转炉直上低合金钢夹杂物检测与分析

Detection and analysis of inclusionsin low alloy structural steel of converter outbound directly casting

依据电镜面扫描、金相法及有机溶液电解法几种夹杂物检测方法的特点,配合T[O]、T[N]值检测进行辅助分析,建立针对不同粒径夹杂物(小于10μm、10~50μm及大于50μm)的系统性定性定量评价方法,应用该方法对转炉直上低合金结构钢Q355在转炉出站、氩气站出站、中包、铸坯几个工艺阶段取样并检测夹杂物数量及类型变化。实验结果表明:各工艺阶段钢中所有粒径夹杂物类型主要为MnO-SiO_(2)-Al_(2)O_(3)复合夹杂物并保持不变;在吹氩搅拌及中包流场的作用下,小型夹杂物不断聚集长大形成同类型大型夹杂物的同时所有粒径夹杂物不断上浮脱离钢液,因此整个生产过程中所有粒径夹杂物数量逐步减少,但最终在铸坯中仍有较多夹杂物存在;在夹杂物数量减少的过程中,小于10μm夹杂物的数量与T[O]数值有相同的变化趋势。

A systematic type and quantitative evaluation method for inclusions with different particle sizes(less than 10μm,10~50μm and larger than 50μm)was established based on the characteristics of several inclusion detection methods including electro-mirror scanning,metallography and organic solution electrolysis,and the auxiliary analysis was performed with T[O]and T[N]value detection.This method was applied to detect the number and type of inclusions by simpling at the low alloy structure steel Q355during the process of Converter outbound、Argon gas station outbound、tundish and slab.The experimental results show that the inclusions of MnO-SiO_(2)-Al_(2)O_(3) are mainly and unchanged in each stage;small inclusions continue to accumulate and grow up to form large inclusions of the same type while all the inclusions with particle size keep floating away from the molten steel with the action of argon blowing agitation and flow field in the tundish,so the number of inclusions of all particle size in steel decreases gradually in the whole process,However,there are still many inclusions in the slab;in the process z of inclusion reduction,the number of inclusions smaller than 10μm has the same trend as T[O]value.