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Development of Nondestructive Evaluation System Using the Excitation Type High Sensitivity Magnetic Sensor to Ddetect Fatigue Damage of Metallic Material

激励式高灵敏度磁传感器检测金属材料疲劳损伤无损评价系统的研制

基本信息

批准号：
15560371
负责人：
OKA Mohachiro
金额：
$ 2.43万
依托单位：
Oita National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

In this project, we have elucidated the following results for the evaluation of fatigue damage in an austenitic stainless steel using the FG magnetic sensor and we developed the non-destructive evaluation system using the excitation type high sensitivity magnetic sensor to detect fatigue damage of metallic material.In order to estimate the amount of bending fatigue damage on austenitic stainless steel plates, we have investigated the relationship between plane bending stress and residual magnetization caused by martensitic structure in austenitic stainless steel plates. Magnetic flux density in the Z component caused by residual magnetization at 1 mm above a specimen is measured by using a high sensitivity thin-film flux-gate magnetic sensor.The eddy current probe which is a new magnetic sensor to detect fatigue damage on austenitic stainless steels consists of an excitation coil and two pick-up coils wound on a ferrite core. The size of the EC probe is 10 mm x 4 mm x 8 mm.Results of this project are shown as follows:1) The value of B_<zmax> clearly increases with the increase of the bending stress (σ_a) and N.2) The value of B_<zmax> is a useful parameter to estimate the amount of fatigue damage.3) We could detect the small leakage magnetic flux density on the specimens such as SUS304, SUS304L, SUS316 and SUS316L caused by the residual magnetization by using the FG magnetic sensor.4) The residual magnetization in SUS316 series is about ten times smaller than SUS304 series.5) This new eddy current probe was surely able to catch the change in electromagnetic properties such as magnetic permeability caused by the transformation from austenite to martensite in SUS304.6) The value of Rc_<max> obviously depends on the number of stress cycles.

在本项目中，我们阐明了利用FG磁传感器对奥氏体不锈钢疲劳损伤进行评估的结果，并开发了利用激励型高灵敏度磁传感器对金属材料疲劳损伤进行无损评估的系统。为了估计奥氏体不锈钢板的弯曲疲劳损伤量，研究了奥氏体不锈钢板中马氏体组织引起的平面弯曲应力与残余磁化强度的关系。采用高灵敏度薄膜磁通门磁传感器测量试样上方1mm处残余磁化引起的Z分量的磁通密度。涡流探头是一种用于检测奥氏体不锈钢疲劳损伤的新型磁传感器，它由一个励磁线圈和两个绕在铁氧体铁心上的拾取线圈组成。结果表明：1)B_<zmax>值随弯曲应力（σ_a）和n的增大而明显增大；2)B_<zmax>值是估计疲劳损伤量的一个有用参数。3)利用FG磁传感器可以检测到SUS304、SUS304L、SUS316、SUS316L等试样由于残余磁化而产生的小漏磁密度。4) SUS316系列的剩余磁化强度比SUS304系列小十倍左右。5)这种新型涡流探头确实能够捕捉到SUS304.6中由奥氏体向马氏体转变所引起的电磁性能的变化，如磁导率的变化。