< r ) Low carbon steel
< r ) Also known as mild steel, the carbon content ranges from % to %. Low carbon steel is easy to accept various processing such as forging, welding and cutting. It is often used to make chains, rivets , bolts, shafts, etc.
< r ) Medium carbon steel
< r ) Carbon steel with carbon content %~%. There are many products including killed steel, semi-killed steel, boiling steel and so on. In addition to carbon, it may also contain a small amount of manganese (%~%). According to product quality, it is divided into ordinary carbon structural steel and high-quality carbon structural steel. Thermal processing and cutting performance are good, but the welding performance is poor. The strength and hardness are higher than low carbon steel, but the plasticity and toughness are lower than low carbon steel. Hot-rolled materials and cold-drawn materials can be used directly without heat treatment, or they can be used after heat treatment. Medium carbon steel after quenching and tempering has good comprehensive mechanical properties. The highest hardness that can be achieved is approximately R(B), b is ~. Therefore, among various uses with medium strength levels, medium carbon steel is the most widely used. In addition to being used as building materials, it is also widely used in the manufacture of various mechanical parts.
< r ) High carbon steel
< r ) Often called tool steel, the carbon content ranges from % to % and can be hardened and tempered. Hammers, crowbars, etc. are made of steel with a carbon content of %. Cutting tools such as drills, taps, reamers, etc. are made of steel with a carbon content of % to %.
< b ), >Classification according to the quality of steel
< r ) According to the quality of steel, it can be divided into ordinary carbon steel and high-quality carbon steel.
< r ) Ordinary carbon structural steel
Also known as ordinary carbon steel, it has wider restrictions on the performance range of carbon content and the content of phosphorus, sulfur and other residual elements. In China and some countries, it is divided into three categories according to the delivery guarantee conditions: Class A steel (similar steel) is steel with guaranteed mechanical properties. Class B steel (Class B steel) is steel with guaranteed chemical composition. Special steel (similar steel) is steel that ensures both mechanical properties and chemical composition, and is often used to manufacture more important structural parts. China currently produces and uses steel with a carbon content of around % (Class A steel), which is mainly used for engineering structures.
Compared with ordinary carbon structural steel, high-quality carbon structural steel has lower content of sulfur, phosphorus and other non-metal inclusions. According to different carbon content and uses, this type of steel is roughly divided into three categories: ① Low carbon steel with a carbon content of less than %, especially those with a carbon content of less than %, etc., due to their good deep drawing and weldability It is widely used as deep drawing parts such as automobile can making. It is the main material for manufacturing ordinary boilers. In addition, low carbon steel is also widely used as carburizing steel in the machinery manufacturing industry. ②~% is medium carbon steel, which is mostly used in the quenched and tempered state to make parts in the machinery manufacturing industry. ③ More than % is high carbon steel, which is mostly used to manufacture spring gears, rollers, etc. According to the different manganese content, it can be divided into two steel groups: ordinary manganese content (~%) and higher manganese content (~% and ~%). Manganese can improve the quench-hardenability of steel, strengthen ferrite, and increase the yield strength, tensile strength and wear resistance of steel. Usually, a mark is added after the grade of steel with high manganese content, such as to distinguish it from carbon steel with normal manganese content.