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Q420 STEEL | STRUCTURAL STEEL

Q420 STEEL | STRUCTURAL STEEL

Q420 steel is a high-strength, low-alloy structural steel with a minimum yield strength of 420 MPa. The “Q” stands for yield strength, and “420” indicates the minimum value. Known for its strength, toughness, and weldability, Q420 is ideal for construction, bridges, and pressure vessels. Its carbon, manganese, and silicon content further enhance its performance, making it suitable for large-span buildings and high-rise frameworks. We offer Q420NB/C/D/E products with thicknesses from 6 to 150mm according to the GB/T 1591 standard. Equivalent grades include S420 (EN), A572 Grade 65 (US), and SM570 (JIS).

Description

What is Q420?

Q420 steel is composed of approximately 97% iron and 3% alloying elements, including carbon, manganese, and silicon. It is a high-strength, low-alloy structural steel produced in solid shapes like plates and beams. Known for its high yield strength (minimum 420 MPa), excellent tensile strength, and good weldability, Q420 steel is ideal for construction structures, bridges, and pressure vessels. It is processed through hot rolling, which enhances its strength and toughness. Q420 steel can be classified into grades such as Q420B, Q420C, Q420D, and Q420E, each with specific performance characteristics.

Characteristics of Q420 Steel

Q420 steel offers high strength, toughness, and good weldability, making it ideal for construction, bridges, and pressure vessels. Its alloy composition, including carbon, manganese, and silicon, enhances mechanical properties, supporting large-span and high-rise structures. For applications requiring better corrosion resistance or low-temperature performance, alternatives like Q355 or S460 are recommended. These grades offer specific advantages, such as improved weather resistance and better performance in extreme environments, complementing Q420’s strengths.

Chemical Compositions

ElementComposition (Weight %)
Carbon (C)0.20-0.23
Silicon (Si)0.50-0.80
Manganese (Mn)1.20-1.60
Phosphorus (P)≤ 0.035
Sulfur (S)≤ 0.035
Chromium (Cr)0.30-0.50
Nickel (Ni)0.30-0.50
Copper (Cu)0.20-0.40
Vanadium (V)0.02-0.10
Titanium (Ti)0.02-0.10

Physical Properties

PropertyMetricImperial
Density7.85 g/cm³0.284 lb/in³
Melting Point1450-1520 °C2642-2768 °F
Boiling PointNot specifiedNot specified
Thermal Conductivity50 W/m·K28.9 BTU/h·ft·°F
Electrical Conductivity2.14 × 10⁶ S/m3.69 × 10⁶ S/m
Specific Heat Capacity0.49 J/g·K0.117 BTU/lb·°F
Thermal Expansion Coefficient12 x 10⁻⁶ /°C6.7 x 10⁻⁶ /°F
Electrical Resistivity46.8 μΩ·cm18.4 μΩ·in

Mechanical Properties

PropertyMetricImperial
Tensile Strength520-680 MPa75420-98520 psi
Yield Strength420 MPa60920 psi
Brinell Hardness (HB)200-230200-230
Rockwell Hardness (HRC)20-2420-24
Vickers Hardness (HV)210-240210-240
Elongation18-20%18-20%
Elastic Modulus210 GPa30500 ksi

Data After QT(Quenching and Tempering) Processing

PropertyMetricImperial
Tensile Strength630-780 MPa91,385-113,045 psi
Yield Strength520-680 MPa75,420-98,600 psi
Impact Toughness≥ 34 J≥ 25 ft-lb
Elongation≥ 16%≥ 16%
Reduction of Area≥ 45%≥ 45%
Elastic Modulus210 GPa30,500 ksi

Industries & Applications

IndustryProducts
Large ShipsHulls, Decks, Bulkheads, Ship Frames
BridgesBridge Girders, Support Beams, Bridge Decks, Suspension Cables
Power Station EquipmentTurbine Components, Boiler Parts, Heat Exchangers, Pressure Vessels
Medium and High-Pressure BoilersBoiler Drums, Steam Pipes, Pressure Tubes, Heat Recovery Systems
High-Pressure VesselsStorage Tanks, Chemical Reactors, Gas Cylinders, Heat Exchangers
Lifting MachineryCrane Booms, Hoist Frames, Winch Drums, Lifting Hooks
Mining MachineryExcavator Arms, Mining Truck Frames, Drill Rigs, Conveyor Belt Supports
Large Welded Structural PartsStructural Beams, Columns, Trusses, Frameworks

Machining

Q420 Heat Treating Instructions

  1. Heating (Austenitizing):
    • Heat the steel to a temperature range of 900-950°C (1652-1742°F).
    • Maintain this temperature to ensure complete austenitization.
  2. Quenching:
    • Rapidly cool the steel in water or oil.
    • This process transforms the microstructure into martensite, increasing hardness and strength.
  3. Tempering:
    • Reheat the steel to a temperature range of 550-650°C (1022-1202°F).
    • Maintain this temperature for a sufficient time to achieve the desired mechanical properties.
    • The tempering process reduces brittleness while maintaining high strength and hardness.

Q420 Surface Finish Processing Methods

  • Galvanization: Adds zinc coating for corrosion resistance.
  • Powder Coating: Enhances durability with customizable colors.
  • Shot Peening: Improves fatigue strength by introducing compressive stress.
  • Electroplating: Provides a protective metal layer to resist wear and corrosion.
  • Pickling and Passivation: Cleans and protects the surface from rust.
  • Polishing: Creates a smooth, reflective finish for aesthetic purposes.
Custom surface treatment requirements can be accommodated upon request.
Disclaimer
The above heat treatment instructions and surface finish processing methods for Q420 steel are provided for informational purposes only. Actual results may vary based on specific conditions and equipment used. Testing is recommended, and a metallurgical expert or material supplier should be consulted to ensure the processes are suitable for your specific application. The user assumes all risks and liability for the use of this information.

Our Service

SteelPRO Group – manufacturer and solution provider for special steel, offering multi-industry application solutions and customised services, 100% quality free, accompanying customers in their growth!

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  • Roundness
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  • Microstructure
  • Non-Destructive Testing
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  • Welding
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  • CNC Machining
  • Lathe
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