Round steel refers to solid long steel with a circular cross-section. The specifications are expressed in diameter in millimeters (mm). For example, “50mm” means round steel with a diameter of 50 mm.
Round steel is divided into three types: hot rolled, forged, and cold drawn. The specification of hot-rolled round steel is 5.5-250 mm. Among them: 5.5-25mm small round steel is mostly supplied in straight strips, often used as steel bars, bolts, and various mechanical parts; round steel larger than 25mm is mainly used to manufacture mechanical parts and tube blanks for seamless steel pipes Wait.
Carbon steel can be divided into low carbon steel, medium carbon steel, and high carbon steel according to its chemical composition (i.e. carbon content).
(1) Low carbon steel
Low carbon steel with a carbon content between 0.10% and 0.30%, also known as low carbon steel, is easy to accept various processing such as forging, welding, and cutting. It is commonly used for making chains, rivets, bolts, shafts, etc.
(2)Medium carbon steel
Carbon steel with a carbon content of 0.25% to 0.60%. There are a variety of products such as calming steel, semi-calming steel, and rolling edge steel. In addition to carbon, can also contain a small amount of manganese (0.70% ~ 1.20%). According to the quality of the product, it is divided into ordinary carbon structural steel and high-quality carbon structural steel. Good hot working and cutting properties, but poor welding properties. Strength and hardness are higher than low carbon steel, while plasticity and toughness are lower than low carbon steel. Hot-rolled and cold-drawn materials can be used directly without heat treatment, or after heat treatment. Tempered medium carbon steel has good overall mechanical properties. The highest hardness achievable is about HRC55 (HB538), σb 600-1100 MPa. Therefore, in the medium strength grade of various applications, the most widely used is medium carbon steel. In addition to being used as construction materials, it is also widely used in the manufacture of various mechanical parts.
(3) High-carbon steel
Usually called tool steel, it contains between 0.60% and 1.70% of carbon and can be quenched and tempered. Hammers, crowbars, etc. are made of steel with a carbon content of 0.75%; cutting tools such as drills, taps and reamers are made of steel with a carbon content of 0.90% to 1.00%.
The quality of steel can be divided into ordinary carbon steel and high-quality carbon steel.
(1) ordinary carbon structural steel, also known as ordinary carbon steel, the carbon content, performance range, and phosphorus, sulfur, and other residual elements have a wider range of restrictions. In China and some countries, the delivery guarantee conditions are divided into three categories: Class A steel (Class A steel) is to ensures the mechanical properties of steel. Class B steel (Class B steel) is steel with guaranteed chemical composition. Special steel (C steel) is a guarantee of both mechanical properties and chemical composition of the steel, commonly used in the manufacture of more important structural components. The most produced and used steel in China is A3 steel (Class A No. 3 steel), which contains about 0.20% carbon and is mainly used for engineering structures.
Some carbon structural steels also add a small amount of aluminum or niobium (or other carbide forming elements) to form nitride or carbide particles to limit grain growth, strengthen the steel and save steel. In China and some countries, in order to meet the special requirements of professional steel, the chemical composition and properties of ordinary carbon structural steel has been adjusted, resulting in the development of a series of ordinary carbon structural steel (such as bridges, construction, reinforcing steel, pressure vessel steel, etc.).
(2) Compared with ordinary carbon structural steel, high-quality carbon structural steel has a lower content of sulfur, phosphorus, and other non-metallic inclusions.
According to the different carbon content and use, this type of steel can be roughly divided into three categories:
① Less than 0.25% C is low carbon steel, especially 08F, 08Al with carbon content less than 0.10%, etc., because of its good deep drawing and weldability, it is widely used as deep drawing parts such as automobiles and can making ……Wait. 20G is the main material for making ordinary boilers. In addition, low-carbon steel is also widely used as carburizing steel for machinery manufacturing.
②0.25～0.60%C is medium carbon steel, which is mostly used in the quenched and tempered states to make parts for the machinery manufacturing industry.
③High carbon steel greater than 0.6% C is used to make springs, gears, rolls, etc.
According to the different manganese content, it can be divided into two steel groups with ordinary manganese content (0.25-0.8%) and higher manganese content (0.7-1.0% and 0.9-1.2%). Manganese can improve the hardenability of steel, strengthen ferrite, and increase the yield strength, tensile strength, and wear resistance of steel. Usually, “Mn” is added after the grade of steel with high manganese content, such as 15Mn, 20Mn, to distinguish it from carbon steel with normal manganese content.
According to the purpose, it can be divided into carbon structural steel and carbon tool steel.
Carbon tool steel has a carbon content of between 0.65 and 1.35%. After heat treatment, high hardness and high wear resistance can be obtained. It is mainly used to manufacture various tools, cutting tools, molds, and measuring tools (see tool steel).
Q195, Q215, Q235, Q255, Q275
Each grade is further divided into A, B, C, and D grades depending on the quality. Up to four, some only one. In addition, there are differences in the deoxidation methods of steel smelting.
Round steel material: Q195, Q235, 10#, 20#, 35#, 45#, Q215, Q345, 12Cr1Mov, 15CrMo, 304, 316, 20Cr, 40Cr, 20CrMo, 35CrMo, 42CrMo, 5CrMo, 5Cr0Mo, 6CrMo, 6 50Cr, 3Cr2W8V, 20CrMnTi, 5CrMnMo, etc.
Standard: (GB699-1988, GB700-1988, GB3077-1988, GB702-1986, QJ/HG02.17-1991)
Round steel specification table
The calculation formula for the theoretical weight of round steel: outer diameter X outer diameter X 0.00617=kg/m
Round steel diameter d (model)
Theoretical weight kg/m
Round steel diameter d (model)
Theoretical weight kg/m