Nickelvac X- 751 UNS N07751 Nickel Superalloy,SAE J775 (HEV-3),E FORU

### **Product Introduction: Nickelvac® X-751 (UNS N07751) Nickel-Based Superalloy** **Nickelvac X-751 (UNS N07751)** is a precipitation-hardenable nickel-chromium superalloy specifically engineered for applications requiring high strength and excellent corrosion resistance at elevated temperatures. As an optimized variant within the Alloy X-750 family, this alloy undergoes specialized heat treatment to achieve superior mechanical properties while maintaining outstanding oxidation resistance and structural stability. The alloy is particularly recognized for its compliance with SAE J775 (HEV-3) specifications, making it suitable for demanding automotive and aerospace applications. The alloy derives its strength from the precipitation of gamma prime [γ'] phase (Ni₃(Al, Ti)) during age hardening, providing an optimal balance of high-temperature capability, fatigue resistance, and environmental durability. --- #### **1. Chemical Composition (Weight %)** The typical chemical composition of Nickelvac X-751 per SAE J775 (HEV-3) is as follows: | Element | Content (%) | Element | Content (%) | |---------|-------------|---------|-------------| | **Nickel (Ni)** | ≥ 70.0 | **Aluminum (Al)** | 0.80 - 1.50 | | **Chromium (Cr)** | 14.0 - 17.0 | **Titanium (Ti)** | 2.25 - 2.75 | | **Iron (Fe)** | 5.0 - 9.0 | **Niobium (Nb)** | 0.80 - 1.20 | | **Cobalt (Co)** | 1.0 max | **Silicon (Si)** | 0.50 max | | **Carbon (C)** | 0.08 max | **Manganese (Mn)** | 1.00 max | | **Copper (Cu)** | 0.50 max | **Sulfur (S)** | 0.010 max | | **Phosphorus (P)** | 0.015 max | **Boron (B)** | 0.006 max | --- #### **2. Physical & Mechanical Properties** **Physical Properties:** | Property | Metric Units | Imperial Units | |----------|-----------------|------| | **Density** | 8.28 g/cm³ | 0.299 lb/in³ | | **Melting Range** | 1390 - 1430 °C | 2530 - 2610 °F | | **Thermal Conductivity** | 11.7 W/m·K | 81.1 Btu·in/hr·ft²·°F | | **Coefficient of Thermal Expansion** | 12.8 μm/m·°C | 7.1 μin/in·°F | | **Modulus of Elasticity** | 214 GPa | 31.0 x 10⁶ psi | | **Specific Heat** | 431 J/kg·K | 0.103 Btu/lb·°F | **Mechanical Properties (Heat Treated Condition):** | Property | Value | |----------|-----------------| | **Tensile Strength** | 1200-1380 MPa | 174-200 ksi | | **Yield Strength (0.2% Offset)** | 830-1030 MPa | 120-150 ksi | | **Elongation** | 15-25% | | **Reduction of Area** | 20-30% | | **Hardness (Rockwell C)** | 28-38 HRC | **Elevated Temperature Properties (at 705°C/1300°F):** | **Tensile Strength** | 620 MPa | 90 ksi | | **Yield Strength** | 480 MPa | 70 ksi | | **Stress Rupture Life (705°C/310 MPa)** | 50+ hours | --- #### **3. Key Characteristics & Product Applications** **Key Characteristics:** - **High Temperature Strength**: Excellent mechanical properties up to 705°C (1300°F) - **Oxidation Resistance**: Superior resistance to scaling and oxidation in high-temperature environments - **Fatigue Resistance**: Excellent performance under cyclic loading conditions - **Creep Resistance**: Good long-term load-bearing capability at elevated temperatures - **Corrosion Resistance**: Good resistance to various corrosive environments - **Thermal Stability**: Maintains microstructural stability during prolonged high-temperature exposure **Product Applications:** Nickelvac X-751 finds extensive use in critical high-temperature applications: - **Automotive Industry**: - Exhaust valve components (SAE J775 HEV-3 compliant) - Turbocharger components - High-temperature fasteners - Engine valve seats and guides - **Aerospace Industry**: - Gas turbine engine components - Turbine blades and discs - Combustion chamber parts - Aircraft engine fasteners - **Power Generation**: - Gas turbine components - Heat exchanger parts - High-temperature bolting - Steam turbine elements - **Industrial Processing**: - Heat treatment fixtures - Furnace components - High-temperature springs - Nuclear reactor components --- #### **4. International Standards & Specifications** Nickelvac X-751 is covered by major international standards: **Primary Specifications:** - **SAE J775 (HEV-3)**: Automotive Engine Valve Quality **Related Standards:** - **UNS**: N07751 - **AMS**: - AMS 5698: Round Wire - AMS 5699: Bars, Forgings, and Rings - **ASTM**: - ASTM B637: Precipitation-Hardening Nickel Alloy - **AECMA/EN**: 2.4669 (European Standard) - **ISO**: 9724 (Nickel Alloy Bars) --- #### **Summary of Key Advantages** - **Optimized Heat Treatment**: Specialized thermal processing for enhanced properties - **Automotive Compliance**: Meets stringent SAE J775 HEV-3 requirements - **High Temperature Capability**: Excellent strength retention up to 705°C (1300°F) - **Proven Reliability**: Established track record in critical applications - **Versatile Performance**: Suitable for automotive, aerospace, and industrial applications - **Good Fabricability**: Can be forged, machined, and formed using standard methods **Technical Note**: The heat treatment for Nickelvac X-751 typically involves solution treatment at 980°C (1800°F) followed by air cooling, then aging at 730°C (1350°F) for 16-20 hours. This specialized thermal processing provides the optimal combination of strength, ductility, and high-temperature performance required for demanding applications like exhaust valves. The alloy maintains good weldability characteristics, though post-weld heat treatment is recommended for critical applications. Machining is best performed in the solution-treated condition, followed by age hardening to achieve final properties.

Packing of Standard Packing: 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 3158 gallon liquid totes Special package is available on request.