This Standard specifies the infrared absorption method after combustion among the determination methods of carbon content of iron and steel. This method is applicable to the determination of carbon content (mass fraction) in iron and steel in the range of 0.001 % or over to and including 5.0 %. When using the working curve of reagent or reference solution, it is applicable to the determination in the range of 0.003 % or over to and including 4.5 % in mass fraction.