Non-destructive quality control procedure for controlling thickness of hardened layer on surface of iron or steel component produced in industrial manufacturing process

摘要

The procedure comprises selection of a batch of components to be tested, from which each (2,3) is tested in a non-destructive Eddy current fashion and a destructive manner to effectively calibrate the non-destructive techniques so that it may be subsequently used to determine non-destructively the hardness layer thickness (4a) of other components. Each component (2,3) is tested at one or more positions on the hardened surface (4a) to determine the impedance components of a coil used in an Eddy current type non-destructive testing technique. The thickness of the hardened layer at the measurement points is then measured using a destructive metallurgical technique. The thickness measurements are used to determine the regression coefficients for the Eddy current measurement technique, i.e. to effectively calibrate the Eddy current measurements. The Eddy current coil may then be used on subsequent components to determine the hardness layer thickness non-destructively.