在利用外穿过式线圈对不锈钢管件进行涡流检测时, 发现深度分别为0.10, 0.15和0.20 mm的三种裂纹无法利用检测信号的相位角进行识别。针对这一现象, 利用阻抗分析方法进行了计算, 得出在不同检测频率下, 管件表面从0.10~1.90 mm不同深度裂纹的相位角, 以及上述无法区分的三种缺陷的幅值。在此基础上, 制作了带有人工缺陷的试样管件并对其进行涡流检测。检测结果表明, 根据检测信号幅值的大小, 可将深度差异为0.05 mm的人工缺陷区分开, 且检测结果稳定可靠。

An encircling coil had been employed to test the defects of stainless steel pipes in eddy current testing. However, the defects with depth of 0.10, 0.15 and 0.20 mm could not be distinguished with the corresponding differences in phase-angles of testing signals which was always true according to the principle of skin effects. Aiming at dealing with this problem, impedance analysis which could show the calculating phase-angles and amplitudes of simulating signal of defects was applied. We calculated phase-angles with depth of defects ranging from 010 mm to 190 mm and amplitude of three depths as shown above. The stainless steel pipes with man-made defects on the surfaces were also made for eddy current testing. The results indicated that defects of 0.10 mm could be found and depth differences of 0.05 mm could be distinguished with the amplitudes which were much more stable and reliable than the phase-angles.