Alloy 907 (UNS N19907) is a precipitation-hardenable nickel-iron-cobalt alloy representing an improved evolution of the low-expansion superalloy family. Building upon the foundation of Alloy 903, this grade incorporates optimized niobium and titanium additions to deliver superior notch-rupture performance at elevated temperatures, addressing a critical limitation of earlier low-expansion alloys while maintaining controlled thermal expansion characteristics.
1. Product Specifications & Physical DataZYTC Alloy supplies UNS N19907 in mill forms suitable for gas turbine rotating components and critical aerospace structures requiring verified low-expansion properties and enhanced elevated-temperature durability. Available Forms: Round bar, billet, straight forgings, and welding wire. Specifications: AMS 5716, AMS 5717, UNS N19907.
| Chemical Composition (Weight %) | Alloy 907 Specification |
|---|
| Nickel (Ni) | 36.0 - 40.0 | | Iron (Fe) | Balance (approx. 42% nominal) | | Cobalt (Co) | 12.0 - 14.0 | | Niobium (Nb) | 4.3 - 5.2 | | Titanium (Ti) | 1.3 - 1.8 | | Silicon (Si) | 0.07 - 0.35 | | Aluminum (Al) | ≤ 0.25 | | Chromium (Cr) | ≤ 1.0 (residual) |
Note: Minimal chromium content requires consideration of oxidation protection for extended service above 650°C . | Physical Properties | Metric | Imperial |
|---|
| Density | 8.33 g/cm³ | 0.301 lb/in³ | | Melting Range | 1330 - 1410°C | 2425 - 2570°F | | Thermal Expansion (25-425°C) | 7.2 µm/m·°C | 4.0 µin/in·°F | | Curie Temperature | 400 - 470°C | 750 - 880°F |
| Mechanical Properties (Precipitation Hardened) | Metric | Imperial |
|---|
| Tensile Strength | 1350 MPa | 196,000 psi | | Yield Strength (0.2% offset) | 1100 MPa | 160,000 psi | | Elongation at Break | 10% | 10% | | Reduction of Area | 36% | 36% | | Poisson's Ratio | 0.36 | 0.36 |
2. Operating Conditions & Selection CriteriaAlloy 907 (UNS N19907) was specifically developed to overcome the notch-rupture limitations observed in first-generation low-expansion alloys. This improvement enables reliable performance in stress-concentrating features such as bolt threads, seal slots, and shaft step transitions . Service Temperature Range: Optimized for continuous operation up to 650°C (1200°F). Notch-rupture strength specifically enhanced within 540-650°C (1000-1200°F) range . Low-Expansion Performance: Maintains controlled thermal expansion (approximately 7.2 µm/m·°C up to 425°C) comparable to Alloy 903, enabling tight-clearance designs in turbine casing and seal applications . Notch-Rupture Enhancement: Modified chemistry (increased Nb, controlled Si) improves grain boundary characteristics, significantly reducing notch sensitivity compared to Alloy 903 . Strength Retention: Tensile strength exceeds 1300 MPa at room temperature; maintains useful strength through 650°C service envelope . Oxidation Limitation: Like other low-expansion superalloys, minimal chromium content results in limited oxidation resistance above 650°C. Protective coatings recommended for extended service . Microstructural Stability: Precipitation-hardened structure (γ' and γ'' phases) optimized for balance of strength and notch ductility .
3. Fabrication & Material ComparisonAlloy 907 (UNS N19907) requires precise thermal and mechanical processing to develop the optimized precipitate structure responsible for its enhanced notch-rupture characteristics. Machining: Best performed in solution-treated condition. Carbide tooling recommended with positive rake angles. Water-based coolants for high-speed operations. Notch-sensitive in final heat-treated condition; avoid sharp radii in design . Welding: Weldable using GTAW and limited SMAW processes. Matching filler metal required. Alloy 907 exhibits improved weldability compared to Alloy 903 due to optimized composition; pre-weld cleaning essential . Forming & Heat Treatment: Hot Working Range: 885-1149°C (1625-2100°F) Forging Range: 927-1149°C (1700-2100°F) Annealing: 983°C (1800°F), air cool Aging (application-dependent): Maximum Tensile Properties: 719°C (1325°F) × 8 hours, cool Maximum Rupture Strength: 774°C (1425°F) × 12 hours, cool
Cold Working: Standard tooling acceptable; soft die materials recommended to minimize galling .
Material Comparison: vs. Alloy 903: Primary differentiator is improved notch-rupture strength at 540-650°C; preferred for components containing stress concentrations such as bolted assemblies and splined shafts . vs. Alloy 909 (successor grade): 909 offers further improvements through silicon additions; 907 represents intermediate generation with established AMS specifications . vs. Inconel 718: Comparable strength with significantly lower thermal expansion; selected where dimensional control trumps absolute oxidation resistance .
Applications Gas turbine engine seals, shafts, and casings High-temperature fastener systems Turbine rotor and stator components Structural rings and containment cases Glass-to-metal sealing applications Precision instrument housings requiring dimensional stability
Contact ZYTC Alloy for certified alloy 907 materials with complete traceability, AMS specifications, technical datasheets, and competitive pricing on standard sizes or custom-forged components. Email:daisy@zytcsteel.com WhatsApp/WeChat: +86 17335753350 |
