Possibilities of manual eddy current testing for measuring the depth of contact-fatigue cracks of the surface of rolling rails

Abstract

The possibility of using the eddy current method to assess the depth of cracks in the surface of rolling rails in operation for planning the work of a rail grinding train is investigated. Experimental studies of the influence of the excitation frequency and the angle of inclination of the eddy current converter, the state of the surface, the depth and angle of inclination of the surface crack on the amplitude and phase of the eddy current signal are carried out. The possibilities of the amplitude-phase method of detuning from interfering factors associated with the slope of the transducer and the curvature of the controlled surface are determined. The resolution of the flaw detector was investigated when evaluating the characteristics of two or more closely spaced cracks - a defect of the "grid" type of cracks. The depth of surface cracks in the range from 0.1 to 1.4 mm was determined by metallographic examination after eddy current control. Optimal control parameters have been experimentally substantiated and a correlation between the crack depth and the projection of the signal amplitude in the direction perpendicular to the direction of change of the interfering factor - the angle of inclination of the transducer - has been established.