パルス磁化後の残留磁気を利用した漏洩磁束探傷法の開発

抄録

In a flaw inspection of ferromagnetic materials by Magnetic Flux Leakage Testing (MFLT), the object to be inspected is sometimes saturated magnetically throughout the flaw inspection. This processing is used to reduce magnetic noise due to a variation of magnetic properties in ferromagnetic materials. However, the processing of the magnetic saturation throughout the flaw inspection leads to an increase in the power consumption. Therefore, we considered MFLT with pulsed magnetic saturation and found that the magnetic noise can be drastically reduced by applying MFLT after an instantaneous magnetic saturation with the pulsed magnetization. Based on the findings, we developed a novel MFLT using residual magnetism of pulsed magnetization. Detections of a flaw by the developed MFLT and the conventional MFLT (without the magnetic saturation) were conducted for a flat plate specimen made of SS400 with an artificial flaw. As the results, the signal to noise ratio of the flaw detection by the developed MFLT was enhanced 6.6 times than that of the conventional MFLT. Accordingly, the developed MFLT is expected as a new flaw inspection method for ferromagnetic materials.