对惰性气体熔融热导法测定钢中氮量的不确定度来源进行了详细分析,对测定过程中的主要不确定度分量(样品称量、标准物质、测量重复性、仪器分辨率和仪器校准等)进行了合理评定,最后以合成标准不确定度乘以95%置信概率下的扩展因子2获得测量结果的扩展不确定度.在对不确定度评定过程中,发现标准物质和测量重复性对合成标准不确定度的影响最大,所以在工作中要特别注意选择合适的标准样品进行曲线校正,并要重复测定后计算结果.%The uncertainty source for the determination of nitrogen in steel by inert gas fusion-thermal conductivity method was detailedly analyzed. The main uncertainty components in determination process ( sample weighing, certified reference material, measurement repeatability, instrumental resolution ratio and calibration) were reasonably evaluated. The expanded uncertainty of measurement results was obtained through multiplying the combined standard uncertainty by 2 (expanded factor under confidence probability of 95 ％). During the evaluation process of uncertainty, it was found that the certified reference material and measurement repeatability had the highest influence on the combined standard uncertainty. Therefore, the selection of proper standard sample curve calibration should be paid much attention in measurement, and the results should be calculated after repeated determination.
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