AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel

AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) Product Information -:- For detailed product information, please contact sales. -: AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) Synonyms -:- For detailed product information, please contact sales. -:

AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) Product Information -:- For detailed product information, please contact sales. -: # **Technical Clarification and Industry Reality** **Important Technical Note:** **ASTM A570/A570M does not include a Grade 55 specification.** The standard officially recognizes only Grades 30, 33, 36, 40, and 45 for Structural Quality (SQ) hot-rolled carbon steel sheet and strip. A product marketed as "AK Steel ASTM A570 Grade 55 (SQ)" would represent either: 1. A **proprietary, non-standard grade** specific to AK Steel, exceeding the published ASTM specification. 2. A potential **misclassification**, where the material should more accurately be described under a different ASTM specification designed for higher strengths, such as **ASTM A1011 (HSLAS)** or **ASTM A607**. For a hot-rolled steel product with a **55 ksi (380 MPa) minimum yield strength**, the appropriate and widely accepted industry standards are **HSLA (High-Strength Low-Alloy) specifications**, not the basic carbon steel A570 series. --- ## **Correct Specification: ASTM A1011 Grade 55 High-Strength Low-Alloy (HSLAS) Steel** The following introduction describes the material that would correctly fulfill the performance implied by "Grade 55" hot-rolled sheet. **Product Introduction: ASTM A1011 Grade 55 HSLAS Steel** **ASTM A1011 Grade 55** is a **hot-rolled, high-strength low-alloy steel sheet** engineered to provide **55 ksi (380 MPa) minimum yield strength** through microalloying and controlled rolling. Unlike conventional carbon steels, this HSLA grade achieves its enhanced strength primarily through the addition of microalloying elements like **vanadium (V), niobium (Nb), or titanium (Ti)**, which provide grain refinement and precipitation strengthening. This allows for higher strength while maintaining **better weldability and formability than a carbon steel of equivalent strength** would possess. It is a standard, widely available material for demanding structural applications. --- ## **International Standard & Key Specifications** * **Correct Primary Standard:** **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. * **Type:** **HSLAS (High-Strength Low-Alloy Steel)**, Class 1 or 2. * **Governing Standard:** **ASTM A568/A568M** for dimensional tolerances and general requirements. * **Related Standards:** * **ASTM A606** – HSLA Steel, Sheet and Strip, with Improved Atmospheric Corrosion Resistance. * **SAE J1392** – Hot Rolled HSLA and Carbon Steel Sheet and Strip. * **Key Distinction:** This is a **microalloyed steel**, fundamentally different from the plain carbon steels of the A570 series. --- ## **Chemical Composition (Weight %, max)** The composition features lower carbon than a carbon steel of similar strength, with specific microalloy additions. | Element | Composition (Grade 55, HSLAS) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | 0.15 max (Typical) | Lower than A570 grades; improves weldability and toughness. | | **Manganese (Mn)** | 1.65 max | Solid solution strengthener. | | **Phosphorus (P)** | 0.025 max | Tightly controlled impurity. | | **Sulfur (S)** | 0.025 max | Tightly controlled for improved formability. | | **Silicon (Si)** | 0.50 max | Deoxidizer. | | **Copper (Cu)** | 0.20 min (optional) | For corrosion-resistant versions. | | **Vanadium (V)** | **0.01 - 0.10** (typical) | **Primary microalloy.** Provides precipitation strengthening. | | **Niobium (Cb/Nb)** | **0.005 - 0.05** (typical) | **Primary microalloy.** Provides grain refinement and precipitation strengthening. | | **Carbon Equivalent (CE)** | **~0.35 - 0.40** | **Lower than a hypothetical A570 Grade 55**, indicating superior weldability. | --- ## **Typical Physical & Mechanical Properties (Hot-Rolled, HSLAS Grade 55)** | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 510 - 690 MPa (74,000 - 100,000 psi) | | **Yield Strength (min)** | **380 MPa (55,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | 22% | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Density** | ~7.85 g/cm³ | | **Formability** | **Good for its strength.** Suitable for moderate bending. Minimum bend radius typically **2-2.5 x thickness**. | | **Weldability** | **Good with proper practice.** Lower carbon equivalent allows welding with standard low-hydrogen procedures. Preheat may be required for thicker sections. | --- ## **Product Applications (for HSLAS Grade 55)** This material is used for structural components where weight savings and higher strength are critical. 1. **Heavy Equipment & Transportation:** Chassis components for heavy trucks, bus frames, trailer main beams, and agricultural equipment. 2. **Structural & Construction:** Heavier purlins/girts, equipment support frames, and industrial access platforms. 3. **Material Handling:** High-capacity storage rack systems and lifting equipment components. --- ## **Summary and Recommendation** **There is no ASTM A570 Grade 55.** A hot-rolled steel product with a 55 ksi minimum yield point is properly classified as an **HSLA steel** under specifications like **ASTM A1011 Grade 55**. * **If you have been offered "A570 Grade 55":** Request the **official material certification** and verify the actual **ASTM specification and grade** listed. It is likely certified to **ASTM A1011**. * **For your design needs:** Specify **ASTM A1011 Grade 55 (HSLAS)**. It is a standard, readily available material that provides 55 ksi yield strength with significantly better weldability and more consistent properties than a non-standard, high-carbon alternative could offer. Choosing the correct, established specification ensures material quality, reliable supply, and predictable fabrication performance. -:- For detailed product information, please contact sales. -: AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) Specification Dimensions Size： Diameter 20-1000 mm Length <4560 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 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) Properties -:- For detailed product information, please contact sales. -:

Applications of AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- For detailed product information, please contact sales. -: Chemical Identifiers AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- For detailed product information, please contact sales. -:

Packing of AK Steel ASTM A 570, Grade 55 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- 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 1031 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