AK Steel ASTM A 607 Class 1 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA)

AK Steel ASTM A 607 Class 1 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 1 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 1 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 1 Formable, Grade 55K Hot-Rolled HSLA Steel** **AK Steel ASTM A607 Class 1, Grade 55K** is a premium **hot-rolled, high-strength low-alloy (HSLA) steel sheet and strip** engineered to deliver an exceptional combination of **55 ksi (380 MPa) minimum yield strength and superior formability**. As a member of the "**Formable**" (Class 1) family, this grade represents an advanced metallurgical solution for applications requiring **both high structural strength and excellent cold-forming characteristics**. The "**K**" designation indicates a **producer-determined strength range** (typically 55-70 ksi yield), with Grade 55K optimized for maximum fabricability at this elevated strength level. Its mechanical properties are achieved through sophisticated **microalloying with vanadium, niobium, and titanium** in an ultra-low-carbon base, making it an ideal solution for weight-critical, complex-formed structural components in demanding industries. --- ## **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 1 - Formable**. This classification guarantees superior ductility and forming characteristics essential for complex manufacturing operations. * **Grade System:** **"K" Grades (Producer-Determined Strength)**. Grade 55K specifies a minimum yield strength of 55 ksi (380 MPa), with the actual range established by the producer to optimize the balance between strength and formability. * **Related Standards:** * **ASTM A1011/A1011M** - Specification for HSLAS (High-Strength Low-Alloy Steel). * **SAE J1392** - Hot Rolled HSLA and Carbon Steel Sheet and Strip. * **ISO 4952** - High yield strength steel sheets and strips. * **Key Metallurgical Feature:** Utilizes precipitation hardening and grain refinement through microalloying rather than high carbon content, enabling Class 1 formability at 55 ksi yield strength. --- ## **Chemical Composition (Weight %, typical)** The chemistry features ultra-low carbon content with precise microalloy additions for strength optimization while maintaining excellent formability. | Element | Composition (Typical for Class 1, Grade 55K) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | **0.06 - 0.10 max** | **Ultra-low.** Fundamental to achieving excellent weldability and formability while enabling strength through microalloying. | | **Manganese (Mn)** | 1.00 - 1.50 | Provides solid solution strengthening; carefully balanced for optimal hardenability. | | **Phosphorus (P)** | 0.025 max | Tightly controlled impurity. | | **Sulfur (S)** | **0.005 - 0.010 max** | **Extremely low.** Critical for preventing cracking during severe forming operations and ensuring excellent through-thickness properties. | | **Silicon (Si)** | 0.10 - 0.35 | Deoxidizer and solid solution strengthener. | | **Columbium (Cb/Nb)** | **0.03 - 0.08** | **Primary microalloy.** Provides powerful grain refinement and precipitation strengthening through Nb(C,N) precipitates. | | **Vanadium (V)** | **0.06 - 0.12** | Complementary microalloy for additional precipitation strengthening via V(C,N). | | **Titanium (Ti)** | **0.010 - 0.035** | Used for grain refinement and sulfide shape control; critical for improving formability. | | **Molybdenum (Mo)** | 0.05 - 0.15 (optional) | May be added for enhanced strength and hardenability control. | | **Aluminum (Al)** | 0.015 - 0.060 | Grain refining deoxidizer. | | **Carbon Equivalent (CE)** | **Typically ≤ 0.30** | **Exceptionally low,** enabling superior weldability with minimal preheat requirements. | **Processing Note:** The specific combination of Cb, V, Ti, and optional Mo is proprietary to the steel producer and is optimized through thermomechanical controlled processing (TMCP) to achieve the optimal microstructure for both strength and formability. --- ## **Typical Physical & Mechanical Properties (Hot-Rolled, Class 1, Grade 55K)** | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 520 - 660 MPa (75,000 - 96,000 psi) | | **Yield Strength (min)** | **380 MPa (55,000 psi)** (Producer's range: typically 55-65 ksi) | | **Elongation in 2-in (50 mm) (min)** | **20% - 24%** | | **Yield-to-Tensile Ratio** | Typically 0.73 - 0.80 | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Strain Hardening Exponent (n-value)** | 0.12 - 0.16 (favorable for stretch formability) | | **Plastic Strain Ratio (r-value)** | 0.9 - 1.1 (indicates good deep drawability) | | **Formability** | **Excellent for 55 ksi strength.** Suitable for **moderate to severe bending, roll-forming, and complex stamping.** Minimum bend radius typically **1.5-2.0× material thickness.** | | **Weldability** | **Excellent.** Can be welded using all common processes with minimal precautions due to extremely low carbon equivalent. | | **Surface Quality** | High-quality surface finish suitable for exposed applications after painting. | | **Impact Toughness** | Typically good; can be specified to meet Charpy V-notch requirements if needed. | --- ## **Product Applications** This material is specifically designed for complex formed components where both high strength and excellent formability are critical for manufacturing and performance. **Primary Industries and Products:** 1. **Automotive Structural & Safety Components:** * **Advanced high-strength automotive frames** and **subframes** * **Crash management systems** and **bumper reinforcements** * **Door intrusion beams** and **seat reinforcement structures** * **Chassis components** requiring complex forming 2. **Heavy Transportation & Equipment:** * **Heavy truck frame reinforcements** and **crossmembers** * **Construction equipment cabs** and **operator protection structures** * **Agricultural equipment frames** and **implement components** * **Mining equipment structural parts** 3. **Industrial & Material Handling:** * **Heavy-duty storage rack components** * **Material handling equipment frames** and **brackets** * **Industrial machinery guards** and **protective structures** 4. **Energy & Infrastructure:** * **Wind turbine components** requiring high strength-to-weight ratio * **Heavy construction equipment parts** * **Transportation infrastructure components** --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Exceptional Strength-Formability Balance:** Achieves 55 ksi yield strength while maintaining formability comparable to lower-strength steels. * **Superior Weldability:** Ultra-low carbon equivalent simplifies welding procedures and reduces fabrication complexity and cost. * **Weight Reduction Potential:** Enables significant material savings through down-gauging while maintaining structural integrity. * **Enhanced Safety Performance:** Good combination of strength and ductility improves energy absorption in impact scenarios. * **Manufacturing Efficiency:** Allows complex part consolidation and reduced assembly requirements. * **Critical Fabrication Considerations:** * **Material Specification:** Ensure procurement specifies **"ASTM A607 Class 1, Grade 55K"** to guarantee both strength and formability properties. * **Tooling Design:** Account for higher springback and greater forming forces compared to lower-strength steels. Progressive die design may require adjustments for springback compensation. * **Forming Lubrication:** May require specialized lubricants for severe forming operations to prevent surface defects and tool wear. * **Thermal Sensitivity:** Avoid prolonged exposure above 400°C (750°F) to prevent over-aging and potential strength reduction. * **Edge Condition:** Proper edge preparation is important for forming operations to prevent crack initiation. * **Quality Assurance:** Request comprehensive material test reports including tensile properties, elongation, chemical analysis, and surface quality verification. * **Alternative Evaluation:** For less severe forming requirements, consider Class 2 grades; for more severe forming at lower strength, consider lower K-grades. **In summary, AK Steel ASTM A607 Class 1, Grade 55K represents an advanced HSLA steel solution that successfully bridges the demanding requirements of high structural strength and complex manufacturability. Its sophisticated microalloyed chemistry enables the production of weight-efficient, complex-formed components at 55 ksi yield strength, making it an essential material for advanced engineering applications where performance, safety, and manufacturing efficiency converge. Successful implementation requires careful attention to fabrication practices and tooling design to fully leverage its unique combination of properties.** -:- For detailed product information, please contact sales. -: AK Steel ASTM A 607 Class 1 Formable, Grade 55K Hot Rolled Carbon Steel, Medium/High Strength Low Alloy (HSLA) Specification Dimensions Size： Diameter 20-1000 mm Length <4567 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 1 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 1 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 1 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 1 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 1038 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