Abstract: In order to study the influence of different refining processes on sulfides in ring gear steel 42CrMoS4 steel， starting from the morphology and distribution of sulfides in the steel， two different alkalinity slag and calcium content processes were designed in the refining process， and four heats were tested for production. The characteristics of composite sulfides with different double-layer structures and the formation mechanism of sulfides in cast billet and rolled steel were compared and analyzed. The results show that after LF makes high alkalinity slag （R=6. 5～7. 2） into RH without calcium treatment， the composite sulfide at 1/4 thickness of the casting billet is in a block morphology as a whole， and the oxide inside the core is also a regular block， the internal oxide of the rolled steel is mainly CaO， and the peripheral sulfide is mainly （Ca， Mn）S with a high CaS ratio， which is basically not deformed， and the grade of class A fine inclusions is 2. 0～3. 0.After LF makes weak alkalinity slag （R=3. 6～4. 2） into RH secondary calcium treatment， the Ca content is increased from about 0. 001 4% to 0. 002 5%～0. 003 2%， the composite sulfide at 1/4 thickness of the casting billet becomes an ellipsoidal morphology as a whole， the core internal oxide is also regular spherical， the internal oxide of the rolled product is calcium-magnesium-aluminate with a low CaO ratio， the peripheral sulfide is mainly （Ca， Mn）S with a low CaS ratio， and the sulfide is spindle-shaped， which has a good deformation ability ，the level of class A fine inclusions is controlled within 2. 0.

Key words: Sulfide, Calcium Treatment, Fusiform, Basicity of Slag, Refining Process, Inclusion

摘要： 为研究不同精炼工艺对齿圈钢42CrMoS4钢中硫化物的影响，从钢中硫化物的形态与分布着手，在精炼工序设计两种不同的碱度渣和钙含量工艺，试验生产4炉。对比分析铸坯和轧材中不同双层结构复合硫化物特征与硫化物形成机理。结果表明，LF造高碱度渣（R＝6.5～7.2）进RH后不进行钙处理，铸坯1/4厚度位置复合硫化物整体成块状形貌，核心内部氧化物同样也成规则的块状，轧材内部氧化物主要以CaO为主，外围硫化物主要是高CaS比例的（Ca，Mn）S，基本不变形，A类细系夹杂物级别为2.0～3.0级；在LF造弱碱度渣（R＝3.6～4.2）进RH后进行二次钙处理，将w［Ca］由0.001 4%左右提升至0.002 5%～0.003 2%，铸坯1/4厚度位置复合硫化物整体成椭球状形貌，核心内部氧化物同样也成规则的球状，轧材内部氧化物为较低CaO比例的钙镁铝酸盐，外围硫化物主要是低CaS比例的（Ca，Mn）S，硫化物成纺锤状，具有很好的变形能力，A类细系夹杂物级别控制在2.0级以内。

关键词: 硫化物, 钙处理, 纺锤状, 渣碱度, 精炼工艺, 夹杂物