FH40 | Grade 50 | High Strength Shipbuilding Steel
FH40 | Grade 50 | High Strength Shipbuilding Steel
FH40 is a high-strength structural steel used in shipbuilding. It complies with the ASTM A131/A131M standard. The designation “FH40” indicates high-strength shipbuilding steel with a minimum yield strength of around 400 MPa. Equivalent grades include LR FH40 and ABS FH40.
This steel features excellent toughness, good welding properties, and resistance to low temperatures. FH40 is commonly used in the construction of ship hulls and offshore structures.
Description
What Is FH40?
FH40 is a type of steel composed of approximately 0.16% carbon, 0.35% silicon, 1.4% manganese, and trace amounts of other elements. It is a solid, structural steel typically used in the shipbuilding industry. This steel is known for its high strength, good toughness, and excellent weldability. FH40 is processed through hot rolling, which enhances its mechanical properties. The material is primarily used in the construction of ship hulls, offshore structures, and other marine applications due to its ability to withstand harsh marine environments.
Characteristics of FH40
FH40 steel is a high-strength, low-alloy steel used primarily in marine and offshore structures. It features excellent weldability and toughness, making it suitable for harsh environments. The steel has good resistance to impact and can withstand extreme temperatures, which is crucial for offshore applications. FH40’s strength allows it to handle heavy loads and stresses.
While FH40 is highly effective in many scenarios, other steel grades might offer enhanced performance in specific conditions. For instance, grades like EH36 or DH36 can provide similar strength but with improved toughness or better performance in colder temperatures. Additionally, grade S355 may be considered for structural applications where higher strength and weldability are required.
FH40 is commonly used in shipbuilding, offshore platforms, and heavy-duty marine structures, where durability and strength are essential.
Chemical Compositions
| Element | Content (%) |
|---|---|
| Carbon, C | 0.18 – 0.23 |
| Silicon, Si | 0.15 – 0.35 |
| Manganese, Mn | 0.90 – 1.30 |
| Phosphorus, P | ≤ 0.035 |
| Sulfur, S | ≤ 0.035 |
| Chromium, Cr | 0.90 – 1.20 |
| Nickel, Ni | 0.30 – 0.60 |
| Copper, Cu | ≤ 0.30 |
Physical Properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting Point | 1425 – 1470°C | 2597 – 2678°F |
| Thermal Conductivity | 50 W/m·K | 86 BTU·in/hr·ft²·°F |
| Electrical Conductivity | 6.2 x 10⁶ S/m | 6.2 x 10⁶ S/m |
| Specific Heat Capacity | 486 J/kg·K | 0.116 BTU/lb·°F |
| Thermal Expansion Coefficient | 12 x 10⁻⁶ /K | 6.7 x 10⁻⁶ /°F |
| Electrical Resistivity | 1.6 x 10⁻⁸ Ω·m | 1.6 x 10⁻⁸ Ω·m |
Mechanical Properties
AC (Air Cooled) Sate
| Property | Metric | Imperial |
|---|---|---|
| Tensile Strength | 510-660 MPa | 74-96 ksi |
| Yield Strength | 390 MPa | 57 ksi |
| Brinell Hardness (HBW) | 124 | 124 |
| Rockwell Hardness (HRB) | 67 | 67 |
| Vickers Hardness (HV) | 131 | 131 |
| Elongation | 20% | 20% |
| Elastic Modulus | 206 GPa | 29.9 Msi |
QT (Quenched & Tempered) State
| Property | Metric | Imperial |
|---|---|---|
| Tensile Strength | 620-690 MPa | 90-100 ksi |
| Yield Strength | 520 MPa | 75 ksi |
| Elongation | 20% | 20% |
| Reduction of Area | 50% | 50% |
| Impact Absorption Energy | 34 J (at -40°C) | 25 ft-lbf (at -40°F) |
| Elastic Modulus | 200 GPa | 29 Msi |
Industries & Applications
| Industry | Application |
|---|---|
| Shipbuilding | Hull Plates, Bulkheads, Deck Structures, Ship Frames |
| Construction | Bridge Girders, Structural Beams, High-rise Columns, Reinforced Concrete Forms |
| Automotive | Chassis Components, Frame Rails, Suspension Arms, Load-bearing Axles |
| Offshore | Oil Rig Platforms, Subsea Pipelines, Marine Risers, Support Structures |
| Pressure Vessels | Storage Tanks, Boiler Drums, Heat Exchangers, Gas Cylinders |
| Defense | Armored Vehicle Hulls, Naval Vessel Structures, Military-grade Barriers, Missile Silos |
| Energy | Wind Turbine Towers, Power Plant Structures, Hydro Power Dam Gates, Nuclear Reactor Vessels |
| Heavy Machinery | Crane Booms, Excavator Arms, Bulldozer Frames, Industrial Press Frames |
| Railways | Railcar Frames, Bridge Supports, Structural Components, Rail Sleeper Bases |
Machining
Heat Treatment
- Preheating: Heat to 600-650°C (1112-1202°F). Hold to ensure even heating.
- Austenitizing: Increase to 870-900°C (1598-1652°F). Hold for uniform heating.
- Quenching: Cool rapidly in water or oil to harden.
- Tempering: Reheat to 550-650°C (1022-1202°F) to reduce brittleness.
- Cooling: Let cool slowly to room temperature.
Surface Finish
- Pickling: Removes scale and rust from the surface.
- Shot Blasting: Cleans the surface and prepares it for further processing.
- Painting: Adds a protective layer to prevent corrosion.
- Galvanizing: Coats the steel with a layer of zinc to protect against rust.
- Oil Coating: Applies a thin oil layer to prevent rust during storage.
*Customization is available upon request.
Disclaimer
The provided heat treatment and surface treatment processes are general guidelines. Actual conditions may vary depending on specific applications and requirements. It is recommended to consult with a professional metallurgist or material scientist to tailor the processes to your particular needs. The information herein is not a substitute for professional advice and should not be relied upon as such.
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