| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of non-destructively and accurately measuring the carburization depth on the inner surface of a steel pipe. SOLUTION: This method of measuring the carburization depth of the steel material having front and back surfaces (hereinafter, respective surfaces are called "first surface" and "second surface") comprises a process 1 of measuring carbon concentration C<SB>o</SB>on the first surface of the steel material, a process 2 of measuring total carbon content A<SB>Ct</SB>from the second surface to the first surface of the steel material, and a process 3 of determining the carburization depth d<SB>i</SB>of the second surface of the steel material based on the expression: d<SB>i</SB><SP>2</SP>=2äA<SB>Ct</SB>-(C<SB>o</SB>-C<SB>b</SB>)<SP>2</SP>/(2×K<SB>o</SB>)+C<SB>b</SB>×t}/K<SB>i</SB>. In this expression, d<SB>i</SB>is carburization depth (mm) of the second surface of the steel material, A<SB>Ct</SB>is total carbon content (g) from the second surface to the first surface of the steel material obtained by measurement, C<SB>o</SB>is carbon concentration (mass%) on the first surface of the steel material obtained by measurement, C<SB>b</SB>is carbon concentration (mass%) of base material, K<SB>o</SB>is constant about the carburization of the first surface of the steel material, K<SB>i</SB>is constant about the carburization of the second surface of the steel material, and t is thickness (mm) of the steel material. COPYRIGHT: (C)2009,JPO&INPIT
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