Metal materials for construction, including black and non-ferrous materials, and composite materials that have been developed in recent years with various non-ferrous metals and their alloys or with other materials.
The construction industry mainly uses steel in ferrous materials, and cast iron is mainly used as cast iron products (such as pressure pipes). Most of China's construction steel is low carbon steel (carbon content less than 0.25%), medium carbon steel (carbon content 0.25 ~ 0.60%) and low alloy steel smelted in open hearth furnace and oxygen top-blown converter, and is made of boiling steel or killed steel. Production, in which the boiling steel is poorer than the killed steel due to impact, aging, cold and brittle performance, and is limited in some structures when used, such as railway bridges, heavy-duty working crane beams. Semi-killed steel has better mechanical properties than boiling steel and is close to killed steel. Its finished product yield is close to boiling steel, which has been promoted in China.
Classification: The product categories of construction steel are generally divided into rebar, wire, coiled screw, round steel,
·The specification range of thread is generally 6-50mm. We usually cover 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 32mm, 36mm, 40mm and so on. State-approved deviations: 6-12 mm deviation at ±7%, 14-20 mm deviation at ±5%, and 22-50 mm deviation at ±4%.
· Rebar is generally fixed length 9m, 12m, of which 9m long thread is mainly used for normal road construction, and 12m long thread is mainly used for bridge construction.
Rebar can be divided into three categories according to strength: HRB335, HRB400, HRB500.
· Usually more than 6.5mm, 8.0mm, 10mm (diameter); in addition to 5.5mm, 6.0mm, 7.0mm and so on. At present, the maximum diameter of the wire rod produced in China can reach 30mm. Another wire production generally allows tolerances of ±0.4 mm.
· Common wire grades are generally divided into three types: Q195, Q215, and Q235. Among them, there are only two grades of Q215 and Q235 for construction steel. The example shows: Q235 (Q- refers to the yield strength of steel, 235 refers to the yield strength of not less than 235Mpa).
According to the rolling speed, the wire can be divided into: normal line, high line and quasi-high line.
3, the disk screw:
Steel for construction, as its name suggests, is a rebar that is wired together like a wire. Generally, it is 6.5-8.0-10-12-14 on the market.
Advantages of the screw: The threaded steel is only 9-12, and the screw can be intercepted as needed.
4, round steel:
Round steel round bar is a solid strip of steel with a circular cross section. The specifications are expressed in millimeters of diameter. For example, "50" means a round steel with a diameter of 50 mm.
Round steel material: 10#, 20#, 35#, 45#, Q215-235, 304, 316, 20Cr, 40Cr, 20CrMo, 35CrMo, 42CrMo, 40CrNiMo, GCr15, 65Mn, 50Mn, 50Cr, 3Cr2W8V, 20CrMnTi, 5CrMnMo, etc. .
Round steel is divided into hot rolling, forging and cold drawing. Hot rolled round bars are available in sizes from 5.5 to 250 mm. Among them: small round steels of 5.5-25 mm are mostly supplied in straight strips, often used as steel bars, bolts and various mechanical parts; round steels larger than 25 mm are mainly used for manufacturing mechanical parts or seamless steel tube blanks.
The role of construction steel:
· Rebar is widely used in various building structures.
·In addition to a large number of reinforcing rods used for building reinforced concrete, wire rods are also suitable for wire rods for wire drawing and mesh (special steel).
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