GB/T 4172-2000 Mechanical and Process Properties of Weathering Steel for Welded Structures
This national standard (GB/T 4172-2000), Mechanical and Process Properties of Weathering Steel for Welded Structures, is a technical standard specified by the National Standardization Administration Committee.
The standard was developed on the basis of the type and grade of steel, in which mechanical and process requirements are specified and a range of test methods and standard chemical compositions are also set out.
The stated purpose of the standard is to ensure the manufacture and acceptance of steel products and to provide guidance on the specification of structural steel products and mechanical and process requirements in welded structures.
Scope
1. This recommended standard applies to weathering steel for welded structures the following alloys:
a) Q235, Q345, Q390 steel;
b) Q420, Q460, Q500, Q550, Q600, Q650 steel;
c) Other weathering steels and experimental grades.
2. The mechanical and process properties specified in this standard apply to the welded state.
3. The welding methods specified in this standard apply to welding in the environment below 550 ℃.
4. This standard does not apply to:
a) All traditional welding methods such as electric arc welding and gas welding;
b) Plasma welding and other high temperature welding.
Mechanical Properties
1. Mechanical Properties of Q235 and Q345 Steels
Minimum tensile strength (Mpa): 235
Yield strength (MPa): 38
Elongation (%): ≥18
2. Mechanical Properties of Q390 Steel
Minimum tensile strength (Mpa): 345
Yield strength (MPa): 190
Elongation (%): ≥18
3. Mechanical Properties of Q420, Q460, Q500, Q550, Q600, Q650 Steels
Minimum tensile strength (Mpa): 420
Yield strength (MPa): 245
Elongation (%): ≥15
Process Properties
1. Welding
Welding process: Manual arc welding, CO2 welding, submerged arc welding, argon arc welding, etc.
2. Cold Bending
The cold bending should be completed according to the design requirements of the steel structure, and the bending should be repeated without affecting its quality and strength.
3. Hot Roll forming
The temperature for hot roll forming should be between 220℃ to 280℃, so that it does not affect the quality and strength of the steel.
4. Heat Treatment
The heat treatment should be performed according to the design requirements, and the tempering temperature should be between 600℃ to 850℃ to obtain the desired mechanical properties.
Conclusion
This GB/T 4172-2000 recommended standard provides the mechanical and process requirements for weathering steel for welded structures, specifying the type and grade of steel, the range of test methods, the standard chemical compositions, and the requirements for welding, cold bending, hot roll forming and heat treatment. This standard provides a reference for the technical design and quality assurance of these steels and is important for welding and welded structures.
