Deoxidation and alloying method for free-cutting steel smelting

The invention belongs to the technical field of free-cutting steel, and particularly relates to a deoxidation and alloying method for free-cutting steel smelting. The free-cutting steel comprises the following elements in percentage by weight: less than or equal to 0.09% of C, less than or equal to 0.08% of Si, 1.10-1.40% of Mn, 0.04-0.09% of P, 0.33-0.42% of S, less than or equal to 0.20% of Cr, Ni and Cu, 30-40ppm of active oxygen in the steel, and the balance of iron and inevitable impurities. The smelting process of the free-cutting steel comprises the steps of blast furnace ironmaking, converter primary smelting, LF refining and small square billet continuous casting. By optimizing deoxidation and alloying schemes in the smelting process, the molten steel oxygen content adjusting efficiency is effectively improved, consumption of a deoxidizing agent is reduced, the alloy yield is increased, and the smelting cost of the free-cutting steel is reduced. 本发明属于易切削钢技术领域，具体涉及一种易切削钢冶炼的脱氧和合金化方法。易切削钢的元素组成按重量百分数计为C：