有重要意义。