Science and technology
Difference between cold rolling and hot rolling
The difference between cold rolling and hot rolling is mainly the temperature of rolling process. "Cold" is normal temperature, "hot" is high temperature.
From the viewpoint of metallography, the boundary between cold rolling and hot rolling should be distinguished by recrystallization temperature. That is, less than recrystallization temperature for cold rolling, higher than recrystallization temperature for hot rolling. Steel recrystallization temperature of 450 ~ 600 ℃.
The main differences between hot rolling and cold rolling are:
1. Appearance and surface quality:
Because of cold plate is, resulting from the hot plate in cold rolling process and cold rolling at the same time also can do some surface finishing so cold plate on the surface quality (such as surface roughness, etc.) better heat plate, so if the product after the sequence on the quality of paint coating, such as there are higher requirements, generally choose the cold plate, hot plate, pickling board and other pickling plate, pickling board surface as the pickling too so into normal metal color, but remained in the high cold plate, cold rolled so surface without pickling plate surface oxide layer, usually hair black, or ferroferric oxide layer. In common parlance, it's like a fire, and if the storage environment is not good, it usually has a bit of rust.
2, performance: in general, hot plate and pipes in the engineering mechanical properties are no more thought, although there are certain work hardening heat pipes in the process of cold rolling, (but do not rule out strict in mechanical properties, that is need to discriminate), cold plate heat plate usually slightly high yield strength, surface hardness is higher, what specific needs to see the degree of cold plate annealing. However, the strength of annealed cold plate is higher than that of hot plate.
3, formability due to hot and cold plate performance basic difference is not too much, so the influence factors of forming performance depends on the difference between surface quality, due to the better surface quality is studied experimentally to, so generally steel plate with the same material, cold plate heat plate forming effect is better.