AISI E4340 H Steel, normalized

AISI E4340 H Steel, normalized Product Information -:- For detailed product information, please contact sales. -: AISI E4340 H Steel, normalized Synonyms -:- For detailed product information, please contact sales. -:

AISI E4340 H Steel, normalized Product Information -:- For detailed product information, please contact sales. -: ## **Technical Specification: AISI 4340H (UNS H43400) Alloy Steel - Normalized Condition** ### **1. Product Overview** This product specification defines **AISI 4340H alloy steel** supplied in the **normalized condition**. The "H" suffix denotes a **hardenability-controlled variant**, where the chemical composition is tailored to guarantee a specific range of hardenability as per end-quench (Jominy) test standards. Normalization involves heating the steel to above its critical temperature (typically 870-925°C) followed by air cooling. This process **refines the grain structure, homogenizes the microstructure, and improves mechanical uniformity** compared to the as-rolled or annealed states. For AISI 4340H, normalization provides an **optimal, stable, and consistent starting condition** for subsequent machining and final heat treatment (quenching and tempering), ensuring predictable transformation behavior due to its controlled hardenability. **Key Value Propositions:** * **Guaranteed Hardenability Consistency:** The "H" grade ensures the material's response to quenching falls within a narrow, predictable band (per SAE J1268), leading to uniform final properties across production batches. * **Refined & Uniform Microstructure:** Normalization eliminates coarse or segregated structures from prior processing, resulting in a fine, uniform mixture of ferrite and pearlite. This enhances machinability and provides a consistent foundation for final hardening. * **Improved Toughness:** Offers better impact resistance and ductility than the as-rolled condition, with a moderately higher strength than the annealed state. * **Ideal Pre-Hardening State:** Commonly specified as the required starting condition for parts that will be finish-machined and then through-hardened, as it minimizes the risk of distortion and unpredictable hardening response. --- ### **2. Chemical Composition (Weight %)** The composition for AISI 4340H is based on standard 4340 but with element ranges adjusted to meet specified hardenability bands. The *actual* heat chemistry is controlled to ensure Jominy test results fall within the defined "H-band" limits. | Element | AISI 4340H Typical Range (%) | Metallurgical Role & Hardenability Impact | | :--- | :--- | :--- | | **Iron (Fe)** | Balance | Base Element | | **Carbon (C)** | 0.37 - 0.44 | Primary hardness determinant. Content is centered to target the hardenability band. | | **Manganese (Mn)**| 0.60 - 0.90 | **Primary hardenability adjuster.** Range is wider than standard 4340 to fine-tune the Jominy curve. | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer; provides solid solution strengthening. | | **Nickel (Ni)** | 1.55 - 2.00 | Enhances hardenability and core toughness significantly. | | **Chromium (Cr)** | 0.65 - 0.95 | Strong hardenability enhancer; range adjusted for band control. | | **Molybdenum (Mo)**| 0.20 - 0.30 | Potent hardenability element; crucial for through-hardening and temper resistance. | | **Sulfur (S)** | ≤ 0.040 | Residual. | | **Phosphorus (P)** | ≤ 0.035 | Residual. | **Hardenability Definition:** Compliance with **SAE J1268** is mandatory. The mill provides a **Jominy Hardenability Certificate** for each heat lot, plotting hardness vs. distance from the quenched end, demonstrating conformity to the prescribed minimum and maximum curves for 4340H. --- ### **3. Typical Mechanical & Physical Properties (Normalized Condition)** *Properties are typical for material normalized from ~900°C (1650°F) and air-cooled. The normalized condition is not the final service state.* | Property | Typical Value | Test Standard / Notes | | :--- | :--- | :--- | | **Hardness** | **220 - 280 HB** (Brinell) | ASTM E10 | | **Tensile Strength** | **750 - 900 MPa** (109 - 131 ksi) | ASTM E8 | | **Yield Strength (0.2% Offset)** | **470 - 620 MPa** (68 - 90 ksi) | ASTM E8 | | **Elongation (in 50mm)** | **18% - 22%** | ASTM E8 | | **Reduction of Area** | **45% - 55%** | ASTM E8 | | **Charpy V-Notch Impact (at 21°C)** | **40 - 60 J** (30 - 44 ft-lbf) | ASTM A370 | | **Machinability** | Good (better than as-quenched, harder than annealed) | Suitable for most machining operations. | | **Microstructure** | Fine, uniform **Pearlite and Ferrite** | Refined grain structure. | | **Density** | 7.85 g/cm³ (0.284 lb/in³) | - | --- ### **4. Heat Treatment Context & Hardenability** * **Normalizing Process:** Heat to **870°C - 925°C (1600°F - 1700°F)**, soak adequately, cool in still air. This refines the grain and homogenizes the structure. * **Purpose of Normalization for 4340H:** To provide a consistent, stress-relieved, and uniform starting microstructure that ensures **predictable and repeatable austenitization** during the final hardening process. This is critical for leveraging the guaranteed hardenability. * **Final Heat Treatment:** After machining, components are **re-austenitized, quenched (oil), and tempered**. The 4340H certification guarantees that a 25-50 mm diameter bar will achieve a specific depth and uniformity of hardness after quenching, based on the Jominy data. --- ### **5. Primary Applications** AISI 4340H in normalized condition is specified for critical components where both **machinability** and **guaranteed heat treatment response** are required. * **Automotive Powertrain:** **Gear blanks**, **pinion forgings**, **crankshafts**, and **axle shafts** that are machined before final carburizing or through-hardening. * **Heavy Equipment:** **Large-diameter pins**, **bushings**, **sprockets**, and **track links** for construction and mining machinery. * **Aerospace Structural Components:** **Bulkheads**, **mounting brackets**, and **landing gear parts** that undergo extensive machining prior to final high-strength heat treatment. * **Industrial Machinery:** **Large gear blanks**, **press columns**, **spindle forgings**, and **rotor shafts**. * **Oil & Gas:** **Large valve bodies**, **flanges**, and **forgings** for wellhead equipment. --- ### **6. International Standards & Procurement** The "H" designation is an SAE/AISI system with direct correlations in other standards frameworks. | Standard | Designation | Equivalent / Governing Specification | | :--- | :--- | :--- | | **SAE / AISI (USA)** | **4340H** (UNS H43400) | **Primary Standard.** Defined by hardenability bands. | | **ASTM (USA)** | **A304** | **Key Product Standard.** "Standard Specification for Carbon and Alloy Steel Bars Subject to End-Quench Hardenability Requirements." | | **SAE (USA)** | **J1268** | Standard for Hardenability Bands and reporting. | | **ISO** | ISO 683-1:2018 | **Alloy steels with specified hardenability bands.** Direct equivalent: **1.6562 H** | | **EN (Europe)** | EN 10083-3 | **34CrNiMo6 + H** | The "+H" indicates hardenability requirements per EN ISO 642. | | **JIS (Japan)** | JIS G4052 | **SCr440H** | Guaranteed hardenability steel for machine structural use. | | **GB (China)** | GB/T 5216 | **40CrNiMoAH** | | **Critical Procurement Specification:** To ensure material conformity, the purchase order must specify: 1. **Material Grade:** AISI 4340H per ASTM A304. 2. **Condition:** Normalized. 3. **Hardenability Requirement:** "To meet SAE J1268 H-band limits for 4340H." 4. **Certification:** Mandatory requirement for a **Mill Test Report** including: * Full chemical analysis. * **Actual Jominy Hardenability Test Certificate** (graph and data) for the heat lot. * Mechanical test results for the normalized condition (hardness, tensile). 5. **Optional:** Grain size requirement (e.g., ASTM grain size 5 or finer per ASTM E112). -:- For detailed product information, please contact sales. -: AISI E4340 H Steel, normalized Specification Dimensions Size： Diameter 20-1000 mm Length <6255 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, normalized Properties -:- For detailed product information, please contact sales. -:

Applications of AISI E4340 H Steel, normalized -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI E4340 H Steel, normalized -:- For detailed product information, please contact sales. -:

Packing of AISI E4340 H Steel, normalized -:- 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 2726 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