Classification and use of hot rolled coils

Hot-rolled coils are made of slabs (mainly continuous casting slabs) as raw materials, which are heated and made into strips by rough rolling mills and finishing mills. The hot steel strip coming out of the last rolling mill of finishing rolling is cooled to the set temperature by laminar flow and then rolled into a steel strip coil by the coiler. The cooled steel strip coil undergoes different finishing operations according to the different needs of users. Lines (leveling, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) are processed into steel sheets, flat coils, and slit steel strip products. Due to the excellent properties of high strength, good toughness, easy processing, and good weldability, hot continuous rolled steel plate products are widely used in ships, automobiles, bridges, construction, machinery, pressure vessels, and other manufacturing industries.

With the increasing maturity of hot rolling dimensional accuracy, shape, surface quality, and other new control technologies and the continuous advent of new products, hot continuous rolled steel plates, and strip products have been more and more widely used and have become more and more powerful in the market. competitiveness.
product category:
Hot continuous rolled steel sheet products include steel strips (coils) and steel sheets cut from them. The steel strip (roll) can be divided into straight hair rolls and finishing rolls (split rolls, flat rolls, and slit rolls).
main products:
Hot continuous rolling can be divided into ordinary carbon structural steel, low alloy steel, and alloy steel according to its material and performance.
According to different uses, it can be divided into cold forming steel, structural steel, automobile structural steel, corrosion-resistant structural steel, mechanical structural steel, a welded gas cylinder and pressure vessel steel, pipeline steel, etc.
General Instructions:
Hot continuous rolled steel plate products have a wide variety of steel grades and specifications and are widely used. They are widely used from general engineering structures to the manufacture of automobiles, bridges, ships, boilers, and pressure vessels. Different uses have different requirements on the material properties, surface quality, size, and shape accuracy of steel plates. Therefore, it is necessary to understand the varieties, materials, characteristics, and uses of hot-rolled steel plates in order to achieve economic efficiency. , Reasonable use.
1. Product introduction of hot continuous rolling steel sheet: Hot continuous rolling steel sheet and strip products are made of slabs (mainly continuous casting slabs) as raw materials, which are heated by rough rolling mills and finishing mills to make strips. The hot steel strip coming out of the last rolling mill of finishing rolling is cooled to the set temperature by laminar flow and then rolled into a steel strip coil by the coiler. The cooled steel strip coil undergoes different finishing operations according to the different needs of users. Lines (leveling, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) are processed into steel sheets, flat coils, and slit steel strip products.
Due to the excellent properties of high strength, good toughness, easy processing, and good weldability, hot continuous rolled steel plate products are widely used in ships, automobiles, bridges, construction, machinery, pressure vessels, and other manufacturing industries.
With the increasing maturity of hot rolling dimensional accuracy, shape, surface quality, and other new control technologies and the continuous advent of new products, hot continuous rolled steel plates, and strip products have been more and more widely used and have become more and more powerful in the market. competitiveness.
General Instructions
Hot continuous rolled steel plate products have a wide variety of steel grades and specifications and are widely used. They are widely used from general engineering structures to the manufacture of automobiles, bridges, ships, boilers, and pressure vessels. Different uses have different requirements on the material properties, surface quality, size, and shape accuracy of steel plates. Therefore, it is necessary to understand the varieties, materials, characteristics, and uses of hot-rolled steel plates in order to achieve economic efficiency. , Reasonable use.
2. Points to consider in mechanical properties
mechanical properties terminology
(1) Mechanical properties: The mechanical properties of steel plates refer to the properties of steel plates that are related to elastic or inelastic reactions or involve stress-strain relationships under force. Tensile strength, yield point, elongation, and impact absorption energy are the main indicators of the mechanical properties of hot-rolled steel sheets. Its size indicates the ability of steel to resist various effects, which is the main criterion for evaluating the quality of steel plate materials, and also the main basis for material selection and strength calculation in the design of steel plate parts.
(2) Mechanical properties experiment: The experiments to measure the mechanical properties of hot-rolled steel sheets mainly include tensile tests and impact tests.
(3) Yield strength: The stress of the sample when the load does not increase or begins to decrease during the tensile process, but the sample can continue to elongate (deform). The lower the yield strength of the steel, the smaller the force required to produce permanent deformation, that is, the easier it is to form.
(4) Tensile strength: when the sample is stretched, the maximum stress it bears before breaking. When the external stress on the material is greater than its tensile strength, it will rupture. Therefore, the greater the tensile strength of the steel plate material, the more it can withstand the large external stress without breaking.
(5) Elongation: the percentage of the length increased by the gauge length of the specimen after the specimen is broken to the original gauge length. The larger the ratio of elongation, the better the performance (plasticity) of the material that can withstand permanent deformation before force failure; otherwise, the worse the plasticity.
(6) Impact energy (shock absorption energy): During the impact test, the work absorbed by a sample of specified shape and size when it is broken under one impact force, the magnitude of the impact energy indicates the resistance of the metal material to the impact load. The higher the impact energy, the stronger the ability of the material to resist sudden brittle fracture.
Selection of hot continuous rolled steel plate products
1) The relationship between mechanical properties and formability and performance
To obtain the desired shape of the steel sheet, it must be permanently deformed, and the process can be local or overall bending, deep drawing, drawing, or a combination of these forming methods.
(1) The yield strength of the thin steel plate indicates the formability and strength after forming. For the forming of ordinary carbon steel plates, the yield point value is too high, and it is often possible to have excessive spring back, easy to break during forming, and abrasive tools: fast wear and defects due to poor plasticity. However, when the material’s yield point is less than 140Mpa, it may not be able to withstand the stress applied during the forming process. For steel plates used for more complex or complex-forming processing or stamping processing, it is usually required to have a relatively low yield strength value, and the higher the yield ratio is. The smaller, the better the formability of the steel sheet is.
(2) The cold formability of medium and heavy plates is directly related to the yield strength and elongation of the material. The lower the yield strength value, the smaller the stress required to produce permanent deformation; the higher the elongation value, the higher the ductility can withstand a large amount of deformation without breaking.
(3) For steel plates used in building structures, bridges, and mechanical structural parts, in order to prevent the components from breaking, the steel plate materials are required to have a characteristic tensile strength, and in order to prevent the deformation of the components, the steel plate materials are required to have a certain yield strength. Steels for this type of application are required to specify minimum values ​​of tensile strength, yield strength or confinement values.
(4) For steel plates used to withstand impact load-deformation, such as steel plates for ships, bridges, oil, and natural gas pipelines, in order to prevent brittle fractures during use, they are required to have a sufficiently high impact toughness-impact power value.
2) Selection of steel plate varieties and categories.
Hot continuous rolled steel sheet products include strips (coils) and steel sheets cut from them. The steel strip (roll) can be divided into straight hair rolls and finishing rolls (sub-rolls, flat sub-rolls, and slitting tape rolls).
Because the straight hair curler is not re-rolled, the size change part of the head and tail of the steel band is not cut off, and it is not straightened and flattened, so the straight hair curler has tongues and fish tails, and is prone to uneven thickness and width of the head and tail, and edge waves. Therefore, for the applications with high requirements on the surface quality and shape of the steel plate, it is not suitable to use hot-rolled straight hair coils but should be used after finishing Line re-coiled and flat hot-rolling is made of slabs (mainly continuous casting slabs) as raw materials, which are heated by rough rolling mills and finishing mills to make strip steel. The hot steel strip coming out of the last rolling mill of finishing rolling is cooled to the set temperature by laminar flow and then rolled into a steel strip coil by the coiler. The cooled steel strip coil undergoes different finishing operations according to the different needs of users. Lines (leveling, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) are processed into steel sheets, flat coils, and slit steel strip products.

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