ASTM B865
Monel K500
Fasteners
K500 vs Monel 400 — Why K500 for Fasteners
Monel 400 (UNS N04400) delivers outstanding corrosion resistance in seawater, HF acid, and chloride environments — but with a tensile strength of only ~480 MPa annealed, it cannot carry the clamping loads required in high-pressure flanged pressure joints and offshore structural connections. Monel K500 solves this completely.
Adding aluminium (2.3–3.15%) and titanium (0.35–0.85%) to the Monel 400 base, then solution-annealing at 980°C and age-hardening at 593°C, creates coherent Ni₃(Al,Ti) gamma-prime precipitates — the same mechanism used in turbine superalloys. This raises UTS to ≥1000 MPa with yield strength ≥690 MPa while elongation stays ≥20%. Three times the strength of Monel 400 with identical corrosion resistance.
K500’s low magnetic permeability additionally qualifies it for non-magnetic naval equipment, minesweeper hardware, and proximity-sensitive subsea instrumentation where ferromagnetic fasteners would cause interference. See our complete exotic alloy fastener range for grade selection guidance.
| Element | Min % | Max % | Typical |
|---|---|---|---|
| Nickel + Cobalt | 63.0 | — | ~65% |
| Copper (Cu) | — | Balance | ~30% |
| Aluminium (Al) | 2.30 | 3.15 | ~2.7% |
| Titanium (Ti) | 0.35 | 0.85 | ~0.6% |
| Iron (Fe) | — | 2.0 | ~1.5% |
| Manganese (Mn) | — | 1.5 | — |
| Carbon (C) | — | 0.25 | — |
| Silicon (Si) | — | 0.50 | — |
| Sulfur (S) | — | 0.010 | — |
Monel K500 Hex Bolts
Machined from ASTM B865 age-hardened UNS N05500 bar stock. Full thread (DIN 933) and partial thread (DIN 931). Heavy hex for ASME flange service. PMI-verified, NABL-tested, dispatched with full MTC. K500 hex bolts are the standard specification for marine propeller shaft locking, offshore deck equipment, and seawater pump flanges where Monel 400 lacks sufficient strength.
| Spec | Details |
|---|---|
| Material | UNS N05500 / Monel K500 |
| Standard | ASTM B865 · AMS 4676 |
| Size Range | M6 — M100 |
| Thread | Metric · UNC · UNF |
| Head | Hex · Heavy Hex · Flanged |
| UTS | ≥ 1000 MPa |
| 0.2% YS | ≥ 690 MPa |
| Elongation | ≥ 20% |
| Hardness | ≤ 35 HRC |
| Condition | Age Hardened |
Monel K500 Stud Bolts
Fully threaded and double-end stud bolts in K500 for ASME B16.5 flanged pressure joints in seawater and offshore service. Matched K500 heavy hex nuts supplied as a certified set. Lengths to 3,000mm. NACE MR0175 compliant for sour service applications.
| Spec | Details |
|---|---|
| Material | UNS N05500 / Monel K500 |
| Standard | ASTM B865 · ASME B16.5 |
| Size Range | M12 — M100 |
| Max Length | 3,000 mm |
| Config | Full Thread · Equal · Unequal End |
| Press. Class | ASME 150# to 2500# |
| UTS | ≥ 1000 MPa |
| NACE | MR0175 Compliant |
Monel K500 Hex Nuts
Standard (DIN 934) and heavy hex (ASME B18.2.2) nuts in age-hardened K500. Manufactured from the same certified B865 heat as matching bolts — identical composition for galvanic compatibility in seawater service. Coupling nuts (DIN 6334) and nyloc options available on request.
| Spec | Details |
|---|---|
| Material | UNS N05500 / Monel K500 |
| Standard | ASTM B865 · DIN 934 · ASME B18.2.2 |
| Size Range | M6 — M100 |
| Types | Std Hex · Heavy Hex · Coupling |
| Thread | Metric · UNC · UNF |
| Hardness | ≤ 35 HRC |
| NACE | MR0175 / ISO 15156 |
Monel K500 Washers
Plain flat (DIN 125) and spring (DIN 127) washers in Monel K500. M5–M100. Maintaining matched alloy material throughout the bolted joint eliminates galvanic couples that accelerate corrosion of a dissimilar washer in permanent seawater immersion. Similar to how we supply Hastelloy B3 washers with B3 stud bolt sets.
| Spec | Details |
|---|---|
| Material | UNS N05500 / Monel K500 |
| Standard | ASTM B865 · DIN 125 · ISO 7089 |
| Size Range | M5 — M100 |
| Types | Plain Flat · Spring · Large OD |
Monel K500 Socket Cap Screws
ISO 4762 socket head cap screws in age-hardened K500 for marine valve bodies, pump casing covers, and enclosed subsea equipment. High-torque socket drive in a compact geometry — combines K500’s 1000 MPa strength with full seawater corrosion resistance in confined access spaces.
| Spec | Details |
|---|---|
| Material | UNS N05500 / Monel K500 |
| Standard | ISO 4762 · DIN 912 · ASTM B865 |
| Size Range | M3 — M36 |
| Drive | Hex Socket (Allen) |
| UTS | ≥ 1000 MPa |
Monel K500 Threaded Rods
Fully threaded rods (DIN 975/976) in Monel K500 for marine hanger rods, subsea cable clamp studs, and offshore structural tie rods. Cut from ASTM B865-certified bar. Lengths to 3,000mm. Metric and inch thread forms. Right and left-hand available.
| Spec | Details |
|---|---|
| Material | UNS N05500 / Monel K500 |
| Standard | DIN 975 · DIN 976 · ASTM B865 |
| Diameter | M6 — M100 |
| Max Length | 3,000 mm |
| Thread | Metric · UNC · UNF · BSW |
| UTS | ≥ 1000 MPa |
ASTM B865 Monel K500 Full Product Matrix
All products machined from ASTM B865 / AMS 4676 certified UNS N05500 bar. Age-hardened in-house. Properties per ASTM A370. Custom sizes on request to sales@akbarfasteners.in.
| Product | Standard | Size Range | UNS No. | UTS | 0.2% YS | Hardness | Condition |
|---|---|---|---|---|---|---|---|
| MONEL K500 BOLTS | |||||||
| Hex Bolts — Full Thread | DIN 933 / ISO 4017 | M6–M100 | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
| Hex Bolts — Part. Thread | DIN 931 / ISO 4014 | M6–M100 | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
| Heavy Hex Bolts | ASME B18.2.3.6M | M12–M100 | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
| STUD BOLTS | |||||||
| Fully Threaded Stud | ASME B16.5 / DIN 976 | M12–M100 | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
| Double-End Stud | DIN 939 / DIN 938 | M6–M100 | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
| NUTS | |||||||
| Hex Nuts | DIN 934 / ISO 4032 | M6–M100 | N05500 | — | — | ≤35 HRC | Age Hard. |
| Heavy Hex Nuts | ASME B18.2.2 | M12–M100 | N05500 | — | — | ≤35 HRC | Age Hard. |
| WASHERS · SCREWS · RODS | |||||||
| Plain Flat Washers | DIN 125 / ISO 7089 | M5–M100 | N05500 | — | — | — | AH / Ann. |
| Socket Cap Screws | ISO 4762 / DIN 912 | M3–M36 | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
| Threaded Rods | DIN 975 / DIN 976 | M6–M100 ≤3000mm | N05500 | ≥1000 MPa | ≥690 MPa | ≤35 HRC | Age Hard. |
Standards We Manufacture & Test To
Every order traced from mill heat to dispatch. Full documentation package standard — same as our Hastelloy B3 stud bolts and all exotic alloy fasteners.
Monel K500 Fastener Applications
The combination of ≥1000 MPa strength, permanent seawater immunity, non-magnetic behaviour, and NACE MR0175 compliance makes K500 the specification-of-choice in the world’s most demanding marine and offshore environments.
Marine & Offshore
riser clamps · splash zone
Seawater Systems
desalination plants
Pump Shafts
pump casing bolts
Oil & Gas
wellhead equipment
Chemical Processing
alkali environments
Naval & Defence
minesweeper hardware
Power Generation
seawater circuit bolts
Subsea Equipment
Xmas tree assemblies
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Related Monel & Nickel Alloy Fasteners
Every component in the same certified UNS N05500 heat, or explore alternative alloys for different service environments.
Monel 400 Fasteners
Annealed Ni-Cu for lower-strength marine applications. Same seawater corrosion resistance, lower cost. ASTM B164. M6–M100.
View Page →Hastelloy B3 Stud Bolts
For HCl and reducing acid environments where Monel is not the specification. ASTM B335, ASME B16.5. Class 150–2500.
View Page →Hastelloy B3 Washers
Plain flat and spring washers in Hastelloy B3 to DIN 125. M5–M100. Complete flanged joint documentation from one source.
View Page →All Hastelloy Grades
Full Hastelloy range as bolts, studs, nuts, washers. Grade selection guidance for your specific service environment.
View All Grades →Need ASTM B865
Monel K500 Fast?
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