用质控图法、稳健统计法和灰色系统理论评定钛合金中氢的测量不确定度

Evaluation of measurement uncertainty of hydrogen in titanium alloy using quality control charting,robust statistics and grey system theory

在实验室期间精密度测量条件下,基于钛合金标样Leco 502-881中氢的质控数据,采用质控图法、稳健统计法和灰色系统理论评定了脉冲加热惰性气体熔融-红外吸收法测量钛合金中氢的不确定度。质控图法需预先采用Anderson Darling(AD)统计量检验数据,要求质控数据符合正态性和独立性;而稳健统计-迭代法不需预先识别和剔除离群值,直接应用全部测量数据,采取多轮迭代以合理分配权重的稳健方式降低正态分布和离群值的影响,是相对于质控图法的进一步优化;质控-灰色评定法对质控数据的分布类型依赖性更小,不需进行复杂的正态性检验,评估过程更加简单。对于氢含量为(45±6)μg/g的钛合金,本文三种方法计算所得的实验室内扩展不确定度分别为5.84μg/g、6.54μg/g(算法一)、6.24μg/g(算法二)和6.12μg/g,k=2,和认可值6μg/g具有较好的一致性。

Based on the data of quality control of hydrogen in titanium alloy Leco 502-881 under the condition of laboratory intermediate precision,the uncertainty for measurement of hydrogen in titanium alloy is evaluated by pulse heating inert gas fusion-infrared absorption method using quality control charting,robust statistics and grey system theory.In order for meeting the requirements of normality and independence,quality control data need to be pretested by Anderson Darling（AD）statistics in quality control charting method.Robust statistics-iterative method does not identify in advance and eliminate outliers,but select all measurement data.Weight distribution way for the method is proved to be scientific and reasonable,which can reduce the effect of normality distribution and outliers by multi-wheel iterations.Comparison with quality control charting method,robust statistics-iterative method is further optimized.The quality control-grey evaluation method has little dependence on distribution type of quality control data.It is not necessary to conduct complicated normality test.Therefore,the evaluation process is more simple.For titanium alloy sample with（45±6）μg/g content of hydrogen,the measurement uncertainty evaluated by the three method were 5.84μg/g,6.54μg/g（first lgorithm）,6.24μg/g（second algorithm）and 6.12μg/g,k=2,which were excellent accordance with the certificated value of 6μg/g.