ASTM A514 Grade F is a quenched and tempered alloy steel plate used in structural applications that require high yield strength combined with good formability and toughness. The Grade F designation is one of several composition variants in the A514 specification, each tailored to provide a balance of strength, weldability, and through-thickness properties. This article describes the chemical composition, mechanical properties, and fabrication considerations for A514 Grade F.
Chemical Composition
The heat analysis of A514 Grade F is controlled within the following ranges and maximums: carbon 0.10 to 0.20%, manganese 0.60 to 1.00%, phosphorus 0.035% maximum, sulfur 0.035% maximum, silicon 0.15 to 0.35%, nickel 0.70 to 1.00%, chromium 0.40 to 0.65%, molybdenum 0.40 to 0.60%, vanadium 0.03 to 0.08%, copper 0.15 to 0.50%, and boron 0.001 to 0.005%. Titanium and zirconium may be added as grain refiners. The combination of nickel, chromium, and molybdenum provides response to quenching and tempering, while boron improves hardenability in the base plate. The carbon equivalent is calculated as C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15, and the resulting value is monitored to control weldability.
Mechanical Properties
The minimum yield strength of A514 Grade F is 690 MPa (100 ksi) for plates up to 65 mm thick, with a minimum tensile strength of 760 to 895 MPa and a minimum elongation of 18% in 50 mm. For plates from 65 mm to 150 mm thick, the minimum yield strength is 620 MPa (90 ksi), with a tensile strength of 690 to 895 MPa and the same minimum elongation. Delivery is in the quenched and tempered condition, and the plate may be ordered with supplemental Charpy V-notch impact testing, commonly 54 J at -40 C. Tensile testing and hardness testing are performed at the mill, and the results are recorded on the original mill test certificate.
Typical Applications
The high strength-to-weight ratio of A514 Grade F makes it suitable for transport trailers, construction equipment, crane booms, mobile aerial work platforms, agricultural equipment, and heavy vehicle frames and chassis. In these applications, the reduced section thickness lowers the self-weight of the structure and increases the useful payload. The grade also serves in components subject to dynamic loading, where the combination of strength and fatigue resistance is important. For warm-formed components, the temperature must be limited and the final properties verified after forming.
Welding Requirements
Welding of A514 Grade F requires matching high-strength low-hydrogen electrodes such as E11018 or E12018. Preheat of 300 to 400 F and strict interpass temperature control are required to prevent hydrogen-induced cracking. Post-weld heat treatment is recommended for heavily restrained joints and thick sections to relieve residual stress and restore toughness in the heat-affected zone. Flame cutting requires preheating to 200 to 300 F to prevent hardening and micro-cracking along the cut edge, especially for plates thicker than 2 inches.
Frequently Asked Questions
What is the typical impact toughness requirement for A514 Grade F?
When supplemental impact testing is ordered, a minimum Charpy V-notch energy of 54 J at -40 C is commonly specified to ensure fracture resistance in cold environments and dynamic loading applications.
How thick can A514 Grade F plates be ordered?
The grade is commonly produced up to 100 mm while maintaining full through-thickness properties. Some mills can supply thicker plates with adjusted mechanical guarantees.
What filler metals are recommended for welding A514 Grade F?
High-strength low-hydrogen electrodes such as E11018 or E12018 are required, with strict adherence to preheat of 300 to 400 F and interpass temperature control.
Does A514 Grade F require post-weld heat treatment?
Post-weld heat treatment is recommended for most welded fabrications to relieve residual stresses and restore toughness, particularly for thick sections and highly restrained joints.
Can A514 Grade F be flame-cut without special precautions?
No. Flame cutting requires preheating to 200 to 300 F to prevent hardening and micro-cracking along the cut edge, especially above 2 inches thickness.
What is the minimum yield strength of A514 Grade F?
The minimum yield strength is 100 ksi (690 MPa) for plates up to 65 mm thick and 90 ksi (620 MPa) for plates 65 to 150 mm thick.