Monel K-500 (UNS N05500)
Monel 400 corrosion resistance with more than twice the strength — 130 ksi tensile, 90 ksi yield and 24 to 37 HRC — for pump shafts, subsea fasteners and oil-tool components.
What Monel K-500 is.
Monel K-500 adds about 3 percent aluminum and 0.6 percent titanium to the nickel-copper base of Monel 400. A 16 hour age at around 1100 °F precipitates a fine intermetallic that raises the yield strength to 90 ksi and hardness to 24 to 37 HRC while keeping essentially the same resistance to seawater, brine and hydrofluoric acid.
ASTM F468 covers K-500 fasteners as Ni 500 with a 130 ksi minimum tensile. We machine studs, bolts and nuts from certified B865 bar and have them aged to the specification, with the ageing cycle on the certificate.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Nickel | Ni | 63.0 | 70.0 |
| Copper | Cu | balance | — |
| Aluminum | Al | 2.30 | 3.15 |
| Titanium | Ti | 0.35 | 0.85 |
| Iron | Fe | — | 2.0 |
| Manganese | Mn | — | 1.5 |
| Carbon | C | — | 0.25 |
| Silicon | Si | — | 0.5 |
| Sulfur | S | — | 0.01 |
Values per ASTM F468-23 Table 1 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Mechanical properties.
| Nominal diameter (in.) | Hardness | Full-size tensile (ksi) | Full-size yield, min (ksi) | Machined tensile, min (ksi) | Machined yield, min (ksi) | Elongation in 4D, min (%) |
|---|---|---|---|---|---|---|
| 0.250 to 0.875 | 24–37 HRC | 130–180 | 90 | 130 | 90 | 20 |
| 1.000 to 1.500 | 24–37 HRC | 130–180 | 85 | 130 | 85 | 20 |
Values per ASTM F468-23 Table 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
| Nut style | Hardness, min | Proof stress, min (ksi) |
|---|---|---|
| Hex and hex flange | 24 HRC | 130 |
| Heavy hex, large hex flange and thick | 24 HRC | 140 |
Values per ASTM F467-24 Table 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Specifications that apply.
How Monel K-500 ships from Houston.
- Studs, hex bolts and cap screws to F468
- Hex and heavy hex nuts to F467
- Pump shafts, valve stems and oil-tool components machined to print
- Certified B865 bar, annealed or aged
Monel K-500 fasteners we make.
Every item is manufactured to your drawing or standard in Monel K-500, imperial or metric, with an EN 10204 3.1 certificate.
What is Monel K-500?
K-500 is the age-hardenable member of the Monel family. Aluminum and titanium form gamma-prime precipitates during a low-temperature age, roughly doubling the yield strength of Monel 400 without a quench. The alloy keeps Monel 400's resistance to seawater and hydrofluoric acid, adds resistance to galling and erosion, and stays non-magnetic well below room temperature, which matters for oil-well logging and survey tools.
Fastener requirements
ASTM F468 lists K-500 as Ni 500 (marking F468W): 130 to 180 ksi full-size tensile, 90 ksi yield to ⅞ inch and 85 ksi above, hardness 24 to 37 HRC. F467 nuts (F467W) carry a 130 ksi proof stress. For sour service NACE MR0175 limits K-500 to 35 HRC in the aged condition; ask for nuts and studs selected to that limit.
Machining and ageing
K-500 is machined in the solution-annealed condition and aged afterwards; the age causes a small, predictable contraction that is allowed for on threads and close-tolerance diameters. Ageing after threading also gives the thread root the full properties, which is the same principle as tempering B7 after threading.
Testing, certification and marking
- Tensile and hardness tested per lot on the finished product
- Grade or alloy marking F468W on bolts and F467W on nuts and manufacturer's identification on every piece
- EN 10204 3.1 material test report with heat number and chemistry; 3.2 witness available
- Ageing cycle recorded on the certificate
Recent Monel K-500 jobs.
Monel 400 (UNS N04400)
The nickel-copper alloy that shrugs off seawater, brine and hydrofluoric acid — the classic marine and chemical fastener material, non-sparking and tough to cryogenic temperatures.
ASTM B637 bar · AMS 5662 / 5663 · API 6A CRAInconel 718 (UNS N07718)
The premier high-strength nickel superalloy — 185 ksi tensile and 150 ksi yield from cryogenic temperatures to 1200 °F, with corrosion and sour-gas resistance to match.
ASTM A1082 bolting · ASTM A564 bar17-4 PH Stainless (Type 630, UNS S17400)
The high-strength stainless — up to 190 ksi in H900, or 115 to 135 ksi with real toughness in the H1150 conditions — for pump shafts, valve stems, subsea and aerospace fasteners.