Non-destructive radiochemical method for determining carbon concentrations in thin sheet 3% Si-Fe alloy

A non-destructive radiochemical method for determining carbon concentrations in thin sheet 3% Si-Fe has been developed. An ingot of 3% Si-Fe was doped with 14C during the melting operation, and subsequently processed to give a 0.30-mm thick sheet. Decarburising annealing conditions were controlled in order to obtain sheets having final carbon concentrations in the range 1.5 to 110 ppm. The β-radiation emanating from a thin surface layer of these sheets was found to be independent of sheet thickness, and linearly correlated to the bulk carbon content determined by the Leco carbon analyser, in the range 1.5 to 110 ppm. The radiochemical method is more sensitive for carbon concentrations below 20 ppm than techniques which rely on sample combustion. (author)