Round steel refers to the solid section for circular strip steel. Its specifications expressed as a number of mm in diameter, such as "50" indicates that the diameter of 50 mm round steel.
The material of round steel, Q195, Q235, 10 #, 20 #, 35 #, 45 #, Q215, Q235, 304, 316, 40 cr, cr, 20 crmo, 35 crmo, 42 crmo, 40 crnimo, GCr15, 65 mn, 50 mn, cr, 3 cr2w8v, 20 crmnti, 5 crmnmo, etc.
Round steel hot rolling, forging and cold drawn three kinds. The specifications of the hot rolled round steel of 5.5 to 250 mm. Among them: 5.5-25 mm small round steel are mostly with straight bundles of supplies, commonly used for reinforcing steel bar, bolt, and various mechanical parts; More than 25 mm round steel, mainly used in the manufacture of machinery parts and seamless steel tube. The difference between the round steel and other steel: 1 appearance is not the same, round steel exterior circle of light, no lines without ribs, and other steel surface appearance has a groove or a rib, thus causing the cohesive force of small round steel and concrete, and the other the cohesive force of steel bar and reinforced concrete. 2 ingredients are different, round steel (level 1) steel belong to the normal low carbon steel, more than other reinforcement for alloy steel. Three different intensity, low intensity of round steel and other steel with high intensity, the diameter of the same size of round steel compared with other steel bar, round steel can withstand strength than other bar is small, but the plastic is better than other steel round steel, the round steel before is pulled with large deformation, and other steel before be pulled deformation is much smaller.
1. According to the chemical classification
Carbon steel according to the chemical composition (i.e., with carbon content) can be divided into low carbon steel, medium carbon steel and high carbon steel.
(1) low carbon steel
Also known as mild steel, carbon content from 0.10% to 0.30% of low carbon steel is easy to accept all kinds of processing such as forging, welding and cutting, often used in the production chain, rivet, bolts, shaft, etc.
(2) the medium carbon steel
Carbon is 0.25% ~ 0.60% of the carbon steel. Have a calming, half killed steel, steel and other steel products. In addition to the carbon can also contain a small amount of manganese (0.70% ~ 1.20%). According to the quality of the products are divided into ordinary carbon structural steel and high quality carbon structural steel. Hot working and cutting performance is good, poor welding performance. Strength and hardness is higher than low carbon steel and the plasticity and toughness lower than that of low carbon steel. Without heat treatment, direct use of hot rolled, cold drawn material, can be used after heat treatment. The medium carbon steel after quenching and tempering has good comprehensive mechanical properties. To achieve the highest hardness about HRC55 (HB538), sigma b for 600 ~ 600 mpa. So in a moderate level of a variety of purposes, medium carbon steel is the most widely used, except as building materials, also used in the manufacture of various kinds of machinery parts.
(3) the high carbon steel
Often called tool steel, carbon content from 0.60% to 1.70%, can be hardening and tempering. Hammer, crowbar, etc by the carbon content of 0.75% steel manufacturing; Cutting tools such as drill, tap, reamer, etc by between 0.90% and 1.00% of the carbon content of steel manufacturing.
2. According to the quality of the steel
According to the quality of the 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 content is relatively wide. In China and some countries according to the guarantee of delivery condition is divided into three categories: class A steel steel (class A) is to ensure that the mechanical properties of steel. B steel steel (class B) is the guarantee of the chemical composition of the steel. Special type of steel (class C) steel is both ensure the mechanical properties and guarantee the chemical composition of steel, often used in the manufacture of the important structures. China is now the production and use of the most is around 0.20% of A3 carbon steel (steel) a class 3, mainly used in engineering structure.
Some carbon structural steel and adding trace amounts of aluminum or niobium (or other) carbide forming elements to form nitrides or carbide particles, to limit the grain growth, make the steel reinforcement, save steel. In China and some countries, in order to adapt to the special requirements of professional steel, the chemical composition and properties of ordinary carbon structural steel, so as to develop a series of ordinary carbon structural steel major steel, such as Bridges, buildings, pressure vessel steel, steel, etc.).
(2) high quality carbon structural steel and ordinary carbon structural steel, sulfur, phosphorus and other non-metallic inclusion content is low. According to carbon content and purpose is different, this kind of steel is roughly divided into three categories: (1) is less than 0.25% C for low carbon steel, notably the carbon less than 0.10% of the 08 f, 08 al and so on, because has the very good deep-drawing property and weldability and is widely used for deep drawing parts such as automobile, can... And so on. The main material of 20 g is making ordinary boiler. In addition, low carbon steel as carburizing steel, widely used in mechanical manufacturing industry. (2) 0.25 ~ 0.60% C for medium carbon steel, used in the quenched and tempered state more, make parts of machinery manufacturing industry. (3) greater than 0.6% C for high carbon steel, used in the manufacture of springs, gears, roll, etc. According to different manganese content, and can be divided into ordinary manganese content (0.25 ~ 0.8%) and high manganese content (0.7 ~ 1.0% and 0.9 ~ 1.2%) steel group. Manganese can improve the hardenability of steel, strengthen the ferrite, improve the steel yield strength, tensile strength and abrasion resistance. Usually in the high manganese steel grades after additional tags "Mn", such as 15 Mn, 20 Mn to distinguish it from normal carbon steel containing manganese content.
3. According to the classification purpose
According to the purposes and can be divided into carbon structural steel, carbon tool steel.
Carbon tool steel carbon content between 0.65 ~ 1.35%, high hardness and high wear resistance can be obtained after heat treatment, mainly used in the manufacture of various tools and cutters, mould and measuring tool (see tool steel).
Carbon structural steel in accordance with the steel yield strength is divided into five grades:
Q195, Q215, Q235, Q255, Q275
Each brand due to different quality is divided into A, B, C, D level, there are four most, some only one; In addition, a steel smelting deoxidizing method.
Deoxidizing method symbols:
F - rimmed steel
B - half killed steel
Z - killed steel
TZ - special killed steel