Experimental investigation for the theory of environment assisted cracking on local environmental conditions

一个基于电影断裂/滑动分解机制的理论公式是由这个项目的调查员负责人提出的。However，它很难评估裂缝增长率，因为它是机械、金属、环境及其相互作用参数的多样性。对当地条件周围裂缝提示的测量需要以包括理论公式中的参数，以确定当地环境条件的定量信息是最重要的。确切地说，这个项目是从1997年开始的，主要的成就可以归结为后续。（1）也可以通过微采样系统的改进从50μL减少到2μL，但仍然需要减少采样量。一种新颖的采样方法是在本研究中开发的，优化也得到了执行。Maximum resolution could be improved to about 5 ppb of Cly D1-Y D1 and SO Y D32-（/）4 Y D3。The Experim ... More 在高温、高压水环境中，对该特殊物质进行了两种低合金和不锈钢的性能进行了改进。（2）表面薄膜形成的局部物理属性被原子力显微镜和磁性力显微镜测量到局部活性环境，并且它被切断了，使电影的电和磁性属性可以在不同的环境中改变。原位接触电耐药性（CER）测量是在高温、高压水的情况下进行的，作为表面薄膜的局部物理特性的原位局部测量。结果显示了该电影对腐蚀潜力、温度和材料的CER的影响。（3） Results showed that the parameter“m”for dissolution characteristics of new bare surface was very important， which depends strongly on crack tip solution chemistry。在参数上“m”was taken into account in the theoretical formulation中的影响。未知的参数是通过反向分析发现的。理论分析的结果与实验结果达成了良好的协议。Less（低）

A theoretical formulation of crack growth rate based on the film rupture/slip dissolution mechanism was proposed by the head of investigators of this project. However, it is difficult to evaluate crack growth rate quantitatively because of diversities of mechanical, metallurgical, environmental and their interaction parameters. Measurements of local conditions around crack tip were required for the parameters included in the theoretical formulation, aiming which quantitative information of the local environmental condition was the most important. Accordingly, this project was started from 1997 and main achievements can be summarized as follows.(1) Although the sampled volume could be reduced from 50μL to 2μL by the improvement of the micro-sampling system, it was still needed to reduce the sampled volume. A novel sampling method was developed in this study and optimization was performed. Maximum resolution could be improved to about 5ppb of ClィイD1-ィエD1 and SOィイD32-(/)4ィエD3. The experim … More ents mentioned above was performed on the specimens made of both low alloy and stainless steels in high temperature, high pressure water environments.(2) Local physical properties of surface film formed due to the local active environment were measured by atomic force microscope and magnetic force microscope, and it turned out that electrical and magnetic properties of films could be changed in different environment. In-situ contact electric resistance (CER) measurements were performed in high temperature, high pressure water as an in-situ local measurement of local physical properties of surface film. Results showed that CER of the film depends on corrosion potential, temperature and materials.(3) Results showed that the parameter "m" for dissolution characteristics of new bare surface was very important, which depends strongly on crack tip solution chemistry. The effect of crack tip strain rate on parameter "m" was taken into account in the theoretical formulation. Unknown parameters were obtained by inverse analysis. The results of theoretical analysis were in good agreement with experimental results. Less