Material Introduction

Steel (Steel): is a steel ingot, billet or steel by pressure processing to make the required various shapes, sizes and properties of the material. Steel is an essential material for national construction and the realization of the four modernizations. It has a wide range of applications and a wide variety. According to the different cross-sectional shapes, steel is generally divided into four categories: profiles, plates, pipes and metal products, and it is also divided into heavy rail and light rail., Large steel, medium steel, small steel, cold-formed steel, high-quality steel, wire rod, medium-thick steel plate, thin steel plate, electrical silicon steel sheet, strip steel, seamless steel pipe steel, welded steel pipe, metal products and other varieties.

Features

Black metal black metal mainly refers to iron, manganese, chromium and its alloys.

Steel The pig iron for steelmaking is put into the steelmaking furnace and melted according to a certain process, that is, steel is obtained.

Non-ferrous metals Metals other than ferrous metals are called non-ferrous metals, such as copper, tin, lead, zinc, aluminum, as well as brass, bronze, aluminum alloys and bearing alloys.

Related Terms

Carbon steel, also known as carbon steel, is an iron-carbon alloy with a carbon content (wc) of less than 2%. In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur and phosphorus. According to the use of carbon steel can be divided into carbon structural steel, carbon tool steel and easy-cutting structural steel three categories. Carbon structural steel can be divided into building structural steel and machine manufacturing structural steel two. According to the carbon content, carbon steel can be divided into low carbon steel (wc≤ 0.25%), medium carbon steel (wc 0.25%~ 0.6%) and high carbon steel (wc >0.6%). According to the phosphorus and sulfur content, carbon steel can be divided into ordinary carbon steel (high phosphorus and sulfur), high-quality carbon steel (low phosphorus and sulfur) and high-quality steel (low phosphorus and sulfur). Generally, the higher the carbon content in carbon steel, the higher the hardness and the higher the strength, but the lower the plasticity.

Carbon structural steel mainly guarantees mechanical properties, so its brand reflects its mechanical properties, which is expressed by Q number, where "Q" is the Chinese Pinyin prefix of the yield point "Qu" word, and the number indicates the yield point value, for example, Q275 indicates the yield point is 275MPa. If the letters A, B, C and D are marked after the grade, it means that the steel quality grade is different, the amount of S and P decreases in turn, and the steel quality increases in turn. If the letter "F" is marked after the grade, it is boiling steel, the mark "B" is semi-killed steel, and the mark "F" or "B" is killed steel. For example, Q235-A · F represents A- grade boiling steel with a yield point of 235MPa, and Q235-c represents C- grade killed steel with a yield point of 235MPa. Carbon structural steels are generally not heat treated and are used directly in the supply state. Usually Q195, Q215, Q235 steel has low carbon mass fraction, good welding performance, good plasticity, good toughness, and a certain strength. It is often rolled into thin plates, steel bars, welded steel pipes, etc., used in bridges, buildings and other structures and manufacturing ordinary rivets, Screws, nuts and other parts. Q255 and Q275 steel has slightly higher carbon mass fraction, higher strength, better plasticity and toughness, and can be welded. Usually rolled and formed steel, bar steel and steel plate are used as structural parts and simple mechanical connecting rods, gears, and couplings. Parts such as joints and pins.

High-quality structural steel This type of steel must ensure both chemical composition and mechanical properties. Its grade is expressed in two digits of the average mass fraction of carbon in steel (w с × 10000). For example, 45 steel indicates that the average mass fraction of carbon in steel is 0.45%;08 steel indicates that the average mass fraction of carbon in steel is 0.08%, and high-quality carbon structural steel is mainly used to manufacture machine parts. Generally, heat treatment is required to improve mechanical properties. Depending on the mass fraction of carbon, there are different uses. 08, 08F, 10 and 10F steels have high plasticity and toughness, excellent cold formability and welding performance, and are often cold-rolled into thin plates, which are used to make cold-stamped parts on instrument shells, automobiles and tractors, such as automobile bodies and tractor cabs. 15, 20 and 25 steels are used to make carburized parts with small size, light load, surface wear resistance and low core strength requirements, such as piston pins, templates, etc.; 30, 35, 40, 45, 50 steel after heat treatment (quenching + high temperature tempering) has good comprehensive mechanical properties, that is, with high strength and high plasticity, toughness, used to make shaft parts, such as 40, 45 steel is often used to make cars, tractors crankshaft, connecting rod, general machine tool spindle, machine tool gear and other shaft parts with little force; 55, 60, 65 steel after heat treatment (quenching + tempering) has a high elastic limit, commonly used in the production of small load, small size (cross-sectional size less than 12~15mm) of the spring, such as pressure and speed spring, plunger spring, cold coil spring, etc.

Carbon tool steel carbon tool steel is basically free of alloying elements of high carbon steel, carbon content in the range of 0.65~1.35, its low production cost, easy to obtain raw materials, good machinability, after processing can be high hardness and high wear resistance, so it is widely used in the manufacture of various cutting tools, molds, measuring tools. However, the red hardness of this kind of steel is poor, that is, when the working temperature is greater than 250 ℃, the hardness and wear resistance of the steel will drop sharply and lose the ability to work. In addition, carbon tool steel such as made of larger parts is not easy to harden, and easy to produce deformation and crack.

Easy-cutting structural steel Easy-cutting structural steel is to add some elements to the steel that make the steel brittle, so that the chips are easy to break into chips when cutting, which is beneficial to improve the cutting speed and extend the tool life. The elements that make steel brittle are mainly sulfur, and lead, tellurium, bismuth and other elements are used in ordinary low-alloy free-cutting structural steel. This steel has a sulfur content ws in the range of 0.08-0.30% and a manganese content wMn in the range of 0.60-1.55%. Sulfur and manganese in steel exist in the form of manganese sulfide, manganese sulfide is very brittle and lubrication efficiency, so that the chip is easy to break, and is conducive to improving the quality of the processing surface.

In addition to containing iron, carbon and a small amount of inevitable silicon, manganese, phosphorus, and sulfur elements, alloy steel also contains a certain amount of alloying elements. The alloying elements in steel include silicon, manganese, molybdenum, nickel, chromium, one or more of vanadium, titanium, niobium, boron, lead, rare earth, etc. This steel is called alloy steel. The alloy steel system of various countries varies with their own resources, production and use conditions. In the past, foreign countries have developed nickel and chromium steel systems, while China has developed alloy steel systems dominated by silicon, manganese, vanadium, titanium, niobium, boron and rare earths. Alloy steel accounts for about ten percent of the total output of steel. It is generally smelted in electric furnaces. Alloy steel can be divided into eight categories according to its use. They are: alloy structural steel, spring steel, bearing steel, alloy tool steel, high-speed tool steel, stainless steel, heat-resistant non-peeling steel, and electrical silicon steel.

Ordinary low alloy steel Ordinary low alloy steel is a kind of ordinary alloy steel containing a small amount of alloying elements (in most cases, the total amount of W is not more than 3%). This kind of steel has high strength, good comprehensive performance, corrosion resistance, wear resistance, low temperature resistance, good cutting performance and welding performance. Under the condition of saving a lot of scarce alloy elements (such as nickel and chromium), usually 1 t ordinary low alloy steel can be used on top of 1.2-1.3 t carbon steel, and its service life and application range are far more than carbon steel. Ordinary low alloy steel can be smelted in the flat furnace and converter by the general smelting method, and the cost is close to that of carbon steel.

Engineering structural steel This refers to the alloy steel used in engineering and building structures, including weldable high-strength alloy structural steel, alloy steel bar, alloy steel for railway, alloy steel for geological oil drilling, alloy steel for pressure vessels, high manganese wear-resistant steel, etc. This kind of steel is used as engineering and building structural parts. In alloy steel, the total content of this kind of steel alloy is low, but the production and use are large.

Mechanical structural steel This type of steel refers to alloy steel suitable for manufacturing machines and mechanical parts. It is based on high-quality carbon steel, appropriately adding one or several 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 treatment, surface hardening treatment). Mainly includes two categories of commonly used alloy structural steel and alloy spring steel, including quenched and tempered alloy steel, surface hardening alloy steel (carburized steel, nitriding steel, surface high frequency quenching steel, etc.), cold plastic forming Alloy steel (cold forging steel, cold extrusion steel, etc.). According to the basic composition of the chemical composition series can be divided into Mn series steel, SiMn series steel, Cr series steel, CrMo series steel, CrNiMo series steel, Nj series steel, B series steel and so on.

Alloy structural steel alloy structural steel carbon content wc lower than carbon structural steel, generally in the range of 0.15 to 0.50%. In addition to carbon, it also contains one or more alloying elements, such as silicon, manganese, vanadium, titanium, boron, nickel, chromium, molybdenum, etc. Alloy structural steel is easy to harden and not easy to deform or crack, which is convenient for heat treatment to improve the performance of steel. Alloy structural steels are widely used in the manufacture of various transmission parts and fasteners for automobiles, tractors, ships, steam turbines, and heavy machine tools. Low carbon alloy steel is generally carburized, and medium carbon alloy steel is generally quenched and tempered.

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 easy to harden, not easy to produce deformation and crack, suitable for manufacturing large size, complex shape of cutting tools, molds and measuring tools. Different uses, the carbon content of alloy tool steel is also different. The carbon content wc of most alloy tool steels is 0.5-1.5%. Hot deformation mold steel with low carbon content, wc in the range of 0.3~0.6; Cutting tool steel generally contains about wc1% carbon; Cold working mold steel has a higher carbon content, such as graphite mold steel carbon content wc up to 1.5, high carbon high chromium cold working mold steel carbon content wc up to more than 2%.

High-speed tool steel High-speed tool steel is a high-carbon high-alloy tool steel. The carbon content in the steel is 0.7-1.4%, and the steel contains alloying elements that can form high-hardness carbides, such as tungsten, molybdenum, chromium, and vanadium. High-speed tool steel has high red hardness. Under the condition of high-speed cutting, the temperature is as high as 500-600 degrees Celsius and the hardness is not reduced, thus ensuring good cutting performance.

Spring steel springs are used under impact, vibration or long-term alternating stress, so spring steel is required to have high tensile strength, elastic limit and high fatigue strength. In the process requirements of spring steel has a certain degree of hardenability, not easy to decarburization, surface quality and so on. Carbon spring steel is a high-quality carbon structural steel with a carbon content of WC in the range of 0.6 to 0.9 (including normal and high manganese content). Alloy spring steel is mainly silicon manganese steel, their carbon content is slightly lower, mainly by increasing the silicon content WSi(1.3~2.8) to improve performance; in addition to chromium, tungsten, vanadium alloy spring steel. Combined with China's resources, and according to the requirements of new technologies for the design of automobiles and tractors, a new steel type with boron, niobium, molybdenum and other elements added to the silicon-manganese steel was developed to extend the service life of the spring and improve the quality of the spring.

Bearing steel Bearing steel is the steel used to make balls, rollers and bearing rings. Bearings are subjected to great pressure and friction during work, so bearing steel is required to have high and uniform hardness and wear resistance, as well as high elastic limit. 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, carbon wc is about l%, chromium wc 0.5-1.65%. Bearing steel is divided into high carbon chromium bearing steel, chromium-free bearing steel, carburizing bearing steel, stainless bearing steel, high temperature bearing steel and anti-magnetic bearing steel six categories.

Electrical silicon steel electrical industrial silicon steel is mainly used to manufacture electrical industrial silicon steel sheet. Silicon steel sheet is a large amount of steel 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 wSi1.0%~ 2.5%, mainly used to manufacture motors; high silicon steel silicon content wSi 3.0%~ 4.5%, generally used to manufacture transformers. Their carbon content wc ≤ 0.06~0.08%.

Rail steel rail mainly bear the pressure and impact load of rolling stock, therefore, it is required to have sufficient strength and hardness and certain toughness. Rail steel is usually used in open furnace and converter smelting of carbon killed steel, the steel containing carbon wc0.6%~ 0.8%, belonging to the medium carbon steel and high carbon steel, but the manganese content in steel WMn is higher, in the range of 0.6%~ 1.1%. Ordinary low alloy steel rails have been widely used, such as high silicon rails, medium manganese rails, copper rails, titanium rails, etc. Ordinary low-alloy rail is more wear-resistant and corrosion-resistant than carbon rail, and its service life is greatly improved.

Shipbuilding steel Shipbuilding steel refers to steel used in the manufacture of marine vessels and large inland hull structures. Because the hull structure is generally manufactured by welding method, shipbuilding steel is required to have better welding performance. In addition, it also requires a certain strength, toughness and certain low temperature resistance and corrosion resistance. In the past, low carbon steel was mainly used as shipbuilding steel. Has a large number of ordinary low alloy steel, the existing steel such as 12 manganese ship, 16 manganese ship, 15 manganese vanadium ship and other steel. These steels have high strength, good toughness, easy processing and welding, resistance to seawater corrosion and other comprehensive characteristics, can be successfully used to manufacture tons of ocean-going ship.

Bridge steel railway or highway bridges bear the impact load of vehicles, bridge steel requires a certain strength, toughness and good fatigue resistance, and the surface quality of steel requirements are higher. Bridge steel often use alkaline open-hearth killed steel, the successful use of ordinary low alloy steel such as 16 manganese, 15 manganese vanadium nitrogen and so on.

Boiler steel Boiler steel mainly refers to the materials used to manufacture superheaters, main steam pipes and heating surfaces of boiler fire chambers. The performance requirements of boiler steel are mainly good welding performance, certain high temperature strength and alkali corrosion resistance, oxidation resistance and so on. Commonly used boiler steel has low carbon killed steel or electric furnace smelting of low carbon steel, carbon content wc in the range of 0.16~0.26. When manufacturing high-pressure boilers, pearlite heat-resistant steel or austenitic heat-resistant steel is applied. The boiler is also built with ordinary low alloy steel, such as 12 manganese, 15 manganese vanadium, 18 manganese molybdenum niobium, etc.

Steel for welding rods This kind of steel is specially used for the manufacture of arc welding and gas welding rod steel wire. The composition of steel varies with the material being welded. According to needs, roughly divided into carbon steel, alloy structural steel and stainless steel three categories. The sulfur and phosphorus content ws and wP of these steels are not more than 0.03%, which is stricter than the general steel requirements. These steels do not require mechanical properties, but only chemical composition tests.

Stainless steel stainless acid resistant steel referred to as stainless steel, it is composed of stainless steel and acid resistant steel two parts. In short, the steel that can resist atmospheric corrosion is called stainless steel, and the steel that can resist the corrosion of chemical media (such as acids) is called acid-resistant steel. Generally speaking, steel with a chromium content of WCR greater than 12% has the characteristics of stainless steel. According to the microstructure of stainless steel after heat treatment, it can be divided into five categories: ferritic stainless steel, martensitic stainless steel, austenitic stainless steel, austenitic ferritic stainless steel and precipitation hardening stainless steel.

Heat-resistant steel Under high temperature conditions, steel with oxidation resistance and sufficient high temperature strength and good heat resistance is called heat-resistant steel. Heat resistant steel includes two types of oxidation resistant steel and hot strength steel. Anti-oxidation steel is also called non-peeling steel. Hot strength steel refers to steel that has good oxidation resistance at high temperatures and has high high temperature strength. Heat-resistant steel is mainly used for parts that are used for a long time at high temperatures.

High-temperature alloy High-temperature alloy refers to a kind of thermally strong material with sufficient durable strength, creep strength, thermal fatigue strength, high temperature toughness and sufficient chemical stability at high temperatures. It is used for thermal power components working at high temperatures above 600 degrees Celsius. According to its basic chemical composition, it can be divided into nickel-based high-temperature alloy, iron-nickel-based high-temperature alloy and cobalt-based high-temperature alloy.

Precision alloy precision alloy refers to the alloy with special physical properties. It is an indispensable material in the electrical industry, electronics industry, precision instrument industry and automatic control system. Precision alloys are divided into seven categories according to their different physical properties, namely: soft magnetic alloys, deformed permanent magnetic alloys, elastic alloys, expansion alloys, thermal bimetals, resistance alloys, and thermocouple alloys. The vast majority of precision alloys are based on ferrous metals, and only a few are based on non-ferrous metals. Note: Wc, Ws, Wmn and Wp represent the mass fractions of C, S, Mn and P respectively.

Common Terms

A standard is a uniform provision for repetitive things and concepts. It is based on the comprehensive results of science, technology and practical experience, approved by the competent agencies by consensus of the parties concerned, and issued in a specific form as a guideline and basis for common compliance. The standards implemented by China's steel products include national standards (GB, GB/T), industry standards (YB), local standards and enterprise standards. 2 Technical conditions The performance indicators and quality requirements that the product should meet are called technical conditions, such as chemical composition, external dimensions, surface quality, physical properties, mechanical properties, process properties, internal organization, delivery status, etc. 3 Guarantee conditions In accordance with the provisions of the technical conditions of metal materials, the production plant should carry out inspection and ensure that the inspection results meet the requirements of the performance, chemical composition, internal organization and other quality indicators, called the guarantee conditions. 4 Quality Certificate The production of metal materials is the same as the production of other industrial products. It is carried out in accordance with uniform standards. The product factory inspection system is implemented. Unqualified metal materials are not allowed to be delivered. For the delivery of metal materials, the manufacturer provides a quality certificate to ensure its quality. The quality certificate of metal materials not only indicates the name, specification, number of pieces delivered, weight, etc. of the material, but also provides all inspection results of the specified guarantee items. 5 The quality certificate is the confirmation and guarantee of the inspection results of the batch of products by the supplier, and is also the basis for the buyer to re-inspect and use. 5 The quality grade is divided into several grades according to the different requirements of steel surface quality, shape and allowable deviation of size. For example, first-class products and second-class products. Sometimes different levels are formulated for a certain requirement, for example, the surface quality is divided into level 1, level 2 and level 3, and the surface decarburization layer depth is divided into group 1 and group 2, all of which indicate the difference in quality. For some metal materials, the standard stipulates that there are several allowable dimensional deviations, and according to the different sizes of allowable deviations, they are divided into several grades, called accuracy grades. The accuracy level is divided into ordinary accuracy, higher accuracy and advanced accuracy according to the allowable deviation. The higher the accuracy level, the smaller the allowable dimensional deviation. When ordering, care should be taken to include the accuracy level requirements in the contract and other relevant documents. 7 The brand of metal material is the name given to each specific metal material. The grade of steel is also called steel number. The grades of metal materials in our country can generally reflect the chemical composition. The grade not only indicates the specific variety of metal material, but also can roughly judge its quality according to it. In this way, the grade simply provides a common concept of the quality of specific metal materials, thus bringing great convenience to the production, use and management. 8 varieties of metal materials, refers to the use, shape, production process, heat treatment state, particle size and other different products. 9 model metal material model refers to the use of Chinese pinyin (or Latin) letters and one or several numbers to represent different shapes, types of profiles and carbide products such as code. Numbers indicate the nominal size of the main part. 10 specifications refer to different sizes of the same variety or the same type of metal materials. The general size is different, the allowable deviation is also different. In product standards, the specifications of varieties are usually arranged in order from small to large. 11 surface state is mainly divided into two kinds of bright and not bright. Common in steel wire and steel strip standards, the main difference is to take bright annealing or general annealing. There are also polishing, polishing, pickling, coating, etc. as the surface state. 12 Edge state The edge state refers to whether the strip is cut or not. For those who cut the edge, the steel strip is cut, and for those who do not cut the edge, the steel strip is not cut. 13 Delivery state delivery state refers to the final plastic deformation processing or final heat treatment state of product delivery. Delivery without heat treatment has hot-rolled (forged) and cold-rolled state. After normalizing, annealing, high temperature tempering, quenching and tempering and solid solution treatment are collectively referred to as heat treatment state delivery, or according to the heat treatment category, respectively, called normalizing, annealing, high temperature tempering, quenching and tempering state delivery. 14 The degree of hardness of the material refers to the use of different heat treatment or work hardening degree, the resulting steel is different. In some strip steel standards, it is divided into special soft steel strip, soft steel strip, semi soft steel strip, low hard steel strip and hard steel strip. 15 Longitudinal and transverse steel standards referred to in the longitudinal and transverse, both refer to the relative relationship with the rolling (forging) and drawing direction, and the processing direction of the parallel is called longitudinal. The sample taken along the processing direction is called the longitudinal sample; the sample taken perpendicular to the processing direction is called the transverse sample. The fracture on the longitudinal specimen is perpendicular to the rolling direction, so it is called transverse fracture. The fracture on the transverse specimen is parallel to the processing direction, so it is called longitudinal fracture. 16 Theoretical quality and actual quality These are two different methods of calculating delivery quality. According to the theoretical quality of delivery, is calculated according to the nominal size and density of the material delivery quality. According to the actual quality of delivery, is according to the material by weighing (weighing) the delivery quality. 17 Nominal size and actual size Nominal size is the nominal size specified in the index and is the ideal size desired in the production process. However, in actual production, the actual size of steel is often greater than or less than the nominal size, and the actual size is called the actual size. 18 Deviation and Tolerance Because it is difficult to reach the nominal size in actual production, the standard stipulates that there is an allowable difference between the actual size and the nominal size, which is called deviation. A negative value of the difference is called a negative deviation, and a positive value is called a positive deviation. The sum of the absolute values of the allowable positive and negative deviations specified in the standard is called the tolerance. The deviation is directional, that is, "positive" or "negative", the tolerance is not directional 19 delivery length steel delivery length, there are four kinds of provisions in the current standard:

Length, where the length of the steel within the scope of the standard and no fixed length, are called the usual length. However, in order to facilitate packaging, transportation and measurement, when each enterprise cuts steel, it is best to cut it into several sizes of different lengths according to the situation, and strive to avoid disorder.

The short-length 20 smelting method refers to the steelmaking furnace smelting, such as open hearth furnace, electric arc furnace, electroslag furnace, vacuum induction furnace and mixed steelmaking. The meaning of the term "smelting method" in the standard does not include the concepts of deoxidation methods (such as fully deoxidized killed steel, semi-deoxidized semi-killed steel and rimmed steel) and casting methods (such as injection, betting and continuous casting). 2l Chemical composition (product composition) refers to the chemical composition of steel products, including main components and impurity elements, and its content is expressed in weight percentage. 22 Smelting composition The melting composition of steel refers to the chemical composition of steel in the middle of pouring after melting (such as deoxidation in the tank). 23 Finished product composition The finished product composition of steel, also known as the verification analysis composition, refers to the chemical composition obtained by drilling or shaving test chips from the finished steel according to the prescribed method (see GB/T222 for details) and analyzing them according to the prescribed standard method. The finished product composition of steel is mainly used for the acceptance of steel by the use department or inspection department. The manufacturer generally does not complete the analysis of the finished product, but should ensure that the composition of the finished product meets the standard requirements. Some main products or sometimes due to some reason (such as process changes, quality instability, smelting composition close to the upper and lower limits, smelting analysis is not obtained, etc.), the production plant also does the finished product composition analysis. 24 High-quality steel and high-quality steel (with A) are also called quality steel and high-quality steel. The difference is that high-quality steel is superior to high-quality steel in some or all of the following aspects. ① Reduce the range of carbon content; ② Reduce the content of harmful impurities (mainly sulfur and phosphorus); ③ Ensure high purity (referring to less inclusion content);④ Ensure high mechanical properties and process performance. Steel prospects for the market prospects, large domestic steel enterprises appear differences. Anshan Iron and Steel lowered its April sheet price on March 18. Last week, Baosteel raised the futures prices of its main products in April. The leading varieties of WISCO and Shougang did not follow the pace of Baosteel, and Shagang introduced a price reduction policy and gave subsidies.