AISI E4340 H Steel, quenched

AISI E4340 H Steel, quenched 845°C, 540°C (1000°F) temper Product Information -:- For detailed product information, please contact sales. -: AISI E4340 H Steel, quenched 845°C, 540°C (1000°F) temper Synonyms -:- For detailed product information, please contact sales. -:

AISI E4340 H Steel, quenched 845°C, 540°C (1000°F) temper Product Information -:- For detailed product information, please contact sales. -: ## **Technical Specification: AISI 4340H (UNS H43400) Steel - High-Toughness, High-Strength Tempered Condition** **Heat Treatment:** Oil Quenched from 845°C (1550°F), Tempered at 540°C (1000°F) --- ### **1. Product Overview** This specification defines **AISI 4340H alloy steel** subjected to a high-temperature tempering treatment. The "H" suffix indicates a **hardenability-guaranteed grade**, ensuring consistent and predictable transformation behavior during quenching within standardized bands. The thermal cycle—**austenitizing at 845°C, oil quenching, and tempering at 540°C**—produces a microstructure of **fully tempered martensite**. This condition represents the **optimum engineering balance between high strength and exceptional toughness** for the 4340 alloy system. Tempering at this elevated temperature allows for extensive recovery and carbide coalescence, resulting in outstanding impact resistance and ductility while maintaining substantial yield strength. This makes it the preferred choice for **critical components subjected to high static loads, fatigue, and potential shock loading** where fracture resistance is paramount. **Core Value Proposition:** * **Optimal Strength-Toughness Balance:** The 540°C temper delivers the best practical combination of high yield strength and superior impact toughness in the 4340 system, maximizing component reliability under complex loading conditions. * **Superior Fracture Resistance:** Exceptionally high Charpy V-Notch values and fracture toughness make this condition highly resistant to crack initiation and propagation, ideal for damage-tolerant designs. * **Excellent Stress Relief & Stability:** The high tempering temperature provides complete relief of quenching stresses, resulting in excellent dimensional stability and minimized risk of stress-corrosion cracking. * **Guaranteed Uniformity:** The 4340H certification ensures consistent through-hardening, eliminating property variations that could compromise performance in safety-critical applications. --- ### **2. Chemical Composition (Weight %)** Composition adheres to AISI 4340H standards, with ranges optimized for hardenability control. The effectiveness of this tempering condition relies particularly on specific alloying elements. | Element | AISI 4340H Typical Range (%) | Role in 540°C Tempering Performance | | :--- | :--- | :--- | | **Iron (Fe)** | Balance | Base Element | | **Carbon (C)** | 0.37 - 0.44 | Provides the fundamental carbon content for martensite formation; tempered carbides contribute to strength retention. | | **Manganese (Mn)**| 0.60 - 0.90 | Primary hardenability controller; ensures complete martensitic transformation upon quenching. | | **Silicon (Si)** | 0.15 - 0.35 | Solid solution strengthener; raises tempering resistance slightly. | | **Nickel (Ni)** | 1.55 - 2.00 | **Critical:** Significantly enhances toughness at this tempering temperature through microstructural refinement and solid solution strengthening. | | **Chromium (Cr)** | 0.65 - 0.95 | Contributes to hardenability and promotes the formation of stable alloy carbides during tempering. | | **Molybdenum (Mo)**| 0.20 - 0.30 | **Essential:** Suppresses temper embrittlement in this temperature range; ensures toughness retention during slow cooling through the embrittlement zone. | | **Sulfur (S)** | ≤ 0.015 (Typical premium grade) | Controlled to minimize inclusion content and optimize transverse properties. | | **Phosphorus (P)** | ≤ 0.015 (Typical premium grade) | Stringently controlled to prevent temper embrittlement. | **Hardenability Certification:** A **Jominy Hardenability Test Certificate** (SAE J1268) is mandatory for each heat lot, validating the material's capability to achieve a fully martensitic structure in the relevant section size after the 845°C oil quench. --- ### **3. Typical Mechanical & Physical Properties (Post Heat Treatment)** *Properties are for a 25mm (1") diameter bar after 845°C Oil Quench + 540°C Temper. This condition offers premium balanced properties.* | Property | Typical Value / Range | Test Standard / Notes | | :--- | :--- | :--- | | **Tensile Strength (UTS)** | **1050 - 1200 MPa** (152 - 174 ksi) | ASTM E8 | | **Yield Strength (0.2% Offset)** | **950 - 1100 MPa** (138 - 160 ksi) | ASTM E8 | | **Elongation (in 50mm)** | **14% - 18%** | ASTM E8 (Good ductility) | | **Reduction of Area** | **50% - 60%** | ASTM E8 (Excellent ductility) | | **Hardness** | **32 - 38 HRC** / **300 - 360 HB** | ASTM E18 / E10 | | **Charpy V-Notch Impact (at 21°C)** | **55 - 85 J** (41 - 63 ft-lbf) | ASTM A370. **Exceptionally high for the strength level.** | | **Fracture Toughness (K_IC)** | **~90 - 120 MPa√m** (Estimated) | Excellent, supporting robust damage-tolerant design. | | **Fatigue Endurance Limit (R=-1)** | **~500 - 600 MPa** (Estimated) | Very good, with excellent resistance to overloads. | | **Ductile-to-Brittle Transition Temperature** | **Below -40°C** (Typical) | Maintains toughness at low temperatures. | | **Modulus of Elasticity** | 205 GPa (29.7 x 10⁶ psi) | - | --- ### **4. Defined Heat Treatment Cycle** This precise thermal history defines the product's supplied condition: 1. **Austenitizing:** Heat uniformly to **845°C ± 10°C (1550°F ± 20°F)**. Soak adequately for complete austenitization and carbide dissolution. 2. **Quenching:** Rapidly cool in **agitated oil** to below 100°C. Achieves 100% martensitic transformation throughout the section. 3. **Tempering:** Reheat to **540°C ± 10°C (1000°F ± 20°F)**. Soak sufficiently (1-2 hours per inch minimum) to ensure complete tempering transformation and stress relief. **Must be followed by relatively rapid cooling** (air cool) to avoid temper embrittlement. **Critical Process Note:** After tempering at 540°C, the steel must be cooled relatively quickly through the temper embrittlement range (approximately 375-575°C) to prevent the segregation of impurities to grain boundaries. The molybdenum content in 4340H provides significant resistance to this phenomenon. --- ### **5. Target Applications** This 4340H condition is specified for **high-integrity components where reliability, damage tolerance, and resistance to unexpected overloads are critical design considerations.** * **Heavy-Duty Mobile Equipment:** **Construction machinery pins**, **mining shovel dipper handles**, **crane hooks**, and **off-highway axle shafts**. * **Power Generation:** **Large turbine generator retaining rings**, **steam turbine rotors**, **hydroturbine shafts**, and **nuclear component supports**. * **Oil & Gas (Critical Service):** **Wellhead equipment** (flanges, hangers), **subsea connector components**, **Christmas tree bodies**, and **large high-pressure bolting**. * **Aerospace (Structural):** **Landing gear support structures**, **engine mounts**, **airframe fittings**, and **helicopter transmission housings**. * **Marine & Defense:** **Ship propeller shafts**, **gun mounts**, and **armored vehicle structural members**. * **Large Industrial Machinery:** **Press frames**, **rolling mill housings**, **crane wheels**, and **heavy forging die blocks**. --- ### **6. International Standards & Procurement** This condition is common in applications requiring certified high toughness alongside substantial strength. | Standard / Aspect | Specification / Guidance | | :--- | :--- | | **Base Material Standard** | **SAE J404 / AISI 4340H** (UNS H43400). | | **Product Standard** | **ASTM A304** (Bars with Hardenability Requirements). | | **Hardenability Standard** | **SAE J1268**. **Jominy certificate is mandatory.** | | **Common Industry Standard** | Often supplied to meet specific **ASTM A320** or **ASTM A193** requirements for high-strength bolting materials in low-temperature service. | | **European Equivalent** | **EN 10083-3: 34CrNiMo6 + H + QT** (tempered to Property Class 1000 or similar). | | **ISO Equivalent** | **ISO 683-1: 1.6562 H**. | | **Pressure Vessel Code** | Approved for use under **ASME Boiler and Pressure Vessel Code**, Section VIII. | **Critical Procurement Specification:** The purchase order must explicitly define toughness requirements: 1. **Material:** AISI 4340H per ASTM A304, supplied heat treated. 2. **Final Properties (Must Include Toughness Specs):** * Yield Strength: 1000-1100 MPa * Tensile Strength: 1100-1200 MPa * **Charpy V-Notch Impact: Min. 54 J @ 21°C** (or specify lower test temperatures as required) * Hardness: 34-37 HRC 3. **Special Requirements:** May specify "free from temper embrittlement" or require rapid cooling from tempering temperature. 4. **Certification:** Requirement for a **Comprehensive Test Package** including: * Full chemical analysis (with P and S levels). * **Jominy Hardenability Test Certificate.** * **Full mechanical test reports** including tensile and **Charpy impact tests at specified temperatures.** * For critical applications, **fracture toughness (K_IC) testing** may be specified. -:- For detailed product information, please contact sales. -: AISI E4340 H Steel, quenched 845°C, 540°C (1000°F) temper Specification Dimensions Size： Diameter 20-1000 mm Length <6264 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, quenched 845°C, 540°C (1000°F) temper Properties -:- For detailed product information, please contact sales. -:

Applications of AISI E4340 H Steel, quenched 845°C, 540°C (1000°F) temper -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI E4340 H Steel, quenched 845°C, 540°C (1000°F) temper -:- For detailed product information, please contact sales. -:

Packing of AISI E4340 H Steel, quenched 845°C, 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 2735 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