This International Standard specifies a method of measuring the total or effective thickness of thin surface-hardened layers, with thicknesses of less than or equal to 0,3 mm, obtained, for example, by mechanical (shot blasting, shot peening, etc.), thermal (flame or induction hardening, etc.) or thermochemical (carbonitriding, carburizing and hardening, etc.) treatment. It is not applicable to thin surface layers which are not continuous with the basis metal. NOTE — Surface-hardened layers with thicknesses of more than 0,3 mm are covered by ISO 2639, Steel — Determination and verification of the effective depth of carburized and hardened cases; and ISO 3754, Steel — Determination of effective depth of hardening after flame or induction hardening.