钙处理对20CrMo齿轮钢硫化物夹杂的影响

在热力学计算的基础上,分析了20CrMo含硫齿轮钢钙处理的工艺条件,并对某厂钙处理后的含硫齿轮钢轧材进行了取样研究。结果表明,RH破空后钙处理的钢水中,硫化物和钙铝酸盐能结合生成复合纺锤状和低熔点夹杂;同时,钙处理前钢中w(O)控制在10×10-6以下,可使加入的钙充分对Al2O3、硫化物进行变性,并有利于形成以MnS为核心的氧硫复合夹杂;而且钢水铝脱氧后调整钢中w(AlS)=0.015%～0.025%,并在温度较高时喂Si-Ca线,可减少凝固过程中硫的偏析。该厂通过钙处理工艺生产的含硫齿轮钢夹杂物形貌良好,各项性能均达到客户的要求。

Effect of Ca-treatment on sulphide inclusions in 20CrMo gear steel

On the basis of thermodynamic calculation the process conditions of Ca treatment of the sulfur bearing 20CrMo gear steel is analyzed and the sample of rolled stock taken from the Ca treated sulfur bearing gear steel is studied in a specific Plant.Results show that in the liquid steel Ca treated in a RH device the sulfide inclusions and calcium aluminates bind together and form the spindle shaped low melting compound inclusions.In the meanwhile control of w(O) in steel below 10×10-6 before Ca treatment is more beneficial to the full modification of Al2O3 and sulfide by the added calcium and to the formation of oxide and sulphide compound inclusion with MnS as its nucleus and after Al deoxidation S segregation can be reduced in the period of solidification only if w(AlS) in steel is adjusted to 0.015 %~0.025 % and Si-Ca cladded wire is fed at higher temperature.The morphology of inclusions in the Ca treated sulfur bearing gear steel are acceptable and all indicators of properties can meet the requirements of customers.