What is hot rolled sheet? Hot rolled sheet is made of steel plate, and it also has another alias, which is hot plate. Its width is generally greater than or equal to 600mm, the thickness is generally two, respectively, 0.35mm to 200mm and 1.2mm to 25mm. people will naturally think of cold rolled plate when they see the hot rolled plate, so I will be the use of hot rolled plate for everyone as well as the difference between hot rolled plate and cold rolled plate to do a specific introduction.
What are the uses of hot rolled sheet
Hot rolled sheet is also called stainless steel hot rolled sheet because it is made of steel plate. It is very important in the plate, according to the use it can be divided into carbon structural steel hot rolled sheet, low alloy knot hook steel hot rolled sheet, carbon tool steel hot rolled sheet, carbon tool steel hot rolled sheet, stainless steel hot rolled sheet and so on. Hot rolled sheet when it is used for structural steel, mainly used in the production of bridges, cruise ships and so on. Secondly, when the hot rolled sheet is used as stainless steel plate, because the raw material is more special, so it is corroded slower, anti-temperature as well as wear-resistant, so it is usually used in the manufacture of buildings, aerospace products, medical equipment and so on.
In addition to the above mentioned hot rolled sheet, there are some hot rolled sheet with specialized purposes. For example, the compressor valve hot rolled steel sheet, welded gas cylinder hot rolled steel sheet, oil drums special hot rolled carbon structural steel sheet.
Difference between hot rolled plate and cold rolled plate
First: hot rolled plate is not processed, so the hand will feel a little rough. The cold rolled plate surface is relatively smooth, and the appearance of a certain degree of gloss, hand touch as if touching the kind of glass at home.
Second: the hardness of the hot-rolled plate is relatively low, making it easier to process, and better ductility. The hardness of the cold rolled plate is higher, so it will encounter difficulties in the processing, but it is not easy to deform because of the higher hardness.
Third: hot rolled plate and cold rolled plate size difference. The thinness of hot rolled plate reaches 0.78mm, cold rolled plate thinness reaches 0.001mm. in addition, the thickness of hot rolled plate can be larger, while the thickness of cold rolled plate is smaller.
Fourth: hot-rolled plate and cold-rolled plate processing methods are different, the production of hot-rolled plate must be in a high-temperature state, while the cold-rolled plate can be produced at room temperature.
Fifth: the price of hot-rolled plate and cold-rolled plate is different. Because the surface of the hot-rolled plate is relatively rough, so the price is lower. And the surface of cold rolled plate is treated, so it is smoother, so the price is higher.
Analysis of the advantages and disadvantages of cold rolled plate and hot rolled plate
Hot rolled plate, the temperature of the rolled part is high, so the deformation resistance is small, and large deformation can be achieved. Take the rolling of steel plate as an example, the general thickness of the continuous casting billet is about 230mm, while after roughing and finishing, the final thickness is 1~20mm. at the same time, due to the small width-thickness ratio of the steel plate, the requirement of dimensional accuracy is relatively low, and it is not easy to plate shape problems to control the convexity of the main. For the organization requirements, generally through the control of rolling and cooling to achieve, that is, control the opening temperature of finishing rolling, final rolling temperature and curling temperature to control the microstructure and mechanical properties of the strip.
Cold rolled plate, generally in the opening before rolling is no heating process. However, due to the strip thickness is small, it is easy to plate shape problems. Moreover, the cold rolled for the finished product, therefore, in order to control the dimensional accuracy and surface quality of the strip, using a lot of very cumbersome process. The production line of cold rolling is long, with many equipments and complicated processes. With the improvement of users' requirements on dimensional accuracy, plate shape and surface quality of strip steel, the control model, l1 and l2 systems, and plate shape control means of the cold rolling unit are relatively more than that of hot rolling. Moreover, the temperature of the rolls and strips is also one of the more important control indicators.
From the definition, the ingot or billet at room temperature is difficult to deform, not easy to process, generally heated to 1100 ~ 1250 ℃ for rolling, this rolling process is called hot rolling. Most of the steel is rolled by hot rolling method. But because the surface of the steel at high temperatures is easy to generate iron oxide, so that the hot-rolled steel surface roughness, size fluctuations, so the requirements of the surface finish, dimensional accuracy, good mechanical properties of the steel, hot-rolled semi-finished or finished products as raw materials and then cold-rolled method of production.
Rolling at room temperature, generally understood as cold rolled, from the point of view of metallurgy, cold rolled and hot rolled boundaries should be distinguished by the recrystallization temperature. That is, below the recrystallization temperature of rolling for cold rolling, higher than the recrystallization temperature of rolling for hot rolling. The recrystallization temperature of steel is 450 to 600 ℃.
Simply put:
1, cold rolled plate surface has a certain degree of gloss hand indeed feel smooth, similar to the kind of water used to drink the very common steel cup.
2, hot-rolled plate without pickling treatment, the market is similar to the surface of many ordinary steel plate, rusted surface is red, not rusted surface is purple-black (iron oxide).
Difference between cold rolled sheet and hot rolled sheet
The performance advantages of cold rolled sheet and hot rolled sheet are:
1, higher precision, cold rolled strip thickness difference of no more than 0.01~0.03mm.
2, thinner dimensions, cold rolled the thinnest can be rolled 0.001mm strip; hot rolled the thinnest can now be up to 0.78mm.
3, the surface quality is superior, cold rolled steel plate can even produce a mirror surface; while the surface of the hot rolled plate has iron oxide, pitting and other defects.
4, cold rolled plate can be adjusted according to user requirements of its mechanical properties such as tensile strength and process properties such as stamping properties.
Cold rolled and hot rolled are two different rolling techniques, as the name suggests, cold rolled is the steel at room temperature in the case of zapping, the hardness of this steel. Hot rolling is steel rolled at high temperatures .
1. hot rolling
with continuous casting slab or primary slab as raw material, heated by a step furnace, high pressure water descaling into the roughing mill, roughing material by cutting the head, tail, and then into the finishing mill, the implementation of computerized? Control of rolling, final rolling that is after laminar cooling (computer-controlled cooling rate) and coiling machine coiling, become a straight hair roll. The head and tail of straight hair curls are often tongue and fishtail shape, thickness,? Width accuracy is poor, the edge is often wave-shaped, folded edge, tower and other defects. Its volume weight is heavy, the inner diameter of the steel coil is 760mm.(Generally the pipe making industry likes to use.) The straight hair roll by cutting head, ? Cutting tail, cutting edge and multiple straightening, leveling and other finishing line processing, and then cut plate or re-roll, that is to become: hot rolled steel plate, flat hot rolled steel coils, longitudinal cut strip and other products. If the hot rolled finishing coils are pickled to remove oxidized skin and coated with oil, they become hot rolled pickled coils. The product has a tendency to locally replace the cold rolled plate, the price is moderate, loved by the majority of users.
Hot-rolled is a slab (mainly for continuous casting billet) as raw material, after heating by the roughing unit and finishing unit made of strip. The hot strip from the last mill of the finishing mill is cooled to a set temperature by laminar flow, and then coiled into steel strip coil by the coiler. The cooled steel strip coil, according to the different needs of the users, will be processed into steel plates, flat coils, and longitudinal cuts through different finishing lines (leveling, straightening, cross-cutting or longitudinal cuts, inspections, weighing, packaging and marking, etc.). To put it simply, a piece of steel billet in the heating (that is, the kind of red-hot steel burnt in the TV) fine over a few rolling, and then cut the edge, corrected to become a steel plate, this is called hot rolling.
2.? Cold rolled
With hot rolled steel coil as raw material, after pickling to remove the oxide skin for cold continuous rolling, the finished product is rolled hard coil, due to continuous cold deformation caused by cold hardening of rolled hard coil strength, hardness rise, toughness and plasticity indicators decline, so the stamping performance will deteriorate, can only be used for simple deformation of the parts. Rolled hard coil can be used as raw materials for hot-dip galvanizing plant, because hot-dip galvanizing unit are set up with annealing line. Rolled hard coil weight is generally 6 ~ 13.5 tons, steel coil inner diameter of 610mm.
General cold rolled plate, coil should be continuous annealing (CAPL unit) or hood furnace annealing to eliminate cold hardening and rolling stress, to achieve the mechanical properties specified in the corresponding standards. Cold rolled steel plate surface quality, appearance, dimensional accuracy are better than hot rolled plate, and the thickness of its products can be rolled thin to 0.18mm or so, so favored by the majority of users. Cold rolled steel coil as a substrate for the deep processing of products, become high value-added products. Such as electro-galvanized, hot-dip galvanized, fingerprint-resistant electro-galvanized, color-coated steel coil and shock-absorbing composite steel plate, PVC?laminated steel plate.
Cold rolled: hot rolled steel coil as raw material, after pickling to remove the oxide skin for cold rolling, the finished product for the rolled hard coil, due to continuous cold deformation caused by cold hardening of the rolled hard coil strength, hardness, toughness and plastic indicators decline, so the stamping performance will deteriorate, can only be used for simple deformation of the parts. Rolled hard coil can be used as raw materials for hot-dip galvanizing plant, because the hot-dip galvanizing unit are set with annealing? Fire line. Rolled hard coil weight is generally 6 ~ 13.5 tons, steel coil at room temperature, the hot-rolled pickled coil for continuous rolling. The inner diameter is 610mm.
Product characteristics: Because it is not annealed, its hardness is very high (HRB greater than 90), the machinability is very poor, and it can only carry out simple directional less than 90 degrees of bending processing (perpendicular to the direction of coiling).
To put it simply, cold rolled is rolled on the basis of hot rolled coil, generally speaking, hot rolled - pickling - cold rolled such a process.
Cold rolled is processed from hot rolled plate at room temperature, although in the process because of rolling will also make the steel plate warming, nevertheless still called cold rolled. As hot rolled after continuous cold deformation into cold rolled, in the mechanical properties are relatively poor, hardness is too high. Must be annealed to restore its mechanical properties, no annealed rolled hard volume called. Rolled hard roll is generally used to do without bending, stretching products, 1.0 thickness rolled hard bending on two or four sides.
1. Cold rolled is processed from hot rolled sheet at room temperature.
2. A piece of steel billet after heating (that is, the kind of burning red hot steel block on TV) fine over a few rolling, and then cut the edge, corrected to become a steel plate, this is called hot-rolled.
By now, I have for the use of hot-rolled plate and the difference between hot-rolled plate and cold-rolled plate has been introduced to the end, we must determine the use of hot-rolled plate products in the selection of whether the use is complete, and finally hope that the introduction of the editorial can help you.