Overview
Rolling of steel products is of paramount importance in the production of modern steel. The billets or ingots of steel are heated to an elevated temperature and passed through a series of metal-walled rolls in order to shape them into the desired size. This process is known as rolling. It is a fundamental operation used in the transformation of metal sheets and bar stock into structural members, pipes, and other forms. Rolling is typically done hot, with metal that has been heated to temperatures ranging from 900-1450°C for easy deformability into the desired shape. In this process, the metal deforms by passing through a series of shaped surfaces (or rolls), each changing the dimension of the metal in a controlled fashion.
Rolling of Initial Billets and Slabs
Plate rolling is the process by which large slabs or plates of steel are rolled into their final shapes, such as the required cross-sectional profile of an I-beam or U Channel. This process enables the steel to be formed into the desired shape and has the advantage of reducing the amount of labor required when compared to fabrication methods. The initial billets and slabs used in plate rolling must be of a uniform thickness and size, and consistent in terms of chemistry and mechanical properties.
The Chinese national standard YB/T004-1991 outlines guidelines and requirements for the preparation and rolling of initial billets and slabs during plate rolling. The standard explains in detail the processes for determining the chemical composition, tensile strength, and other mechanical properties of the steel, as well as preparation of the steel for the rolling process. This includes not just the heating of the steel, but also any annealing and cleaning that is necessary to ensure the quality of the finished product. Moreover, it provides detailed guidelines for both hot-rolling and cold-rolling of steel sheets and strips.
Terminology and Classification
The YB/T004-1991 standard provides a standard terminology for the different types of steel products that can be produced. For instance, it defines a “flat-rolled product” as “any steel product with cross sections in the form of circles, ovals, squares, or rectangles, or any irregular shape.” It also defines “hot-rolled products” as those “worked at a temperature equal to or higher than that at which the recrystallization starts and in which the grains of the original structure are rearranged.”
The standard further divides steel products into two major classes: hot-rolled and cold-rolled steel. Hot-rolled steel is produced by heating the steel to temperatures above the recrystallization point and then rolling it in a series of rolls. Cold-rolled steel, on the other hand, is produced by rolling the steel at temperatures below the recrystallization point. Both processes have a wide range of applications and are used to produce many different kinds of steel product.
Conclusion
The Chinese national standard YB/T004-1991 is an important document that outlines the guidelines and requirements for the preparation and rolling of initial billets and slabs of steel during the plate rolling process. It provides detailed instructions on the composition, tensile strength, and other mechanical properties of the steel, as well as the processes for heating, annealing and cleaning the steel for rolling. Moreover, the standard also includes a standard terminology for different steel products and classifies them into either hot-rolled or cold-rolled steels. The standard is essential for ensuring quality control during the plate rolling process.
