Control of peeling defects of hot rolled coil
The slab is rolled into hot-rolled coil after hot feed, and cold-rolled sheet, galvanized and other products are produced after cold rolling. Generally, the production quality of hot rolled coil is stable, but occasionally a small amount of surface inclusion, peeling phenomenon occurs, which brings adverse effects on production control and product management, and needs to be controlled.
The analysis shows that the skin on the surface of the coil is caused by the argon bubble that passes through the stopper remaining in the casting blank. To this end, the corresponding control measures are:
1, control the argon flow of the plug rod
The flow rate of argon gas through the stopper is controlled so that the argon gas passing through the stopper does not cause excessive disturbance to the liquid level of the crystallizer, and the argon gas can be opened to the maximum extent under the premise of reducing the water orifice of the plug. Argon flow rate of 1.0L /min can achieve better results.
2. Strictly control the casting process
Reasonable casting process can form a good flow field and a good flow state of molten steel in the mold, which is conducive to improving the quality of the casting billet.
3. Reduce the fluctuation of crystallizer liquid surface
Most of the peeling inclusions occur in the mold when the water is changed, and the biggest feature of the water is the disturbance of the flow field of the mold caused by the fluctuation of the liquid level, and the exclusion of bubbles and inclusions in the mold has a permanent effect. The time of the water exchange port is required to be controlled within 3 s, and the liquid level fluctuation is required to be less than 5mm when the pulling speed is lowered, so as to stabilize the flow field of the mold to the maximum extent, reduce the fluctuation of the liquid level, and thus reduce the generation of skin defects in the casting billet.
4, optimize the production process control
In order to reduce the slagging phenomenon caused by the low tonnage and liquid level of the large bale during the bale changing, the time of the large bale changing is required to be controlled within 1'35 ", so that the medium bale is controlled above the specified tonnage. The liquid level of the ladle is controlled above 700mm to ensure the tonnage of the ladle and the depth of the ladle liquid surface to the maximum extent to prevent the phenomenon of slag rolling.
In short, the treatment of peeling needs to be closely linked to all aspects of the production process, to find the causes of defects early and accurately, and to strengthen the control of field operations, and ultimately to eliminate the occurrence of coil defects.
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