The Paton Welding Journal, 2024, №07



2024 №07 (03)

DOI of Article 10.37434/tpwj2024.07.04

2024 №07 (05)

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The Paton Welding Journal, 2024, #7, 22-28 pages

Fatigue cracks detection in the fillet zone of steel blades of industrial gas turbines using eddy current method

V. Uchanin¹, G. Nardoni², P. Nardoni²

¹G.V. Karpenko Physico-Mechanical Institute of the NASU 5 Naukova Str., 79060, Lviv, Ukraine. E-mail: vuchanin@gmail.com
²I&T Nardoni Institute, Via della Cascina Pontevica, 21, 25124, Brescia, Italy

Abstract
The results of experimental investigations aimed at the development of an effective eddy current technique for detection of fatigue cracks originated in the critical fillet zone of gas turbine blades fabricated of ferromagnetic steels are discussed. The proposed inspection technique is based on the use of selective eddy current probes (ECP) of double-differential type, providing high sensitivity when the clearance between the ECP operational surface and the inspected surface in the fillet zone is changed during the scanning. The experimental investigations signals from ECP of MDF 0501 type (operational surface diameter — 5 mm) allowed minimizing the lift-off effect by selecting the optimal operational frequency and choosing the optimal scanning parameters of the inspected zone. The effectiveness of the proposed inspection technique was confirmed with the application of a real gas turbine blade with the 2 mm long and 0.2 mm deep artificial defect in the fillet zone, which characterizes the sensitivity threshold specified in accordance with the technical assignment. The inspection technique has also been successfully used during its tests at enterprises of power engineering.
Keywords: gas turbine blade, fillet zone, eddy current ECP, operational frequency

Received: 11.04.2024
Received in revised form: 12.06.2024
Accepted: 31.07.2024

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Suggested Citation

V. Uchanin, G. Nardoni, P. Nardoni (2024) Fatigue cracks detection in the fillet zone of steel blades of industrial gas turbines using eddy current method. The Paton Welding J., 07, 22-28.

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