ASTM A36 hot rolled steel sheets are easily to occur iron oxide residual problems in production, which leads to surface pock and the qualified rate of production decline. That further affects enterprise benefits. In view of the actual production situation, the following measures should be taken:
1. Optimize the heating process. The heating should be based on entrance temperature of the finishing rolling machine. The heating temperature should be uniform, and the temperature difference on 2 ends should be controlled within 20 degrees. If the rolling machine break down, you should reasonably arrange temperature holding time of ASTM A36 steel billets to be rolled, in case too long temperature holding time facilitates increase of iron oxide skin.
2. Optimize finishing rolling enter speed. In order to ensure the effect of the roll descaling and ensure the quality of the rolled piece, the inlet speed of the rolling mill of different sizes should be optimized.
3. Optimize the descaling process. The number of descaling working pumps is increased to ensure the descaling pressure; double beams can be used in the descaling after the furnace and before the finishing rolling. Control rolling rhythm, avoid more than two points (including two points) descaling and the phenomenon of rolling.
4. The improvement of nozzles. If the thickness of the intermediate ASTM A36 steel billet changes greatly, the distance between the upper nozzle and the slab should not be too far away. The nozzle height should be lowered to ensure that the blow force of the nozzles is not decreased, and the nozzle angle is adjusted at the same time.
5. Add water retaining chain. In order to ensure the seal of the descaling water, two water retaining chains and a backjet are added, and 9 reverse nozzle are set up, and a water collector with a slope inside the descaling box is set up.
6. Improve the finishing roll surface.
With above measures, the pock defects of ASTM A36 hot rolled steel sheets is reduced from 10% to 0.2%, rolled commuted rate decreased from 12% to 5.24%, the effect is significant.
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