METHOD FOR QUANTITATIVELY DETERMINING THE LENGTH OF A SOFT ZONE AREA OF A PARTIALLY HARDENED WORKPIECE

The invention relates to a method for quantitatively determining the length of a soft zone area (3) of a partially hardened metallic workpiece (1), which has at least one hardened (2) and one unhardened area (3), by using at least one multifrequency eddy current sensor (4). The invention is characterized in that a workpiece is displaced, while being isolated each time, relative to the multifrequency eddy current sensor (4) whereby an eddy current field generated by a multifrequency eddy current sensor (4) contactlessly interacts with the workpiece (1) in a spatially delimited manner and gives rise to eddy currents therein that, in turn, generate a measurement signal in the multifrequency eddy current sensor (4), whereby the spatially delimited eddy current field has a largest extension, which is oriented longitudinally to the workpiece surface and which is greater than a maximum extension (b) of the soft zone area (3) along the workpiece surface. In addition, a number of n workpieces are measured for calibrating purposes, whereby the measurement signals of the n workpieces are used while assuming a predetermined standard size of the soft zone width, i.e. the specified size of an extension of the soft zone area orientated longitudinally to the workpiece surface, in order to create a calibrating curve. Finally, an absolute soft zone width (b) is, while taking the calibrating curve as a basis, assigned to the measurement signals obtained from each individual workpiece (1).