Influence of surface contamination of rolled coil

  • Effect of surface contamination of the rolled sheet: The less oil composition remains on the cold rolled steel coil after rolling, the less the organic matter is formed during annealing. However, the reduction of the oil composition should be limited because the lower the concentration of the oil composition in the emulsion, the increased amount of wear products due to the increase in the friction coefficient, and the wear product is a catalyst for the carbonation process.

    The wetting layer is applied to the blank before the cold rolling on the continuous pickling line, and the low concentration (<1.0%) metastable emulsion based on mineral oil is cold rolled. The process features a two-layer lubrication system. A lubricating layer on the rolled stock is formed on the continuous pickling line and the wash cooling layer is formed during the cold rolling process. It is reasonable to reduce the substances (Fe, S, Si, C1, K, Ca) which act as catalysts for the carbon-containing compound during annealing, and the sources thereof are pickles after pickling and wear metal particles of steel during pickling and cold rolling. It should be noted that the Fe2 and Fe3 present on the surface of the coil are catalysts for the cracking of oil-retaining hydrocarbons, which form a polymer and carbon black film on the coil during annealing.

    In order to reduce the amount of wear metal particles and oil composition on the steel coil after pickling, the following pickling parameters are maintained: the inhibitor protects the cold rolled steel coil from corrosion by not less than 80%; and the whole descaler roll is actuated to make the coil Work with large bending, keep the flat frame under the work roll after the work roll is not less than 1%; improve the cleaning and drying efficiency (pH ≮ 6); evaluate the continuous pickling by means of the sampling rating (reflection rate is not less than 70%) The degree of surface contamination of the coil at the exit of the unit. During cold rolling, the lubricant is sprayed at the exit of the rolling mill. The total consumption should be no less than 1250m3/h; the steel coil should be washed continuously in the third frame; ensure that the temperature of the lubricant does not exceed 50 °C. In order to improve the surface cleaning performance of the cold-rolled sheet, in order to improve the surface cleanliness of the cold-rolled sheet, the reflection rate is >90%, which is equivalent to 12 mg/m2 in 80% of cases. The amount of reduction in the "smoke black" defect on the surface of the finished coil is also reduced.