试样表面碳对红外吸收常规法测定钢中超低碳影响的研究

GB/T 20123-2006高频感应-红外吸收法（常规法）因表面碳影响，仅适用于钢中碳含量大于0.005%的测定，不能满足大生产过程中钢中超低碳测定的需求。研究表明：日常制取后直接测定的生产试样表面碳是吸附碳，标准样品试样表面碳除含吸附碳外，还含化合碳。国家标准GB/T 20126-2006（预热法）定值的标准样品事先预热冷却后用于常规法校正，可有效消除表面碳对钢中超低碳常规法测定的影响，使常规法能应用于超低碳钢日常测定。

Influence of surface carbon of sample on the determination of ultra-low carbon in steel by infrared absorption routine method

Due to the influence of surface carbon, high frequency induction-infrared absorption method (conventional method) (GB/T20123-2006) was only applicable to the determination of carbon higher than 0.005% in steel. It could not meet the determination requirements of ultra-low carbon in steel in large-scale production process. The research results showed that the surface carbon on production sample after daily preparation for direct determination was adsorbed carbon. The surface of standard sample contained both adsorbed carbon and combined carbon. The standard sample certified by GB/T 20126-2006 (preheating method) was preheated and then cooled for conventional calibration, which could effectively eliminate the effect of surface carbon on determination of ultra-low carbon in steel by conventional method. Therefore, the conventional method could be also used in the routine determination of ultra-low carbon in steel.