CARBURIZING SENSING METHOD

[Problem] To provide a carburizing sensing method with which it is possible to sense minute carburizing which cannot be easily sensed with existing carburizing sensing methods. [Solution] The present invention comprises: inserting a carburizing material (PO) which is known to give off carburization in an inner surface of a pipe into an excitation coil (11) and a detector coil (12), and establishing the value of a parameter (K) which is represented with the formula (1) below with the current value of the exciting current which passes through the excitation coil designated I(A), the length of the excitation coil designated L(mm), the number of turns of the excitation coil designated N, and the frequency of the excitation current which passes through the excitation coil designated F(kHz), such that it is possible to detect carburization which arises in the carburizing material based on an output signal from the detector coil; and thereafter, setting the conditions of the excitation coil such that the value of the parameter (K) may be obtained, and then sensing the presence of carburization on the inner surface of the pipe which is to be inspected. K = (I N/L) F-3/2 (1)