Patent ID: 7423423

Claim:
A method for quantitatively determining a width of a soft zone area of a partially hardened metallic workpiece, which has at least one hardened and one unhardened area, with at least one multifrequency eddy current sensor, wherein: a single workpiece is individually moved relative to the multifrequency eddy current sensor so that a spatially limited eddy current field generated by the multifrequency eddy current interacts with the workpiece contactlessly, generates eddy currents therein which generate a measuring signal in the multifrequency eddy current sensor, in which the spatially limited eddy current field has a greatest extension along a longitudinal direction of a surface of the workpiece, the greatest extension of the eddy current field being greater than a maximum extension of the soft zone area along the longitudinal direction of the surface of the workpiece; and measuring a number n of workpieces for calibrating purposes, using the measuring signals of the n workpieces to plot a calibration curve using a predetermined standard size of a width of the soft zone with a desired size of an extension oriented in a longitudinal direction of the soft zone area of the n workpieces, and assigning an absolute soft zone width to the measuring signals based on the calibration and which are obtained from each individual workpiece.