UNS N09925 | ASTM B637 | Size: M3 to M33 | 3/16" to 2" | Length: 3 mm to 200 mm
Introduction to Incoloy 925 Fasteners
Unifit Fastener is a trusted manufacturer, supplier and exporter of Incoloy 925 Fasteners to critical industrial segments in India and international market. UNS N09925 (Incoloy 925) is a precipitation-hardened nickel-iron-chromium alloy that offers exceptional corrosion resistance and high tensile strength, making it essential in the oil and gas, offshore drilling, chemical processing and power generation industries.
Our Incoloy 925 Fasteners are produced to meet the ASTM B637 / ASME SB637 standards, which guarantee dimensional accuracy, structural integrity, and consistent mechanical performance. Our fasteners are widely available in various shapes, such as hex bolts, studs, threaded rods, nuts, washers and anchor bolts, and are designed to withstand the most rigorous of conditions where other stainless steel fasteners would fail, such as in high temperature and corrosive situations.
Unifit Fastener has advanced CNC machining capabilities, an in-house quality testing system and a dedicated export team, all of which provide a means to supply Incoloy 925 Fasteners to customers in the Middle East, Europe, Southeast Asia, South America and North America. Standard or custom sizes, we have a flexible order quantity with competitive lead times.
Request a QuoteWhat Is Incoloy 925 Alloy?
Incoloy 925 (also referred to as Alloy 925 or Nickel Alloy 925) is an age-hardenable nickel-iron-chromium alloy strengthened with additions of molybdenum, copper, titanium, and aluminum. Its unique metallurgical design enables it to deliver mechanical properties far superior to standard austenitic alloys while maintaining excellent resistance to stress-corrosion cracking (SCC) and pitting in aggressive chloride environments — a critical requirement for subsea, downhole, and offshore installations.
Classified under UNS N09925 and covered by ASTM B637 / ASME SB637 (for bars, billets, and forgings), this alloy is widely recommended by NORSOK, Shell DEP, and ExxonMobil specifications for corrosion-critical fastener applications.
Incoloy 925 Fasteners Specifications
| Parameter | Details |
| Specifications | ASTM / ASME B637, DIN, ISO, BS, JIS, GB |
| Grade / UNS No. | Incoloy 925 / UNS N09925 / NCF 925 (JIS) |
| Size (Metric) | M0.2 to M33 | Custom Sizes Available |
| Size (Imperial) | 3/16" to 2" | Custom Sizes Available |
| Length | 3 mm to 200 mm | Custom Lengths Available |
| Dimensions | DIN 931, 933, 934, 976, ASME B18.2.1, B18.3 |
| Thread Standards | UNF, BSW, BSF, METRIC, UNC, or as required |
| Thread Configuration | ASME B1.1 2A/3A, B1.13M 6h-6G Metric Coarse |
| Head Styles | Hex, Heavy Hex, Square, Oval, Flat, Truss, Pan, Socket |
| Form | Hex, Threading, Square, Round, Eye, U-Bolt, J-Bolt |
| Manufacturing Method | Hot Forging, Cold Forging, CNC Machining |
| Surface Coating | Phosphating, HDG, Oxidation, PTFE, Teflon, Zinc, Cadmium |
| Raw Material Source | American, European, Japanese, Korean, Russian, Indian |
| Test Certificate | EN 10204 / 3.1 MTC, PED 97/23/EC, Merkblatt AD 2000 W2 |
| Packing | Bulk in cartons / pallets, or as per customer requirements |
Incoloy 925 Fasteners Chemical Composition
| Grade | Ni | Cr | Fe | Mo | Cu | Ti | Al | C | Mn | Si | S |
| Incoloy 925 | 42.0–46.0 | 19.5–22.5 | 22.0 min | 2.5–3.5 | 1.5–3.0 | 1.9–2.4 | 0.1–0.5 | 0.03 max | 1.0 max | 0.5 max | 0.03 max |
Incoloy 925 Fasteners Mechanical Properties
| Property | Imperial | Metric (SI) |
| Tensile Strength | 140 ksi | 965 N/mm² |
| 0.2% Proof / Yield Strength | 110–140 ksi | 758–965 N/mm² |
| Elongation (5.65√S0 & 4D) | — | 18% |
| Reduction of Area | — | 25% |
| Impact Strength (-60°C, Longitudinal) | 35 ft·lb av (32 ft·lb min) | 47 J av (43 J min) |
| Hardness | — | 38 HRC max |
| Density | — | 8.08 g/cm³ |
| Melting Point | 2392°F–2491°F | 1311°C–1366°C |
| Max. Service Temperature | — | Up to 650°C |
ASTM B637 UNS N09925 Physical Properties
| Physical Property | Value |
| Young's Modulus | 199 GPa (199,000 MPa / 28,900 ksi) |
| Specific Heat (20°C) | 435 J/(kg.K) |
| Electrical Resistivity (20°C) | 1.17 × 10-6 Ω·m |
| Magnetic Permeability (20°C) | 1.001 |
| Electrical Conductivity (20°C) | 0.25 (1.48% IACS) mΩ/mm² |
| Thermal Conductivity (20°C) | 12 W/(m·K) |
| Density | 8080 kg/m³ |
Incoloy 925 Equivalent Grades
| Standard | UNS | JIS | Werkstoff Nr. (WNR) | Trade Name |
| Alloy 925 | N09925 | NCF 925 | — | Incoloy® Alloy 925 |
Incoloy 925 Stud Bolt Size Chart (Pipe Size vs Flange Rating)
| Pipe Size | Stud Size | Flange Rating | Studs Per Set |
| 1/2" | 3/4"-10 × 4-1/4" | 900# | 4 |
| 3/4" | 3/4"-10 × 4-1/2" | 900# | 4 |
| 1" | 7/8"-9 × 5" | 900# | 4 |
| 1-1/4" | 7/8"-9 × 5" | 900# | 4 |
| 1-1/2" | 1"-8 × 5-1/2" | 900# | 4 |
| 2" | 7/8"-9 × 5-3/4" | 900# | 8 |
| 2-1/2" | 1"-8 × 6-1/4" | 900# | 8 |
| 3" | 7/8"-9 × 5-3/4" | 900# | 8 |
| 4" | 1-1/8"-8 × 6-3/4" | 900# | 8 |
| 6" | 1-1/8"-8 × 7-1/2" | 900# | 12 |
| 8" | 1-3/8"-8 × 8-3/4" | 900# | 12 |
| 10" | 1-3/8"-8 × 9-1/4" | 900# | 16 |
| 12" | 1-3/8"-8 × 10" | 900# | 20 |
| 14" | 1-1/2"-8 × 10-3/4" | 900# | 20 |
| 16" | 1-5/8"-11 × 11-1/4" | 900# | 20 |
| 18" | 1-7/8"-8 × 12-3/4" | 900# | 20 |
| 20" | 2"-8 × 13-3/4" | 900# | 20 |
| 24" | 2-1/2"-8 × 17-1/4" | 900# | 20 |
Applications & Industries for Incoloy 925 Fasteners
Incoloy 925 fasteners are engineered for service in highly aggressive and corrosive environments where failure is not an option. The key industries and application areas include:
| Industry / Application | Why Incoloy 925? |
| Oil & Gas (Upstream / Downstream) | Exceptional SCC resistance in H2S and CO2-rich sour gas environments; meets NACE MR0175 / ISO 15156 |
| Offshore & Subsea Equipment | Outstanding pitting resistance in deep-sea chloride environments; reliable at high pressures |
| Petrochemical Plants | High thermal stability and resistance to organic acids and sulfur compounds |
| Chemical Processing Equipment | Resistant to hydrochloric, sulfuric, and phosphoric acid in process conditions |
| Power Generation Plants | Performs in steam, high-temperature water, and boiler environments up to 650°C |
| Shipbuilding & Marine | Excellent resistance to seawater corrosion, biofouling, and galvanic coupling |
| Pharmaceutical Equipment | For high-strength corrosion-resistant fasteners in CIP/SIP environments; confirm project specification before selecting Incoloy 925 over 825 or 316L |
| Pulp & Paper Industry | Resistant to bleaching chemicals and highly oxidizing liquors |
| Sugar & Fertilizer Plants | Long service life in chloride and ammonium-rich processing environments |
| Cement & Construction | High-strength fasteners for structural and pre-stressed concrete applications |
| Gas Processing (Sour Service) | Ideal for wellhead equipment and Christmas trees exposed to H2S |
| Heat Exchangers & Condensers | Resists pitting and erosion-corrosion in tube sheet and shell assemblies |
Quality Standards & Certifications
Unifit's ISO 9001:2015 QMS mandates OES/XRF chemical verification on all incoming N09925 bar stock, tensile and impact testing per ASTM B637, and 100% dimensional inspection for every Incoloy 925 fastener order. EN 10204/3.1 MTCs are issued with every shipment. Our manufacturing process conforms to internationally recognized standards and is audited by third-party inspection agencies.
| Certification / Standard | Scope |
| ISO 9001:2015 | Quality management system for manufacturing and supply |
| ASTM B637 / ASME SB637 | Specification for UNS N09925 bars, forgings, and fasteners |
| EN 10204 / 3.1 MTC | Manufacturer's material test certificate with chemical and mechanical data |
| PED 97/23/EC (2014/68/EU) | Pressure Equipment Directive compliance for European projects |
| Merkblatt AD 2000 W2 | German pressure vessel material standard |
| NACE MR0175 / ISO 15156 | Sour service qualification for oil and gas applications |
| ADNOC, SABIC, KOC, Saudi Aramco | Approved vendor status for major Middle East oil producers |
| SGS / TUV / Bureau Veritas | Third-party inspection and testing upon customer request |
Manufacturing Process Overview
Understanding how Incoloy 925 fasteners are made helps in appreciating the quality standards Unifit Fastener upholds:
- Raw Material Procurement: Incoloy 925 bars and billets sourced from approved mills in USA, Japan, Europe, and India
- Chemical Verification: Incoming material verified for chemical composition via OES/XRF analysis
- Forming: Hot forging for heavy-hex and large-diameter fasteners; cold forging for smaller precision items
- Heat Treatment: We solution-anneal Incoloy 925 at 980C then age at 720C for 8 hours — a two-stage thermal cycle that activates gamma prime precipitation and achieves NACE MR0175 hardness compliance at 38 HRC max.
- CNC Threading: Precision thread rolling or cutting to UNF, BSW, BSF, UNC, or METRIC standards
- Surface Finishing: Phosphating, Teflon, PTFE, HDG, or as-forged, per customer specification
- Dimensional Inspection: 100% dimensional inspection per DIN 931/933 and ASME B18.2.1
- Mechanical Testing: Tensile, yield, hardness, and impact testing per ASTM standards
- Non-Destructive Testing (NDT): UT / MT / PT available on request for critical components
- Documentation: EN 10204/3.1 MTC issued with every shipment; radiography and NACE compliance on request
Incoloy 925 vs. Other High-Performance Alloys for Fasteners
| Property | Incoloy 925 | Incoloy 825 | Inconel 625 | Super Duplex 2507 | SS 316L |
| UNS Designation | N09925 | N08825 | N06625 | S32750 | S31603 |
| Tensile Strength | 965 MPa | 586 MPa | 827 MPa | 795 MPa | 485 MPa |
| Yield Strength | 758 MPa | 241 MPa | 414 MPa | 550 MPa | 170 MPa |
| Max. Temp. (°C) | 650 | 550 | 980 | 300 | 400 |
| NACE MR0175 Sour Service | Yes | Limited | Yes | Yes | No |
| Age-Hardenable | Yes | No | Yes (cold work) | No | No |
| SCC Resistance (Chloride) | Excellent | Good | Excellent | Very Good | Fair |
| Relative Cost (approx.) | High | Moderate | Very High | Moderate-High | Low |
| Primary Application | Downhole / Sour Service | General Corrosion | High Temp / Corrosion | Seawater / Sour | General Chemical |
Global Export Coverage
Unifit Fastener exports Incoloy 925 Fasteners worldwide. Our export-ready inventory and logistics partnerships ensure timely delivery to any port.
| Region | Countries |
| Middle East | UAE, Saudi Arabia, Qatar, Kuwait, Oman, Bahrain, Jordan, Iraq, Iraq |
| Southeast Asia | Thailand, Singapore, Malaysia, Philippines, Indonesia, Sri Lanka, Bangladesh, Vietnam |
| Europe | United Kingdom, Germany, Italy, France, Belgium, Netherlands, Spain, Poland, Croatia |
| North America | USA, Canada, Mexico |
| South America | Brazil, Argentina, Colombia, Chile, Peru, Paraguay |
| Africa | Nigeria, Ghana, South Africa, Kenya, Egypt, Senegal, Tanzania |
| East Asia | China, Japan, South Korea |
| Oceania / Others | Australia, New Zealand, Papua New Guinea |
FAQs - Incoloy 925 Fasteners
The following FAQs are optimized for Google Featured Snippets and voice search.
The UNS (Unified Numbering System) designation for Incoloy 925 is N09925. It corresponds to Werkstoff Nr. (WNR) — (not assigned) and JIS NCF 925.
Incoloy 925 fasteners are primarily covered by ASTM B637 and ASME SB637, which govern bars, forgings, and fasteners made from UNS N09925 nickel alloy. Additional dimensional standards include ASME B18.2.1, DIN 931/933, and ISO 4014.
Incoloy 925 contains 42.0–46.0% Nickel, 19.5–22.5% Chromium, 22.0% min Iron, 2.5–3.5% Molybdenum, 1.5–3.0% Copper, 1.9–2.4% Titanium, 0.1–0.5% Aluminum, with controlled limits on Carbon, Manganese, Silicon, and Sulfur.
Incoloy 925 fasteners have a tensile strength of 140 ksi (965 N/mm²) and a 0.2% proof stress of 110–140 ksi (758–965 N/mm²), depending on heat treatment condition.
Yes. Incoloy 925 meets the requirements of NACE MR0175 / ISO 15156 for sour service applications. Its age-hardenable microstructure provides superior resistance to sulfide stress cracking (SSC) and stress-corrosion cracking (SCC) in H2S and CO2-containing environments, making it ideal for downhole tubing hangers, wellhead equipment, and Christmas tree components.
Unifit Fastener supplies Incoloy 925 Fasteners in metric sizes M0.2 to M33 and imperial sizes 3/16" to 2", with custom sizes available upon request. Lengths range from 3 mm to 200 mm, or as per customer specifications.