NON-DESTRUCTIVE EVALUATION OF ION-NITRIDED AND CARBONITRIDED LAYERS ON BH11 AND D2 TOOL STEELS: EDDY CURRENT TESTING AND BARKHAUSEN NOISE METHODS

Authors

  • Velichko Machev Department of Materials Science, Todor Kableshkov University of Transport, Sofia, Bulgaria
  • Viktor Georgiev Department of Materials Science, Todor Kableshkov University of Transport, Sofia, Bulgaria

DOI:

https://doi.org/10.68302/std2026.vol2.143

Keywords:

Barkhausen noise, eddy current testing, ion nitriding, nitrocarburising, non-destructive testing, tool steels

Abstract

This paper systematises the destructive reference characteristics of ion-nitrided and carbonitrided layers on BH11 (4CrSMoVSi, VS4659) and D2 (Cr12MoV) tool steels produced in glow-discharge plasma at 550 °C and ∼400 Pa, and investigates their suitability for calibrating and validating non-destructive testing (NDT) methods. Two principal NDT techniques are examined—eddy current testing (ECT) and the Barkhausen noise method (BNM)—whose complementary depth sensitivity enables simultaneous estimation of effective case depth (δ, 55–145 µm) and surface hardness (1150–1300 HV₀.₁). Concrete calibration procedures, an integrated inline station concept, and a validation strategy including statistical process control (SPC) are proposed. Multi-frequency ECT (50–200 kHz) proves most sensitive to total diffusion-zone depth, while BNM (50–200 Hz magnetisation) captures near-surface hardness changes. A combined data-fusion model reduces MAE in δ estimation to ±10–15 µm and provides reliable OSZ classification (accuracy > 92 %).

Supporting Agencies

The authors thank the staff of the Heat Treatment Laboratory – TU -Sofia, Plovdiv for specimen preparation and destructive testing. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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References

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Published

17.09.2026

Issue

Vol. 2 (2026): Proceedings of the International Conference on Secure Systems Design and Technology Development.

Section

ENGINEERING SCIENCES AND PRODUCTION TECHNOLOGY

License

Copyright (c) 2026 Velichko Machev, Viktor Georgiev

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

How to Cite

[1]
V. Machev and V. Georgiev, “NON-DESTRUCTIVE EVALUATION OF ION-NITRIDED AND CARBONITRIDED LAYERS ON BH11 AND D2 TOOL STEELS: EDDY CURRENT TESTING AND BARKHAUSEN NOISE METHODS”, SysTechDev, vol. 2, pp. 173–176, Sep. 2026, doi: 10.68302/std2026.vol2.143.