基于多级磁化的高速漏磁检测技术研究

Study on high-speed magnetic flux leakage testing technology based on multistage magnetization

高速漏磁检测过程中,有效磁化时间非常短,磁后效影响不可忽略,导致被测构件无法实现磁饱和,漏磁信号无法产生。提出一种基于多级磁化的高速漏磁检测技术,使得高速下被测构件建立饱和磁场,抑制磁后效影响。首先建立多级磁化理论模型,采用Biot-Savart定律分析了多级磁化技术机理,通过涡流效应分析了多级磁化技术对磁后效的抑制作用,利用有限元方法计算分析不同磁化结构作用下钢管内涡流分布状态及缺陷漏磁场分布情况。最后设计高速漏磁检测平台,对不同运行速度下钢管内部缺陷检测进行实验研究。结果表明,多级磁化技术可有效实现磁场叠加,提高磁场均匀性,抑制磁后效对高速磁化过程的影响,提高漏磁检测方法的检测速度,实验结果和理论分析具有很好的一致性。

In the process of high-speed magnetic flux leakage testing,the effective magnetization time is very short,and the effect of magnetic aftereffect can not be ignored. This leads to the non-magnetic saturation of the measured component,and then the magnetic flux leakage signal can not be produced. In this work,a high-speed magnetic flux leakage testing technology capable of establishing the saturated magnetic field at high-speed is proposed based on multistage magnetization,which can inhibit the effect of magnetic aftereffect.Firstly,the multistage magnetization theory model is built. Based on Biot-savart law,the mechanism of multistage magnetization is analyzed. The inhibition of multistage magnetization technology on the magnetic aftereffect is analyzed by the eddy current effect. By using the finite element analysis method,the distribution of the eddy current and the magnetic flux leakage field under the different magnetization structures are calculated. Finally,a high-speed magnetic flux leakage testing platform is designed,and the experimental study of the internal defect detection of steel pipe under different speeds is investigated. Results show that multistage magnetization technology can effectively achieve magnetic field superposition and improve magnetic field homogeneity. In further,it can inhibit the effect of magnetic aftereffect on high-speed magnetization process,and improve the testing speed of magnetic flux leakage testing method.The experimental results and theoretical analysis have very good consistence.