MP159 is a multiphase cobalt nickel alloy that develops extremely high strength through a combination of cold work and aging. It reaches roughly 260 ksi tensile with good ductility and keeps that strength to around 1100F, well beyond conventional fastener alloys.
It is used where a fastener or fitting must be both very strong and corrosion resistant at temperature, notably in engine and airframe attachment hardware.
Stocked as bar and wire in the cold worked or cold worked and aged condition.
Sizes and stock
- Round bar: up to 1.51" DIA
Processing capabilities
- Billet conversion and open die, closed die and ring forging
- Solution treat, age and anneal to the applicable spec
- Saw cutting, trepanning, gun drilling and CNC machining
- Ultrasonic, penetrant dye, micrography and physical testing
Specifications
Material is released to the applicable specification with mill test reports and, on request, independent lab verification.
Why engineers specify MP159
- Extremely high strength for a corrosion resistant alloy
- Retains strength to about 1100F
- Good ductility and stress corrosion resistance at strength
- Established fastener and hardware material
Nominal chemistry
Percent by weight, nominal composition per the governing specification. The mill test report for your heat is the controlling document.
Typical mechanical properties
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| Cold worked and aged | 260 ksi min | 245 ksi min | 8% min | - |
Typical published values for reference only, not for design. Properties vary with section size, product form and processing. Order to the specification and condition your drawing requires.
Typical applications
- High strength aerospace fasteners
- Engine attachment hardware
- Springs in hot corrosive service
- Highly loaded fittings
Fabrication notes
Machining
Nickel and cobalt superalloys work harden aggressively. Use rigid setups, sharp tooling, slow speeds, positive feed that stays under the hardened skin, and flood coolant. Age hardened material machines far more slowly than solution treated material, so rough before aging wherever the print allows.
Welding
Most solid solution grades weld readily with matching filler. Age hardenable grades such as 718 and Waspaloy are welded in the solution treated condition and aged afterward to control strain age cracking.
Forming
Hot working ranges are narrow and forces are high. Cold form in the annealed condition with intermediate anneals, and stress relieve before final heat treatment.
MP159 compared with similar grades
MP35N
Similar multiphase system with lower strength and excellent corrosion resistance.
A286
Much lower strength, lower cost, very widely used for engine fasteners.
Designations and cross reference
- Material family
- Nickel & Cobalt Alloys
Working from an obsolete, foreign or superseded designation? Send it over and we will cross reference it to a current grade and specification.
Quality, testing and traceability
Supplied with mill test reports and heat traceability, with ultrasonic inspection, penetrant dye, micrography, grain size, stress rupture and mechanical testing available on request.
We are AS9100D and ISO 9001:2015 registered. If our stock does not already carry the inspection your specification requires, we can quote the material with that work performed. More on our quality system
Available forms
Custom sizes converted from billet, plus saw cut, waterjet and near-net blanks. See custom conversions
MP159 frequently asked questions
What is MP159?
MP159 is a multiphase cobalt nickel alloy that develops extremely high strength through a combination of cold work and aging. It reaches roughly 260 ksi tensile with good ductility and keeps that strength to around 1100F, well beyond conventional fastener alloys.
What forms is MP159 available in?
We supply MP159 in bar. Custom sizes are converted from billet, and we can provide saw cut, waterjet or near net blanks so material arrives closer to your finished part.
What specifications can MP159 be supplied to?
Commonly ordered specifications include AMS 5841, AMS 5842. Material is released to the specification and condition on your purchase order, with mill test reports supplied as standard.
What conditions can MP159 be ordered in?
We can supply Cold worked and aged. If our stock is not already in the condition you need, we can quote it with the heat treatment performed before shipment.
Can you cut MP159 to size?
Yes. Saw cutting, waterjet, laser and shearing are available, along with trepanning, gun drilling, lathe turning and CNC machining, so you can order blanks or rough machined pieces rather than full lengths.
Do you provide test reports and additional testing on MP159?
Every order ships with mill test reports and heat traceability. If your print calls for ultrasonic inspection, penetrant dye, magnetic particle, chemical assay, micrography, hardness or mechanical testing and our stock does not already carry it, we can quote the material with that work performed.
Can MP159 be supplied to DFARS domestic melt requirements?
Tell us at quote stage if the order is DFARS or domestic melt restricted and we will confirm availability against that requirement before you commit.
What do you need to quote MP159?
Grade, form, dimensions, quantity, specification and condition, plus any testing or certification requirements and the date you need it. Send a drawing if you have one. Quotes are typically ready within 24 hours.
How does MP159 compare with MP35N?
Similar multiphase system with lower strength and excellent corrosion resistance.