China Alloy Structural Steel Grades (2)

（1） China Alloy Structure Steels Steel Number China alloy structure steels are the most commonly used structural steels in the country. Alloy structure steels are produced and available in a variety of grades, shapes, and sizes. These steels are usually characterized by their strength, durability, weldability, and a combination of other qualities. The most popular steel grades in China include Q235, Q345, Q390, and Q420. The specification for each grade of steel is determined by its physical and mechanical properties and its chemical composition. Steel grades of higher strength are commonly used in a variety of structural members, including structural frames, beams, and trusses. Based on their composition, the steel grades can be classified into the following groups: A. High Strength Low Alloy (HSLA) steel: high strength low alloy steels use a combination of alloying elements such as chromium, manganese, molybdenum, or vanadium to achieve higher strength properties than is possible with conventional carbon steels. Common HSLA steel grades include Q345, Q390, and Q420. B. Corrosion Resistant steels: these steels are resistant to corrosion and are usually used in parts of structures that are exposed to the elements or corroding environments such as pipes and tanks. C. Tool steels: these steels are usually characterized by their hardness and strength and are used in the production of tools and dies. Common grades include 4140, 42 CrMo 4, and 1055. D. Wear-resistant steels: these steels are resistant to wear and abrasion and are commonly used in parts of structures such as bearing components and bulldozers. Typical grades include 42 CrMo 4 and 1055. Each grade of steel has a unique set of mechanical and physical properties, which determine its strengths, limitations and uses in construction. Q235, the most commonly used grade of steel in China, has a minimum yield strength of approximately 235MPa and a tensile strength of about 400MPa. This steel is very ductile, easily weldable, and has good formability. Its high corrosion resistance makes it suitable for use in interior parts or applications where high corrosion resistance is required. Q345, on the other hand, is a medium strength alloy steel with a yield strength of 345MPa and a tensile strength of 470MPa. This steel is usually used in girders, columns, and other structural members where increased strength is required. Q390 is a high strength structural steel with a minimum yield strength of 390MPa and a tensile strength of 490MPa. This steel is used in structural components subjected to large loads or high pressure, and applications that require maximum strength and weight reduction. Lastly, Q420 is a low-alloy high strength steel with a minimum yield strength of 420MPa and a tensile strength of 480MPa. It is normally used in highly loaded parts such as cranes, components for bridges, and other large structural members. These are just some of the common steel grades used in China. There are many other steel grades that have various physical and mechanical properties, composition, and other properties that make them suitable for various structural applications.