gb 4172-84
high strength weathering steel
This standard was first issued in 1984 by the National Standards Committee of China, and applies to weatherproof steel used in welding structure. In order to ensure its strength and corrosion resistance under any climate condition, the standard stipulates requirements for chemical composition, mechanical properties, impact test and welding parameters of Chinas low-alloy high-strength weathering steel.
Chemical composition
The chemical composition of steel according to GB 4172-84 stipulates the content of C, Si, Mn, Ni, V and other elements, and the total content of these elements should not exceed 0.50% in the finished product. Among them, the content of C and V should not exceed 0.20%, and the sum of Ni, V and Nb should not exceed 0.25%.
Mechanical properties
Under the action of various working conditions, the mechanical properties of Chinas low-alloy high-strength weatherproof steel should meet the requirements of GB/T 4172-84. This standard stipulates that the tensile strength is higher than 490MPa, the yield point is higher than 345MPa, and the elongation after fracture should be not less than 22%. The extension should be expressed as a percentage and should be tested by the round steel sample.
Impact test
In order to determine whether the weatherproof steel meets the mechanical properties stipulated in GB 4172-84, the standard requires that a single-notched impact test should be performed, and the impact test should be performed using 27J steel samples. Where the ratio of impact energy to samples longitudinal area is not less than 27 J/cm2, it meets the requirements of the impact test.
Welding parameters
Welding parameters are important to ensure the strength of welding and the performance of weatherproof steel. GB 4172-84 specifies requirements for the welding current, welding time and welding voltage, the welding current should be not less than 200 amperes, the voltage should be not less than 24 volts, and the welding time should be not less than 4 seconds.
Conclusion
GB 4172-84 stipulates the requirements for chemical composition, mechanical properties, impact test and welding parameters of Chinas low-alloy high-strength weatherproof steel, which is important to ensure its strength and corrosion-resistance under any climate condition. With the use of advanced technology and appropriate welding process, this standard will ensure that high strength weatherproof steel can provide stable performance in harsh environment.
