含硫-铝钢GS35C-A硫化钙夹杂热力学分析和工艺改进

针对试验GS35C-A钢（/%:0.34～0.35C,0.20～0.22Si,0.69Mn,0.013～0.016P,0.026～0.045S,0.027～0.046A1,0.000 8～0.001 9Ca）夹杂物变性进行了热力学计算,并对工艺1BOF-LF（硫合金化）-RH-钙处理-CC]和优化工艺2BOF-LF-RH-钙处理-硫合金化-CC]对应的钢中夹杂物形貌及数量进行了研究。结果表明:（1）随着钢液中S]的升高,生成CaS所需的平衡钙含量降低,钙处理变性生成低熔点夹杂物时钢液中的Al]逐渐降低;（2）优化工艺2后RH离站Ca、S含量分别从优化前（工艺1）的0.001 9%和0.045%降至0.000 8%和0.026%,平均连浇炉数由原2.5炉提高至8炉;（3）优化前（工艺1）中间包典型夹杂物组分为硫化钙包裹的镁铝尖晶石,优化后（工艺2）中间包夹杂物为铝酸钙;RH离站、中间包钢中每mm²夹杂物个数分别从优化前9.09和6.23降至5.06和3.76。

Thermodynamic Analysis on Calcium Sulphide Inclusions in Bearing Sulphur-Aluminium Steel GS35C-A and Process Improvement

The thermodynamic calculation on deformation of inclusions in tested steel GS35C-A (/% : 0. 34 ~0. 35C, 0. 20 ~0. 22Si, 0. 69Mn, 0. 013 ~0. 016P, 0. 026 ~0. 045S, 0.027 ?0. 046Al, 0.000 8 - 0.001 9Ca) has been carried out, and the morphology and amounts of inclusions in steel produced by corresponding process 1 BOF-LF ( sulphur alloying)-RH-calcium treatment-CC] and optimized process 2 BOF-LF-RH-calcium treatment- sulphur alloying- CC] are studied. Results show that (a) with increasing S] in liquid the balancing calcium content in steel to form CaS decreases； and in process of forming low point melting inclusions modified by calcium treatment the Al] in liquid gradually decreases； (b) with decreasing end RH Ca and S content in liquid respectively from 0. 001 9% and 0. 045% ( process 1) to 0. 000 8% and 0. 026% ( optimized process 2) , the average continuous-continuous casting heats increases respectively from 2. 5 heats to 8 heats; ( c) before optimization by process 1 the typical inclusion in liquid in tundish consists of sulphide around magnesia aluminium spinel, while after optimization by process 2 the inclusion in liquid in tundish is calcium aluminate; and as compared with before optimization, after optimization the number of inclusions per mm² in steel at end RH and in tundish decreases respectively from 9.09 and 6.23 to 5.06 and 3.76.