镁对非调质钢中组织及硫化物的影响

为了探究不同镁含量对非调质钢中组织和硫化物形态、尺寸、分布及成分的影响,采用蔡司金相显微镜、扫描电子显微镜、小样电解等方法,分析了经高温电阻炉冶炼不同镁添加量的49MnVS3非调质钢。结果表明,由于镁蒸气压较高,在实验室冶炼中大量挥发,导致钢中镁的实际平均收得率仅为3.10%;镁的质量分数为0～22×10^-6时,随着镁的质量分数的增加,钢中硫化物形态由Ⅱ类逐渐向Ⅰ类、Ⅲ类转变;钢中硫化物尺寸增大,硫化物的分布均匀性得到显著改善;钢中复合夹杂物比例明显增加,但MnS的比例出现下降;形成了细小弥散的氧化物,增加了奥氏体形核质点,具有细化组织的趋势。

Effect of Mg on microstructure and sulfide in non quenched and tempered steel

In order to explore the effects of various Mg content on the microstructure of steel as well as the morphology, size, distribution, and composition of sulfide in non quenched and tempered steel, the 49MnVS3 steels with various Mg additions were analyzed after high temperature electric resistance furnace experiments by optical microscopy, scanning electron microscopy and tiny sample electrolysis. The results show that due to a low boiling point, great amounts of Mg element was vaporized during experiments, resulting in a low yield of Mg, 31% in final samples on average; with increasing Mg mass percent from 0 to 00022%, the morphology of sulfide in steel was modified from II type to I and III type. The size of sulfide in experimental steel was increased, and its uniformity was greatly improved; the mass percent of composite inclusions was obviously increased, whereas the mass percent of MnS decreased. The great amounts of tiny and dispersed oxides increased the amount of austenite nucleation, contributing to a great tendency of gain refinement of steel.