TOTAL CARBON AMOUNT MEASURING INSTRUMENT AND CARBURIZED DEPTH EVALUATION DEVICE FOR FERRITIC STEEL PIPE CONTAINING CHROMIUM

摘要

PROBLEM TO BE SOLVED: To provide an instrument which accurately measures a total amount of carbon including a carburized layer of a ferritic steel pipe containing Cr.

SOLUTION: The total carbon amount measuring instrument calculates the total amount of carbon including the carburized layer of the ferritic steel pipe containing Cr from DC magnetic characteristics and includes: an electromagnet provided with an excitation coil and yokes for magnetizing a pipe wall portion of the steel pipe in an axial direction; a detection coil which is disposed between the yokes and is wound in a circumferential direction of the steel pipe to detect a magnetic flux change of the pipe wall portion of the steel pipe; a magnetic measurement part which measures the DC magnetic characteristics of the pipe wall portion of the steel pipe in accordance with a magnetic field intensity of the electromagnet and a magnetic flux density based on an integral of an output value of the detection coil; and an arithmetic part provided with prescribed data of relation between the DC magnetic characteristics of the pipe wall portion of the steel pipe and the total amount of carbon. The total amount of carbon including the carburized layer is calculated from the measured DC magnetic characteristics of the pipe wall portion of the steel pipe.

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