AMS 6434 Ultrahigh Strength Steel Sheet,Plate

AMS 6434 Ultrahigh Strength Steel Sheet/Plate Product Information -:- For detailed product information, please contact sales. -: AMS 6434 Ultrahigh Strength Steel Sheet/Plate Synonyms -:- For detailed product information, please contact sales. -:

AMS 6434 Ultrahigh Strength Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Datasheet: AMS 6434 Ultrahigh-Strength Steel (Modified 4340)** ## **1. Product Overview** **AMS 6434** is a premium **ultrahigh-strength, low-alloy steel** specification developed for critical aerospace and defense applications requiring exceptional strength-toughness combination and reliable performance under extreme loading conditions. As a vacuum-arc remelted (VAR) modification of the AISI 4340 alloy system, this steel delivers superior mechanical properties through enhanced cleanliness, refined microstructure, and optimized heat treatment response. AMS 6434 represents the pinnacle of conventional ultrahigh-strength steel technology, bridging the gap between standard alloy steels and more exotic materials while offering excellent manufacturability and proven service history in demanding applications. ## **2. International Standards & Designations** | System/Authority | Designation | Specification Title / Relationship | | :--- | :--- | :--- | | **Aerospace (US)** | **AMS 6434** | Steel Bars, Forgings, and Tubing, 0.80Cr - 1.8Ni - 0.25Mo (0.40C) (4340) Vacuum Arc Remelted | | **SAE** | **AMS 6434** | Standard within Aerospace Material Specifications | | **Military (US)** | **MIL-S-8844** | Similar requirements for ultrahigh-strength components | | **ASTM** | **A579/A579M** | Superstrength Alloy Steel Forgings (Grade 8 approx. equivalent) | | **ASME** | **SA-434** | Equivalent specification for boiler and pressure vessel applications | | **NATO** | **STANAG 7141** | EP4 Classification (Approximate equivalent) | | **Common Names** | VAR 4340, Premium 4340, Ultrahigh-Strength 4340, AMS 6434 Steel | ## **3. Chemical Composition (% by Weight)** AMS 6434 maintains the balanced 4340 chemistry with enhanced controls for ultrahigh-strength applications. | Element | AMS 6434 Requirements | Typical % Range | Metallurgical Function | | :--- | :--- | :--- | :--- | | **Carbon (C)** | **0.38 - 0.43** | 0.39 - 0.41 | Primary strengthener, forms tempered martensite | | **Manganese (Mn)** | **0.65 - 0.85** | 0.70 - 0.80 | Austenite stabilizer, enhances hardenability | | **Phosphorus (P)** | **≤ 0.010** | ≤ 0.008 | Ultra-low for improved toughness | | **Sulfur (S)** | **≤ 0.010** | ≤ 0.005 | Ultra-low for enhanced transverse properties | | **Silicon (Si)** | **0.20 - 0.35** | 0.25 - 0.30 | Deoxidizer, solid solution strengthener | | **Nickel (Ni)** | **1.65 - 2.00** | 1.70 - 1.90 | Enhances toughness and hardenability | | **Chromium (Cr)** | **0.70 - 0.90** | 0.75 - 0.85 | Improves hardenability and corrosion resistance | | **Molybdenum (Mo)** | **0.20 - 0.30** | 0.22 - 0.27 | Enhances temper resistance and hardenability | | **Copper (Cu)** | **≤ 0.35** | ≤ 0.20 | Residual element | | **Vanadium (V)** | -- | ≤ 0.05 | Optional microaddition for grain refinement | | **Iron (Fe)** | Balance | Balance | Matrix material | **Special Processing Requirements:** - **Melting:** **Vacuum Arc Remelting (VAR)** mandatory for enhanced cleanliness - **Inclusion Control:** Stringent limits on oxide and sulfide inclusions - **Grain Size:** ASTM 6 or finer required - **Macroetch:** Must show sound, uniform structure ## **4. Mechanical & Physical Properties** Properties are achieved through precise heat treatment and are typically specified for specific strength levels. | Property | Standard Heat Treat Condition | Test Standard | Notes | | :--- | :--- | :--- | :--- | | **Heat Treatment** | **Austenitize:** 845-870°C (1550-1600°F), Oil Quench
**Temper:** 205-425°C (400-800°F) depending on strength required | AMS 2759/1 | | | **Ultimate Tensile Strength** | **1,380 - 1,930 MPa (200 - 280 ksi)** | ASTM E8 | Depends on tempering temperature | | **Yield Strength (0.2%)** | **1,240 - 1,725 MPa (180 - 250 ksi)** | ASTM E8 | Typically 90-95% of UTS | | **Elongation** | **7 - 12%** (in 4D) | ASTM E8 | Decreases with increasing strength | | **Reduction of Area** | **25 - 40%** | ASTM E8 | Good toughness for strength level | | **Hardness** | **40 - 52 HRC** | ASTM E18 | Varies with tempering temperature | | **Fracture Toughness (K_IC)** | **55 - 110 MPa√m** | ASTM E399 | Excellent for strength level | | **Fatigue Strength (10⁷ cycles)** | **550 - 700 MPa** (rotating beam, polished) | -- | Superior to non-VAR materials | | **Modulus of Elasticity** | **205 GPa (29.7 × 10⁶ psi)** | -- | | | **Shear Modulus** | **80 GPa (11.6 × 10⁶ psi)** | -- | | | **Density** | **7.85 g/cm³ (0.284 lb/in³)** | -- | | | **Thermal Conductivity** | **44.5 W/m·K** @ 100°C | -- | | **Typical Strength Levels:** - **280 ksi (1930 MPa):** Tempered at ~205°C (400°F) - **260 ksi (1790 MPa):** Tempered at ~260°C (500°F) - **220 ksi (1520 MPa):** Tempered at ~370°C (700°F) - **200 ksi (1380 MPa):** Tempered at ~425°C (800°F) ## **5. Key Characteristics & Advantages** * **Exceptional Strength-Toughness Balance:** Optimized chemistry and VAR processing provide superior mechanical properties * **Superior Cleanliness:** Vacuum remelting significantly reduces inclusions, enhancing fatigue and fracture resistance * **Excellent Hardenability:** Can be through-hardened in sections up to 125mm (5 inches) diameter * **Good Fabricability:** Can be machined, forged, and welded with proper procedures * **Proven Reliability:** Extensive service history in aerospace applications * **Predictable Heat Treatment Response:** Consistent properties achievable through standard heat treatment * **Good Fatigue Performance:** Enhanced by clean steel and refined microstructure * **Cost-Effective:** Provides premium performance at lower cost than maraging steels ## **6. Primary Applications** AMS 6434 is specified for the most demanding structural applications in aerospace, defense, and high-performance industries. * **Aircraft Landing Gear:** Critical components including pistons, trunnions, and structural fittings * **Aerospace Structural Components:** High-strength fasteners, attachment fittings, and airframe structures * **Helicopter Components:** Rotor hubs, mast supports, and dynamic system components * **Missile & Rocket Components:** Motor cases, structural frames, and guidance system parts * **High-Performance Automotive:** Racing suspension components, drive shafts, and safety-critical parts * **Oil & Gas Industry:** Downhole tools, drill string components, and high-pressure equipment * **Industrial Machinery:** High-stress shafts, gears, and press components * **Tooling Applications:** Dies, molds, and tooling for high-pressure applications ## **7. Heat Treatment Guidelines** * **Annealing:** 845-870°C (1550-1600°F), slow furnace cool to 595°C (1100°F), then air cool * **Normalizing:** 870-900°C (1600-1650°F), air cool * **Austenitizing:** 845-870°C (1550-1600°F) in neutral atmosphere, hold 1 hour per inch of thickness * **Quenching:** Rapid oil quench to below 65°C (150°F) * **Tempering:** Immediately after quenching; typical range 205-425°C (400-800°F) for 2+ hours * **Stress Relieving:** 595-650°C (1100-1200°F) for 1 hour per inch, slow cool ## **8. Processing & Fabrication** * **Machining:** Best performed in annealed condition (~22 HRC) * **Forging:** Forge at 1150-900°C (2100-1650°F); slow cool after forging * **Welding:** Requires preheat (205-315°C/400-600°F) and post-weld heat treatment * **Grinding:** Use soft wheels and light passes to avoid grinding burns * **Surface Enhancement:** Suitable for shot peening, nitriding, and carburizing ## **9. Comparison with Similar Materials** | Property | **AMS 6434** | 4340 (Standard) | 300M | 4340M | | :--- | :--- | :--- | :--- | :--- | | **Tensile Strength** | 1380-1930 MPa | 1380-1930 MPa | 1930-2070 MPa | 1520-1790 MPa | | **Fracture Toughness** | 55-110 MPa√m | 45-75 MPa√m | 55-75 MPa√m | 80-110 MPa√m | | **Cleanness** | **Excellent (VAR)** | Good | Excellent (VIM-VAR) | Excellent (VAR) | | **Fatigue Performance** | Superior | Good | Excellent | Very Good | | **Cost Factor** | 1.8-2.2 | 1.0 | 3.0-4.0 | 2.0-2.5 | | **Primary Advantage** | **Balanced cost/performance** | Economy | **Maximum strength** | **Enhanced toughness** | ## **10. Quality Assurance** * **Melt Method Certification:** VAR process verification * **Chemical Analysis:** Full spectrographic analysis * **Mechanical Testing:** Tensile, impact, and hardness testing * **Metallurgical Examination:** Macroetch, microcleanliness, grain size * **Non-Destructive Testing:** Ultrasonic, magnetic particle, or dye penetrant * **Heat Treatment Records:** Complete documentation of thermal processing --- **Disclaimer:** This technical datasheet provides reference information for AMS 6434 ultrahigh-strength steel. Final design and specification must be based on the complete requirements of the latest edition of **AMS 6434**. This material requires specialized processing and heat treatment knowledge for optimal performance. Consultation with qualified metallurgical engineers is essential for critical applications. All property data represents typical values and should be verified through testing of actual production material. Performance may vary based on specific processing history and section size. -:- For detailed product information, please contact sales. -: AMS 6434 Ultrahigh Strength Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6418 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. -: AMS 6434 Ultrahigh Strength Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AMS 6434 Ultrahigh Strength Steel Sheet,Plate -:- For detailed product information, please contact sales. -: Chemical Identifiers AMS 6434 Ultrahigh Strength Steel Sheet,Plate -:- For detailed product information, please contact sales. -:

Packing of AMS 6434 Ultrahigh Strength Steel Sheet/Plate -:- 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 Sheet/Plate 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 2889 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