| 摘要 |
Disclosed is a method for continuous thermal treatment of a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle. |
| 主权项 |
1. A process for the continuous heat treatment of a steel strip wherein:
the strip passes through successive heat treatment chambers, a rapid cooling of the strip, in particular of greater than 200° C./sec, is carried out in at least one of the chambers by spraying liquid onto the strip, or spraying a fluid composed of gas and liquid or spraying a mist-type combination of gas and liquid, and, after the rapid cooling, a protective metal layer is deposited on the strip by dip coating,wherein:
the fluid sprayed for the cooling of the strip is a fluid having a pickling property with regard to the iron oxides or oxides of other alloying elements contained in the steel to be treated, in order to limit the oxidation of the strip and reduce the oxides that have been able to be formed on the strip in order to reduce or eliminate the surface defects during the hot-dip metal coating operation, the fluid is sprayed under a pressure and at a distance from the strip such that the combined effect of the pickling property and of the mechanical action of the sprayed fluid reduces the layer of oxides at the surface of the strip, and wherein the temperature of the strip at the end of cooling is that needed to achieve the desired treatment cycle, in particular between 200° C. and 750° C., typically above 200° C. |
