Контроль массовой доли кислорода в высокоглиноземистых оксидных включениях в рельсовой стали ПАО “ЧелМК” методом фракционного газового анализа

Abstract

Determination of oxygen mass content in high-aluminous inclusions is necessary for certification of rails of special function as per GOST 51685. Measurements of quality characteristics of rail products fall into the scope of state regulation and should be carried out by accredited test laboratories using standardized or certified measuring techniques. As far as standardized measuring techniques of oxygen mass content in high-aluminous inclusions are absent, there was a need to develop and certify a measurement technique. To determine the parameter, nitrogen, oxygen and hydrogen analyzer LECO ON836 together with the infrared pyrometer IS 5 are used at the PJSC “ChelMK”. Besides, special software is used for processing of measurement results obtained by phase gas analysis method and identification of oxide inclusions OxSeP, developed by the team of Baikov Institute of Metallurgy and Materials Science of the Russian Academy of Sciences under the guidance of a famous Russian scientist, professor, corresponding member of the Russian Academy of Sciences Grigorovich K.V. The main stages of measurement technique development were as follows: temperature calibration of the analyzer in case of furnace power change, calculation of calibration coefficient and displacement coefficient of the calibration chart, measurement of the total oxygen mass content in the standard sample and steel samples, processing of the obtained results using OxSeP software, calculation of oxygen mass content in high-aluminous inclusions. All stages of testing are illustrated. Metrological characteristics of the developed measurement technique have been established by using the state standard sample No. 790-75, SG-4. Normative document of the enterprise NDP MH 203–2016 “Measuring technique (method). High-aluminous oxide inclusions in steels. Oxygen mass content determination. Fractional gas analysis method” was developed based on the results of experimental studies in the PJSC “ChelMK”, metrological examination was carried out by ICRM CJSC, measuring technique (method) certification number № 01.00034/01.2061–2016. Measuring technique NDP MH 203–2016 was included into the accreditation scope of Central Analytical Laboratory of the PJSC “ChelMK”.