Cold rolling: hot-rolled steel coils are used as raw materials, and the oxide scale is removed by pickling and then cold-rolled continuously. The finished product is a hard-rolled coil. Due to the cold work hardening caused by continuous cold deformation, the strength, hardness, and toughness of the hard-rolled coils increase. The plastic index will decrease, so the stamping performance will deteriorate and it can only be used for parts with simple deformation. Hard rolled coils can be used as raw materials in hot-dip galvanizing plants because hot-dip galvanizing units are equipped with annealing lines. The weight of hard-rolled coils is generally 6 to 13.5 tons. The steel coils are continuously rolled on the hot-rolled pickled coils at room temperature.
Advantage
1. The cold-rolled steel plate has uniform thickness and commercial scale, which can fully meet the requirements of high-precision public services.
2. Ultra-thin strips that cannot be produced by hot rolling can be obtained, and the thickness can be less than 0.001mm.
3. The appearance quality of cold-rolled steel coils is superior, and there are no pitting, pressed oxide scale and other common defects of hot-rolled coils. Rolls with different surface roughness can be produced according to user requirements to facilitate the next process. processing.
4. Cold-rolled coil length and excellent mechanical and process properties, higher strength, lower yield limit, and outstanding deep drawing performance.
5. It can complete high-speed rolling and full continuous rolling with high yield.
Related differences
1. Appearance and surface quality: Since the cold plate is obtained from the hot plate after the cold rolling process, and some surface finishing is also performed at the same time as the cold rolling, the cold plate has a better surface quality (such as surface roughness) than the hot plate. It comes well, so if there are high requirements for the coating quality such as subsequent painting of the product, cold plates are generally selected. Hot plates are divided into pickled plates and unpickled plates. The surface of the pickled plates has been pickled so it becomes It has a normal metallic color, but it has not been cold-rolled, so the surface is still not as high as the cold plate. The surface of the unpickled plate usually has an oxide layer that is black, or there is a black layer of iron tetroxide, which in layman's terms looks like it has been roasted. , and if the storage environment is not good, it will usually be embroidered.
2. Performance: Generally speaking, there is no difference in the mechanical properties of hot plates and cold plates in engineering. Although the cold plates have certain work hardening during the cold rolling process, (but this does not rule out situations where strict mechanical performance requirements are required) , then they need to be treated differently). The yield strength of the cold plate is usually slightly higher than that of the hot plate, and the surface hardness is also higher. The specific situation depends on the degree of annealing of the cold plate. But no matter how annealed, the strength of the cold plate is higher than that of the hot plate.
3. Forming performance. Since the performance of hot and cold plates is basically not much different, the influencing factors of forming performance depend on the difference in surface quality. Since the surface quality of cold plates is better, generally speaking, the same material Steel plates and cold plates have better forming appearance than hot plates.
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