AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel

AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel, Structural Quality (SQ) Product Information -:- For detailed product information, please contact sales. -: AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel, Structural Quality (SQ) Synonyms -:- For detailed product information, please contact sales. -:

AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel, Structural Quality (SQ) Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AK Steel ASTM A570 Grade 40 (SQ) Hot Rolled Carbon Steel** **AK Steel ASTM A570 Grade 40 (Structural Quality - SQ)** is a **medium-strength, hot-rolled carbon steel sheet and strip** designed for **structural and fabricated components requiring higher load capacity than standard grades**. This grade offers a **minimum yield strength of 40 ksi (275 MPa)**, providing a significant strength increase over Grade 36 while maintaining good fabricability. As part of the A570 specification, the "SQ" designation indicates production to standard **Structural Quality** requirements, making it a cost-effective solution for applications where enhanced strength is needed without the complexity or cost of alloy steels. --- ## **International Standard & Key Specifications** * **Primary Standard:** **ASTM A570/A570M** - Standard Specification for Steel, Sheet and Strip, Carbon, Hot-Rolled, Structural Quality. * **Quality Designation:** **Structural Quality (SQ)** - Standard commercial quality suitable for structural applications. * **Governance:** Manufactured according to standard mill practices for hot-rolled products. Dimensional tolerances typically reference **ASTM A568**. * **Related Standards:** * **ASTM A1011** - Standard Specification for Steel, Sheet and Strip, Hot-Rolled, Carbon, Structural, High-Strength Low-Alloy. * **SAE J1392** - Hot Rolled HSLA and Carbon Steel Sheet and Strip. * **ASTM A36** - Carbon Structural Steel (plate equivalent). * **Key Position:** Represents the **highest standard strength level** in the basic A570 carbon steel series, bridging the gap between conventional carbon steels and HSLA grades. --- ## **Chemical Composition (Weight %, max)** The composition utilizes controlled carbon and manganese levels to achieve the 40 ksi yield strength while maintaining acceptable weldability. | Element | Composition (%) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | **0.25 max** (typically at higher end) | Primary strengthener; controlled near maximum limit for Grade 40 strength. | | **Manganese (Mn)** | **0.90 max** (typically at higher end) | Enhances strength and hardenability; crucial for achieving 40 ksi yield. | | **Phosphorus (P)** | 0.04 max | Impurity, controlled for formability. | | **Sulfur (S)** | 0.05 max | Impurity, controlled for weldability. | | **Silicon (Si)** | - (Residual) | Deoxidizer; typically 0.10-0.30%. | | **Carbon Equivalent (CE)** | **~0.38 - 0.45** | Higher than lower grades; requires more attention during welding. | **Note:** To consistently achieve 40 ksi yield strength, mills typically target the upper ranges of the carbon and manganese limits within the specification. --- ## **Typical Physical & Mechanical Properties (Hot-Rolled, Grade 40)** | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 425 - 585 MPa (62,000 - 85,000 psi) | | **Yield Strength (min)** | **275 MPa (40,000 psi)** | | **Elongation in 2-in (50 mm) (min)** | **21%** | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Density** | ~7.85 g/cm³ (0.284 lb/in³) | | **Formability** | **Moderate to Good.** Suitable for light to moderate bending and forming. Minimum bend radius typically **1-2 x material thickness**. | | **Weldability** | **Good with proper procedures.** Due to higher carbon equivalent, may require preheat for thicker sections or restrained joints. | --- ## **Product Applications** AK Steel A570 Grade 40 (SQ) is specified for applications requiring the highest practical strength from basic carbon steel, particularly in weight-sensitive or load-critical components. **Primary Industries and Products:** 1. **Heavy-Duty Structural Components:** * **Primary purlins and girts** in industrial buildings with longer spans. * **Heavy framing members** for equipment supports and platforms. * **Trailer main rails and crossmembers.** 2. **Transportation Equipment:** * **Heavy truck chassis components.** * **Bus frame rails and structural members.** * **Agricultural equipment frames and implement parts.** 3. **Material Handling & Storage:** * **Heavy-duty storage rack systems** (uprights and beams). * **Industrial platforms, stair treads, and catwalks.** * **Pallet rack components** for high-load applications. 4. **Industrial Machinery & Equipment:** * **Machine bases and frames.** * **Guard rails and protective barriers.** * **Support structures** for mechanical systems. 5. **Construction & Infrastructure:** * **Bridge deck forms.** * **Temporary shoring and bracing.** * **Sign support structures.** --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Higher Strength:** 40 ksi minimum yield provides 11% increase over Grade 36, enabling lighter designs or higher load capacity. * **Cost-Effective Strength:** Most economical way to achieve 40 ksi yield in hot-rolled sheet/strip without alloy additions. * **Good Availability:** Widely produced and stocked by service centers. * **Predictable Performance:** Well-established material with known characteristics. * **Critical Fabrication Considerations:** * **Welding Requirements:** **Higher carbon equivalent necessitates careful welding practices.** For thicknesses >3/16" (4.8 mm) or highly restrained joints, **preheat of 200-300°F (95-150°C)** is recommended. Use **low-hydrogen electrodes** (E7018) for SMAW. * **Forming Limitations:** Reduced formability compared to lower-strength grades. More springback and higher forming forces required. * **Surface Condition:** Standard hot-rolled mill scale must be removed for painting/galvanizing. **Pickled and Oiled (P&O)** condition recommended for critical coating applications. * **Notch Sensitivity:** Higher strength increases sensitivity to sharp notches and sudden section changes in design. * **Strain Aging:** Pronounced tendency for strain aging after cold working; may require stress relief for critical formed parts. * **Alternative Consideration:** For better weldability and formability at similar strength levels, consider **ASTM A1011 HSLAS Grade 45** or **ASTM A607 Grade 45**. **In summary, AK Steel ASTM A570 Grade 40 (SQ) represents the practical upper limit of conventional hot-rolled carbon steel, providing 40 ksi minimum yield strength for applications requiring enhanced load capacity. While offering cost-effective strength, it demands more careful fabrication practices, particularly in welding and forming, compared to lower-strength carbon steels. Proper application engineering and fabrication procedures are essential to leverage its strength advantages successfully.** -:- For detailed product information, please contact sales. -: AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel, Structural Quality (SQ) Specification Dimensions Size： Diameter 20-1000 mm Length <4557 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 40 Hot Rolled Carbon Steel, Structural Quality (SQ) Properties -:- For detailed product information, please contact sales. -:

Applications of AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- For detailed product information, please contact sales. -: Chemical Identifiers AK Steel ASTM A 570, Grade 40 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- For detailed product information, please contact sales. -:

Packing of AK Steel ASTM A 570, Grade 40 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 1028 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