A flexible magnetic saturation pulse eddy current detection probe and detection method

Abstract

A flexible magnetic saturation pulse eddy current test probe and a test method. The probe includes a magnetic saturation coil, a pulse eddy current exciting coil and a detection coil. The magnetic saturation coil is a planar spiral coil in larger diameter, and the pulse eddy current exciting coil and the detection coil are planar spiral coils in equal diameter; the three coils are stacked together coaxially and are separated from each other by insulation layers. The stacked coils are sealed by an outer insulation layer to form the flexible magnetic saturation pulse eddy current test probe. The test method includes the steps of: applying an intensive voltage pulse signal to the magnetic saturation coil to generate an intensive magnetic field and saturate a to-be-tested ferromagnetic test piece; meanwhile, applying a low-voltage pulse signal into the pulse eddy current exciting coil which then detects a detection voltage signal, thus achieving defect detection to interior of a thick board. Compared with common pulse eddy current probe, the test probe increases detection depth on ferromagnetic materials; meanwhile, the test probe is also suitable for nondestructive testing on structures having complex surfaces; the test probe and the test method solve the problems of poor portability and poor applicability on curved surfaces in a common large-size magnetic saturation device.

Description

technical field [0001] The invention relates to an electromagnetic non-destructive testing probe and a system, in particular to a flexible magnetic saturation pulsed eddy current testing probe and a testing method. Background technique [0002] The core meltdown accident of the Fukushima nuclear power plant in Japan highlights the importance of nuclear power structure safety. In addition to the loss of full power supply that may cause the core to fail to cool and cause a core accident, the occurrence and development of defects such as local thinning of a large number of nuclear-grade pipes necessary for cooling may also lead to leakage or even major rupture of nuclear-grade pipes, which has a great impact on nuclear energy structures. security poses a serious threat. There are a large number of special parts such as flow rate measurement parts, L elbows, and T-shaped joints in nuclear-grade pipelines. Due to the complexity of the flow, thinning defects in downstream pipelin...

AI Technical Summary

Problems solved by technology

However, the existing magnetic saturation devices generally use a large-scale Helmholtz coil device or a strong static magnetic field generated by a larger electromagnet device to magnetically saturate the detected object. The large-scale Helmholtz coil device is generally fixed in the laboratory. Portability is poor, and the applicability of larger electromagnet devices to structures with complex surfaces is poor, which greatly limits the detection range of magnetic saturation pulsed eddy current probes; on the other hand, for ferromagnetic materials, traditional pulsed eddy current The probe has the following two disadvantages when realizing detection. One is that it only has high detection sensitivity for surface / near-surface defects on the same side of the probe, and poor detection sensitivity for defects on the opposite side of the probe. Second, even for defects on the same side of the probe, when When the defect depth is large, there are problems of signal saturation and quantification

As for flexible magnetic saturation pulsed eddy current probes suitable for curved surfaces, there are no relevant research reports at home and abroad.

Images