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DH420 | High-Strength Shipbuilding Steel

DH420 | High-Strength Shipbuilding Steel

SteelPRO Group provides DH420 high-strength shipbuilding steel plates in stock, offering excellent toughness,  good weldability, and high impact resistance. Commonly used in construction, heavy machinery, shipbuilding, and offshore structures.

Class Cert.: ABS/BV/CCS/DNV/KR/LR/NK/RINA/RS/PRS
Material: Low Alloy Steel
Thickness: 6mm-80mm, or customized
Width: 900mm-4800mm, or customized
Length: 3000mm-25000mm, or customized
Condition of Delivery: TMCP/Q+T/TMCP+T, or as request
Stock: In stock
Origin: Hebei/Henan/Jiangsu, China
Port: Qingdao

Looking for other Grade 420 high-strength steel?
Click here for AH420.

Description

What Is DH420?

DH420 Steel is a high-strength structural material used in shipbuilding and offshore platforms. The “D” indicates toughness rated at -20°C, “H” denotes high strength, and “420” refers to a minimum yield strength of 420 MPa.

This steel offers excellent yield and tensile strength, remaining stable under heavy loads with strong resistance to deformation. Its toughness ensures high impact resistance, minimizing the risk of cracking under sudden shocks. DH420 also provides good machinability and supports heat treatment to meet diverse performance requirements.

It is widely used in vessels, fishing boats, and offshore structures, especially for components up to 150 mm thick, proving reliable in harsh marine environments.

Characteristics of DH420

  • High strength and toughness
  • Good wear and impact resistance
  • Excellent hardenability for deeper hardness
  • Stable performance under high temperatures
  • Suitable for molds, dies, and heavy-duty tools

Chemical Compositions

ElementContent (%)
Carbon, C≤0.20
Silicon, Si≤0.55
Manganese, Mn≤1.70
Phosphorus, P≤0.025
Sulfur, S≤0.025
Nitrogen, N≤0.020

Physical Properties

PropertyMetricImperial
Density7.74 g/cm³0.280 lb/in³
Melting Point1495 °C2723 °F
Thermal Conductivity (@ 100 °C)24.9 W/m·K14.4 BTU/(hr·ft·°F)
Thermal Conductivity (@ 500 °C)28.7 W/m·K16.6 BTU/(hr·ft·°F)
Specific Heat Capacity (0-100 °C)460 J/(kg·K)0.11 BTU/(lb·°F)
Coefficient of Thermal Expansion (0-100 °C)10.3 µm/m·°C5.7 µin/in·°F
Coefficient of Thermal Expansion (0-649 °C)12.1 µm/m·°C6.7 µin/in·°F
Electrical Resistivity0.55 µΩ·m5.5 x 10⁻⁷ Ω·cm

Mechanical Properties

Thickness (mm)Yield Strength (MPa)Tensile Strength​ (MPa)Elongation (%) Transverse/LongitudinalTest Temperature (°C)Impact Energy (KV J) Transverse/Longitudinal
8-260≥ 420530-680≥ 19/21-20℃≥ 28/42

Industries & Applications

IndustryCommon Products
ShipbuildingHulls, Decks, Bulkheads, Offshore platforms
Marine StructuresCargo ship components, Passenger vessels, Oil rigs, Mooring systems
DefenseArmored vehicles, Naval ships, Underwater equipment, Structural reinforcements
ConstructionBridges, High-strength building supports, Industrial frameworks, Cranes

Machining

Heat Treatment

  • Annealing: Heat to 850-900°C, hold until uniform, then cool slowly in the furnace.
  • Normalizing: Heat to 880-920°C, air cool to room temperature.
  • Quenching: Heat to 880-920°C, hold, then quench in water or oil.
  • Tempering: Reheat to 200-600°C based on desired hardness, then air cool.

Surface Treatment

  • Shot Blasting: Removes rust and impurities, improving surface adhesion.
  • Galvanizing: Adds a zinc layer for corrosion resistance.
  • Painting or Coating: Provides extra corrosion protection for outdoor use.
  • Phosphating: Enhances wear resistance and paint adhesion.
  • Pickling: Uses acid to clean and prepare the surface for further treatment.

*Customization is available upon request.

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!

Our Quality Control

  • Roundness
  • Tolerance
  • Microstructure
  • Non-Destructive Testing
  • Destructive Testing
  • Process Control

Service Integration Processing

  • Welding
  • Metal Fabrication
  • CNC Machining
  • Lathe
  • Forming

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