Haynes75 Alloy

Haynes75 (designated as UNS N06075) is a nickel-chromium (Ni-Cr) based solid solution strengthened alloy, well-regarded for its moderate high-temperature performance and reasonable oxidation resistance. Distinguished from the Co-Cr-Ni based Haynes25 alloy which emphasizes ultra-high temperature stability, Haynes75 is optimized for applications with relatively lower stress and temperature demands, typically up to 650°C (1200°F). Its strengthening mechanism relies on the solid solution effect of chromium in the nickel matrix, endowing it with a balance of properties suitable for various industrial scenarios.

1. Chemical Composition (Mass Fraction, %)

2. Physical Properties

2.1 Basic Physical Parameters

• Density: Approximately 8.47g/cm³ at room temperature (25°C), lighter than Haynes25 (9.13g/cm³) due to differences in major element composition. This lower density can be advantageous in applications where weight is a consideration, such as in some aerospace sub-components.
• Melting Temperature Range: Around 1350°C (2462°F). A relatively stable melting point simplifies the casting process, ensuring consistent quality when forming components.
• Thermal Expansion Coefficient (CTE):

◦ 20 – 100°C: ~13.0×10⁻⁶/°C. The relatively low CTE in this temperature range reduces thermal stress during initial heating, which is beneficial for components that experience frequent start-stop cycles.

• Thermal Conductivity (λ):

◦ 200°C: ~14.0W/(m·K). This value enables efficient heat transfer in applications where uniform heating or cooling is required, preventing localized overheating or cooling that could lead to material degradation.

2.2 Magnetic Properties

• Haynes75 is non-magnetic under normal conditions. This property makes it suitable for applications where magnetic interference needs to be avoided, such as in some electronic and precision instrument components.

3. Mechanical Properties (Typical Values)

• Good High-temperature Ductility: At 650°C, the high elongation (≥40%) ensures that the alloy can be formed into complex shapes through processes like forging and rolling. This is crucial for manufacturing components with intricate geometries, such as those in gas turbine applications.
• Moderate High-temperature Strength: The tensile strength and yield strength at 650°C are sufficient to withstand the mechanical loads in applications with relatively low stress levels, such as in certain industrial heating elements.

4. High-temperature Oxidation & Corrosion Resistance

• Protective Oxide Film: Similar to Haynes25, Haynes75 forms a Cr₂O₃ protective film at high temperatures. This film effectively isolates the alloy from the oxidizing atmosphere, providing long-term protection against oxidation.
• Suitability for Oxidizing Environments: It can be used in environments with moderate temperatures and oxidizing conditions, such as in some industrial furnace linings where the temperature does not exceed 650°C for extended periods.
• Aircraft Engine Components: Although not as high-performance as Haynes25 for extreme conditions, Haynes75 can be used in some non-critical engine components, such as certain brackets and casings that are exposed to moderate temperatures (up to 650°C). Its good formability allows for the production of complex shapes required for engine assembly.
• Furnace Components: It is suitable for manufacturing furnace linings, trays, and fixtures in industrial furnaces operating at temperatures up to 650°C. Compared to some other materials, it offers better oxidation resistance and mechanical stability, leading to longer service life and reduced maintenance costs.
• Automotive Exhaust Components: In some automotive applications where the exhaust gas temperature is relatively low (up to 650°C), Haynes75 can be used to make exhaust pipes and muffler components. Its corrosion resistance to exhaust gases helps to extend the lifespan of these parts.
• Sample Holders and Fixtures: Haynes75 can be used to fabricate sample holders and fixtures for materials testing at moderate high temperatures (up to 650°C). Its stable mechanical properties at these temperatures ensure accurate test results.
• Hot Working: Forging can be carried out at temperatures around 1100 – 1200°C. The initial forging temperature should be carefully controlled to avoid excessive grain growth, and the final forging temperature should be high enough to prevent work hardening.
• Cold Working: Cold rolling and drawing can be performed, with a total deformation of up to 40 – 50% for sheet materials. Intermediate annealing at around 1000 – 1050°C for 30 – 60 minutes, followed by air cooling, can be used to restore ductility during cold working.
• Welding: Haynes75 can be welded using common methods such as TIG welding. A filler metal with a similar Ni-Cr composition is recommended. Preheating to 100 – 150°C (optional for thin sheets) can help reduce the risk of cracking. Post-weld heat treatment at around 1050 – 1100°C for 1 hour, followed by air cooling, can relieve welding stress and improve the corrosion resistance of the weld joint.
• Machining: Machining is best done in the solution-treated state. High-speed steel or carbide tools can be used, and the use of cutting fluids is recommended to reduce tool wear and prevent overheating of the workpiece. Finish machining can be carried out after final forming to achieve the required precision dimensions.

5. Application Products & Industry Scenarios

5.1 Aerospace & Defense Field

5.2 Industrial Heating & Furnace Field

5.3 Mechanical & Automotive Field

5.4 Metallurgical & Materials Testing Field

6. Processing & Welding Recommendations

In summary, Haynes75 is a cost-effective alloy for applications that require moderate high-temperature performance, oxidation resistance, and good formability. Its specific properties make it a suitable choice for a wide range of industries, especially those with relatively lower temperature and stress requirements compared to more extreme high-temperature applications.