地磁场在缺陷微磁检测中的作用分析

Analysis of Effect of Earth's Magneitc Field in Micromagnetic Testing

地磁场在缺陷微磁检测中的作用是实现微磁检测定量化的理论基础;通过微磁学理论分析地磁场反复磁化铁磁性物质的物理过程,由于磁畴壁的移动,在缺陷区产生固定磁畴结点,固定磁畴结点内的磁场在缺陷处发生泄漏,形成可识别的缺陷信号,固定磁畴结点一旦产生其磁场强度远大于地磁场,地磁场对缺陷微磁检测的影响只会改变检测信号的幅值,不会改变缺陷信号的特征,揭示了缺陷磁场失而复得的原因,同时实验验证了地磁场在应力致磁效应中起到偏置磁场的作用,为在役设备微磁检测奠定了理论基础。

The effect of geomagnetic field is the theoretical basis of micromagnetic quantitative testing. It was proposed from the point of micromagnetics that fixed domain node was formed in the defect area of the ferromagnetic materials by repeated geomagnetic magnetization, and because of the leakage of its magnetic field, the defect was tested and distinguished. When the fixed domain node was formed, its magnetic strength will be greater than the earth＇ s magnetic field, so the earth＇ s magnetic field only influenced on the amplitude of the testing signal, and didn＇ t change the features of the defect signal, which revealed the cause of defect magnetic restoration, and the test results confirmed that geomagnetic has the bias effect in stress induced magnetic effect, which gives the theory resource for on line micromagnetic testing.