Alloy Structural Steel (GB 3077-88)
Alloy structural steel is a kind of steel which is used for making steel parts and components. Alloy structural steel is defined as a kind of steel combining the properties of carbon steel and alloy steel. The characteristics of alloy structural steel are its high strength, good welding ability, and low cost.
GB 3077-88 is the national standard for alloy structural steel in China. It was first released in 1988, and is continuously updated by the State Council of China, covering various aspects of alloy structural steel production, including chemical composition, technical requirements, inspection, etc. Among all grades of alloy structural steel, 10, 20, 35, 45, and 40Cr are the most important, with considerable use.
Chemical Composition of Steel
The chemical composition of alloy structural steel is very important to its performance in applications. Alloy steel must contain specific elements in certain proportions to ensure certain mechanical properties, such as strength, ductility, and properties for welding, forming and machining. Generally, the composition of alloy structural steel consists of Carbon, Silicon, Manganese, Phosphorus, Sulfur, Nickel, Chromium, Molybdenum and Vanadium. The details can be found in the current national standard GB 3077-88 for alloy structural steel.
Mechanical Properties of Steel
Besides chemical composition, the mechanical properties of alloy structural steel are also significant to its performance in applications. The mechanical properties needed in the production of parts and components can be determined by doing tests such as tensile tests, bending tests, and toughness tests. Generally, the mechanical properties of alloy structural steel include strength, hardness, ductility, yield strength and ultimate strength, etc.
Inspection
It is very important to inspect the alloy structural steel during its production and before delivery. All inspections should be done according to the current national standard GB 3077-88. For mechanical tests, the test pieces should meet the technical requirements of the standard. For chemical composition, the finished product should be analyzed using X-ray fluorescence spectrometry and neutron spectrometry methods.
Conclusion
In conclusion, alloy structural steel is a kind of steel widely used in the production of parts and components. Its characteristics include high strength, good weldability, and low cost. In China, the national standard for alloy structural steel is GB 3077-88, covering the chemical composition, technical requirements, and inspection requirements. The inspection should be strictly done according to the current national standard GB 3077-88.
