火花放电原子发射光谱法测定合金钢中镁

Determination of magnesium in alloy steel by spark discharge atomic emission spectrometry

在钢铁冶炼工程中,采用镁处理可以更好地控制夹杂物的形态和尺寸,因此准确测定钢中残余镁意义重大。目前相关国家标准中镁的定量限无法满足合金钢中镁的检测要求。实验采用镁质量分数为0.00005%~0.0043%的纯铁标准化样品和低合金钢国际标准样品绘制校准曲线,通过扣除干扰校正消除基体效应,实现了火花放电原子发射光谱法对合金钢中痕量镁的测定。方法的定量分析范围为0.0001%~0.0010%,检出限和定量限分别为0.000 03%和0.000 1%。采用电子探针-能谱仪对镁处理后钢坯进行了夹杂物形貌分析,发现其夹杂物尺寸比较小,主要成分为MgO、Al2O3相互包裹而成的MgO·Al2O3,酸溶性较差。选择含镁钢铁标准样品CRM 196-2和BS 4130进行方法验证,测定值与认定值吻合,相对标准偏差(RSD,n=5)为2.6%~9.2%;采用实验方法对生产试样进行分析,测定值与化学湿法结果一致。

The shape and size of inclusions can be well controlled by magnesium treatment in steel smelting process,so it is of great significance to accurately determine the content of residual magnesium in steel.At present,the quantification limit of magnesium in relevant national standards cannot meet the detection requirements of magnesium in alloy steel.The calibration curve was prepared using standardized sample of pure iron and international standard samples of low alloy steel containing 0.000 05%-0.004 3%of magnesium(mass fraction).The matrix effect was eliminated by interference deduction and correction.The determination method of trace magnesium in alloy steel by spark discharge atomic emission spectrometry was established.The quantitative analysis range of was 0.000 1%-0.001 0%.The limit of detection and the limit of quantification were 0.000 03% and 0.000 1%,respectively.The morphology of inclusions in steel billet after magnesium treatment was analyzed by electron probe-energy disperse spectroscopy.It was found that the inclusion size was relatively small.The main components were MgO and Al2O3,which were wrapped together to form MgO·Al2O3 with poor acid solubility.The certified reference materials of magnesium-bearing steel(CRM196-2 and BS4130)were used for method verification.The found results were consistent with the certified values.The relative standard deviations(RSD,n=5)were between 2.6% and 9.2%.The production sample was analyzed according to the experimental method,and the found results were consistent with those obtained by chemical wet method.