| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of precisely measuring the Si concentration of a steel product in no contact manner by improving a conventional eddy current process with insufficient measuring precision. SOLUTION: The relation between the set of a DC magnetizer 3 and the differential magnetic permeability of a steel product to be measured 1 is preliminarily examined, and the DC magnetizer 3 is set by a magnetic force controller 4 so as to have a certain fixed differential magnetic permeability in eddy current measurement. Prior to the measurement of the steel product with unknown Si concentration, a calibration curve for determining Si concentration from a sensor output in a differential magnetic permeability used for the measurement is formed by use of a sample with known Si concentration. In the measurement of the unknown Si concentration, the DC magnetizer is set by the magnetic force controller 4 so that the steel product to be measured 1 has a prescribed differential magnetic permeability, and the output of an eddy current sensor 2 is read by an eddy current sensor electronic circuit 5. The Si concentration is determined from the output value by use of the preliminarily formed calibration curve.
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