Non-destructive Surface Integrity Evaluation of Nickel-Based Superalloys Using Eddy Current Testing

Research and Review Journal of Nondestructive Testing, vol. 3

Abstract

Manufacturing aerospace engine components requires extensive development and rigorous testing, often involving numerous experiments and destructive analyses that lead to high costs and significant material waste. Surface Integrity (SI) in low-pressure aero-engine regions is a critical quality factor, predominantly influenced by thermo-mechanical loads during manufacturing and the prior processing history of semi-finished products. Traditionally, SI assessment relies on destructive post-production testing, limiting efficiency and resource utilization. This paper demonstrates that high-frequency eddy current technology can non-destructively quantify changes in residual stresses and phase contributions in nickel-based superalloys by calibrating electrical conductivity. Controlled variations in SI characteristics were induced using a laser heat treatment process. Calibration of high-frequency eddy current signals against these variations revealed a strong correlation between electrical conductivity and the microstructural changes associated with residual stress and phase alterations. The findings indicate that this non-destructive evaluation method is promising for real-time, in-process monitoring of SI, potentially reducing reliance on costly and wasteful destructive testing in aerospace component manufacturing.

Authors 7

1. Jakob Lötfering Aachen Manufacturing Technology Institute MTI

   RWTH Aachen University

   Affiliation as printed

   Manufacturing Technology Institute MTI of RWTH Aachen University , Aachen , Germany;

2. Martin H. Schulze

   Fraunhofer Institute for Ceramic Technologies and Systems

   Affiliation as printed

   Fraunhofer IKTS , Dresden , Germany;

3. Till Schulze

   Fraunhofer Institute for Ceramic Technologies and Systems

   Affiliation as printed

   Fraunhofer IKTS , Dresden , Germany;

4. Stefan Gräfe Aachen Fraunhofer-Institut Für Produktionstechnologie IPT

   Fraunhofer Institute for Production Technology IPT

   Affiliation as printed

   Fraunhofer-Institut für Produktionstechnologie IPT , Aachen , Germany;

5. Markus Meurer Aachen Manufacturing Technology Institute MTI

   RWTH Aachen University

   Affiliation as printed

   Manufacturing Technology Institute MTI of RWTH Aachen University , Aachen , Germany;

6. Henning Heuer

   Fraunhofer Institute for Ceramic Technologies and Systems

   Affiliation as printed

   Fraunhofer IKTS , Dresden , Germany;

7. Thomas Bergs Aachen Fraunhofer-Institut Für Produktionstechnologie IPT Manufacturing Technology Institute MTI

   RWTH Aachen University · Fraunhofer Institute for Production Technology IPT

   Affiliation as printed

   Fraunhofer-Institut für Produktionstechnologie IPT , Aachen , Germany;

   Manufacturing Technology Institute MTI of RWTH Aachen University , Aachen , Germany;