高级别管线钢钙处理冶金效果研究

针对管线钢L360QS进行了钙处理实验研究,考查钢液中[Ca]、[S]对夹杂物变性的影响.结果表明,钢中的硫被脱到0.002%~0.003%(质量分数)范围内的较低水平,脱硫率最高达85.0%,与实验预期吻合.随着钢液中[S]增加,夹杂物中CaS+MnS的平均质量分数相应增加,但夹杂物中的CaS含量不一定增加.钙对夹杂物变性作用非常明显,[Ca]相对高的管线钢,其夹杂物绝大多数都变性为球形的含CaS钙铝酸盐复合夹杂,不存在MnS夹杂和MgO·Al₂O₃夹杂.为使氧化夹杂和硫化夹杂都变性完全,钢液中的硫的质量分数应控制在0.002%左右,钙的质量分数应控制在0.003 5%~0.004 0%,且[Ca]/[S]>1.9.

Metallurgy effect of calcium treatment in high grade pipeline steel

Calcium treatment experiments were carried out on L360QS pipeline steel. The effect of calcium and sulfur contents in molten steel on the inclusions modification was investigated. The result shows that sulfur content in molten steel is decreased to the range of 0.002% to 0.003% and the highest desulfurization rate reaches 85.0%,which achieves the expected result. With the sulfur content increasing,the average CaS + MnS content in inclusions increases in liquid steel,however,the CaS content don' t. The effect of calcium content in liquid steel on inclusions modification is greatly obvious,and almost all inclusions in the pipeline steel with high calcium content are modified into spherical calcium aluminate complex inclusions,in which the CaS is uniformly dispersed,and there are few MnS inclusion and MgO·Al₂O₃ inclusions. In order to modify both oxide and sulphide inlusions completely,the sulfur content in molten steel should be controlled about 0.002%,and the calcium content in molten steel should be in the range of 0.003 5% to 0.004 0%,as well as the Ca/S should be above 1.9.