高碳磨球钢中Ds类夹杂物的形成机理及工业控制

Formation mechanism and industrial control of Ds inclusions in high carbon grinding ball steel

Ds类非金属夹杂物尺寸大、延展性差,严重影响TL-1D磨球钢疲劳寿命等关键性能指标。对某企业TL-1D磨球钢进行全流程取样分析,结果表明该企业此钢种Ds类非金属夹杂物超标,且该钢种中的Ds类非金属夹杂物主要为Al_(2)O_(3)-CaO-MgO-CaS,在LF精炼钙处理后大量出现。总结出Ds类夹杂物形成机理为,首先以Al_(2)O_(3)为中心开始形核,之后其与钢液中[Mg]和[Ca]结合并长大形成CaO-Al_(2)O_(3)-MgO球状夹杂物,最后球状夹杂物外层与CaS结合形成Al_(2)O_(3)-CaO-MgO-CaS包裹体。工业试验结果证实,钙处理不利于TL-1D钢中Ds类非金属夹杂物的控制,会造成夹杂物尺寸增大,由此提出在TL-1D磨球钢生产精炼环节进行非钙处理的生产工艺方案。试验结果表明,钢液中钙含量处于饱和状态,优化后精炼渣成分趋于液相区,提升了精炼环节精炼渣系对夹杂物的软熔吸附性能,提高了Ds类非金属夹杂物上浮至渣层时的吸附去除率,最终使连铸坯的初检合格率由95.4%提高至97.0%。研究结果对磨球钢工业生产具有参考价值。

Ds non-metallic inclusions have large size and poor ductility, which seriously affect the fatigue life and other key performance indicators of TL-1D grinding ball steel. The whole process sampling analysis of TL-1D grinding ball steel in an enterprise showed that the Ds non-metallic inclusions of this steel grade exceeded the standard. The main Ds non-metallic inclusions in this steel grade were Al_(2)O_(3)-CaO-MgO-CaS, which appeared greatly after LF refined calcium treatment. The formation mechanism of Ds non-metallic inclusions was summarized. Firstly, Al_(2)O_(3) as the core began to nucleate, then it combined with [Mg] and [Ca] in the molten steel and grew up to form CaO-Al_(2)O_(3)-MgO spherical inclusions. Finally, the outer layer of spherical inclusions and CaS formed Al_(2)O_(3)-CaO-MgO-CaS outer envelope. The results of industrial tests confirm that calcium treatment is not conducive to the control of D_S non-metallic inclusions in TL-1D steel, resulting in an increase in the size of inclusions. Then the production process scheme of non-calcium treatment in the refining process of TL-1D grinding ball steel production was proposed. The test results show that the calcium content in the molten steel is in a saturated state, and the optimized refining slag composition tends to liquid zone, which improves the soft melt adsorption performance of the refining slag system on inclusions in the refining process, improves the adsorption removal rate of Ds non-metallic inclusions when they float to the slag layer, and finally the initial inspection pass rate of continuous casting billet increases from 95.4% to 97.0%. The research results have reference value for the industrial production of grinding ball steel.