非金属夹杂物三维形貌及其包裹的非夹杂物颗粒物来源分析

钢中非金属夹杂物的分离提取过程,需要解决外来因素的干扰问题,准确判断是否来源于钢中,是夹杂物检测与表征方法的重点。分析了在实验室环境下,以U75V重轨钢为代表,采用酸溶法和非水溶液电解法分离提取出钢中非金属夹杂物,利用扫描电镜对夹杂物的基本形貌和成分进行了系统的分析研究。结果表明,利用电磁搅拌装置的酸溶法能有效得到耐酸类的夹杂物形貌和成分,其最佳溶液配比为盐酸(1+1);采用非水溶液电解法能够得到耐酸类和不耐酸类的微米和纳米尺度的非金属夹杂物,电解时间控制在8～10 h。与此同时,U75V重轨钢的酸溶和电解法分析结果表明,夹杂物中存在大尺寸不规则状的颗粒物,经分析判断该类是外来的颗粒物,被定义为非夹杂物,主要来源于空气中、自来水、干燥箱和电解槽内等,其成分为MgO、CaO、SiO₂和Al₂O₃,与钢中的氧化物夹杂物成分接近,从而对生产过程中控制夹杂物的措施易造成不准确的指导。因此,在分离提取钢中夹杂物的过程中,需要严格的保护操作,杜绝不利因素的干扰,准确得到钢中夹杂物的三维形貌、尺寸、化学成分等详细信息,能够为工艺改进或实验研究提供有效的支持。

Three-dimensional morphology of non-metallic inclusions and the source analysis of wrapped non-inclusion particles

The separation and extraction of non-metallic inclusions in steel should solve the interference problems of external factors. The accurate judgment of source (whether from steel or not) is the key point for the detection and characterization of inclusions. The heavy rail steel U75V was selected for analysis under laboratory conditions. The non-metallic inclusions in steel were separated and extracted by acid dissolution method and non-aqueous electrolysis method. The morphology and composition of inclusions were systemically analyzed and characterized by scanning electron microscope (SEM). The results showed that the morphology and composition of acid-resistant inclusions could be effectively acquired by acid dissolution method equipped with an electromagnetic stirring device. The optimized solution medium was hydrochloric acid (1+1). The acid-resistant and acid-nonresistant non-metallic inclusions in micro and nano-scale could be obtained by non-aqueous electrolysis method. The electrolysis time was controlled at 8-10 h. Meanwhile, the analytical results of U75V steel by acid dissolution method and electrolysis method indicated that large-size and irregular particles existed in inclusions. The analysis revealed that these particles belonged to foreign particles, which were defined as non-inclusions. They were mainly from air, tap water, drying oven and electrolysis device, etc. Their chemical composition was mainly composed of MgO, CaO, SiO₂ and Al₂O₃, which were closed to that of oxide inclusions in steel. As a consequence, it may cause inaccurate guidance for the control strategy of inclusions during steelmaking. Therefore, the protective operation should be carried out during the separation and extraction process of inclusions in steel to avoid the interference of adverse factors. Thus, the detailed information such as three-dimensional morphology, size and chemical composition of inclusions in steel could be accurately obtained, which could provide effective support for process improvement or experimental research.