In addition to iron, carbon and a small amount of unavoidable silicon, manganese, sulfur and phosphorus elements, alloy steel also contains a certain amount of alloying elements. The common alloying elements are silicon, manganese, molybdenum, nickel, chromium, vanadium, titanium , niobium, boron, aluminum, rare earth, etc.
Alloy steel accounts for about ten percent of the total steel output, and is generally smelted in an electric furnace. According to the application, alloy steel can be divided into several categories, which are: alloy structural steel, spring steel, bearing steel, alloy tool steel, high-speed tool steel, stainless acid-resistant steel, heat-resistant skin-resistant steel and electrical silicon steel, and Some special-purpose alloys, etc.
Alloy structural steel: The carbon content of alloy structural steel is lower than that of carbon grooved steel, generally in the range of 0.15 to 0.50%. In addition to carbon, it also contains one or several alloying elements, such as silicon, manganese, vanadium, titanium, boron, nickel, chromium, aluminum, etc. Alloy structural steel is easy to harden and not easy to deform or crack, and it is convenient to improve the properties of steel through heat treatment. Alloy structural steel is widely used in the manufacture of various transmission parts or fasteners for automobiles, tractors, ships, steam turbines, and heavy machine tools. Low-carbon alloy structural steel is generally carburized, and medium-carbon alloy structural steel is generally quenched and tempered.
Spring steel: Spring steel is an important material for making springs. Spring is an important part of machinery, and it is widely used, such as automobiles, tractors, railway vehicles and other transportation tools, as well as instrument industry, etc. are inseparable from it. Springs are used under shock, vibration or long-term alternating stress. Therefore, the spring is required to have high tensile strength, elastic limit, and high fatigue strength. In terms of technology, spring steel is required to have certain hardenability, not easy to decarburize, and good surface quality. Carbon spring steel is high-quality carbon structural steel with a carbon content in the range of 0.6 to 0.9% (including normal and high manganese content); alloy spring steel is mainly silicon-manganese steel, and their carbon content Slightly lower, mainly by increasing the silicon content (1.3 ~ 2.8) to improve performance. In addition, there are alloy spring steels containing chromium, tungsten, and vanadium, and new steel types that add elements such as boron, niobium, and molybdenum to silicon-manganese steel.
Alloy tool steel: Alloy tool steel is medium and high carbon steel containing various alloying elements such as silicon, chromium, tungsten, molybdenum and vanadium. Alloy tool steel is used to manufacture more important cutting tools, molds and measuring tools. For tools with different requirements, the requirements for material properties are also different. But there are also some common requirements, that is, high hardness, wear resistance, good hardenability, hot hardness, sufficient toughness and small deformation, etc. Most alloy tool steels have a carbon content of 0.5-1.5%. The carbon content of steel for hot deformation molds is low, in the range of 0.3 to 0.6%; the carbon content of steel for cutting tools is generally about 1%; the carbon content of steel for cold working molds is relatively high, such as graphite mold steel carbon content Up to 1.5%, the carbon content of high-carbon and high-chromium cold-working mold steel is as high as 2% or more.
Electrothermal Alloys: Electrothermal Alloys are mainly used for heating elements of electric heating furnaces. It has the characteristics of large specific resistance, large power load, small temperature coefficient of resistance and good high-temperature oxidation resistance. The alloying elements contained in the electrothermal alloy include nickel, chromium, aluminum, etc. There are two commonly used electrothermal alloys: iron-chromium-aluminum alloy: Common grades of iron-chromium-aluminum alloys are: Cr13Al4, Cr17Al5, 1Cr25Al5. Chromium-nickel alloys: The common grades of chromium-nickel alloys are as follows: Cr20Ni80, Cr15Ni60, Cr20Ni30, etc.
