Terms related to steel products

Carbon steel

Carbon steel, also known as carbon steel, is an iron-carbon alloy with a carbon content of less than 2%. Carbon steel generally contains a small amount of silicon, manganese, *, and phosphorus in addition to carbon.

According to the purpose, carbon steel can be divided into carbon structural steel, carbon tool steel and free-cutting structural steel. Carbon structural steel can be divided into two types: building structural steel and machine-made structural steel.

According to carbon content, carbon steel can be divided into low carbon steel (wc≤0.25%), medium carbon steel (wc 0.25% to 0.6%) and high carbon steel (wc >O.6%) according to phosphorus, *content can be Carbon steel is divided into ordinary carbon steel (phosphorus, * higher), high quality carbon steel (phosphorus, * lower) and high quality steel (phosphorus, * lower)

The higher the carbon content in general carbon steel, the higher the hardness and the higher the strength, but the lower the plasticity

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Carbon structural steel

This type of steel mainly guarantees mechanical properties, so its grades reflect its mechanical properties, and are represented by Q+ numbers. “Q” is the pinyin prefix of the “Qu” of the yield point, and the number indicates the yield point value. For example, Q275 indicates that the yield point is 275MPa. If the letters A, B, C, D are marked after the grade, it means that the quality grade of the steel is different, the quantity of s, P is reduced in turn, and the steel quality is increased in turn. If the letter “F” is marked after the brand, it is boiling steel. The label "b" is a semi-static steel, and the steel without the label "F," or "b" is a killed steel. For example, Q235-A.F indicates a grade A boiling steel with a yield point of 235 MPa. Q235-c indicates a yield point of 235 MPa. Class C killed steel

Carbon structural steels are generally not subjected to heat treatment, but are used directly in the supply state. Usually Q195, Q215, Q235 steels have low mass fractions of carbon, good welding performance, good ductility, toughness, certain strength, and often rolled into Thin plate, steel bar, welded steel pipe, etc., used in bridges, construction and other structures and manufacturing ordinary rivets, screws, nuts and other parts. Q255 and Q275 steel carbon slightly higher mass fraction, high strength, good plasticity, toughness, can be welded , Rolling forming steel, strip steel and steel plates for structural parts and connecting rods, gears, couplings, pins etc.

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High-quality structural steel

This kind of steel must ensure chemical composition and mechanical properties at the same time. Its grade is the use of two digits to express the average carbon mass fraction in steel (wс × 10000). For example, 45 steel means that the average carbon mass fraction in steel is 0.45% ; 08 steel means that the average carbon content in steel is 0.08%

High-quality carbon structural steel is mainly used in the manufacture of machine parts. It is generally subjected to heat treatment to improve the mechanical properties. According to the different carbon mass fraction, there are different uses. 08, 08F, 10, 10F steel, plastic, high toughness, with excellent Cold formability and weldability, often cold-rolled into thin sheets, used to make instrument housings, cold stampings on automobiles and tractors, such as car bodies, tractor cabs, etc.; 15,20,25 steel for smaller sizes , light load, surface wear resistance, carburizing parts with low requirements for core strength, such as piston pin, sample plate, etc.; 30, 35, 40, 45, 50 steel after heat treatment (quenching + high temperature tempering) has good The comprehensive mechanical properties, ie, high strength and high plasticity, toughness, are used to make shaft parts. For example, 40, 45 steel is commonly used in the manufacture of automobiles, tractor crankshafts, connecting rods, general machine tool spindles, machine tool gears and Other shaft parts with little force; 55, 60, 65 steel heat treatment (quenching + medium temperature tempering) has a high elastic limit and is often used for making small loads (smaller than 12 to 15 mm in cross section) Springs, such as regulators and governor springs, plunger springs, cold coil springs, etc.

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Carbon tool steel

Carbon tool steel is a high-carbon steel that is basically free of alloying elements. Its carbon content is in the range of 0.65% to 1.35%. Its production cost is low, its source of raw materials is easy to obtain, and its machinability is good. After processing, it can obtain high hardness and High wear resistance, so it is widely used steel, used to make a variety of cutting tools, molds, measuring tools

However, the red hardness of this type of steel is poor, ie, when the operating temperature is greater than 250° C., the hardness and wear resistance of the steel will drop sharply and lose their workability. In addition, if the carbon tool steel is made into a larger part, it is difficult to quench. Hard and prone to deformation and cracks

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Free-cutting knot

Structure Steel

The free-cutting structural steel is made by adding some elements to the steel to make the steel brittle, so that the chips can be brittle and broken into pieces easily when the steel is cut, thereby improving the cutting speed and prolonging the tool life. The elements that make the steel brittle are mainly*, Elements such as lead, antimony, and bismuth are used in ordinary low-alloy free-cutting structural steels.

The steel containing amount ws is in the range of 0.08% to 0.30%, and the amount of manganese in the wMn is in the range of 0.60% to 1.55%. The * and manganese in the steel are in the form of manganese, and the manganese is very brittle and has Lubrication performance, so that the chips are easy to break, and help to improve the quality of the processing surface

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alloy steel

In addition to iron, carbon and a small amount of unavoidable elements of silicon, manganese, phosphorus, and *, the steel also contains a certain amount of alloying elements. The alloying elements in the steel include silicon, manganese, molybdenum, nickel, chromium, vanadium, and titanium. One or more of yttrium, barium, boron, lead, rare earth, etc. This steel is called alloy steel.

The alloy steel systems in various countries vary according to their respective resources, production and use conditions. In the past, nickel and chromium steel systems were developed in foreign countries, while silicon, manganese, vanadium, titanium, niobium, boron, and rare earth were found in China. Alloy steel system

Alloy steel accounts for about 10% of the total output of steel and is generally smelted in an electric furnace.

According to the application, the alloy steel can be divided into 8 categories. They are: alloy structural steel, spring steel, bearing steel, alloy tool steel, high-speed tool steel, stainless steel, heat-resistant steel, and silicon steel for electricians.

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Ordinary low

Gold Steel

Ordinary low-alloy steel is a common alloy steel containing a small amount of alloying elements (in most cases, the total amount w does not exceed 3% in total). This type of steel has a relatively high strength, good overall performance, and is resistant to corrosion and wear. , low temperature resistance and good cutting performance, welding performance, etc.

In the case of large savings of scarce alloying elements (such as nickel and chromium), LT ordinary low-alloy steels can usually be used with 1.2-1.3 tons of carbon steel. Its service life and use range are far more than that of carbon steel. Ordinary low alloys. The steel can be smelted in an open hearth furnace or a converter using general smelting methods. The cost is also close to that of carbon steel.

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Engineering structure

Alloy steel

This refers to alloy steels used in engineering and building structures, including weldable high-strength alloy structural steels, alloy steel bars, railway alloy steels, geological oil drilling alloy steels, alloy steels for pressure vessels, high manganese wear-resistant steels, etc. This kind of steel is used for engineering and building structural parts. In alloy steels, the total content of such steel alloys is relatively low, but the production and usage are relatively large.

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Mechanical structure

Alloy steel

This type of steel refers to alloy steels that are suitable for the manufacture of machinery and mechanical parts. It is based on high-quality carbon steel, suitably adding one or more alloying elements, to improve the strength, toughness and hardenability of steel. This kind of steel is usually used after heat treatment (such as quenching and tempering, surface hardening treatment). It mainly includes two types of commonly used alloy structural steel and alloy spring steel, including quenched and tempered alloy steel, surface hardened alloy. Steel (carburized steel, nitrided steel, surface high-frequency quenched steel, etc.), alloy steel for cold plastic forming (cold forging steel, cold extrusion steel, etc.). According to the basic composition of chemical composition can be divided into Mn series Steel, SiMn steel, Cr steel, CrMo steel, CrNiMo steel, Nj steel, B steel, etc.

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Alloy structure

steel

The carbon content of the alloy structural steel wc is lower than that of the carbon structural steel, and is generally in the range of 0.15% to 0.5%. In addition to carbon, it also contains one or more alloying elements such as silicon and manganese. , vanadium, titanium, boron and nickel, chromium, molybdenum, etc.

Alloy structural steels are easy to harden and hard to deform or crack, facilitating heat treatment to improve the properties of the steel

Alloy structural steels are widely used in the manufacture of various transmission parts and fasteners for automobiles, tractors, ships, steam turbines, and heavy-duty machine tools. Low-carbon alloy steels are generally carburized, and medium-carbon alloy steels are generally tempered and tempered.

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Alloy tool

steel

Alloy tool steel is a medium and high carbon steel containing a variety of alloying elements such as silicon, chromium, tungsten, molybdenum, vanadium, etc. Alloy tool steel is easily hardened, hardly deformed and cracked, and is suitable for making large sizes and shapes. Complex cutting tools, molds and measuring tools

Different uses, alloy tool steel carbon content is also different. Most alloy tool steel carbon content wc is 0.5% to 1.5%. Hot deformed die steel with low carbon, wc in the 0.3% ~ 0.6% range; The steel for cutting tools generally contains about 1% carbon; the steel for cold working molds has a higher carbon content, such as the carbon content of graphite mold steels 1.5%, and the carbon content of high-carbon high-chromium type cold working mold steels is as high as 2c. %the above

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High-speed tools

steel

High-speed tool steel is high-carbon high-alloy tool steel. The carbon content in the steel is 0.7% to 1.4%. The steel contains alloy elements that can form high-hardness carbides, such as tungsten, molybdenum, chromium, and vanadium.

High-speed tool steel with high red hardness, high-speed cutting conditions, the temperature up to 500-600 oc hardness does not decrease, thus ensuring good cutting performance

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Spring steel

Springs are used under impact, vibration or long-term alternating stress, so spring steels are required to have high tensile strength, elastic limit, and high fatigue strength. In the process, the spring steel must have certain hardenability, and it is not easy to decarburize. Good quality

Carbon spring steels are high quality carbon structural steels (including normal and high manganese content) with carbon content wc in the range of 0.6%~0.9%. Alloy spring steels are mainly silicon-manganese steels, their carbon content. The amount is slightly lower, mainly by increasing the silicon content of WSi (1.3% ~ 2.8%) to improve performance; in addition there are chromium, tungsten, vanadium alloy spring steel. In recent years, combined with our resources, and according to the requirements of the new technology of automobile and tractor design Developed a new steel grade based on silicon-manganese steel with boron, niobium, molybdenum and other elements to extend the service life of the spring and improve the quality of the spring.

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Bearing steel

Bearing steel is a steel used to make balls, rollers and bearing rings. Bearings are subjected to extreme pressure and friction during operation, so bearing steels are required to have high and uniform hardness and wear resistance, as well as high elasticity. Limits The requirements for the uniformity of the chemical composition of the bearing steel, the content and distribution of non-metallic inclusions, and the distribution of carbides are very strict.

Bearing steel, also known as high-carbon chromium steel, containing carbon wc is about l%, chromium content wc is 0.5% -1.65%. Bearing steel is divided into high-carbon chromium bearing steel, chromium-free bearing steel, carburizing bearing steel, not Rust bearing steel, medium and high temperature bearing steel and anti-magnetic bearing steel six categories

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Electrician silicon steel

Silicon steel for the electrical industry is mainly used for the manufacture of silicon steel sheets for the electrical industry. Silicon steel sheets are used in the manufacture of motors and transformers.

According to the chemical composition of silicon steel can be divided into low silicon steel and high silicon steel. Low silicon steel silicon content wsi1.O% ~ 2.5%, mainly used to manufacture motor; high silicon steel silicon content wsi3.O% ~ 4.5%, generally used to manufacture transformers Their carbon content wc≤O.06%~0.08%

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Rail steel

The rails are mainly subjected to the pressure and impact load of locomotives and rolling vehicles. Therefore, they are required to have sufficient strength, hardness and certain toughness. The commonly used rail steels are carbon-killed steels smelted by open hearth furnaces and converters. These steels contain carbon wc0.6. %.0.8%, which belongs to medium carbon steel and high carbon steel, but the content of manganese in steel is higher, ranging from 0.1% to 0.1% in O.6%

In recent years, ordinary low-alloy steel rails have been widely used, such as high-silicon rails, medium-manganese rails, copper-containing rails, and titanium-containing rails. Common low-alloy steel rails are more wear-resistant than carbon rails, corrosion-resistant, and their service life is greatly improved.

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Shipbuilding steel

Shipbuilding steel refers to the steel used for manufacturing sea vessels and large inland river hull structures. Since hull structures are generally manufactured by welding methods, shipbuilding steels are required to have better welding performance. In addition, certain strength, toughness and certain requirements are also required. Low temperature and corrosion resistance. In the past, low carbon steel was mainly used as shipbuilding steel. Recently, ordinary low alloy steels have been widely used. Existing steels such as 12 manganese ships, 16 manganese ships, 15 manganese vanadium ships and other steels. These steels have comprehensive properties such as high strength, good toughness, easy processing and welding, and resistance to seawater corrosion. They can be successfully used to manufacture tons of ocean-going giant ships.

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Bridge steel

Railway or highway bridges bear the impact load of the vehicle, and the bridge steel requires certain strength, toughness and good fatigue resistance, and the surface quality of the steel is required to be high. The bridge steel often adopts alkaline open hearth killed steel and has been successfully used recently. General low-alloy steels such as 16 manganese, 15 manganese vanadium nitrogen, etc.

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Boiler steel

Boiler steel mainly refers to the materials used to make superheater, main steam pipe and boiler fire room heating surface. The performance requirements for boiler steel are mainly good welding performance, certain high temperature strength and alkali corrosion resistance, oxidation resistance, etc. The commonly used boiler steels are low-carbon killed steel smelted by open hearth smelting or low-carbon steel smelted by electric furnaces. The carbon content wc is in the range of 0.16% to 0.26%. For high-pressure boilers, pearlite heat-resistant steel or austenitic steel is used. Body heat-resistant steel. In recent years, ordinary low-alloy steel has also been used to construct boilers such as 12-manganese, 15-manganese vanadium, 18-manganese-molybdenum crucibles, etc

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Welding rod steel

This kind of steel is specially used for manufacturing arc welding and gas welding electrode wire. The composition of steel differs depending on the welding material. According to the requirements, roughly divided into three categories of carbon steel, alloy structural steel and stainless steel. These steel *, phosphorus content ws ,w P not more than 0.03%, stricter than the general steel. These steels do not require mechanical properties, but only for chemical composition inspection

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stainless steel

Stainless steel is short for stainless steel. It consists of stainless steel and acid-resistant steel. In short, the steel that resists atmospheric corrosion is called stainless steel, and the steel that resists the corrosion of chemical media (such as acids) is called acid-resistant steel. In general, steels with a chromium content w cr greater than 12% have the characteristics of stainless steel.

The microstructure of stainless steel after heat treatment can be further divided into five categories: ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, austenitic-ferritic stainless steel, and precipitation hardened stainless steel

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Heat-resistant steel

In high temperature conditions, the steel with oxidation resistance and sufficient high temperature strength and good heat resistance is called heat-resistant steel. The heat-resistant steel includes two types of oxidation resistant steel and heat resistant steel. The oxidation resistant steel is also called leather. Steel. Hot-strength steels are steels that have good oxidation resistance at high temperatures and have high high-temperature strength. Heat-resistant steels are mainly used for parts that are used at high temperatures for extended periods of time.

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Superalloy

Superalloy is a kind of heat-strength material that has enough permanent strength, creep strength, thermal fatigue strength, high temperature toughness, and sufficient chemical stability at high temperature. It is used for thermal power components operating at high temperatures around 1000oC.

According to their basic chemical composition, they can be divided into nickel-based superalloys, iron-nickel-based superalloys and cobalt-based superalloys.

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Precision alloy

Precision alloy is an alloy with special physical properties. It is an indispensable material in the electrical industry, electronics industry, precision instrumentation industry and automatic control systems.

According to their different physical properties, precision alloys are divided into seven categories: soft magnetic alloys, permanent magnetic alloys, elastic alloys, expanded alloys, hot bimetals, resistance alloys, and thermocouple alloys. Most of the precision alloys are black. Metal-based, only a few are based on non-ferrous metals