Inconel 718 Washers - UNS N07718 | ASTM B637 Certified Manufacturer & Exporter
Unifit Fastener | Trusted by 500+ Engineers Worldwide | Global Shipping in 7-14 Days
Unifit Fastener | Trusted by 500+ Engineers Worldwide | Global Shipping in 7-14 Days
Inconel 718 washers (UNS N07718 / W.Nr. 2.4668) distribute bearing loads up to 150,000 psi (1034 MPa) across flange faces without plastic deformation — a capability that eliminates the need for load-distribution plates in flanged joints operating above 400°C. Manufactured per ASTM B637, ASTM B670, and AMS 5596, Unifit Fastener's Inconel 718 washers are available in flat, Belleville, spring, and fender profiles from M2 to M100 metric and 1/4" to 2" imperial, with Rockwell hardness restricted to 40 HRC max for NACE MR0175 sour-gas service compliance. This precipitation-hardened alloy is the preferred choice for the most severe industrial applications where washers made of stainless steel or carbon steel are limited to a far more restricted range of temperatures—from -423°F to +1300°F (-252°C to +704°C).
Unifit Fastener produces and stocks all types of Inconel 718 washers, ranging from flat to slot to belleville, fender to sealing, split to machine, and star to square to countersunk washers, both metric and imperial. Each washer produced is made according to ASTM B637 and AMS 5596, mechanically tested, and full material test certified. If you are in offshore oil drilling, aerospace, nuclear power, or chemical processing, our Inconel 718 washers are sure to provide reliable, consistent performance when it counts.
Request a Quote| Parameter | Details |
| Material / Grade | Inconel 718 (UNS N07718 / W.Nr. 2.4668) |
| ASTM Standard | ASTM B637 (machined/forged); ASTM B670 / AMS 5596 (stamped, Belleville) |
| BS Standard | BS and all International Standards |
| Size Range | M2 to M100 (Metric) | 1/4" to 2" (Imperial) | 3 mm to 200 mm |
| Thickness Range | 0.5 mm to 12 mm (custom available) |
| Form | Flat, Fender, Spring, Belleville, Star, Sealing, Slot, Square, Countersunk, Tab, Dome, Machine, Spherical |
| Manufacturing Process | Machined, Forged, Stamped, CNC Precision |
| Finish | Mill finish, Bright annealed, Polished |
| Hardness | 36-44 HRC (Max 40 HRC for NACE MR0175 sour service) |
| Surface Treatment | Passivation, Electro-polishing (on request) |
| Property | Solution Annealed Condition | Precipitation Hardened (Aged) Condition | Unit / Notes |
| Ultimate Tensile Strength (UTS) | 135 ksi (930 MPa) Min | 185 ksi (1275 MPa) Min | Minimum |
| 0.2% Yield Strength | 70 ksi (482 MPa) Min | 150 ksi (1034 MPa) Min | Minimum |
| Elongation | 30% Min | 12% Min | In 2 in. (50 mm) |
| Hardness | Typically 20-35 HRC | 36-44 HRC | Rockwell C Scale |
| Density | 8.19-8.20 g/cm³ | 8.19-8.20 g/cm³ | Approximate |
| Melting Range | 1260-1336°C (2300-2437°F) | 1260-1336°C (2300-2437°F) | Solidus-Liquidus |
| Nominal Size | Inner Dia (mm) | Outer Dia (mm) | Thickness (mm) | Approx. Weight (kg/1000 pcs) |
| M6 | 6.4 | 12.5 | 1.6 | 1.14 |
| M8 | 8.4 | 17.0 | 1.6 | 2.14 |
| M10 | 10.5 | 21.0 | 2.0 | 4.08 |
| M12 | 13.0 | 24.0 | 2.5 | 6.27 |
| M16 | 17.0 | 30.0 | 3.0 | 11.30 |
| M20 | 21.0 | 37.0 | 3.0 | 17.20 |
| M24 | 25.0 | 44.0 | 4.0 | 32.30 |
| M30 | 31.0 | 56.0 | 4.0 | 53.60 |
DIN 9021 washers feature an outer diameter approximately 3x the inner diameter, delivering extended bearing surfaces ideal for flanged joints and softer flange materials.
| Nominal Size | Inner Dia (mm) | Outer Dia (mm) | Thickness (mm) | Approx. Weight (kg/1000 pcs) |
| M6 | 6.4 | 18.0 | 1.6 | 2.79 |
| M8 | 8.4 | 24.0 | 2.0 | 6.23 |
| M10 | 10.5 | 30.0 | 2.5 | 12.20 |
| M12 | 13.0 | 37.0 | 3.0 | 22.20 |
| M16 | 17.0 | 50.0 | 3.0 | 40.90 |
| M20 | 22.0 | 60.0 | 4.0 | 76.80 |
| M24 | 26.0 | 72.0 | 5.0 | 139.00 |
| M30 | 33.0 | 92.0 | 6.0 | 273.00 |
| Nominal Size | Approx. Weight (kg/1000 pcs) |
| M6 | 0.83 |
| M8 | 1.60 |
| M10 | 2.53 |
| M12 | 3.82 |
| M16 | 8.91 |
| M20 | 15.20 |
| M24 | 26.20 |
| M30 | 44.30 |
| Nominal | SAE Inner Dia (in) | SAE Outer Dia (in) | SAE Thick (in) | USS Inner Dia (in) | USS Outer Dia (in) | USS Thick (in) |
| 1/4" | 0.281 | 0.625 | 0.065 | 0.312 | 0.734 | 0.065 |
| 5/16" | 0.344 | 0.688 | 0.065 | 0.375 | 0.875 | 0.083 |
| 3/8" | 0.406 | 0.812 | 0.065 | 0.438 | 1.000 | 0.083 |
| 7/16" | 0.469 | 0.922 | 0.065 | 0.500 | 1.250 | 0.083 |
| 1/2" | 0.531 | 1.062 | 0.095 | 0.562 | 1.375 | 0.109 |
| 5/8" | 0.656 | 1.312 | 0.095 | 0.688 | 1.750 | 0.134 |
| Element | C | Mn | Si | S | P | Cr | Ni | Mo | Cb+Ta | Ti | Al | Co | Cu | Fe |
| % (Max/Range) | 0.08 max | 0.35 max | 0.35 max | 0.015 max | 0.015 max | 17-21 | 50-55 | 2.8-3.3 | 5.13 | 0.65-1.15 | 0.20-0.80 | 1.00 max | 0.30 max | Balance |
The high niobium (Cb+Ta) content at approximately 5.13% is the key strengthening agent in Inconel 718, forming gamma double-prime precipitates that deliver exceptional strength without making the alloy overly susceptible to strain-age cracking during welding - a critical advantage over older Inconel grades.
| Standard | Designation | UNS No. | WERKSTOFF Nr. | JIS | GOST |
| Inconel 718 | Alloy 718 | N07718 | 2.4668 | NCF718 | KhN45MVTYuBR (approx) |
Inconel 718's unique metallurgical composition delivers a performance profile unmatched by stainless steel, carbon steel, or other nickel alloys in high-stress, high-temperature environments:
| Industry / Sector | Specific Application | Why Inconel 718? |
| Oil & Gas / Offshore Drilling | Wellhead flanges, subsea bolted assemblies, Christmas trees | Sour gas resistance, NACE compliance, high preload retention |
| Aerospace & Defense | Turbine engine fasteners, airframe structures, rocket motors | High strength-to-weight ratio, extreme temp performance |
| Nuclear Power Generation | Reactor internals, pressure vessel flanges, control rod assemblies | Neutron embrittlement resistance, radiation stability |
| Gas Turbine / Power Generation | Combustor hardware, compressor discs, exhaust flanges | Creep and fatigue resistance at 650°C+ |
| Marine & Seawater Systems | Seawater heat exchangers, propulsion system flanges, desalination plants | Chloride corrosion and pitting resistance |
| Chemical & Petrochemical | Process vessel flanges, reactor internals, pump housings | Acid and alkali resistance, stable across pH extremes |
| Pharmaceutical & Food Processing | Hygienic flanged joints requiring FDA-compatible alloys | Corrosion resistance, non-reactive surface |
| Heat Exchangers & Condensers | Shell-and-tube flanges, plate heat exchanger bolting | Thermal cycling fatigue resistance |
| Pulp & Paper Industry | Digesters, bleaching equipment, piping system flanges | Resistance to organic acids and hot chloride solutions |
| Specialty Chemicals | High-pressure autoclaves, fluorine-service equipment flanges | Resistance to fluorine-related compounds |
| Property | Inconel 718 | SS 316L | SS 304 | Monel 400 | Hastelloy C276 |
| Maximum Recommended Service Temperature | 704°C (1300°F) | 480°C (900°F) | 420°C (800°F) | 500°C (930°F) | 680°C (1256°F) |
| Ultimate Tensile Strength (UTS) | 1275 MPa (Aged) | 485 MPa | 515 MPa | 550 MPa | 790 MPa |
| Yield Strength (0.2% Offset) | 1034 MPa (Aged) | 170 MPa | 205 MPa | 240 MPa | 355 MPa |
| Chloride SCC Resistance | Excellent | Poor | Very Poor | Excellent | Excellent |
| H2S / Sour Gas Service | Yes (NACE MR0175) | Limited | No | Yes | Yes |
| Cryogenic Service | Yes (to -252°C) | Yes (to -196°C) | Yes (to -196°C) | Yes (to -160°C) | Limited |
| Weldability | Excellent | Excellent | Excellent | Good | Good |
| Relative Cost | High | Low-Medium | Low | Medium | Very High |
| Test Type | Standard / Method |
| Tensile Strength Testing | ASTM E8 / EN 10002-1 |
| Hardness Verification | Rockwell C (ASTM E18) - HRC 36-44; max 40 for NACE |
| Chemical Spectro Analysis | OES (Optical Emission Spectroscopy) |
| PMI - Positive Material Identification | Portable XRF / OES |
| 100% Dimensional Inspection | CMM / Optical comparator per DIN / ASME |
| Ultrasonic Testing (UT) | ASTM A388 for critical applications |
| Intergranular Corrosion Test (IGC) | ASTM A262 Practice E |
| Pitting Resistance Test | ASTM G48 Method A |
| Micro & Macro Examination | ASTM E112 |
| Flattening / Flaring Test | Per applicable ASTM standard |
| Radiography (100%) | Available for aerospace critical parts |
| Third Party Inspection (TPI) | SGS, Bureau Veritas, DNV, TUV |
Inconel 718 Washers are manufactured per ASTM B637, ASTM B670 / AMS 5596, and DIN / ASME B18.22.1 dimensional standards. Sour-gas applications require NACE MR0175 / ISO 15156 compliance, restricting hardness to a maximum of 40 HRC.
Inconel 718 Washers maintain reliable mechanical properties up to approximately 704°C (1300°F). For cryogenic applications, the alloy performs exceptionally well down to -252°C (-423°F).
Standard sizes range from M2 to M100 in metric and 1/4" to 2" in imperial SAE and USS profiles. Custom outer diameters from 3 mm to 200 mm and non-standard thicknesses are available on request.
Inconel 718 offers significantly higher tensile and yield strength due to niobium-based precipitation hardening, making it the better choice where mechanical load-bearing capacity is primary. Inconel 625 has superior corrosion resistance in highly oxidizing acids and seawater but lower strength in the annealed condition.