AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA)

AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) Product Information -:- For detailed product information, please contact sales. -: AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) Synonyms -:- For detailed product information, please contact sales. -:

AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AK Steel ASTM A607 Class 2, Grade 55K Hot-Rolled HSLA Steel** **AK Steel ASTM A607 Class 2, Grade 55K** is a premium **hot-rolled, high-strength low-alloy (HSLA) steel sheet and strip** engineered to deliver **55 ksi (380 MPa) minimum yield strength** with excellent **structural performance, good weldability, and adequate formability**. As part of the "**Structural**" (Class 2) designation, this grade is optimized for applications where **high load-bearing capacity, structural integrity, and reliable fabrication characteristics** are paramount. The "**K**" designation indicates a **producer-determined strength range** (typically 55-70 ksi yield), allowing for precise mechanical property optimization. Achieving its superior strength through **advanced microalloying with vanadium and/or niobium** in a controlled low-carbon chemistry, this material provides an outstanding strength-to-weight ratio for demanding structural applications where 55 ksi yield strength is required. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A607/A607M** - Standard Specification for Steel, Sheet and Strip, High-Strength, Low-Alloy, Columbium or Vanadium, or Both, Hot-Rolled and Cold-Rolled. * **Class Distinction:** **Class 2 - Structural**. This classification emphasizes **structural reliability, weld quality, and cost-performance balance** over maximum formability. * **Grade System:** **"K" Grades (Producer-Determined Strength)**. Grade 55K specifies a minimum yield strength of 55 ksi (380 MPa), with the producer establishing the optimal range to balance strength with other critical properties. * **Related Standards:** * **ASTM A1011/A1011M** - Specification for HSLAS (High-Strength Low-Alloy Steel). * **SAE J1392** - Hot Rolled HSLA and Carbon Steel Sheet and Strip. * **ASTM A370** - Standard Test Methods and Definitions for Mechanical Testing. * **Key Feature:** Delivers **55 ksi yield strength with good structural characteristics and manageable fabricability**, representing a high-performance option for weight-sensitive structural designs. --- ## **Chemical Composition (Weight %, typical)** The chemistry is carefully controlled to achieve 55 ksi yield strength while maintaining weldability and adequate formability for structural applications. | Element | Composition (Typical for Class 2, Grade 55K) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | 0.15 - 0.22 | Provides fundamental strength while maintaining weldability at this strength level. | | **Manganese (Mn)** | 1.20 - 1.60 | Critical for achieving 55 ksi yield strength through solid solution strengthening. | | **Phosphorus (P)** | 0.035 max | Impurity, kept at minimum levels for good ductility. | | **Sulfur (S)** | 0.04 max | Impurity, tightly controlled for optimal weldability. | | **Silicon (Si)** | 0.15 - 0.50 | Deoxidizer and solid solution strengthener. | | **Columbium (Cb/Nb)** | 0.01 - 0.06 | Key microalloy for grain refinement and precipitation strengthening. | | **Vanadium (V)** | 0.03 - 0.12 | Important microalloy for precipitation strengthening, particularly effective at this strength level. | | **Copper (Cu)** | 0.20 min (optional) | May be specified for enhanced atmospheric corrosion resistance. | | **Carbon Equivalent (CE)** | Typically 0.40 - 0.48 | Requires careful attention to welding procedures and parameters. | **Processing Note:** The specific balance of microalloying elements (Cb vs. V) is optimized by the producer based on their processing capabilities and the desired balance of properties. --- ## **Typical Physical & Mechanical Properties (Hot-Rolled, Class 2, Grade 55K)** | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 520 - 660 MPa (75,000 - 96,000 psi) | | **Yield Strength (min)** | **380 MPa (55,000 ksi)** | | **Elongation in 2-in (50 mm) (min)** | **17% - 19%** | | **Yield-to-Tensile Ratio** | Typically 0.73 - 0.82 | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Density** | ~7.85 g/cm³ (0.284 lb/in³) | | **Formability** | **Moderate.** Suitable for **simple to moderate bending and forming.** Minimum bend radius typically **2.0-2.5× material thickness** for 90° bends across the rolling direction. Significant springback should be anticipated. | | **Weldability** | **Good with strict procedures.** Preheat of **250-350°F (120-175°C) is generally required** for thicknesses >3/16 inch (5 mm). **Low-hydrogen welding practices are essential.** | | **Surface Quality** | Standard hot-rolled finish; available in pickled and oiled condition for improved surface preparation. | | **Impact Properties** | Typically adequate for structural applications; can be specified to meet specific Charpy V-notch requirements if needed. | --- ## **Product Applications** AK Steel ASTM A607 Class 2, Grade 55K is designed for structural components where 55 ksi yield strength provides significant weight savings or increased load capacity compared to lower-strength materials. **Primary Industries and Products:** 1. **Heavy Structural Framing:** * **Primary load-bearing members** in industrial buildings and structures. * **Heavy-duty purlins, girts, and framing systems** for long-span applications. * **Structural supports and braces** for equipment and machinery. 2. **Transportation & Heavy Equipment:** * **Heavy truck frame components** and chassis reinforcements. * **Trailer main beams and structural members** for high-capacity applications. * **Construction and agricultural equipment frames** requiring 55 ksi strength. * **Mining equipment structural components.** 3. **Material Handling & Industrial:** * **Extra-heavy-duty storage rack systems** and components. * **Crane runway beams** and support structures. * **Heavy industrial platforms, walkways, and access structures.** 4. **Infrastructure & Construction:** * **Bridge components** and temporary structures. * **Heavy formwork and shoring systems.** * **Support structures** for signs, signals, and lighting. 5. **Energy Sector:** * **Support structures** for power generation equipment. * **Components** in material handling systems for bulk materials. --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **High Strength Performance:** 55 ksi minimum yield strength enables lighter designs or higher load capacities. * **Good Structural Reliability:** Provides consistent mechanical properties for predictable performance. * **Cost-Effective High Strength:** Offers premium strength at a competitive price compared to alternative high-strength materials. * **Versatile Application:** Suitable for a wide range of structural applications requiring 55 ksi yield strength. * **Critical Fabrication Considerations:** * **Welding Requirements:** Due to the higher carbon equivalent: * **Preheat is mandatory:** 250-350°F (120-175°C) for most thicknesses and joint configurations. * **Low-hydrogen processes essential:** Use E7018 electrodes or equivalent low-hydrogen filler metals. * **Control heat input:** Avoid excessive heat input to prevent HAZ embrittlement. * **Consider post-weld heat treatment** for thick sections or highly restrained joints. * **Forming Limitations:** * **Not suitable for severe forming operations.** * **Significant springback** requires compensation in tooling design. * **Minimum bend radii are larger** than for lower-strength steels. * **Surface Preparation:** * Mill scale must be thoroughly removed for optimal coating adhesion. * **Pickled and oiled condition strongly recommended** for painting applications. * **Quality Assurance:** * Request certified test reports confirming 55 ksi minimum yield strength. * Consider specifying supplementary requirements for impact testing if low-temperature service is anticipated. * **Alternative Materials Evaluation:** * For applications requiring **better formability** at similar strength, consider **ASTM A607 Class 1 grades**. * For applications requiring **better weldability** with less preheat, evaluate **ASTM A1011 HSLAS grades** with similar strength. **In summary, AK Steel ASTM A607 Class 2, Grade 55K provides a high-performance 55 ksi yield strength solution for structural applications where strength and reliability are prioritized. While offering excellent load-bearing capacity and weight-saving potential, it requires careful attention to welding and forming procedures to ensure successful fabrication and optimal performance in service. Proper engineering design and fabrication practices are essential to fully leverage its strength advantages while managing its fabrication requirements effectively.** -:- For detailed product information, please contact sales. -: AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) Specification Dimensions Size： Diameter 20-1000 mm Length <4571 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 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) Properties -:- For detailed product information, please contact sales. -:

Applications of AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) -:- For detailed product information, please contact sales. -: Chemical Identifiers AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) -:- For detailed product information, please contact sales. -:

Packing of AK Steel ASTM A 607 Class 2 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) -:- 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 1042 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