基于相控技术的钢板电磁超声检测方法

摘要

In order to improve the electromagnetic ultrasonic echo signal in the steel plate,an electromagnetic ultrasonic detection method for steel plate based on phase control technique was proposed.The phase control focusing technique and the transduction mechanism of electromagnetic ultrasonic transducer in steel plate were studied,and the excitation transducer array was composed of multi array elements.With the time delay rule,the equiphase superposition of ultrasonic was achieved in the target area,and the ultrasonic focusing was realized.In addition,the experimental verification was carried out on Q235 steel plate with the discrete structure.The results show that the proposed method can effectively compensate the phase deviation caused by the sound path difference between exciting and receiving transducers.When the excitation voltage is consistent,the amplitude of the echo signal received at 658 mm from the transducer array increases as 2 times as that of echo signal with the single excitation of central transducer.With the three-element excitation transducer array detection method,the ultrasonic focusing of defects can be realized.Furthermore,the amplitude of defect echo signal at 520 mm increases as 1.83 times as that of echo signal with the single excitation of central transducer.%为了提高钢板中电磁超声回波信号，提出了一种基于相控技术的钢板电磁超声检测方法．研究了相控聚焦技术和钢板中电磁超声换能器的换能机理，通过多阵元组成激发换能器阵列，运用延时法使超声波在目标区等相位叠加，实现超声波聚焦，并在 Q235钢板上采用分立式结构进行实验验证．结果表明：该方法有效弥补了收发换能器间声程差引起的相位偏移，激励电压一致时，658 mm处接收的回波信号幅值提高为中心换能器单独激发时的2倍；采用三阵元激励换能器阵列检测方法可实现缺陷处的超声波聚焦，520 mm 处缺陷回波幅值提高为中心换能器单独激发时的1.83倍．