AISI E4340 H Steel, oil quenched

AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper Product Information -:- For detailed product information, please contact sales. -: AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper Synonyms -:- For detailed product information, please contact sales. -:

AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper Product Information -:- For detailed product information, please contact sales. -: ## **Technical Specification: AISI 4340H (UNS H43400) Alloy Steel - Quenched & Tempered to a Defined Condition** **Heat Treatment:** Oil Quenched from 800°C (1470°F), Tempered at 540°C (1000°F) --- ### **1. Product Overview** This specification defines **AISI 4340H alloy steel** supplied in a precise **quenched and tempered (Q&T) condition**. The "H" suffix signifies that this is a **hardenability-guaranteed grade**, meaning its chemical composition is controlled to yield a predictable and consistent depth of hardening as verified by end-quench (Jominy) testing. The specified heat treatment—**austenitizing at 800°C, oil quenching, and tempering at 540°C**—produces a high-strength, tempered martensitic microstructure. For 4340H, this process leverages its guaranteed hardenability to ensure **uniform through-hardening** and **tight mechanical property ranges** across the entire cross-section of a component, making it a premium choice for high-integrity, load-critical parts. **Core Value Proposition:** * **Predictable & Consistent Properties:** The guaranteed hardenability band ensures minimal batch-to-batch variation in final strength, toughness, and hardness after the specified Q&T cycle. This is critical for quality control in high-volume or safety-critical manufacturing. * **Optimum Strength-Toughness Balance:** Tempering at 540°C (1000°F) achieves an excellent compromise, providing high yield strength while retaining significant ductility and impact resistance. * **Assured Through-Hardening:** For a given bar diameter (e.g., 25-50 mm), the 4340H certification guarantees a fully martensitic structure after oil quenching from 800°C, minimizing the risk of soft spots or non-uniform core properties. * **Ready for High-Stress Service:** The material is supplied in its final, serviceable condition, requiring only finishing operations. --- ### **2. Chemical Composition (Weight %)** The composition adheres to the AISI 4340H standard, where element ranges are designed to meet specific hardenability bands per SAE J1268, rather than fixed minima/maxima. | Element | AISI 4340H Typical Range (%) | Role in this Q&T Condition | | :--- | :--- | :--- | | **Iron (Fe)** | Balance | Base Element | | **Carbon (C)** | 0.37 - 0.44 | Primary source of hardness & strength; content is centered for predictable hardenability. | | **Manganese (Mn)**| 0.60 - 0.90 | **Key hardenability controller.** Adjusted per heat to ensure Jominy curve falls within the H-band. | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer, provides solid solution strengthening. | | **Nickel (Ni)** | 1.55 - 2.00 | Enhances core toughness and hardenability significantly. | | **Chromium (Cr)** | 0.65 - 0.95 | Strong hardenability enhancer; contributes to tempering resistance. | | **Molybdenum (Mo)**| 0.20 - 0.30 | Critical for achieving full hardenability in sections, prevents temper embrittlement. | | **Sulfur (S)** | ≤ 0.040 | Residual. | | **Phosphorus (P)** | ≤ 0.035 | Residual (kept low to ensure good toughness). | **Hardenability Certification:** Each heat lot is accompanied by a **Jominy Hardenability Test Certificate** (per SAE J1268), proving the material's transformation characteristics conform to the 4340H band. This data predicts the achievable hardness profile in a part of given size after the 800°C oil quench. --- ### **3. Typical Mechanical & Physical Properties (Post Heat Treatment)** *Properties are typical for a 25mm (1 inch) diameter bar after the specified 800°C Oil Quench + 540°C Temper cycle. The "H" grade ensures tight ranges.* | Property | Typical Value / Range | Test Standard / Notes | | :--- | :--- | :--- | | **Tensile Strength (UTS)** | **1030 - 1170 MPa** (149 - 170 ksi) | ASTM E8 | | **Yield Strength (0.2% Offset)** | **930 - 1080 MPa** (135 - 157 ksi) | ASTM E8 | | **Elongation (in 50mm)** | **14% - 18%** | ASTM E8 | | **Reduction of Area** | **45% - 55%** | ASTM E8 | | **Hardness** | **302 - 352 HB** / **32 - 38 HRC** | ASTM E10 / E18 | | **Charpy V-Notch Impact (at 21°C)** | **40 - 60 J** (30 - 44 ft-lbf) | ASTM A370 | | **Modulus of Elasticity** | 205 GPa (29.7 x 10⁶ psi) | - | | **Fatigue Strength (Rotating Bending, R=-1)** | **~500 - 600 MPa** (Estimated, polished specimen) | High, but highly dependent on surface finish. | | **Core Microstructure** | Uniform **Tempered Martensite** | Fine, acicular structure providing strength and toughness. | --- ### **4. Defined Heat Treatment Cycle** This is the exact thermal history defining the product's supplied condition: 1. **Austenitizing:** Heat uniformly to **800°C ± 15°C (1470°F ± 25°F)**. Soak adequately (approx. 1 hour per inch). 2. **Quenching:** Rapidly cool in **well-agitated oil** to below 100°C. This transforms austenite to martensite. 3. **Tempering:** Reheat to **540°C ± 15°C (1000°F ± 25°F)**. Soak (typically 1-2 hours per inch), then air cool. This stress-relieves the martensite and sets the final property balance. **Importance of 800°C Austenitizing:** Slightly lower than the typical 830-850°C range, it helps refine the prior austenite grain size, potentially enhancing toughness, while still fully dissolving carbides for maximum hardenability. --- ### **5. Target Applications** This specific 4340H Q&T condition is selected for components where **consistency, reliability, and high strength** are non-negotiable. * **Automotive Performance & Heavy Truck:** **High-performance crankshafts**, **connecting rods**, **axle shafts**, and **transmission gears**. * **Aerospace (Non-Premium):** **Landing gear components** (bolts, pins), **engine mounts**, **actuator shafts**, and **flight control linkages**. * **Oil & Gas Drilling:** **Drill collars**, **tool joints**, **mud pump pistons rods**, and **valve stems** for high-pressure systems. * **Industrial Machinery:** **Heavy-duty gear shafts**, **extruder screws**, **hydraulic cylinder rods**, and **large bearing races**. * **Power Generation:** **Turbine shafts**, **generator retaining rings**, and **high-strength fasteners**. --- ### **6. International Standards & Procurement** Procurement focuses on both the hardenability standard and the achieved Q&T properties. | Standard / Aspect | Specification / Guidance | | :--- | :--- | :--- | | **Base Material Standard** | **SAE J404 / AISI 4340H** (UNS H43400). Governs chemistry and hardenability. | | **Product Standard** | **ASTM A304** (Standard Specification for Carbon and Alloy Steel Bars Subject to End-Quench Hardenability Requirements). | | **Hardenability Standard** | **SAE J1268** (Hardenability Bands). A Jominy certificate is mandatory. | | **Heat Treat Verification** | While the process defines the state, final acceptance is typically based on **achieved mechanical properties** (UTS, YS, Hardness) as per purchase order. | | **European Equivalent** | **EN 10083-3: 34CrNiMo6 + H + QT**. The "+H" indicates hardenability verification per EN ISO 642. | | **ISO Equivalent** | **ISO 683-1: 1.6562 H** (with similar hardenability requirements). | | **JIS Equivalent** | **JIS G4052: SCr440H** (Guaranteed Hardenability). | **Critical Procurement Specification:** To ensure compliance, the purchase order must specify: 1. **Material:** AISI 4340H per ASTM A304, supplied heat treated. 2. **Heat Treatment:** "Oil quenched from 800°C and tempered at 540°C" or, more commonly, **the required final mechanical property ranges** (e.g., YS: 960-1050 MPa, HRC: 34-37). 3. **Certification:** Requirement for a **Mill Test Report** including: * Full chemical analysis. * **Jominy Hardenability Test Certificate** for the heat lot. * **Mechanical Test Reports** (tensile, hardness, impact) from the finished Q&T material, proving conformance to specified property ranges. -:- For detailed product information, please contact sales. -: AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper Specification Dimensions Size： Diameter 20-1000 mm Length <6256 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 E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper Properties -:- For detailed product information, please contact sales. -:

Applications of AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper -:- For detailed product information, please contact sales. -:

Packing of AISI E4340 H Steel, oil quenched 800°C (1470°F), 540°C (1000°F) temper -:- 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 2727 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