影响20CrMnTiH(TS)齿轮钢夹杂物控制因素的分析和工艺优化

20CrMnTiH（TS）钢冶金流程为60 t 顶底复吹转炉-LF-VD-150 mm×150 mm方坯连铸。钢厂20CrMnTiH（TS）钢夹杂物一次检验不合格率达2.0%,主要为B类（复合钙铝酸盐+镁铝尖晶石,以及部分三氧化二铝）和D类夹杂（钙铝酸盐,部分为复合钙铝酸盐+镁铝尖晶石+氮化钛）,尺寸＞20μm。通过采用低磷铁水和优质废钢,转炉终点C]≥0.09%,转炉出钢加40 kg硅钙和40 kg钢芯铝替代原只加80 kg钢芯铝预脱氧,LF精炼采用SiC70替代SiC45进行扩散脱氧,VD后喂Ti线,保证精炼终渣碱度为3.0,控制连铸时钢包余钢量＞2 t 等工艺措施使TO]从12×10^-6降至8×10^-6,一次夹杂物检验不合格率下降至0.5%。

Analysis on Influence Factors of Control of Inclusions in Gear Steel 20CrMnTiH (TS) and Process Optimization

The metallurgical flow sheet for steel 20CrMnTiH (TS) is 60 t top and bottom combined blowing converter- LF- VD- 150 mm X 150 mm billet casting. The unqualified rate of inclusions in steel 20CrMnTi H(TS) at first examination at steelworks is up to 2% main inclusions are B series ( compound calcium aluminate + magnesia-alumina spinel, and partial alumina) and D series ( calcium aluminate, and partial compound calcium aluminate + magnesia-alumina + titanium nitride) ,that size is more than 20 μm. With the process measures including using low phosphorus hot metal and high quality scrap, converter end C] ≥0, 09% , adding 40 kg silicon-calcium and 40 kg aluminium cladding steel to replace original only adding 80 kg aluminium cladding steel for pre-deoxidation in converter tapping , using SiC70 to replace SiC45 to diffusion-deoxidize in LF refining, feeding Ti wire after VD, insuring refining end slag basicity 3. 0, and controlling heel liquid more than 2 t, the TO] decreases from original 12 X 10^-6 to 8 x 10^-6 and the unqualified rate of inclusions in steel at first examination decreases to 0.5%,