| Through analysis of the peeling after cold rolling of narrow strip special steel,we discovered mass reduction iron.This is the fundamental cause of cold rolling peeling,and the immediate cause is the micro-cracks of billets in furnace.Base on characteristics include 50 ? 65 Mn etc,we have analyzed phase transformation characteristic of billet in furnace,and have researched intermediate billet qualities with different conditions also.The results indicated that the Ac1 temperature of special steel is in range of billets hot charging temperature,as a result of furnace structure characteristic,there is a long time phase change of billets in preheating zone.Then pearlite?ferrite and austenite had co-existence,so structural stress appeared and microcracks formed interior billets.The billets oxidized deeply with micro-cracks expanding,the same time scale was full of internal of cracks and decarburization was forming.But hot rolled can not get rid of the scale completely,the scale would expose and peel with cold rolled deeply.Base on field condition and facilities,we have optimized pattern of production?charging temperature?tundish temperature?constant pulling rate of casting with the range of ±0.05m/s,meanwhile we product steel according to special use in cold billets to keep from micro-cracks and stop internal oxidation of billets.The surface peeling has been significantly improved in cold rolled through market tracking.Not only got the accepts of customers,but also improved quality and brand effect,meanwhile,we will lay foundation towards high-end special steel. |
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