In the field of modern architecture and engineering, steel structures have been widely used due to their high strength, light weight, and short construction period. As the core material of steel structures, the grade and performance of steel directly affect the quality and safety of steel structures. This article will provide a detailed summary of the grades and properties of commonly used steel for steel structures.

Carbon structural steel
Q195： The low carbon content limits its strength, but also endows it with excellent plasticity and toughness, and its processing and welding performance are equally impressive. The common use is to roll thin plates and coils, such as roof panels, decorative panels, and general dust removal pipes, all of which are made from their cold and hot rolled thin steel plates as raw materials. The wire rod is often cold drawn into low-carbon steel wire or galvanized into galvanized low-carbon steel wire, used for binding, tensioning and fixing, or for making steel wire mesh, rivets, etc.
Q215： The strength is slightly higher than Q195 steel, and the purpose is roughly the same as Q195. In practical applications, it is also widely used to manufacture hardware parts such as welded steel pipes, galvanized welded pipes, furnace supports, foundation screws, bolts, round nails, wood screws, etc.
Q235： Moderate carbon content, excellent comprehensive performance, and coordinated strength, plasticity, and welding performance make it the most widely used carbon structural steel. It is often rolled into steel shapes such as coil, round steel, square steel, flat steel, angle steel, I-beam, channel steel, window frame steel, as well as medium thick steel plates. It is widely used in construction and engineering structures, such as making steel bars, building factory frames, high-voltage transmission towers, bridges, vehicles, boilers, containers, ships, etc. It can also be used to manufacture mechanical parts with low performance requirements. C and D grade steel can also be used as some professional steel.
Q255： The performance is similar to Q235, with slightly improved strength and reduced plasticity. The application scope is not as wide as Q235, mainly used for riveting and inspection structures.
Q275： High strength and hardness, good wear resistance, suitable for manufacturing shafts, agricultural machinery, wear-resistant parts, rail joint clamps, pads, wheels, rollers, etc.
Low alloy high-strength structural steel
Q295： The alloy element content in steel is extremely low, and its strength is not high, but its plasticity, cold bending, welding, and corrosion resistance are good. Mainly used for building structures, industrial plants, low-pressure boilers, low and medium pressure chemical containers, oil tanks, pipelines, cranes, tractors, vehicles, and general engineering structures with low strength requirements.
Q345、Q390： The comprehensive mechanical properties are good, with excellent welding performance, cold and hot processing performance, and corrosion resistance. C, D, and E grade steels also have good low-temperature toughness. Commonly used for welding structural components of ships, boilers, pressure vessels, oil storage tanks, bridges, power plant equipment, lifting and transportation machinery, and other higher loads.
Q420： High strength, especially in the state of normalizing or normalizing and tempering, with high comprehensive mechanical properties. Mainly used for large ships, bridges, power station equipment, medium and high pressure boilers, high pressure vessels, locomotives and vehicles, lifting machinery, mining machinery, and other large welded structural components.
Q460： The highest strength, it has high comprehensive mechanical properties in the state of normalizing, normalizing and tempering, or quenching and tempering. It is completely deoxidized with aluminum and has quality grades of C, D, and E. It is a backup steel grade that can ensure good toughness of steel and is used for various large-scale engineering structures and lightweight structures that require high strength and high load.
Reasonable selection of steel grades is crucial in practical steel structure engineering. It is necessary to comprehensively consider the specific needs of the project, such as the stress situation of the structure, the environmental conditions it is in, and the service life. On the premise of meeting the safety and performance requirements of the project, economic considerations should be taken into account to ensure the quality and stability of the steel structure.
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