ASTM A514 Grade F is a high-yield, quenched and tempered alloy steel plate primarily used for structural applications where weight savings and high strength are critical. It is part of a family of steels often referred to by the trade name T-1 steel.
Key Specifications
Yield Strength: Minimum 100 ksi (approx. 690 MPa) for thicknesses up to 2.5 inches.
Tensile Strength: Typically 110–130 ksi.
Condition: Delivered in a quenched and tempered state to achieve its high-strength and tough mechanical properties.
Thickness Range: Standard availability for Grade F is typically up to 2.5 inches (63.5 mm).
The key properties of ASTM A514 Grade F are defined by its high strength, toughness, weldability, and quenched & tempered microstructure. Below is a systematic breakdown of its critical mechanical, chemical, and physical characteristics.
1. Mechanical Properties (Per ASTM A514/A514M)
These are the minimum specified values that define the grade.
| Property | Value (≤ 1.25 in. / 31.75 mm thick) | Value (1.25 in. to 2.5 in. / 31.75-63.5 mm thick) |
|---|---|---|
| Yield Strength (0.2% Offset) | 100 ksi (690 MPa) | 90 ksi (620 MPa) |
| Tensile Strength | 110 - 130 ksi (760 - 895 MPa) | 100 - 130 ksi (690 - 895 MPa) |
| Elongation (in 2 in.) | 18% min | 16% min |
| Charpy V-Notch Impact Toughness | Typically 20-25 ft-lb (27-34 J) min. @ -50°F (-46°C) | Same requirement applies. |
| Typical Hardness (Not Specified) | HBW 280-340 (approx. HRC 29-36) | Slightly lower for thicker sections. |
2. Key Chemical Composition (Typical/ Max %)
The defining feature of Grade F is its "lean" alloy design for weldability.
| Element | Content (Typical Range / Max) | Purpose & Note |
|---|---|---|
| Carbon (C) | 0.15 - 0.20% (Max 0.23%) | Lower than Grade E for better weldability. |
| Manganese (Mn) | 0.80 - 1.10% | Strengthening and hardenability. |
| Chromium (Cr) | 0.40 - 0.65% | Hardenability and strength. |
| Molybdenum (Mo) | 0.15 - 0.25% | Enhances strength and temper resistance. |
| Boron (B) | 0.0005 - 0.005% (Often NOT added) | Key difference: Grade F is often produced without Boron, unlike Grade E. |
| Silicon (Si) | 0.15 - 0.35% | Deoxidizer. |
| Carbon Equivalent (CEV/Pcm) | ~0.60 - 0.70 (IIW formula) | Lower than Grade E, indicating superior weldability and lower crack sensitivity. |
3. Physical & General Properties
Condition: Supplied in Quenched & Tempered (Q&T) condition.
Density: ~0.284 lb/in³ (7.85 g/cm³).
Modulus of Elasticity: ~29,000 ksi (200 GPa).
Poisson's Ratio: ~0.29.
4. Performance & Fabrication Properties
Weldability: Good (for a 100 ksi steel). Its lower carbon equivalent makes it significantly more weldable than Grade E. Requires low-hydrogen procedures, preheat (often 300-500°F), and controlled cooling.
Machinability: Fair to moderate. Requires more power and appropriate tooling compared to mild steel.
Flame Cutting: Possible with strict preheat (300-500°F) and slow cooling to prevent edge hardening and cracking. Plasma or waterjet cutting is preferred.
Fatigue Strength: Excellent, due to the clean, homogeneous Q&T microstructure.
5. Primary Applications
It is selected for its optimal balance of strength, weight, and fabricability:
High-Strength Structural Welded Fabrications: Crane booms, excavator arms, mining equipment frames.
Critical Bridge Components (especially movable sections).
High-Rise Building Columns & Braces.
Components where welding complexity makes Grade E too risky or costly.
Core Distinction from A514 Grade E
Grade F is engineered to provide identical mechanical strength (100/90 ksi) as Grade E but with a leaner alloy chemistry. This results in a lower carbon equivalent, superior weldability, and reduced hydrogen-induced cracking risk, making it the preferred choice for modern, heavily welded structures.
1. What is A514 Grade F steel used for?
A514 Grade F is primarily used in high-strength structural applications like heavy construction equipment, crane booms, mining machinery, and bridges where a superior strength-to-weight ratio is required.
2. What is the yield strength of A514 Grade F?
For plates up to 1.25 inches (31.75 mm) thick, the minimum yield strength is 100 ksi (690 MPa). For thicker plates, the yield strength decreases, typically to 90 ksi (620 MPa) up to 2.5 inches.
3. Can A514 Grade F be welded?
Yes, it can be welded, but it requires strict procedures including preheating, the use of low-hydrogen electrodes, and often post-weld heat treatment to prevent cracking due to its high hardenability.
4. How does A514 Grade F differ from Grade E?
The main difference is in chemistry: Grade F has lower carbon and alloy content (and no boron), resulting in better weldability and a lower carbon equivalent, while both grades offer the same minimum yield strength.
5. What is the hardness of A514 Grade F?
The typical hardness range for A514 Grade F is approximately HBW 280-340 (Brinell) or HRC 29-36, but hardness is not a specified property in the ASTM standard.
6. Is A514 Grade F the same as T1 steel?
Yes, A514 Grade F is often commercially referred to as "T1 Type F" or "modified T1." The "T1" name originally came from a trademark, but it's commonly used for this family of high-strength, quenched and tempered steels.
7. What is the European equivalent of A514 Grade F?
The closest European equivalent is S690QL or S690Q/QL1 according to EN 10025-6, which has a similar 690 MPa yield strength and quenched & tempered condition.
8. Can you flame cut A514 Grade F?
Yes, but it requires preheating (typically 300-500°F) and controlled cooling to prevent hardening and cracking along the cut edge. Plasma or waterjet cutting are often preferred alternatives.
9. What is the chemical composition of A514 Grade F?
It has a lower carbon content (max 0.20%) compared to Grade E, along with reduced levels of chromium, molybdenum, and no boron, resulting in a lower carbon equivalent for improved weldability.
10. Why choose A514 Grade F over Grade E?
Choose Grade F when weldability and fabrication ease are top priorities for complex structures, as its leaner chemistry reduces the risk of welding-related cracking compared to the higher-alloy Grade E.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
