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Classification of chemical composition of steel

18 Aug,2023

1. Non-alloy steel: Non-alloy steel is also called carbon steel. Except for a certain amount of silicon (generally <0.40%) and manganese (generally 0.80%) and other alloying elements added for deoxidation, the steel does not contain other alloying elements. of steel. According to the level of carbon content, it can be divided into low carbon steel ([C]≤0.25%), medium carbon steel (0.25%≤[C]0.60%) and high carbon steel ([C]>0.60%). The higher the carbon content, the higher the yield point and tensile strength, but the lower the plasticity and impact. In addition, according to the quality and use of steel, carbon steel is usually divided into three categories: ordinary carbon steel, high-quality carbon structural steel and tool carbon steel.

Low carbon steel is widely used as deep drawing parts such as automobiles and cans because of its good deep drawability and weldability. 20G is the main material for manufacturing ordinary boilers. In addition, low carbon steel is also widely used as infiltration Carbon steel is used for structural parts in the machinery manufacturing industry; medium carbon steel is mostly used in the quenched and tempered state to make parts in the machinery manufacturing industry; high carbon steel is mostly used to make springs, gears, rolls, etc.

2. Low alloy steel: the total content of alloy elements is less than 5%, which means that in addition to silicon and manganese as alloy elements or deoxidizing elements, the steel also contains other alloy elements such as chromium nickel, platinum, iron, vanadium, copper, tungsten , aluminum, drill, saw, aluminum and rare earth elements, etc., and some also contain some non-metallic elements such as boron, nitrogen and other steel. Microalloyed steels are also low alloy steels.

3. Alloy steel: The total content of alloy elements is generally greater than 5%. According to the main alloy elements contained in the steel, alloy steel can be divided into manganese steel, silicon steel, boron steel, chromium-nickel-tungsten steel, chromium-manganese silicon steel, etc.

4. Stainless steel: refers to the general term for steel with certain chemical stability in the atmosphere, water, acid, alkali and salt solutions, or other corrosive media. Stainless steel that is resistant to corrosion by weak media such as air, steam, and water, and steel that is corrosion-resistant by strong media such as acids, alkalis, and salts is called corrosion-resistant steel. Stainless steel is stainless, but not necessarily corrosion-resistant, while corrosion-resistant steels generally have better stainless properties. Stainless steel is mainly marked by chromium, and the chromium content should be greater than 12%. According to the different chemical composition, it can be divided into: chromium-nickel stainless steel (300 series Ni>5%), chromium-manganese series (200 series) stainless steel, chromium stainless steel (400 series, Ni<5%) and heat-resistant stainless steel ( Cr > 20%), etc.

Classification of steel varieties

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