AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS)

AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) Product Information -:- For detailed product information, please contact sales. -: AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) Synonyms -:- For detailed product information, please contact sales. -:

AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) Product Information -:- For detailed product information, please contact sales. -: **Product Name:** AK Steel ASTM A1018, Grade 40 Hot-Rolled Carbon Steel, Structural Steel (SS) --- ### **1. Overview** AK Steel's ASTM A1018 Grade 40 is a **normalized** hot-rolled carbon steel sheet and strip, engineered for critical structural and pressure vessel applications that demand a higher strength level combined with guaranteed toughness and material uniformity. Distinguished from its as-rolled counterpart (ASTM A1011 Grade 40) by a mandatory normalizing heat treatment, this grade provides a refined, homogeneous microstructure. With a minimum yield strength of 40 ksi (275 MPa), it delivers an optimal balance of increased load-bearing capacity, superior internal soundness, and excellent low-temperature notch toughness, making it a reliable choice for code-governed and safety-critical fabrications. --- ### **2. International Standards** This product conforms to the following specification, which mandates both specific strength levels and a controlled manufacturing process: * **ASTM A1018 / A1018M:** Standard Specification for Steel, Sheet and Strip, Heavy-Thickness Coils, Hot-Rolled, Carbon, Commercial, Drawing, Structural, High-Strength Low-Alloy, and High-Strength Low-Alloy with Improved Formability, Grade 40. * The standard requires the steel to be supplied in the **normalized** or an equivalent controlled-processed condition. This is a defining requirement that ensures enhanced properties. --- ### **3. Chemical Composition (Typical, % by Weight)** The chemistry is designed to achieve the specified 40 ksi yield strength while responding favorably to the normalizing heat treatment, ensuring consistent through-thickness properties. | Element | Content (Maximum, unless specified) | Role & Implication | | :--- | :--- | :--- | | **Carbon (C)** | 0.22% - 0.28% (Typical range) | The primary strengthening element. Controlled to provide the necessary strength while maintaining adequate weldability post-normalization. | | **Manganese (Mn)** | 0.90% - 1.20% | A major solid-solution strengthener. Enhances hardenability and works synergistically with carbon to achieve yield strength. | | **Phosphorus (P)** | 0.035% max | Residual impurity; minimized to preserve ductility and notch toughness. | | **Sulfur (S)** | 0.035% max | Residual impurity; controlled to improve transverse ductility and weldability. | | **Silicon (Si)** | 0.10% - 0.30% | Acts as a deoxidizer (killed steel practice); contributes to strength. | | **Aluminum (Al)** | Typically present (for grain refinement) | Used in killed steel to control initial austenite grain size, which is further refined during normalization. | | **Key Process:** | **Normalized.** The steel is reheated to approximately 1600°F (870°C) and cooled in still air. This process produces a uniform, fine-grained ferrite-pearlite microstructure, relieves internal stresses, and homogenizes the material. | | --- ### **4. Physical & Mechanical Properties** The normalized condition guarantees properties that are more consistent and tougher than those of as-rolled steel of the same grade. | Property | Specification Minimum (ASTM A1018 Grade 40) | Typical Value / Description | | :--- | :--- | :--- | | **Yield Strength (min)** | 40 ksi (275 MPa) | Very consistent through the thickness of the material. | | **Tensile Strength** | 55 ksi min (380 MPa) | Typically ranges from 55 - 75 ksi (380 - 515 MPa). | | **Elongation in 2" (min)** | 20% (for typical thicknesses) | Maintains good ductility for forming operations. | | **Key Distinguishing Property** | **Enhanced Notch Toughness** | The normalized, fine-grained microstructure provides significantly better impact resistance (as measured by Charpy V-Notch testing) and a lower ductile-to-brittle transition temperature compared to as-rolled A1011 Grade 40. This is a primary reason for its specification. | | **Microstructure** | Uniform, fine-grained ferrite-pearlite | Results in isotropic mechanical properties (similar longitudinal and transverse). | | **Through-Thickness Consistency** | Excellent | Normalization ensures uniform properties from surface to centerline, which is critical for thick plates. | | **Surface Finish** | Standard hot-rolled mill finish. | | --- ### **5. Key Features & Advantages** * **Superior Toughness & Homogeneity:** The normalization process refines the grain structure, providing exceptional and reliable resistance to brittle fracture. This is non-negotiable for pressure vessels and structures in low-temperature or dynamic service. * **Excellent Weldability with Predictable HAZ:** The homogeneous, fine-grained base metal leads to a more stable and tougher heat-affected zone (HAZ) after welding, minimizing the risk of weld-related failures. * **Consistent Properties in All Directions:** Offers isotropic forming and mechanical behavior, providing predictable performance during fabrication. * **Ideal for Thick Sections:** Specifically suited for heavier gage coils and plate. Normalization eliminates the property degradation often found at the mid-thickness of thick as-rolled plate. * **Code-Compliant for Critical Service:** A preferred material for construction under the ASME Boiler and Pressure Vessel Code, API standards, and other codes where normalized steels are specified for safety and reliability. --- ### **6. Product Applications** ASTM A1018 Grade 40 is specified for demanding applications where enhanced strength must be paired with guaranteed toughness and material consistency. * **Pressure Vessels & Boilers:** Shells, heads, and critical components for industrial pressure vessels, heat exchangers, and boiler drums (ASME Section I & VIII). * **Structural Applications in Severe Environments:** Offshore platform components, bridge bearings, crane runway girders, and structural members in cold climates. * **Heavy Machinery & Mining Equipment:** Frames, booms, and buckets for excavators, loaders, and mining machinery subject to impact and fatigue. * **Energy Sector Components:** Support structures for power generation equipment, wind turbine tower sections (flanges, door frames), and penstocks. * **Storage Tanks for Critical Services:** Tanks for liquefied gases (when designed appropriately) or other products where low-temperature toughness is a concern. --- ### **7. Fabrication & Processing Notes** * **Descaling:** Mill scale must be removed via abrasive blasting or pickling prior to welding or high-quality coating application. * **Forming:** Good for cold bending and forming. The normalized state provides uniform yield strength, leading to predictable springback. Minimum bend radii are larger than for lower-strength steels. * **Welding:** Highly weldable with proper procedure. Use low-hydrogen welding processes and consumables (e.g., E7018, ER70S-6). Preheating (150-250°F / 65-120°C) is often recommended for thicknesses above 0.75 inches to prevent hydrogen-induced cracking, though requirements are less stringent than for as-rolled steel of similar chemistry. * **Post-Weld Heat Treatment (PWHT):** May not be required for many applications due to the normalized starting condition. However, complex or highly restrained weldments may require stress relieving per applicable construction codes. * **Thermal Cutting:** All standard methods (plasma, laser, oxy-fuel) are suitable. --- **Disclaimer:** *This profile is a technical summary. AK Steel is now part of Cleveland-Cliffs Inc.* For engineering and procurement, always consult the latest official **ASTM A1018** standard and the certified **Mill Test Report (MTR)** from the manufacturer. The MTR will explicitly state the **normalized condition** and provide the actual chemistry, mechanical properties, and often Charpy impact test data. This grade is specified by its full ASTM designation, including the **Grade 40** and reference to the **A1018** specification, to ensure receipt of the normalized product. -:- For detailed product information, please contact sales. -: AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) Specification Dimensions Size： Diameter 20-1000 mm Length <4592 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 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) Properties -:- For detailed product information, please contact sales. -:

Applications of AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) -:- For detailed product information, please contact sales. -: Chemical Identifiers AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) -:- For detailed product information, please contact sales. -:

Packing of AK Steel ASTM A 1018, Grade 40 Hot Rolled Carbon Steel, Structural Steel (SS) -:- 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 1063 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