| 摘要 |
<p>The quality of rolled steel products, e.g. sheet, plate, or sectional is improved by rapid cooling of the surface as it emerges from the last stage of rolling. Cooling takes place in three stages at varying rates of heat extraction, the first moderate, to just above the Ms point of the steel. During the second the flux is regulated to hold the surface temperature constant until the austenite transformation is complete. In the third a powerful flux is applied so that the slowest rate of cooling, at any point in the material, is sufficiently high for austenite to be transformed into bainite, with the formation of pearlite. Homogenisation follows, e.g. in still air. This process produces in steels of low, less than 0.2%, Carbon content, uniformly high mechanical properties. The product is suitable for welding. As section thickness increases this is a more effective process than the known quench arcto-anneal method.</p> |
