Improving understanding of microstructurally modified reference samples through Barkhausen noise data analysis

Magnetic non-destructive testing (NDT) method Barkhausen noise (BN) is industrially relevant technique used in quality control, particularly after manufacturing processes such as grinding, hardening or surface treatments. BN is sensitive to microstructural and stress-related changes in surface layers of ferromagnetic materials, making it valuable tool for detecting surface anomalies and residual stress variations. As with many NDT methods, BN requires reference samples for certification to ensure measurement repeatability and reliability. Traditionally, these samples are produced through mechanical or thermal treatments, but laser heating with temperature control systems has emerged as promising method creating controlled and reproducible surface modifications. Despite its advantages, the long-term stability of laser-treated reference samples has not been widely studied and needs further studies. This paper highlights reference sample production techniques, common practices in industry, and investigates long-term stability changes such as ageing effects and drift phenomena during extended use. The study discusses a simple methodology for evaluating sample usability and criteria for timely replacement of reference samples in industrial BN-based quality control. Statistical tools were needed for identification of long-term effects for monitoring sample integrity during long-term use. Possibilities for developing intelligent data management assistant for reference sample data evaluation are considered.