In structural design, some sheet metal parts can often be seen in the material column of cold rolled steel plate t2, Q235, such materials, I did not understand when I first engaged in structural design, the material column It is simple shoes Q235, this material is also subdivided, is it cold rolled and hot rolled?
1. Appearance and surface quality: the cold plate is obtained from the hot plate after the cold rolling process, and the cold rolling will also carry out some surface finishing, so that the surface quality of the plate cold (such as surface roughness) is higher than hot plate comes in handy, so if there are higher requirements for coating quality, such as product back painting, cold plate and plate are generally selected hot is divided into plates pickled and without chopping. The pickled plate is normal metallic color, but not cold rolled, so the surface is still not as high as the cold plate. The surface of the plate without pickling usually has a layer of oxide on the surface, which is black, or there is a black layer of iron tetroxide, which is usually fire-baked. And if the storage environment is not good, it will usually bring some embroidery.
In short, our common cold plate is the one with a glossy surface, which looks good, is not dirty and has no rust, and the hot plate is the common one that does not look good and dirty.
2. Forming performance, the performance of hot and cold plates is basically not too different,
The key is the difference in use. Hot rolling is used for structural parts and cold rolling is mainly used for stamping parts. The mechanical properties and surface quality of cold rolled plates are better than those of hot rolled plates. The carbon content has not changed, it is the same.
There is no difference in chemical composition such as carbon content and its mechanical properties, but because cold rolling has more rolling and smoothing process than hot rolling, that is, more work hardening process. , the surface hardness of the cold plate is slightly higher than that of the hot plate. The resistance is also slightly higher, but is generally ignored. In fact, the difference lies in the condition of the surface. Generally, the surface quality and finish of the cold plate is better than that of the hot plate, and the hot plate (not pickled) is a little black (due to the oxide layer).
The cold rolled plate is obtained after the hot rolled plate is pickled and cold rolled by the cold rolling mill. The common cold plate is rolled with an annealing process, but the surface hardness is even higher than that of the hot plate.
