Non-destructive surface inspection system for steel and other ferromagnetic materials using magneto-resistive sensors

Abstract A versatile computerised magnetic surface inspection system utilising magneto-resistive (MR) sensors has been developed. An unbiased 1 mm MR element sensor mounted to a computer controlled X - Y table stage is raster scanned across the sample surface. Domain patterns and surface scribed defects have been mapped by measuring the vertical component of the stray fields present on various ferromagnetic surfaces.