Based on the difference of precipitation amount and solid solution quantity of niobium in various processes,the quality and property of steel can be improved by adding niobium.Therefore,the analysis of niobium precipitates in steel had important significance to study the strengthening mechanism of niobium in steel and improve the process.The precipitates from niobium microalloyed steel was extracted in 50 g/L potassium chloride and 10 g/L citric acid solution by constant-current electrolysis at 0.05 A/cm2 in range of 5-10 ℃.The polycarbonate filtration membrane and extracts were treated by microwave digestion using aqua regia and sulfuric acid as solvent.Tartaric acid was added as complexing agent to inhibit the hydroly-sis of niobium.The content of niobium compounds in steel was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES).The results showed that the polycarbonate filtration membrane and extracts could be completely dissolved by microwave digestion.The addition of 5 mL of tartaric acid (200 g/L)was enough to fully complex niobium.Nb 316.340 nm with little interference was selected as the analytical line.The treatment method of calibration curve was same with that of sample to eliminate the negative factors such as physical interference.The correlation coefficient of calibration curve was higher than 0.9997,and the detection limit of method was 0.0062 mg/L.The content of niobium compounds in three steel samples was determined,and the relative standard deviations (RSD)were less than 0.12%. The determination results were consistent with those obtained by national standard method GB/T 223.40—2007.The proposed method was applicable for the extraction and determination of niobium com-pounds in niobium microalloyed steel,and the results were reliable.%向钢中添加铌元素,利用其在不同工艺下析出量与固溶量的不同,可以改善钢材质量与性能.因此分析钢中析出铌对于研究铌在钢中的强化机理、改进工艺具有重要意义.用50g/L氯化钾+10g/L柠檬酸的水溶液,在5~10℃下以电流密度0.05 A/cm2进行恒电流电解提取铌微合金化钢中析出物,以王水、硫酸作为溶剂对聚碳酸酯滤膜和提取物进行微波消解处理,加入酒石酸作为络合剂抑制铌的水解,以电感耦合等离子体原子发射光谱仪(ICP-AES)测定钢中化合铌含量.研究表明,通过微波消解仪可以将聚碳酸酯滤膜和提取物完全溶解,加入5 mL酒石酸溶液(200g/L)即可达到完全络合铌的目的.以干扰较少的Nb316.340 nm为分析谱线,并使校准曲线和试样在处理方式上保持一致以消除物理干扰等不利因素.校准曲线线性相关系数大于0.9997,方法检出限为0.0062 mg/L.对3个钢种的化合铌含量进行测定,相对标准偏差在0.12%以内;并与国家标准方法GB/T 223.40—2007进行比对,结果相符.实验方法可以满足对铌微合金化钢中化合铌的提取与测定,结果可靠.
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