EMAT, which is based on magnetostrictive effects, was employed to detect flaws in a sample with surface oxide scale. Chromium molybdenum steel (SCM415) was annealed at 600C to 900C from two to eight hours and subjected to EMAT to survey its signal properties. Oxide scales has ferromagnetism. The data from these samples were compared to an actually used samples. The EMAT signal derived from the actual sample was found to be too noisy due to Barkhausen effect to identify reflections from internal flaws and to reconstruct flaw images in a computer. This study proposes spectrum analysis and statistical methods based on noise probability to decrease this noise.

Date Published: 1 April 2010
PDF: 9 pages
Proc. SPIE 7647, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 76474K (1 April 2010); doi: 10.1117/12.847962

Published in SPIE Proceedings Vol. 7647:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010
Masayoshi Tomizuka, Editor(s)