含硫汽车钢中硫化物形态控制工艺实践

Process Practice of Sulfide Form Control in Sulfur-containing Automobile Steel

对含硫汽车钢中A类夹杂物超标进行分析,主要是长条状MnS硫化物形态控制较差。通过硫化物变性机理分析和[A1]-[S]热力学计算,摸索出控制硫化物形态的关键工艺点,结合钢种成分和现场工艺流程,对脱氧工艺、造渣工艺、过程Al控制工艺、真空及钙处理工艺进行优化。结果表明:在成分设计时,考虑到钢水可浇性问题,同时满足提供硫化物形核质点的需要,当钢液中[S]含量为0.025%时,[A]含量应在0.010%-0.015%。通过工艺优化措施后,含硫汽车曲轴42CrMoA中成品氧含量在8-15 ppm之间,平均为12 ppm,说明钢液氧含量控制较低,钢水纯净度较好。非金属夹杂物评级中A细最小值为1.0,最大值为2.0;A粗最小值为1.0,最大值为2.0,说明硫化物变性和弥散化效果较好。

This paper carries out the analysis on the Class A inclusions in sulfur-containing automobile steel,mainly on the long strip MnS,meaning the morphology control of sulfide was poor.Through the analysis of sulfide denaturation mechanism and[AI]-[S]thermodynamic calculation,the key process points for contolling the sulfide morphology were explored.Combined with steel composition and on--site process,the deoxidation process,slagging process,proce-dure Al control process,vacuum and calcium treatment process were optimized.The results show that in the composition design,considering the castability of molten steel and meeting the needs of providing sulfde nucleation particles,when the[S]content in liquid steel is 0.025%,the[Al]content should be 0.010%-0.015%.Afer the process optimiza-tion,the oxygen content of the finished product of sulfur-containing automobile crankshaft steel 42CrMoA is between 8-15 ppm,with an average of 12 ppm,indicating the low oxygen content and the good purity of liquid steel.The minimum and maximum of A fine in the rating of non-mtallic inclusion are 1.0 and 2.0 respectively.The minimum and maximum of A erude are also 1.0 and 2.0,indicating that the sulfide denaturation and dispersion effect is good.