Carbon structural steel, carbon steel one. Carbon is about 0.05% to 0.70%, individual up to 0.90%. It can be divided into ordinary carbon steel and quality carbon structural steel categories. Many applications, the amount of large, mainly for railways, bridges, all types of construction. Manufacture of various metal components to withstand static load and mechanical parts and general weldments unimportant heat treatment is not required.

One kind of carbon steel. Carbon is about 0.05% to 0.70%, individual up to 0.90%. It can be divided into ordinary carbon steel carbon steel and quality carbon structural steel categories. The former contains impurities, low price, for the performance of less demanding place. Most of its carbon content of 0.30% or less. Manganese content of not more than 0.80%, the strength is low. But the good ductility, toughness, cold deformation properties. With few exceptions. Usually without heat treatment. Use directly. Made more bars, shaped steel, steel and so on. Many applications, the amount of large, mainly for railways, bridges, all types of construction. Manufacture of various metal components to withstand static load and mechanical parts and general weldments unimportant heat treatment is not required. Quality carbon structural steel pure steel. Fewer impurities, good mechanical performance, after heat treatment. According manganese content is divided into ordinary manganese content (less than 0.80%) and high manganese content (0.80% to 1.20%) groups. Carbon content of 0.25% or less. Many do not use direct heat treatment. Or carburizing, carbonitriding and other treatment. Manufacture of small gears, shafts, piston pins. Carbon content of 0.25% to 0.60%. Typical steel have 40,45,40Mn, 45Mn and so on. More after quenching. Manufacture of mechanical parts and fasteners. Carbon content greater than 0.60%, such as 65,70,85,65Mn, 70Mn and so on. More as spring steel.

1. Press the chemical composition

Carbon steel by chemical composition (ie carbon content) can be divided into low-carbon steel, carbon steel and high carbon steel.

⑴ low-carbon steel, also known as mild steel, carbon content from 0.10 to 0.30% low carbon steel easy to accept all kinds of processing such as forging, welding and cutting, commonly used in the manufacturing chain, rivets, bolts, shaft.

⑵ carbon steel carbon content of 0.25% to 0.60% carbon steel. It has killed steel, semi-killed steel, rimmed steel and other products. In addition to carbon also contain small amounts of manganese (0.70% to 1.20%). By product quality is divided into ordinary carbon steel and quality carbon structural steel. Good thermal processing and cutting, welding performance is poor. Strength, hardness higher than the low-carbon steel, while the ductility and toughness lower than low carbon steel. Do not heat treated, the direct use of hot-rolled sheet, cold-drawn material, can also be used after heat treatment. Quenching and tempering of steel has good mechanical properties. The highest attainable hardness of about HRC55 (HB538), σb is 600 ~ 1100MPa. So at moderate intensity levels for various applications, carbon steel the most widely used, except as a building material, also used extensively for the manufacture of mechanical parts.

⑶ high carbon steel often called tool steel. Carbon content from 0.60 to 1.70 percent. It can be hardened and tempered. Hammers, crowbars and other carbon content of the steel of 0.75%. Cutting tools such as drills, wire-tapping, reamers, etc. by the carbon content of steel of 0.90 to 1.00%.

2. Press the quality classification of steel

According to the quality of steel can be divided into ordinary carbon steel and quality carbon steel.

⑴ ordinary carbon steel, also known as ordinary carbon steel. Restrictions on carbon content, performance range as well as phosphorus, sulfur and other residual element content wider. In China and some countries are divided into three categories based on the delivery guarantee conditions: Group A steel (A type of steel) is to ensure that the mechanical properties of the steel. B steel (B class steel) is to ensure that the chemical composition of the steel. Special type of steel (C type of steel) is the only guarantee to ensure that the mechanical properties of the steel and chemical composition. Commonly used in the manufacture of the more important structural parts. China is currently the largest production and use of carbon content is about 0.20% of the A3 Steel (Group No. 3 steel). Mainly used in engineering structures. Some carbon structural steel also add a small amount of aluminum or niobium (or other carbide forming elements) forming a nitride or carbide particles. To limit grain growth. Strengthen the steel. Save steel. In China and some countries. In order to meet the special requirements of specialized steel. The chemical composition and properties of ordinary carbon steel is adjusted. In order to develop a series of ordinary carbon steel professional steel (such as bridges, buildings, steel, pressure vessel steel, etc.).

⑵ quality carbon structural steel and ordinary carbon steel compared. Low content of sulfur, phosphorus and other non-metallic inclusions. Depending on the carbon content and uses. This kind of steel roughly divided into three categories: ① less than 0.25% C low carbon steel. Especially in the carbon is less than 0.10% of the 08F, 08Al, etc. Because having a good deep drawability and weldability and is widely used as deep drawing parts such as automotive, canning ...... and so on. 20G is the production of common boiler main material. In addition, low-carbon steel is also widely as carburizing steel. For mechanical manufacturing. ②0.25 ~ 0.60% C is carbon steel. More use of quenched and tempered condition. Production machinery manufacturing industry parts. ③ greater than 0.6% C high carbon steel. Used for manufacture of springs, gears, rollers and the like. Depending on the amount of manganese. It can be divided into ordinary manganese content (0.25 to 0.8%) and high manganese content (0.7% to 1.0% and 0.9 to 1.2%) two steel groups. Manganese can improve the hardenability of steel, strengthened ferritic. Improve the yield strength, tensile strength and abrasion resistance. Usually after a high grade manganese steel additional markings "Mn". Such as 15Mn, 20Mn to distinguish normal manganese content of carbon steel.

3. By Application

By end-use is divided into carbon structural steel, carbon tool steel. Carbon tool steel carbon content between 0.65 to 1.35%. After heat treatment to obtain high hardness and high wear resistance. Mainly used in the manufacture of tools, cutting tools, dies and gauges (see tool steel). Carbon steel in accordance with the yield strength of steel is divided into five grades: Q195, Q215, Q235, Q255, Q275 due to the different quality of each grade divided into A, B, C, D grade. Up to four. Some only one. Another method of deoxidation of steel smelting difference. Deoxy method symbol: F-- b-- boiling steel semi-killed steel Z-- killed steel TZ-- special killed steel

Folding mechanical properties

Such steel is mainly to ensure that the mechanical properties. So the grades reflect its mechanical properties. With Q + digits, where "Q" is the yield point "bend" the pinyin word prefix. Numbers indicate the yield point value. For example Q275 that yield point 275Mpa. If the label behind the letter grades A, B, C, D. It means that different quality grades of steel. Volume containing S, P successively reduced. In turn improve the quality of steel. If the label behind grade letter "F" was boiling steel. Marked "b" semi-killed steel. Not marked "F" or "b" to those killed steel. For example Q235-A · F that yield point 235Mpa Class A boiling steel. Q235-C that yield point 235Mpa the C-class special killed steel or killed steel.

Folding mass fraction

Carbon structural steel under normal circumstances do not heat treated. And in the supply of state directly. Typically Q195, Q215, Q235 low carbon content steel, good welding performance, good ductility, toughness, a certain intensity, often rolled into thin sheets, welded steel pipes, and so on. For bridges, buildings and other structures and manufacturing ordinary screws, nuts and other parts. Q255 and Q275 carbon steel mass fraction higher, higher strength, ductility and toughness. It can be welded. Usually rolled into steel, strip steel and steel for structural parts and manufacturing simple mechanical linkage, gears, couplings, pins and other parts.