金属材料缺陷的电磁超声/涡流复合检测技术研究

Research on electromagnetic ultrasonic/eddy current composite inspection technology for metal material defects

电磁超声检测和涡流检测因其非接触、检测速度快、对试件表面要求低等优点而被广泛应用于金属材料的缺陷检测中,但电磁超声检测存在近表面的检测盲区,涡流检测对内部深层缺陷灵敏度不高。基于电磁超声和涡流的复合检测方法,设计了能同时满足电磁超声检测和涡流检测的复合式探头,建立了电磁超声和涡流复合检测有限元模型,并对金属试件中不同类型的缺陷进行了检测实验。仿真和实验结果表明,该复合探头不仅能快速检测表面裂纹,而且可激发出具有明显指向性的纵波,一定程度上削弱了波形转换产生的干扰波,可实现对内部缺陷的准确定位、识别,为电磁超声和涡流复合式检测技术在板材的复杂缺陷检测中的应用提供了基础。

Electromagnetic ultrasonic testing and eddy current testing are widely used in the detection of defects in metallic materials because of their obvious advantages in non-contact, fast detection speed, and low requirements on the specimen surface etc. However, there is a blind area near the surface in electromagnetic ultrasonic testing, and eddy current detection is not sensitive to the internal defects. In this paper, based on the combination of electromagnetic ultrasonic and eddy current testing, the structure of the composite probe is designed which can meet the requirements of both electromagnetic ultrasonic testing and eddy current testing. The finite element model of electromagnetic ultrasonic and eddy current testing is established, and different kinds of defects in metal specimen are tested. The simulation and experimental results show that the composite probe not only can detect the surface crack quickly, but also can stimulate the longitudinal wave with obvious directivity, weaken the interference wave generated by the waveform transformation to a certain extent, and realize the accurate positioning and recognition of the internal defects. It provides a basis for the application of electromagnetic ultrasonic and eddy current testing technology in the inspection of complex defects of plates.