热轧冷轧的区别（The difference between hot rolling and cold rolling）.doc

热轧冷轧的区别（The difference between hot rolling and cold rolling） The difference between hot rolling and cold rolling Hot rolled plate is low in hardness, easy to process and good in ductility. Cold rolled plate hardness is high, processing is relatively difficult, but it is difficult to deformation, higher strength. Hot rolled plate strength is relatively low, the surface quality (almost oxidation, low smoothness), but good plasticity, general plate, cold-rolled plate, high strength, high hardness and high surface smoothness, generally can be used as a thin plate stamping. Hot rolled steel sheets are much less mechanical and less ductile, but have better toughness and ductility. Due to work hardening of cold rolled steel plate, a certain degree of toughness is low, but can yield better than that used to cold spring piece parts, at the same time as the yield point is close to the tensile strength, so the use of risk is not predictable, prone to accidents in the load exceeds the allowable load. By definition, the ingot or billet is difficult to deform at room temperature and is difficult to process. It is generally heated to 1100~1250 degrees for rolling. This process is called hot rolling. Most steels are rolled by hot rolling. But because the surface under high temperature steel is easy to produce iron oxide, the surface roughness of hot rolled steel, the size of fluctuations, so the surface is smooth, accurate size, good mechanical properties of the hot rolled steel, semi-finished or finished products and raw materials for the production of cold rolling method. Rolling at room temperature is generally understood as cold rolling. From the standpoint of metallography, the boundaries between cold rolling and hot rolling should be distinguished by recrystallization temperature. That is, the rolling below the recrystallization temperature is cold rolling, and the rolling is higher than the recrystallization temperature. The recrystallization temperature of steel is 450~600