AISI 4140 Steel Foil/Strip

AISI 4140 Steel Foil, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled Product Information -:- For detailed product information, please contact sales. -: AISI 4140 Steel Foil, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled Synonyms -:- For detailed product information, please contact sales. -:

AISI 4140 Steel, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled Product Information -:- For detailed product information, please contact sales. -: # **AISI 4140 Steel (Fully Annealed Condition)** ## **1. Introduction & Heat Treatment Specification** This document describes **AISI 4140 steel** in a **fully annealed (softened) condition**, achieved through a precise and controlled heat treatment cycle. This treatment is designed to produce a microstructure with maximum softness, uniformity, and stability, resulting in optimal machinability and dimensional stability for subsequent manufacturing processes. This specific annealing process is often referred to as a **full anneal** or **process anneal**. **Defined Heat Treatment Cycle:** 1. **Heat:** Uniformly to **815°C (1500°F)** and hold for sufficient time to achieve complete austenitization. 2. **Furnace Cool:** Slowly cool at a controlled rate of **11°C/hour (20°F/hour)** down to **665°C (1230°F)**. This very slow cooling through the critical temperature range promotes the formation of a coarse, soft microstructure (coarse pearlite and ferrite). 3. **Air Cool:** From 665°C (1230°F) to room temperature in still air. ## **2. Chemical Composition** AISI 4140 is a versatile medium-carbon, chromium-molybdenum alloy steel known for its excellent hardenability, strength, and toughness. | Element | Composition Range (% by weight) | Role in the Annealed Condition | | :--- | :--- | :--- | | **Carbon (C)** | 0.38 - 0.43 | Provides the foundation for hardenability. In this annealed state, it forms soft, lamellar pearlite, making the material machinable. | | **Manganese (Mn)** | 0.75 - 1.00 | Enhances hardenability and solid solution strength. Contributes to the stability of the annealed microstructure. | | **Phosphorus (P)** | ≤ 0.035 | Residual impurity, kept low. | | **Sulfur (S)** | ≤ 0.040 | Residual impurity, kept low. May be slightly elevated in "leaded" or "re-sulfurized" free-machining variants (e.g., 4140 Leaded). | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer and solid solution strengthener. | | **Chromium (Cr)** | 0.80 - 1.10 | Increases hardenability and wear resistance potential. Forms carbides that are spheroidized during slow cooling, aiding machinability. | | **Molybdenum (Mo)** | 0.15 - 0.25 | Enhances hardenability, improves high-temperature strength, and reduces the risk of temper embrittlement. Promotes carbide stability. | ## **3. Physical & Mechanical Properties (Annealed Condition)** The specified full anneal results in the softest possible state for AISI 4140, with low strength and high ductility. * **Physical Properties:** * **Density:** 7.85 g/cm³ (0.284 lb/in³) * **Melting Point:** ~1416°C (2580°F) * **Modulus of Elasticity:** 190-205 GPa (28,000-29,700 ksi) * **Poisson's Ratio:** 0.29 * **Thermal Conductivity:** ~42.6 W/m·K at 100°C * **Coefficient of Thermal Expansion:** 11.2 µm/m·°C (20-100°C) * **Microstructure:** Coarse lamellar pearlite (and/or spheroidized carbides) in a ferrite matrix. * **Mechanical Properties (Typical):** * **Tensile Strength:** 560 - 700 MPa (81,000 - 102,000 psi) * **Yield Strength (0.2% Offset):** 360 - 420 MPa (52,000 - 61,000 psi) * **Elongation (in 50mm):** 25% - 30% * **Reduction of Area:** 55% - 65% * **Hardness (Brinell):** 170 - 217 HB (Approx. 86-96 HRB) * **Machinability Rating:** **Good to Excellent (~70-75% of B1112 standard).** This is the **optimal condition for heavy machining**, offering consistent chip formation, low tool wear, and good surface finish. ## **4. Product Applications (in Annealed Condition)** Material in this condition is almost exclusively used as **forging stock** or **machining stock** for components that will be heat-treated (hardened and tempered) to their final, high-strength state after near-net-shape manufacturing. * **Precision Machining Stock:** Ideal for CNC machining of complex **gears, shafts, spindles, hydraulic cylinders, tool holders, and die components** prior to final heat treatment. * **Forging Blanks:** Standard starting material for **hot forging** into near-final shapes for automotive (crankshafts, axle shafts), aerospace (landing gear parts), and industrial components. * **General Fabrication & Prototyping:** Used for **brackets, fixtures, and non-critical structural parts** where easy machining, drilling, and tapping are required. Can be later case-hardened or through-hardened if needed. * **Fastener Manufacturing:** Base material for high-strength **bolts, studs, and pins** that will be thread-rolled and then heat-treated. * **Tooling Pre-forms:** Blanks for plastic injection molds, die-casting dies, and other tooling that will be machined and then surface hardened or through-hardened. ## **5. International Standards & Equivalent Grades** | Standard / Country | Designation | Note / Status | | :--- | :--- | :--- | | **AISI / SAE (USA)** | **4140** | The primary reference standard. | | **ASTM (USA)** | A29 / A322 (Grade 4140) | Standard specification for alloy steel bars. Can be supplied annealed. | | **UNS** | G41400 | Unified Numbering System. | | **DIN (Germany)** | **42CrMo4** / **1.7225** | The most common direct equivalent in Europe. | | **EN (Europe)** | 1.7225 / 42CrMo4 | | | **JIS (Japan)** | **SCM440** | A very close equivalent. | | **GB (China)** | **42CrMo** | Widely used Chinese equivalent. | | **ISO** | **ISO 683-18: Type 42CrMo4** | International standard. | ## **6. Subsequent Processing & Heat Treatment** * **Hardening (Typical for Final Use):** * **Austenitize:** 830-850°C (1525-1560°F). * **Quench:** Oil (standard for sections up to ~75mm). Water or polymer for larger sections. * **Temper:** 425-650°C (800-1200°F) to achieve desired final strength/toughness. * **Normalizing:** If grain refinement is needed after forging or heavy machining, heat to 870-900°C (1600-1650°F) and air cool. * **Stress Relieving:** After heavy machining, heat to 595-650°C (1100-1200°F) and air cool to relieve internal stresses without significantly softening the material. * **Weldability:** **Good in the annealed condition.** Preheating to 150-260°C (300-500°F) is recommended for thick sections. Post-weld heat treatment (stress relief or full re-heat treatment) is **strongly advised** for critical applications to restore properties in the heat-affected zone (HAZ). ## **7. Conclusion** **AISI 4140 steel in the fully annealed condition (815°C furnace cool at 11°C/hr to 665°C, air cool) represents the ideal starting point for manufacturing high-performance components.** This specific thermal cycle produces the most uniform and machinable microstructure, minimizing tool wear and ensuring dimensional stability during complex machining operations. It is the preferred and most cost-effective supply condition for parts that will later be heat-treated to achieve the renowned high strength, toughness, and wear resistance of hardened 4140 steel. Its widespread availability and well-understood processing characteristics make it a fundamental material in the inventory of industries ranging from automotive and aerospace to tooling and general engineering. -:- For detailed product information, please contact sales. -: AISI 4140 Steel, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled Specification Dimensions Size： Diameter 20-1000 mm Length <6209 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 4140 Steel, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4140 Steel Foil, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4140 Steel Foil, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled -:- For detailed product information, please contact sales. -:

Packing of AISI 4140 Steel Foil/Strip, annealed at 815°C (1500°F) furnace cooled 11°C (20°F)/hour to 665°C (1230°F), air cooled -:- 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 Foil/Strip 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 2680 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