Alloy steel for engineering structures This refers to alloy steel used in engineering and building structures, including weldable high-strength alloy structural steel, alloy rebar steel, railway alloy steel, geological and petroleum drilling alloy steel, pressure vessel alloy steel, high manganese wear-resistant steel, etc. This type of steel is used as components in engineering and building structures. Among alloy steels, this type has a relatively low total alloy content but is produced and used in large quantities.
9.Alloy steel for mechanical structures
This type of steel refers to alloy steels suitable for manufacturing machines and mechanical parts. It is based on high-quality carbon steel with the appropriate addition of one or more alloying elements to improve the strength, toughness, and hardenability of the steel. This type of steel usually requires heat treatment before use. It mainly includes two categories: commonly used alloy structural steels and alloy spring steels, which include quenched and tempered alloys, surface-hardened alloys, and cold plastic forming alloys. According to the basic chemical composition system, it can be divided into Mn series steels, SiMn series steels, Cr series steels, CrMo series steels, CrNiMo series steels, Ni series steels, B series steels, etc.
Ordinary low-alloy steel Ordinary low-alloy steel is a type of ordinary alloy steel that contains a small amount of alloying elements (in most cases its total W does not exceed 3). This type of steel has relatively high strength and good overall performance while possessing corrosion resistance, wear resistance, low-temperature resistance as well as good cutting performance and welding performance. Under conditions that save scarce alloy elements significantly, typically 1 ton of ordinary low-alloy steel can replace 1.2-1.3 tons of carbon steel in use; its service life and range far exceed those of carbon steel. Ordinary low-alloy steel can be smelted using general smelting methods in open hearths or converters at costs close to those of carbon steels. Alloy steel for mechanical structures This type of steel refers to alloy steels suitable for manufacturing machines and mechanical parts. It is based on high-quality carbon steel with the appropriate addition of one or more alloying elements to improve the strength, toughness, and hardenability of the steel. This type of steel usually requires heat treatment before use. It mainly includes two categories: commonly used alloy structural steels and alloy spring steels, which include quenched and tempered alloys, surface-hardened alloys, and cold plastic forming alloys. According to the basic chemical composition system, it can be divided into Mn series steels, SiMn series steels, Cr series steels, CrMo series steels, CrNiMo series steels, Ni series steels, B series steels, etc. Precision alloys Precision alloys refer to alloys with special physical properties. They are indispensable materials in the electrical industry, electronics industry, precision instrument industry and automatic control systems.
Precision alloys are further divided into seven categories based on their different physical properties: 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; only a few are based on non-ferrous metals. High-temperature alloys High-temperature alloys refer to thermal-strength materials that have sufficient long-term strength at high temperatures along with creep strength, thermal fatigue strength and adequate chemical stability for working under conditions around 1000°C.
According to their basic chemical composition differences they can be divided into nickel-based high-temperature alloys iron-nickel-based high-temperature alloys and cobalt-based high-temperature alloys. Heat-resistant steels Steel that has oxidation resistance along with sufficient high-temperature strength and good heat-resistance performance under high temperature conditions is called heat-resistant steel. Heat-resistant steels include two categories: oxidation-resistant steels (also known as non-scaling steels) and thermal-strength steels which have good oxidation resistance at elevated temperatures along with higher strength at those temperatures. Heat-resistant steels are mainly used for parts that require long-term use at elevated temperatures. Stainless Steel 'Stainless acid-resistant' stainless refers to stainless-steel which consists mainly of stainless-steel components resistant to atmospheric corrosion while acid-resistant components resist corrosion from chemical media (such as acids). Generally speaking if the chromium content wCr exceeds 12%, it exhibits characteristics typical of stainless-steel; stainless-steels can also be classified into five major categories based on their microstructure after heat treatment: ferritic stainless-steel martensitic stainless-steel austenitic stainless-steel duplex (austenitic-ferritic) stainless-steel precipitation-hardened stainless-steel. 'Boiler Steel' 'Boiler Steel' primarily refers to materials used for manufacturing superheaters main steam pipes and boiler furnace heating surfaces. The performance requirements for boiler stee include good welding properties certain levels of high-temperature strength alkali corrosion resistance oxidation resistance etc Commonly used boiler stee includes low-carbon quieting stee smelted in open hearths or electric furnaces with carbon content wC ranging from O .16% -0 .26%. For manufacturing high-pressure boilers pearlitic heat-resistant stee or austenitic heat-resistant stee is applied In recent years ordinary low-alloy stee has also been widely adopted for constructing boilers such as those made from manganese vanadium molybdenum niobium etc.' 'Bridge Steel' 'Railway or highway bridges bear impact loads from vehicles so bridge stee must possess certain levels of strength toughness fatigue resistance while also having higher surface quality requirements Bridge stee often uses alkaline open-hearth quieting stee Recently ordinary low-alloy stees such as manganese vanadium nitrogen have been successfully adopted.' 'Shipbuilding Steel' 'Shipbuilding Steel' refers specifically to the types utilized in constructing marine vessels large inland ship hull structures Since hull structures generally employ welding methods shipbuilding stels must exhibit good welding properties Additionally they require certain levels of strength toughness along with some degreeof low temperature corrosion resistance Historically low-carbon stels were primarily utilized However recently there has been significant adoptionof ordinarylow-alloy stels existing types like manganese ships vanadium ships etc These types possess comprehensive characteristics such ashighstrength excellent toughness easeofprocessing welding seawater corrosionresistance making them suitablefor constructing tensofthousands ton ocean-going giants.' 'Rail Steel' 'Rail tracks primarily endure pressuresand impact loads from locomotives thus requiring sufficientstrength hardness alongside some degreeof toughness Typically employed rail stels consistof carbon quieting stels smelted via open hearths converters containingcarbon wC between0 .6%-0 .8% categorizedas medium-highcarbonsteels However these rails contain higher manganese levels WMn rangingfromO .6%-1 .1%. '
In recent years ordinarylow-alloy rail tracks have been widely adopted includinghighsilicon rails medium-manganese rails copper-containing rails titanium-containing rails etc Ordinarylow-alloy rail tracks exhibit superior wear-resistance corrosion-resistance significantly extending service life comparedto carbonsteelrails. Electrical siliconsteel Silicon steel for the electrical industry is mainly used to manufacture silicon steel sheets for the electrical industry. Silicon steel sheets are a type of steel that is widely used in the manufacturing of motors and transformers. According to chemical composition, silicon steel can be divided into low silicon steel and high silicon steel. Low silicon steel has a silicon content of wsi 1.0% to 2.5%, mainly used for manufacturing motors; high silicon steel has a silicon content of wsi 3.0% to 4.5%, generally used for manufacturing transformers. Their carbon content is wc ≤ 0.06% to 0.08%. Bearing Steel Bearing steel is used to manufacture balls, rollers, and bearing rings. Bearings bear great pressure and friction during operation, so bearing steel requires high and uniform hardness and wear resistance, as well as a high elastic limit. The requirements for the uniformity of the chemical composition of bearing steel, the content and distribution of non-metallic inclusions, and the distribution of carbides are very strict.
Bearing steel is also known as high carbon chromium steel, with a carbon content wc of about 1%, and chromium content wc ranging from 0.5% to 1.65%. Bearing steel can be divided into six categories: high carbon chromium bearing steel, non-chromium bearing steel, carburized bearing steel, stainless bearing steel, medium-high temperature bearing steel, and anti-magnetic bearing steel. Spring Steel Springs are used under impact, vibration or long-term alternating stress conditions; therefore, spring steel requires high tensile strength, elastic limit, and fatigue strength. In terms of process requirements, spring steel should have certain hardenability, not easily decarburized, and good surface quality.
Carbon spring steel refers to high-quality carbon structural steels with a carbon content wc in the range of 0.6% to 0.9% (including normal and higher manganese content). Alloy spring steels are mainly silico-manganese types with slightly lower carbon content that improve performance by increasing silicon content WSi (1.3% to 2.8%). Additionally, there are alloy spring steels containing chromium, tungsten, and vanadium. In recent years, based on China's resources and according to new technology requirements in automobile and tractor design, new types of steels have been developed by adding elements such as boron, niobium, molybdenum on the basis of silico-manganese steels to extend the service life of springs and improve their quality. High-Speed Tools High-speed tool steels are high-carbon high-alloy tool steels with a carbon content wc ranging from 0.7% to 1.4%. These steels contain alloying elements that can form hard carbides such as tungsten, molybdenum, chromium, vanadium; high-speed tool steels have high red hardness which ensures good cutting performance even at temperatures reaching up to 500-600°C during high-speed cutting. | 
