A Synthetic Study on the New Non-destructive Evaluation by Magnetic Measurements

目前使用的金属疲劳无损检测方法对研究材料中的裂纹和断裂是有用的。裂纹是由位错堆积产生的，位错密度局部最大。很少有调查人员在裂缝出现之前进行过无损检测。在本研究中，我们研究了位错在裂纹形核之前的无损评估。核电站，特别是压力容器，是无损检测应用的重要和迫切的领域之一。压力容器的劣化决定了核反应堆的使用寿命。由于大多数压力容器是由A533B钢制成的，本研究通过循环试验研究了A433B钢塑性变形对结构敏感性能的影响。结果表明，磁滞测量是压力容器Mate…无损检测的最佳方法岩手大学的研究小组发现了两个对位错敏感的参数。在恰好高于矫顽场H_C的低场范围内测量了磁化率，得到了X_C与H的关系：X_C=c/H^3.参数c对位错密度及其分布很敏感.参数c已获得许可(日文3158182号)。另一个参数是H_C/X_H，它对塑性变形的早期阶段很敏感。核电站使用的是SUS不锈钢，从NDE的角度来看，它是非常重要的。但磁法还没有在不锈钢无损检测中得到实际应用。研究了实际应用困难的原因，明确了金属疲劳或塑性变形产生的马氏体相与位错、孪晶等晶格缺陷并不完全对应。我们的结论是，应该找到一个直接对应于晶格缺陷的新参数，并积累大量关于磁性和晶格缺陷之间的数据。较少

The currently employed nondestructive tests for metal fatigue are, useful in the investigation of cracks and fractures in the materials. The cracks are produced by the pile of dislocations, where the dislocation density is maximum locally. Few investigators have conducted nondestructive tests before the appearance of cracks. In the present study, we investigate the nondestructive evaluation of dislocations before the nucleation of cracks takes place.One of the important and urgent areas for the application of nondestructive tests is the nuclear power station, especially the pressure vessel. The deterioration of the pressure vessel determines the life time of the nuclear reactor. Since most pressure vessels are made of A533B steel, in the present study the structure sensitive properties are investigated in connection with the plastic deformation in A433B steel by the round robin tests. The results show that the hysteresis measurement is the best method as NDE of the pressure vessel mate … More rials.The Iwate University group has found two parameters which are sensitive to dislocations. The magnetic susceptibility is measured in the low-field range just above the coercive field H_C and the relation between X_C and H is obtained : X_C = c/H^3. The parameter, c, is sensitive to dislocation density and its distribution. The parameter, c, is licensed (Japanese No. 3158182). The other parameter is H_C/X_H, Which is sensitive in the early stage of plastic deformation.SUS stainless steel is used in the nuclear power station and very important from the viewpoint of NDE.The NDE of SUS 304 stainless steel has been studied for 50 years using the Martensitic transformation. But the magnetic method has not been put to practical use of NDE in the stainless steel. The reason of the difficult practical use has been studied and it is made clear ; The Martensitic phase due to metal fatigue or plastic deformation does not exactly correspond to the lattice defects such as the dislocations and twins. We have concluded that a new parameter, which corresponds to the lattice defects directly, should be found and much data between magnetic properties and lattice defectsshould be accumulated. Less