AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel

AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel, Structural Quality (SQ) Product Information -:- For detailed product information, please contact sales. -: AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel, Structural Quality (SQ) Synonyms -:- For detailed product information, please contact sales. -:

AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel, Structural Quality (SQ) Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AK Steel ASTM A570 Grade 45 (SQ) Hot Rolled Carbon Steel** **AK Steel ASTM A570 Grade 45 (Structural Quality - SQ)** is a **high-strength, hot-rolled carbon steel sheet and strip** that represents the premium strength level within the standard A570 carbon steel series. This grade is engineered to deliver a **minimum yield strength of 45 ksi (310 MPa)** through optimized chemistry and rolling practices, providing substantial load-bearing capacity for demanding structural applications. While maintaining the fundamental characteristics of carbon steel, Grade 45 offers significantly enhanced strength compared to lower grades, making it suitable for components where weight reduction or increased load capacity is critical. The "SQ" designation confirms its production to standard Structural Quality requirements. --- ## **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 for structural applications. * **Governance:** Produced according to standard hot-rolled mill practices. 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 (for plate equivalents). * **Key Position:** Represents the **maximum strength level** achievable within the conventional A570 carbon steel specification, utilizing carbon and manganese as primary strengtheners without microalloying. --- ## **Chemical Composition (Weight %, max)** The chemistry is carefully controlled at the upper limits of the specification to consistently achieve the 45 ksi yield strength requirement. | Element | Composition (%) | Role in Performance | | :--- | :--- | :--- | | **Carbon (C)** | **0.25 max** (typically at maximum limit) | Primary strengthening element; essential for achieving 45 ksi yield strength. | | **Manganese (Mn)** | **0.90 max** (typically at maximum limit) | Critical for strength enhancement and hardenability; works synergistically with carbon. | | **Phosphorus (P)** | 0.04 max | Impurity, controlled to minimize embrittlement. | | **Sulfur (S)** | 0.05 max | Impurity, controlled for weldability and ductility. | | **Silicon (Si)** | 0.10-0.30 (typical) | Deoxidizer; contributes to strength. | | **Carbon Equivalent (CE)** | **~0.40 - 0.48** | Relatively high; requires careful welding procedure control. | **Important Note:** To reliably meet the 45 ksi minimum yield strength, mills must operate at the upper boundaries of the carbon and manganese ranges, resulting in higher carbon equivalent values that impact weldability and formability. --- ## **Typical Physical & Mechanical Properties (Hot-Rolled, Grade 45)** | Property | Value / Description | | :--- | :--- | | **Tensile Strength** | 450 - 620 MPa (65,000 - 90,000 psi) | | **Yield Strength (min)** | **310 MPa (45,000 ksi)** | | **Elongation in 2-in (50 mm) (min)** | **19%** | | **Modulus of Elasticity** | ~200 GPa (29 x 10⁶ psi) | | **Density** | ~7.85 g/cm³ (0.284 lb/in³) | | **Formability** | **Moderate.** Suitable for simple bending and straight forming. Minimum bend radius typically **2-3 × material thickness**. Significant springback expected. | | **Weldability** | **Fair with strict procedures.** High carbon equivalent necessitates controlled welding practices with preheat and low-hydrogen consumables. | --- ## **Product Applications** AK Steel A570 Grade 45 (SQ) is specified for applications requiring the highest strength available from conventional hot-rolled carbon steel, particularly where cost constraints limit the use of microalloyed HSLA steels. **Primary Industries and Products:** 1. **Heavy Structural Framing:** * **Primary load-bearing members** in industrial structures and mezzanines. * **Heavy-duty purlins and girts** for long-span building systems. * **Support beams and columns** for equipment platforms. 2. **Transportation & Heavy Equipment:** * **Heavy truck frame rails and crossmembers.** * **Trailer main beams and structural components.** * **Agricultural equipment frames and implement parts.** 3. **Material Handling & Storage:** * **Extra-heavy-duty storage rack systems.** * **Crane runway beams and supports.** * **Industrial catwalks and platforms** for heavy loads. 4. **Construction & Infrastructure:** * **Heavy formwork and shoring systems.** * **Temporary bridge components.** * **Heavy-duty sign and signal supports.** 5. **Industrial Applications:** * **Machine bases and structural frames.** * **Heavy guards and barriers.** * **Support structures** for processing equipment. --- ## **Advantages and Critical Fabrication Considerations** * **Advantages:** * **Maximum Carbon Steel Strength:** Provides the highest yield strength (45 ksi) available in the A570 specification. * **Cost-Effective High Strength:** More economical than microalloyed HSLA steels at similar strength levels. * **Good Availability:** Produced by multiple mills and widely available through service centers. * **Critical Fabrication Considerations:** * **Welding Challenges:** **High carbon equivalent requires stringent welding controls.** Mandatory **preheat of 250-350°F (120-175°C)** for thicknesses >1/8" (3 mm). **Low-hydrogen processes essential** (E7018 for SMAW, ER70S-6 for GMAW with Ar/CO₂ mix). Post-weld heat treatment may be necessary for thick sections. * **Limited Formability:** Reduced ductility compared to lower-strength grades. Complex forming operations may cause cracking. Not recommended for severe bending or deep drawing. * **Notch Sensitivity:** High strength increases susceptibility to crack initiation at sharp notches, corners, or weld defects. * **Strain Aging Pronounced:** Significant yield strength increase and ductility reduction can occur after cold working, potentially affecting subsequent fabrication or service performance. * **Surface Preparation:** Mill scale must be thoroughly removed for coating adhesion. **Pickled and Oiled (P&O)** condition strongly recommended. * **Alternative Materials:** For better weldability and formability at 45 ksi strength, consider **ASTM A1011 HSLAS Grade 50** or **ASTM A607 Grade 50** (HSLA steels with lower carbon content). **In summary, AK Steel ASTM A570 Grade 45 (SQ) represents the practical upper limit of conventional hot-rolled carbon steel technology, offering 45 ksi minimum yield strength for applications where maximum strength from carbon steel is required. While providing cost-effective high strength, it presents significant fabrication challenges in welding and forming that must be carefully managed through proper procedures and design considerations. For applications requiring both high strength and good fabricability, microalloyed HSLA steels often provide a more balanced solution.** -:- For detailed product information, please contact sales. -: AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel, Structural Quality (SQ) Specification Dimensions Size： Diameter 20-1000 mm Length <4558 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 45 Hot Rolled Carbon Steel, Structural Quality (SQ) Properties -:- For detailed product information, please contact sales. -:

Applications of AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- For detailed product information, please contact sales. -: Chemical Identifiers AK Steel ASTM A 570, Grade 45 Hot Rolled Carbon Steel, Structural Quality (SQ) -:- For detailed product information, please contact sales. -:

Packing of AK Steel ASTM A 570, Grade 45 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 1029 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