What is hot and cold rolled steel plate? How to distinguish? What high hardness? Which will produce noisy eye?
Cold and hot rolling are two different rolling technology, as the name suggests, is in the cold rolled steel at normal temperature of rolled steel, the hardness of hot rolled steel is large. Under the condition of high temperature hot rolled.1. continuous casting slab or as raw material, after reheating furnace heating, scale into the roughing mill in addition to high pressure water, roughing material by cutting head, tail, and then enter the finishing mill, the implementation of the computer controlled rolling, after finishing through the laminar cooling (computer controlled cooling rate) and coiler, become straight hair volume. Hair straightenerrollhead, tail tongue shapeand thefishtail shape, thickness and width precision, edgehaswavy, folding, pyramid and other defects. The volume weight heavier, steel coil diameter is 760mm. (love. General pipe industry) thestraightthroughcutting head cutting, cutting tail, cutting edge and multi pass straightening and leveling finishing line processing, again Cutting board or heavy volume, which becomes: hot rolled steel plate and flat steel coils, slittingstripand other products. In hot finishing rolling by pickling descaling and oil is made by pickling hot-rolled coils. The product has a tendency to partial substitution of cold-rolled plate, moderate price, loved by the masses of users.
By definition, ingot or billet is difficult to deform under normal temperature, easy processing, generally heated to 1100 to 1250 DEG C for rolling, the rolling process of hot rolled steel rolling. Most are called hot method. But because the surface under high temperature steel is easy to produce iron oxide, the surface roughness of hot rolled steel, size fluctuation so large, smooth surface, precise size, good mechanical properties of the hot rolled steel, semi-finished or finished products and raw materials for the production of cold rolling method. Under normal temperature, generally understood as cold, from the metal science point of view, the boundaries of cold rolling and hot rolling should be differentiated by the recrystallization temperature is lower than rolling recrystallization. The temperature is higher than the recrystallization temperature of cold rolling, rolling for hot rolled steel. The recrystallization temperature is 450 ~ 600 degrees. The difference: the simple point that 1, cold rolled plate surface has a certain gloss hand feels smooth, Similar to that used for drinking water is very common, such as hot rolled.2 steel cup without pickling treatment, is on the market and many are similar to ordinary steel plate surface, rusty surface is red, the surface of the rusty purple black (iron oxide).The performance advantages of cold rolled plate and strip is: 1, high precision, cold rolled strip thickness not more than 0.01~0.03mm.2, thinner, cold rolled steel strip rolling thickness 0.001mm hot rolling; now the thin can reach 0.78mm.3, the surface quality is more superior, cold rolled steel plate can even produce mirror surface; and the surface of hot rolled plate there are defects such as pitting of iron oxide,.4, cold rolled plate can be adjusted according to the running properties such as tensile strength and technological properties such as stamping performance requirements of the user.
As the name suggests, hot rolling, rolling temperature is high, so the deformation resistance is small, can achieve large deformation in rolling steel plate. For example, the general continuous casting slab thickness is about 230mm, and after roughing mill and finishing mill, the final thickness of 1~20mm. at the same time, because the steel plate width thickness ratio is small, the size precision is relatively low, not easy appear the flatness problem, mainly to control the convexity. For the organization required, generally through controlled rolling and cooling control is realized, microstructure and mechanical properties of the rolling temperature, finishing temperature and coiling temperature to control strip finishing. Cold, generally in the heating process is not open before rolling. However, because the strip thickness is small, it is easy to appear the flatness problem. Moreover, after cold rolling is finished, therefore, in order to control the dimensional accuracy and surface quality of steel strip, using a lot of tedious process. The cold rolling production line, equipment, process complex With the user to improve the shape and surface quality of the strip size precision, plate, cold rolling mill control model, L1 and L2 system, the shape control means relative to hot. And temperature is one of the important control index of rolls and strip.
