不同浇铸阶段高强钢铸坯洁净度研究

采用氧氮分析、金相法、大样电解法、扫描电镜和能谱分析等方法,对不同浇铸阶段高强钢铸坯(头坯、正常坯、尾坯)的洁净度进行研究。结果表明,与正常坯相比较,头坯和尾坯中T[O]含量均有不同程度的提高;头坯中氮含量大幅升高,而尾坯中氮含量变化很小;头坯、尾坯的显微夹杂物均有所增加,显微夹杂物主要为TiN、Al2O3-TiN和球状钙铝酸盐类复合夹杂物;头坯中大型夹杂物最多(8.77mg/10kg),尾坯次之(5.71mg/10kg),正常坯中最少(1.75mg/10kg),大型夹杂物主要为TiN、SiO2、Al2O3-SiO2和Al2O3-SiO2-CaO,另外还有少量的MgO-CaO夹杂物和含有TiO2的复合夹杂物,这些夹杂物主要来源于结晶器卷渣。

Cleanliness of high strength steel slabs in different casting stages

By means of oxygen and nitrogen analyzer, metallographic examination, SLIME, SEM, EDS, etc, the cleanliness of high strength steel slabs (first slab, normal slab and final slab) in different casting stages was studied. The results show that, compared with the T[O] and nitrogen content in the normal slab, the T[O] content in the first slab and final slab has increased obviously, the [N] content has increased substantially in the first slab yet changed little in the final slab. Compared with the normal slab, the micro-inclusions in the first slab and final slab have increased obviously, which are mainly TiN, Al₂O₃-TiN and spherical calciumaluminum composites. The quantity of large inclusions is maximal in the first slab, which is 8.77mg/10kg, followed by the end slab (5.71mg/10kg), and then the normal slab (1.75mg/10kg). The inclusions are mainly TiN, Al₂O₃-SiO₂, Al₂O₃-SiO₂-CaO, plus a small quantity of MgO-CaO and composite inclusions containing TiO₂. Most of large inclusions come from slag entrapment in the mould.