摘要
Abstract
To address the non-magnetic properties of austenitic stainless steel and conventional flexible printed circuit board(FPCB)coils in eddy current detection,the frequency optimization method of eddy current testing based on FPCB laminated structure coil is adopted for collaborative detection of surface and near surface defects of 304 austenitic stainless steel plate.A dual-stacked FPCB array probe with one excitation coil and four receiving coils was designed,whose excitation and receiving coils feature a stacked structure,doubling the number of turns.A four-channel detection platform was established,and the current-carrying capacity of the excitation coil was estimated using empirical formulas,confirming the reliability of the excitation signal under a 5 V sinusoidal wave.Based on skin effect theory,combined with eddy current penetration depth simulations and frequency influence experiments,the optimal detection frequencies for surface and subsurface defects were determined as 120 kHz and 18 kHz,respectively.After wavelet denoising preprocessing,defect features were extracted through time-domain(amplitude difference and root mean square difference)and frequency-domain(main frequency peak shift)analyses.Experimental results demonstrate that the array probe stably detects surface defects with a depth of 0.5 mm and subsurface defects at 1 mm depth.Notably,the C2 and C3 receiving coils,exhibiting enhanced magnetic field reception capabilities,achieved detection of surface defects as shallow as 0.2 mm and subsurface defects at 3 mm depth.This research provides theoretical foundations and technical support for online inspection of austenitic stainless steel components.关键词
奥氏体不锈钢/涡流检测/双频优化/表面及近表面缺陷/双叠层FPCB阵列探头Key words
austenitic stainless steel/eddy current detection/dual-frequency optimization/surface and subsurface defects/dual-stacked FPCB array probe分类
矿业与冶金
