高速漏磁检测饱和场建立过程及影响因素研究

在高速漏磁检测过程中,随着检测速度增加,有效磁化时间减少,导致被测构件饱和场无法建立,影响磁化效果。采用方波激励模拟外磁场瞬变情况,建立瞬磁场作用下钢管内部磁场响应模型,对钢管内部饱和场建立过程及影响因素进行研究;分析高速漏磁检测时缺陷漏磁场特征,利用有限元方法计算磁场强度和钢管材质对磁化滞后时间及缺陷检测的影响;设计高速漏磁检测实验平台,对不同运行速度和不同外磁场强度下钢管缺陷进行实验研究。结果表明,外磁场瞬变时,钢管内壁中心磁场明显滞后于外磁场,钢管内部饱和场建立时间与磁场强度和材料电导率有关,提高外磁场强度,可快速建立饱和场,减弱磁化滞后时间和涡流效应影响,提升缺陷检测效果和漏磁检测速度,实验结果和理论分析具有很好的一致性。

Study on the establishment process and influence factors of high speed magnetic flux leakage testing

During the high speed magnetic flux leakage testing, the effective magnetization time decreases with the testing speed increase. It may lead to the non magnetic saturation of the measured component. The magnetization effectiveness could be affected. To solve this problem, the square wave excitation is used to simulate the external magnetic field transients. The internal magnetic field response model of the steel pipe under the transient magnetic field is formulated. The formulation process and influencing factors of the internal saturation field of the steel pipe are studied. The features of the defect leakage magnetic field during high speed magnetic flux leakage detection are analyzed. By using finite element analysis, the influences of magnetic field intensity and steel pipe material on magnetization lag time and defect detection are calculated. The high speed magnetic flux leakage testing platform is designed. Experimental research on the steel pipe defects under different operating speeds and external magnetic field strengths are investigated. Results show that the central magnetic field of the inner wall of the steel pipe obviously lags behind the external magnetic field when the external magnetic field transients. The internal saturation field of the steel pipe is related to the magnetic field strength and the material conductivity. When the intensity of the external magnetic field is increased, the saturation field can be quickly established. Meanwhile, the defect detection effect and magnetic flux leakage detection speed can be improved. There is a good consistence between experiment results and theoretical analysis.