Alloy 945 (UNS N09945) is a precipitation-hardenable nickel-iron-chromium superalloy engineered for demanding oil and gas applications requiring high strength coupled with exceptional corrosion resistance. Strategic additions of molybdenum, copper, niobium, titanium, and aluminum enable this alloy to achieve yield strengths exceeding 900 MPa while maintaining resistance to sulfide stress cracking and chloride-induced stress corrosion cracking in aggressive sour environments .
1. Product Specifications & Physical DataZYTC Alloy supplies UNS N09945 in mill forms suitable for downhole equipment, wellhead components, and high-pressure systems requiring NACE MR0175/ISO 15156 compliance. Available Forms: Pipe, tube, sheet, plate, bar, rod, wire, strip, and forgings. Specifications: API 6ACRA, NACE MR0175/ISO 15156 (Level VII, Level VI at 450°F), ASTM B805, UNS N09945 .
| Chemical Composition (Weight %) | Alloy 945 Specification |
|---|
| Nickel (Ni) | 45.0 - 55.0 | | Chromium (Cr) | 19.5 - 23.0 | | Iron (Fe) | Balance | | Molybdenum (Mo) | 3.0 - 4.0 | | Niobium (Nb) | 2.5 - 4.5 | | Copper (Cu) | 1.5 - 3.0 | | Titanium (Ti) | 0.5 - 2.5 | | Aluminum (Al) | 0.01 - 0.7 | | Carbon (C) | 0.005 - 0.04 | | Manganese (Mn) | ≤ 1.0 | | Silicon (Si) | ≤ 0.5 | | Sulfur (S) | ≤ 0.03 |
Note: Composition ranges reflect industry standards; 945X variant offers enhanced strength levels with 140 ksi minimum yield . | Physical Properties | Metric | Imperial |
|---|
| Density | 8.1 - 8.2 g/cm³ | 0.293 - 0.296 lb/in³ | | Melting Range | 1270 - 1377°C | 2317 - 2510°F |
| Mechanical Properties (Precipitation Hardened) | Metric | Imperial |
|---|
| Tensile Strength | ≥ 1194 MPa | ≥ 173.2 ksi | | Yield Strength (0.2% offset) | ≥ 920 MPa | ≥ 133.4 ksi | | Elongation at Break | ≥ 27.8% | ≥ 27.8% | | Hardness (max., aged) | 42 HRC | 42 HRC |
*Note: 945X variant achieves 965 MPa (140 ksi) minimum yield strength; cold-worked versions available up to 210 ksi .*
2. Operating Conditions & Selection CriteriaAlloy 945 (UNS N09945) was specifically developed to address limitations of existing alloys in deep, high-pressure sour wells while maintaining microstructural stability and corrosion resistance . Service Temperature Range: Optimized for continuous operation up to 232°C (450°F) for sour service per NACE MR0175; mechanical properties maintained through 550°C for non-sour applications . Sour Gas Resistance: Approved for NACE Level VII and Level VI at 450°F environments containing H₂S, chlorides, and CO₂. Superior resistance to sulfide stress cracking (SSC) and stress-corrosion cracking (SCC) . Localized Corrosion: Molybdenum and niobium provide excellent resistance to pitting and crevice corrosion in chloride environments . Microstructural Stability: Optimized chemistry minimizes formation of detrimental intergranular phases (delta phase) that can promote hydrogen embrittlement, unlike some competing alloys . General Corrosion: Nickel, molybdenum, and copper combination provides outstanding resistance to reducing media; chromium maintains passivity in oxidizing conditions .
3. Fabrication & Material ComparisonAlloy 945 (UNS N09945) offers good fabricability with proper techniques, though its age-hardenable nature requires attention to heat treatment sequencing. Machining: Good machinability in both solution annealed and aged conditions. Rigid tooling with positive rake angles recommended to minimize work hardening. Carbide tools preferred for production runs . Welding: Readily welded using GTAW, GMAW, and pulsed GMAW processes. Matching filler metals recommended. Post-weld heat treatment typically required to restore precipitation-hardened properties in weld zone . Forming & Heat Treatment : Solution Annealing: 1010-1066°C (1850-1950°F) × 0.5-4 hours, water quench Age Hardening (two-stage): First Stage: 704-732°C (1300-1350°F) × 6-8 hours Furnace cool to 599-621°C (1110-1150°F) Second Stage: Hold 8 hours, air cool
Hot Working: 927-1177°C (1700-2150°F) Cold Working: Standard tooling acceptable; soft die materials recommended to minimize galling
Material Comparison: vs. Alloy 718: Higher strength capability with improved microstructural stability; less prone to delta phase formation and hydrogen embrittlement . vs. Alloy 925: Significantly higher yield strength (125+ ksi vs. 110 ksi); preferred where design requires reduced section sizes . vs. Alloy 725: Comparable corrosion resistance with higher strength capability; 945 offers better age-hardening response .
3. Applications Downhole oil and gas components: tubing hangers, packers, landing nipples, tool joints Surface wellhead equipment: valves, Christmas tree components High-strength piping systems for sour service Pump shafts and fasteners Subsea completion equipment OCTG (Oil Country Tubular Goods)
Contact ZYTC Alloy for certified alloy 945 materials with complete traceability, NACE MR0175 certification, technical datasheets, and competitive pricing on standard sizes or custom-forged components. Email:daisy@zytcsteel.com WhatsApp/WeChat: +86 17335753350 |
