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

W Chen,A.N Kalashnikov,R.E Challis,M.G Somekh

doi:10.13189/ujms.2013.010403

W Chen, A.N Kalashnikov + Show 2 more

Open Access

https://doi.org/10.13189/ujms.2013.010403

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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.

Highlights

Motivation for Development of Ultrasonic NDE for the Assessment of Steel Surface an oil or water bath quickly [1,2,3]
The estimate of the time of flight between the excitation and the echo from the interface is converted into the case depth if the longitudinal velocity of ultrasound in the hardened layer is known [7]. This technique is applicable for case depths above 10 mm [8] that is too deep for crankshafts
If the ultrasound velocity in the hardened layer changes by 1% comparing to the core, and the length of this layer(s) is about 10% of the ultrasonic pathway, the relative change in the ultrasound velocity measured for this sample will be ε v = 1% ×10% = 0.1%, (8)

Summary

Introduction

Motivation for Development of Ultrasonic NDE for the Assessment of Steel Surface an oil or water bath quickly [1,2,3]. The properties of hardness [2] These alloys depend on their chemical composition This can be most notably carbon), macrostructure (size of individual iron done by applying a set force to an indenter of a particular crystals – grains) and microstructure

Relating Ultrasonic Velocity to Surface Hardness

Assessment of Case Hardening by Measuring Two Distinct Times-of-Flight

Recorded Waveforms and Processed Results

Accuracy and Variation of the Velocity Estimates

Findings

Conclusions