AISI 8740 Steel, annealed

AISI 8740 Steel, annealed 815°C (1500°F) Product Information -:- For detailed product information, please contact sales. -: AISI 8740 Steel, annealed 815°C (1500°F) Synonyms -:- For detailed product information, please contact sales. -:

AISI 8740 Steel, annealed 815°C (1500°F) Product Information -:- For detailed product information, please contact sales. -: **Product Overview: AISI 8740 Steel (Annealed at 815°C / 1500°F)** This document provides a technical introduction to **AISI 8740** alloy steel supplied in a soft, machinable **annealed** condition, processed at **815°C (1500°F)**. This specific thermal treatment is designed to produce a microstructure with the lowest possible hardness and maximum ductility, making it the optimal pre-material for extensive and complex machining operations prior to final heat treatment. **1. International Standard Designations** * **AISI/SAE (USA):** 8740 * **ASTM (USA):** A29/A29M (Standard Specification for General Requirements for Steel Bars), A322 (Standard Specification for Steel Bars, Alloy, Standard Grades) * **UNS:** G87400 * **Common Delivery Condition:** Supplied as annealed per ASTM A29. * **Similar/Equivalent Standards:** * **DIN (Germany):** 1.6546 / 41CrMo4 (Close analog, slight compositional variance) * **EN (Europe):** 1.7225 / 42CrMo4 (Widely recognized equivalent) * **JIS (Japan):** SCM440 * **GB (China):** 42CrMo **2. Chemical Composition (Weight %)** AISI 8740 is a versatile chromium-molybdenum-nickel alloy steel valued for its excellent combination of strength, toughness, and hardenability. | Element | Content (%) | Primary Function | | :--- | :--- | :--- | | **Carbon (C)** | 0.38 - 0.43 | Provides the foundation for final hardness and strength after quenching. | | **Manganese (Mn)** | 0.75 - 1.00 | Enhances hardenability and strength. | | **Silicon (Si)** | 0.15 - 0.35 | Acts as a deoxidizer and increases strength. | | **Chromium (Cr)** | 0.40 - 0.60 | Improves hardenability, wear, and corrosion resistance. | | **Nickel (Ni)** | 0.40 - 0.70 | Significantly increases toughness and core hardenability. | | **Molybdenum (Mo)** | 0.20 - 0.30 | Promotes deep hardening, increases strength, and improves resistance to tempering. | | **Phosphorus (P)** | ≤ 0.025 | Residual impurity, minimized for toughness. | | **Sulfur (S)** | ≤ 0.025 | Residual impurity; controlled levels can influence machinability. | | **Iron (Fe)** | Balance | - | **3. Heat Treatment: Annealing at 815°C (1500°F)** * **Process:** The steel is slowly heated to **815°C (1500°F)**, held to achieve complete austenitization and chemical homogenization, and then **cooled very slowly in the furnace**. * **Purpose & Resulting Structure:** This full anneal aims to produce the **softest and most ductile state** possible. The slow cooling promotes the formation of a **coarse lamellar pearlite** structure within a **ferrite** matrix. This coarse, soft microstructure minimizes cutting forces and tool wear during machining, enabling high material removal rates and good surface finishes. **4. Resulting Physical & Mechanical Properties (Annealed Condition)** *Critical Note: These properties are for the material as-supplied for machining. They do NOT represent its in-service capabilities, which are developed only after final quenching and tempering.* * **Microstructure:** Coarse pearlite and ferrite. * **Hardness:** **149 - 197 HBW** (Approx. 80 - 92 HRB). This low, consistent hardness is the key metric for superior machinability. * **Tensile Strength:** 520 - 670 MPa (75,000 - 97,000 psi) * **Yield Strength (0.2% Offset):** 310 - 460 MPa (45,000 - 67,000 psi) * **Elongation (in 50mm):** ≥ 22% * **Reduction of Area:** ≥ 60% * **Machinability Rating:** **Excellent** for a medium-carbon alloy steel. The annealed structure offers optimal chip formation and low cutting forces. **Physical Properties (Approximate at 20°C):** * **Density:** 7.85 g/cm³ * **Modulus of Elasticity:** 205 GPa (29,700 ksi) * **Poisson's Ratio:** 0.29 * **Thermal Conductivity:** ~42.7 W/m·K * **Coefficient of Thermal Expansion:** 12.3 x 10⁻⁶/K (20-100°C) **5. Product Advantages in this Annealed Condition** * **Optimal Machinability:** The low hardness and uniform coarse structure facilitate complex machining, deep drilling, and precision threading with extended tool life and reduced production costs. * **Dimensional Stability:** The stress-relieved nature of the full anneal minimizes the risk of part distortion or movement during and after machining. * **Consistent Starting Point:** Provides a homogeneous and predictable foundation, ensuring a uniform response to subsequent hardening heat treatment across the entire component. * **Formability:** Suitable for certain cold-forming operations prior to heat treatment due to its high ductility. **6. Typical Applications (As-Supplied, Annealed)** This material is procured as **machine bar stock**, **forgings**, or **blanks** for high-performance components that are fully machined before final hardening. End-use applications include: * **Aerospace Components:** Blanks for landing gear parts, engine mounts, and critical structural fittings. * **Automotive and Heavy Truck:** Pre-forms for transmission gears, axle shafts, crankshafts, and connecting rods. * **Oil & Gas Industry:** Machined blanks for drill string tools, valve bodies, and high-pressure fittings. * **Power Transmission:** Gears, pinions, and splined shafts for industrial and vehicular applications. * **Tooling:** Jigs, fixtures, and non-marring die components. **7. Available Form & Supply** * **Form:** Commonly supplied as **hot-rolled or cold-drawn round bars**. Also available in squares, hexagons, and as forged or rolled blanks. * **Condition:** **Annealed at 815°C (1500°F)**, typically meeting the soft annealed requirements of ASTM A29. * **Surface:** Black (as-annealed), pickled, or rough-turned. * **Sizes:** Available in a comprehensive range of standard diameters and custom dimensions. **Disclaimer:** The annealed condition is a precursor state for manufacturing. All final performance characteristics (high tensile strength, fatigue resistance, core toughness) are imparted during the subsequent quench and temper process. The material's hardenability should be considered based on end-quench (Jominy) test data per relevant standards. Final material specifications, including possible magnetic particle inspection requirements for aircraft quality (e.g., AMS), must be confirmed with the supplier for the intended critical application. -:- For detailed product information, please contact sales. -: AISI 8740 Steel, annealed 815°C (1500°F) Specification Dimensions Size： Diameter 20-1000 mm Length <6380 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. -: AISI 8740 Steel, annealed 815°C (1500°F) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 8740 Steel, annealed 815°C (1500°F) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 8740 Steel, annealed 815°C (1500°F) -:- For detailed product information, please contact sales. -:

Packing of AISI 8740 Steel, annealed 815°C (1500°F) -:- 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 2851 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