| 摘要 |
PROBLEM TO BE SOLVED: To remarkably reduce a burden on preliminary creation of a calibration curve in surface depth measurement using a potentiometric method.SOLUTION: A hardening depth measuring device 10 relating to the invention comprises: a power source 11 that supplies current I to two current proves 22 and 23 to be arranged in contact with a surface 31 of a steel material 30; a potentiometer 12 that measures a potential difference Vd between two detection probes 24 and 25 to be arranged in contact with the surface 31 of the steel material 30; and a control section 13 that calculates hardening depth D of the steel material 30 on the basis of the potential difference Vd between the detection probes 24 and 25 which occurs when the current I flows between the two current probes 22 and 23. The control section 13 includes means that preliminarily creates a calibration curve, which shows a relationship between the hardening depth D of the steel material 30 and the potential difference Vd between the two detection probes 24 and 25, from the hardening depth D of a test piece of the steel material 30 whose hardening depth D is known, a resistivity &rgr;of a hardened layer 32 and a resistivity &rgr;of an unhardened layer 34. |
