汽车用高品质非调质钢生产过程中的非金属夹杂物研究

Study on Non-metallic Inclusions of High Quality Microalloyed Forging Steel for Automobile

研究了"顶底复吹转炉炼钢-LF精炼-VD真空处理-喂硫线增硫"工艺生产高品质汽车用非调质钢铸坯的全过程,特别关注了冶炼过程中非金属夹杂物的演变规律。对冶炼过程全程提取钢样和渣样,分析了钢样和渣样的化学成分。采用SEM-EDX系统地分析了钢样中非金属夹杂物的形貌和成分。实验结果表明:采用制定工艺路线,能生产出[P]的质量分数在0.012%以下,T[O]的质量分数为10×10-6左右的非调质钢铸坯。连铸坯中观察到的非金属夹杂物绝大部分是纯MnS夹杂物,尺寸较大呈浅色不规则形状。铸坯中只存在很少量的、尺寸较小的氧化物夹杂。这些氧化物和MnS组成复合的夹杂物,呈深色在MnS夹杂物的中心,其尺寸较小约为2μm。研究表明:此工艺路线生产出的超低氧高品质非调质钢完全能满足汽车用的需要。

The manufacture process “BOF-LF-VD-CC” of microalloyed forging steel for automobile was investigated systematically, especially the formation principle of non-metallic inclusions. Steel and slag samples were taken in every stage of manufacture process, and these samples were analyzed. The morphology and composition of non-metallic inclusions in steel sample were analyzed using SEM-EDX systematically. The results show,that phosphorus content and total oxygen content in slab could be controlled below 0. 012% and around 0. 001%respectively. Most inclusions found in the slab were large pure irregular MnS. Few complex inclusions （oxide with MnS） around 2 μm were found,in which oxide was wrapped by MnS. The ultra-low oxygen microalloyed forging steel manufactured by this route could satisfy the requirements for automobile.