Monel K500 is a precipitation-hardenable nickel-copper alloy that combines the excellent corrosion resistance characteristic of Monel 400 with the added advantage of greater strength and hardness. These amplified properties, strength and hardness, are obtained by adding aluminum and titanium to the nickel-copper base and by a thermal processing used to effect precipitation, typically called age hardening or aging. When in the age-hardened condition, Monel K-500 has a greater tendency toward stress-corrosion cracking in some environments than Monel 400. Alloy K-500 has approximately three times the yield strength and double the tensile strength when compared with alloy 400. Plus, it can be further strengthened by cold working prior to precipitation hardening. The strength of this nickel steel alloy is maintained to 1200° F but stays ductile and tough down to temperatures of 400° F. Its melting range is 2400-2460° F.
This nickel alloy is spark resistant and non-magnetic to -200° F. However, it is possible to develop a magnetic layer on the surface of the material during processing. Aluminum and copper may be selectively oxidized during heating, leaving a magnetic nickel rich film on the outside. Pickling or bright dipping in acid can remove this magnetic film and restore the non-magnetic properties.
Chemical composition
| Element | Ni | Al | C | Fe | Mn | Si | Ti | S | Cu |
| Weight(%) | 63.0 min | 2.30~3.15 | 0.18 max | 2.0 max | 1.5 max | 0.5 max | 0.35~0.85 | 0.010 max | 27.0~33.0 |
Advantages
- Corrosion resistance in an extensive range of marine and chemical environments. From pure water to non-oxidizing mineral acids, salts and alkalis.
- Excellent resistance to high velocity sea water
- Resistant to a sour-gas environment
- Excellent mechanical properties from sub-zero temperatures up to about 480C
- Non-magnetic alloy
Applications
- Sour-gas service applications
- Oil and gas production safety lifts and valves
- Oil-well tools and instruments like drill collars
- Oil well industry
- Doctor blades and scrapers
- Chains, cables, springs, valve trim, fasteners for marine service
- Pump shafts and impellers in marine service
