Detection of quenching cracks in 100Cr6 bearing steel by the eddy current method

Abstract

The article describes the research results in the identification and location of hardening cracks in 100Cr6 bearing steel using a proprietary control and measurement device for non-destructive testing using the eddy current method, Wirotest M2, and the automatic AutoWir-S1 station. A contact head with a frequency of 861 kHz was used for testing. The system recorded changes in voltage amplitude and resonance frequency. A clear decrease in the values of both parameters indicated the presence of discontinuities. The edge effect caused an increase in the voltage amplitude and a decrease in frequency, but these changes did not affect the detection of cracks. The smallest crack detected had a maximum width of approximately 20 µm and was invisible to the naked eye. The obtained surface charts clearly illustrate the course and location of individual discontinuities.

Keywords

• NDT
• non-destructive testing
• eddy current method
• quenching
• detection of cracks