50Cr5MoV支承辊用钢氧和夹杂物控制实践

Practice on control of oxygen and inclusions for 50Cr5MoV backup rolls

结合生产实践,采用"EAF(电炉初炼)→LF(炉外精炼)→VD(真空脱气)→LF返加热→VC(真空浇铸)"工艺,通过配料配碳,EAF初炼炉控碳减少钢水过氧化,LF精炼过程准确控制精炼渣成分深度脱氧和脱硫,VD过程有效控制真空脱气处理时间和真空度,LF返加热控制软吹气量来避免卷渣,浇铸过程采用精炼中间包、真空浇铸和水口吹氩等手段,50Cr5MoV材质支承辊钢锭氧质量分数控制在20×10-6以下,锻件高倍分析下夹杂物含量合格,该类支承辊锻件超声波探伤合格,加工过程夹杂物外露现象明显减少。

Combined with production practice,the carbon content reasonably was controlled in scrapped charge process and during arc furnace to decrease peroxidation of molten steel,final slag composition was aimed during LF process to remove oxygen and sulphur deeply,vacuum degassing time and efficient vacuum degree was carried out during VD process,gas flow was controlled during back to LF process to reduce slag entrapment,the refining ladle was adopted during the whole steel-making process and blowing argon around the ladle nozzle was carried out during VC process.Results shows final oxygen mass fraction of backup roll were all below 20×10-6 and forging inclusions in microscope was qualified,ultrasonic examination was qualified and inclusions exposure were effectively reduced during subsequent machining process.