Experimental Ultrasonic Assessment of Steel Induction Hardening by Measuring Two Distinct Times-of-Flight

Abstract

Ultrasonic NDE of case hardening of steel parts presents an attractive alternative to destructive assessment still used in industry. This experimental study showed that the ultrasonic assessment could be conducted by measuring two average times of flight across different dimensions of a hardened test sample. The consistently observed difference in the corresponding average ultrasound velocities was above the estimated accuracy of the measurements, and the scattered individual calculated values formed distinct clusters. The results were obtained by using a high resolution data acquisition instrument with the equivalent sampling frequency of 1.5 GHz and 512 averages, and differential measurements of the time of flight by determining zero crossings of the echo waveforms.

Waveform acquisition with resolutions exceeding those of the ADCs employed

“…Examples of using acquired ultrasonic waveforms for quality control of hardened steel samples are presented in [52]. This application required substantial values for both N A and N I because high ultrasound attenuation in the steel samples lowered the input SNR, and the ultrasound velocity needed to be estimated with rather high resolution [52].…”

“…Examples of using acquired ultrasonic waveforms for quality control of hardened steel samples are presented in [52]. This application required substantial values for both N A and N I because high ultrasound attenuation in the steel samples lowered the input SNR, and the ultrasound velocity needed to be estimated with rather high resolution [52]. The TDR measurements discussed in [48,Section 4] were characterised by quite low additive noise and they required high time domain resolution, thus, resulting in lower N A but higher N I .…”

Pulsed eddy current and ultrasonic data fusion applied to stress measurement

“…Since each NDE method just can measure one of those physical properties, and no NDE technology can measure all the properties related to the desired feature, their results are imperfect, ambiguous and somewhat unreliable. This study will try to allay this problem [3][4][5][6][7].…”