Comparative study of eddy current and Barkhausen noise methods in microstructural assessment of heat treated steel parts

Journal: Nondestructive Testing and Evaluation

Publication date: 29 Apr 2014

Abstract:

The present paper describes details of the comparison on the capability of eddy current (EC) and magnetic Barkhausen noise (MBN) techniques in the assessment of different microstructures in mild steel. Read more

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Use of Eddy-Current Method for Determining the Thickness of Induction-Hardened Layer in Cast Iron

Journal: Metal Science and Heat Treatment

Publication date: 30 November 2013

Abstract:

Cast iron with globular graphite is studied after surface induction hardening. Hardness profiles of iron bars are plotted for determining the thickness of the hardened layer. Relations between the thickness of the hardened layer and the output voltage are obtained by the method of dual frequency (induced voltage and normalized impedance) for checking the applicability of the eddy current method. The correlation coefficient and the error of the evaluation of the thickness of the hardened layer are determined with the help of the relations obtained.

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Determination of presence of undesirable carbides at surface of cast iron parts using differential eddy current technique

Journal: Materials Science and Technology

Publication date: 18 Nov 2013

Abstract:

Machinability of grey cast iron parts can greatly suffer from the formation of carbide at the surface, resulting in a decrease in cutting tool life and higher production costs. Therefore, detection of the hardened layer and its hardness are the key factors in quality control and inspection processes. In the present paper, a number of metallurgical parameters (surface carbide, surface hardness and hardened depth) have been investigated using the non-destructive differential eddy current technique. The results show the high potential of the proposed method as a fast and accurate technique in inspecting and in consequent separation of undesirable parts. Read more

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Dual-Frequency Approach to Assess Surface Hardened Layer Using NDE Technology

Journal: Journal of Materials Engineering and Performance

Publication date: 15 September 2012

Abstract:

Inspection and quality control of induction hardened parts require a good understanding of the depth of the hardened layer. Traditional destructive methods to determine the case depth are considered to be costly and time-consuming. The eddy current (EC) technique is sensitive to micro-structural changes; hence, it can be used to determine the case depth based on the differences in magnetic properties between the hardened layer and the core of the specimen. In this study, identical rods of AISI 1045 mild carbon steel were surface hardened using induction hardening technique. In order to investigate the applicability of the EC technique, the relations between obtained effective and total case depths and the EC outputs (induced voltage, normalized impedance, phase angle, and their harmonic characteristics) were studied. The results show a maximum of correlation coefficient of 94% in determining case depths by EC technique.

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