MP35N / UNS R30035 (also ATI 35N): A Versatile Alloy For The Aerospace, Oil & Gas, & Motor Sport Industries

UNS R30035, more readily known by its trademark names MP35N™ – SPS Technologies LLC / Latrobe Speciality Metals / Carpenter Technology Corporation – and ATI 35N™ – ATI Speciality Metals – is a cobalt-nickel alloy with a unique combination of properties that provide ultra high strength, toughness, ductility, and outstanding corrosion resistance.

UNS R30035 is used for aerospace applications, in the oil and gas industry (where its resistance to crevice and stress corrosion cracking in harsh environments – hydrogen sulphide, salt water and other chloride environments, as well as attack from mineral acids (nitric, hydrochloric and sulphur) – makes it stand out from other materials), and in formula class motor racing and high specification supercars where the high strength to weight ratio is used to maximum effect.

UNS R30035 is used for fasteners, valve components – especially stems, springs, high pressure door dogs, and pins – and specialist engineering components. Its use in bar form is only limited by the maximum diameter (3” – 76.2 mm) that the product is currently available in.

This article is one of a series that we are providing for our customers, and other stockists who come to us to source their metal, to help explain and provide technical guidance in the use of the metal:

  • Article 1: Types of UNS R30035 and the basic properties.
  • Article 2: Properties required to comply with AMS 5844 and AMS 5845.
  • Article 3: Properties required to comply with NACE MR0175 / ISO 15156.
  • Article 4: Machining of UNS R30035.
  • Article 5: Welding of UNS R30035.

Broder Metals Group Ltd stocks UNS R30035 to meet NACE MR0175 / ISO 15156 as well as material compliant with AMS 5844. The latter comes with capability tests to meet AMS 5845 – if that means nothing to you, please read on to understand the types of UNS R30035 in our stock and the basic properties of the metal.

UNS R30035 chemistry is made up of is 33-37% Nickel, 19-21% Chrome, and 9-10.5% Molybdenum, small additions of Titanium and Iron (1% max each), Carbon, Manganese, Silicon, Phosphorous and Sulphur (all less than 0.15% each). Cobalt is the balancing element (around 33%).

As UNS R30035 is a multi-phase alloy, it is not just the expensive chemistry above that produces the benefits to justify use of the product. The material is produced by vacuum induction melting followed by VAC-ARC remelting to provide exceptional control of chemistry and ingot solidification. However, what makes the product conspicuous is the combination of cold work reduction applied in conjunction with the final ageing temperature, giving a wide range of mechanical and corrosion resistant properties.

UNS R30035 related specifications are as follows:

  • AMS 5758
    • Solution heat treated and centreless ground bars up to 1.75” diameter.
    • Broder Metals Group do not stock this specification and concentrate instead on material that meets the higher strength specifications below.
  • AMS 5844
    • Solution heat treated and cold drawn bars up to 1.75” diameter.
  • AMS 5845 – Solution heat treated, cold drawn and aged bars up to 1.75” diameter.
    • Most of our customers find the material in the final aged condition too difficult to machine, so prefer the unaged AMS 5844 material, which can be upgraded to AMS 5845 through a final ageing process after they have produced the fastener or component they require. Our AMS 5844 material comes with an aged capability test result which shows what the material properties will be after ageing the component.
    • Broder Metals Group also offer the option for the customer to provide us with the components they have machined from our material and we will age the components for them if they are not able to undertake the ageing process themselves. This can be based on the capability test results or we can undertake final full mechanical testing after ageing (at an ISO 17025 approved test house, under intent of 3.2 if required) to provide a fully certified product.
  • AMS 7468
    • Bolts and screws, forged head, roll threaded after aging.
    • Can be produced from our material.
  • Compliant to NACE standard MR0175 / ISO 15156 – sulphide stress cracking resistant material for oil field equipment.
    • A category of this grade that we also stock.

Our next article will go into the AMS 5844 / 5845 grades in more detail.

Broder Metals Group hope that these articles are useful and would welcome enquiries for our stock range and any questions not covered.

Copyright © 2019 Broder Metals Group
Acknowledgement: all values quoted are courtesy of Carpenter Technology Corporation: “MP35N: A Superalloy for Critical OIL and Gas Applications”

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Types of MP35N UNS R30035 and the basic properties