AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F)

AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) Product Information -:- For detailed product information, please contact sales. -: AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) Synonyms -:- For detailed product information, please contact sales. -:

AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) Product Information -:- For detailed product information, please contact sales. -: **Product Name:** AK Steel ASTM A1011, Class 2 Formable, Grade 55F Hot-Rolled High-Strength Low-Alloy Steel (Improved Formability) --- ### **1. Overview** AK Steel's ASTM A1011 **Grade 55F, Class 2 Formable** is a high-performance steel engineered to deliver a **55 ksi (380 MPa) minimum yield strength** with the **enhanced formability** characteristic of the "F" (Improved Formability) series. This grade occupies a strategic position, offering a higher strength-to-weight ratio than Grade 50F while providing demonstrably better formability than the microalloyed Grade 55K. Its chemistry and processing are optimized to achieve strength primarily through solid-solution strengthening and grain refinement, rather than intensive precipitation hardening, resulting in a more ductile and formable microstructure. It is the ideal choice for components requiring substantial structural performance combined with the ability to undergo complex forming operations. --- ### **2. International Standards** This product is manufactured to the specific requirements of the following standard for improved formability steels: * **ASTM A1011 / A1011M:** Standard Specification for Steel, Sheet and Strip, Hot-Rolled, Carbon, Structural, High-Strength Low-Alloy and High-Strength Low-Alloy with **Improved Formability**. * **Grade:** 55F. The "F" suffix explicitly places it in the "Improved Formability" category, which has distinct chemical and mechanical property targets focused on enhanced ductility. * **Formability Class:** **Class 2.** This classification denotes its standard structural formability level within the F-series, but the inherent "F" chemistry provides superior forming characteristics compared to a 55K grade at the same class. --- ### **3. Chemical Composition (Typical, % by Weight)** The Grade 55F chemistry is a precisely balanced, **low-carbon, high-manganese system** designed for optimal formability at high strength. | Element | Content (Typical / Maximum) | Role & Implication | | :--- | :--- | :--- | | **Carbon (C)** | 0.08% - 0.13% max | Kept very low to ensure excellent ductility, weldability, and formability. This is the cornerstone of the "F" grade's improved performance. | | **Manganese (Mn)** | 1.30% - 1.65% | **Primary strengthening element.** High manganese provides robust solid-solution strengthening, enabling the 55 ksi yield strength while maintaining a formable ferritic matrix. | | **Phosphorus (P)** | 0.025% max | Tightly controlled to maximize toughness and formability. | | **Sulfur (S)** | 0.010% max (Calcium-treated) | Ultra-low sulfur with calcium treatment is typical to ensure excellent through-thickness properties (Z-direction) and prevent cracking during forming. | | **Silicon (Si)** | 0.10% - 0.40% | Deoxidizer. | | **Aluminum (Al), Total** | 0.010% min | Critical grain refiner. Essential for achieving the fine-grained structure that provides both strength and ductility. | | **Niobium (Nb) / Vanadium (V)** | **Minimal or absent** | **Key Distinction from 55K:** The "F" grade philosophy minimizes strong carbide-forming microalloys to avoid the embrittling effects of intense precipitation hardening, prioritizing formability. | | **Nitrogen (N)** | Tightly Controlled | Managed to optimize AlN formation for grain refinement. | | **Key Characteristic:** | **High-Manganese, Low-Carbon Solid Solution Steel.** Strength is derived from a fine-grained ferritic microstructure strengthened predominantly by dissolved manganese atoms, yielding a more uniform and ductile deformation behavior. | | --- ### **4. Physical & Mechanical Properties** The properties reflect a high-strength steel engineered with a focus on formability. | Property | Specification Minimum (ASTM A1011, Grade 55F, Class 2) | Typical Value / Description | Comparison vs. 55K | | :--- | :--- | :--- | :--- | | **Yield Strength (min)** | 55 ksi (380 MPa) | 55-62 ksi. | **Same** | | **Tensile Strength** | 70 ksi min (485 MPa) | 70-80 ksi. | **Typically lower with a controlled upper limit**, leading to a more favorable Y/T ratio. | | **Yield-to-Tensile Ratio (Y/T)** | **Lower than standard 55K** | Typically 0.78 - 0.83. This lower ratio is a critical indicator of improved formability, allowing for greater uniform elongation and more predictable springback. | **Superior for forming** | | **Elongation in 2" (min)** | **Higher than standard 55K** (e.g., 18-21% min) | Typically meets or exceeds minimums, often 20-24%. Provides significantly more usable ductility for forming operations. | **Better ductility** | | **Total Elongation** | Higher | More elongation is available for stretching and drawing complex shapes. | **Better for stretch-forming** | | **Strain Hardening Exponent (n-value)** | Higher | Promotes more uniform metal flow during stretching, reducing the risk of localized thinning. | **Better for forming** | | **Modulus of Elasticity** | 29,000 ksi (200 GPa) | | Same | | **Notch Toughness** | **Very Good.** The fine-grained, ferritic microstructure provides reliable impact resistance for structural applications. Its toughness profile is consistent and predictable. | | Generally good and consistent, though microalloyed 55K may achieve higher peak toughness in optimal conditions. | --- ### **5. Key Features & Advantages** * **Superior Formability at 55 ksi Strength:** Enables the fabrication of more complex, deeply drawn, or tightly bent parts from 55 ksi material, opening new design possibilities. * **Excellent Weldability:** The ultra-low carbon equivalent ensures excellent weldability with minimal preheat requirements, simplifying fabrication. * **Predictable and Consistent Performance:** Offers a more uniform forming response and consistent mechanical properties compared to heavily precipitation-hardened grades, which can be sensitive to processing variations. * **Optimal Balance for Weight-Sensitive Designs:** Provides a compelling alternative where Grade 50F is not strong enough and Grade 55K is too difficult to form. --- ### **6. Product Applications** Grade 55F is ideal for high-strength components that undergo significant forming during manufacture. * **Automotive Structural & Safety Components:** A-pillar reinforcements, B-pillars, seat risers, and chassis members that require 55 ksi strength for crash management and are stamped into complex profiles. * **Heavy Equipment Cab & ROPS Structures:** Formed components for operator cabs, roll-over protective frames, and access doors on construction and agricultural machinery. * **Commercial Vehicle Frames:** Formed crossmembers, brackets, and reinforced sections in truck and trailer frames where weight savings and formability are needed. * **Material Handling Equipment:** Complexly formed parts for high-capacity forklift masts, loader arms, and conveyor system supports. * **General Heavy Fabrication:** Brackets, supports, and enclosures that require 55 ksi strength but must be bent or formed to fit complex assemblies. --- ### **7. Fabrication & Processing Notes** * **Forming:** **Well-suited for demanding cold forming.** Capable of **bending, roll-forming, and moderate drawing operations**. **Minimum recommended bend radii are typically 3x to 4x material thickness**—an improvement over 55K Class 2. **Springback is significant but manageable** with proper tooling design. Not recommended for the most severe deep draws. * **Welding:** **Excellent weldability for its strength.** Use low-hydrogen processes (GMAW with 90/10 Ar/CO₂, FCAW). **Preheat (150-200°F / 65-95°C) is recommended** for thicknesses over 0.75". Use matching-strength filler metals (e.g., 80 ksi tensile). * **Cutting:** Plasma and laser cutting are ideal. Shearing requires high tonnage. * **Selection Guide:** * Use **55F** when you need **55 ksi yield strength and have moderate to complex forming requirements**. It is the preferred choice for formable 55 ksi applications. * Use **55K Class 2** when you need **55 ksi strength for primarily straight or simply bent structural members** where maximum as-supplied toughness may be the priority. * Use **50F** if the design can tolerate **50 ksi strength** and requires **even more aggressive forming**. --- **Disclaimer:** *This profile is a technical summary. AK Steel is now part of Cleveland-Cliffs Inc.* Grade 55F is a specialized product. Always consult the latest official **ASTM A1011** specification and the certified **Mill Test Report (MTR)**. The "F" designation is specific and must be explicitly stated on purchase orders: **"ASTM A1011, Grade 55F."** Review MTR data for tensile strength, elongation, and yield-to-tensile ratio to confirm the improved forming characteristics. Prototyping for forming and welding is strongly recommended. -:- For detailed product information, please contact sales. -: AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) Specification Dimensions Size： Diameter 20-1000 mm Length <4604 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) Properties -:- For detailed product information, please contact sales. -:

Applications of AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) -:- For detailed product information, please contact sales. -: Chemical Identifiers AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) -:- For detailed product information, please contact sales. -:

Packing of AK Steel ASTM A 1011, Class 2 Formable, Grade 55F Hot Rolled Carbon Steel, Medium/High Strength Low Alloy Steel (HSLA-F) -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1075 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition