A286 galling

[kevlar49]

Will I still have galling problems with A286 on A286 if they are both aged to AMS 5737?

 

[EdStainless]

What is the minimum strength required by 5737?
And is there any lubrication?

It would be better to have dissimilar metals, but at higher strengths it makes less of a difference.

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Plymouth Tube

 

[CoryPad]

Can you share any application details?

 

[kevlar49]

A286 bearing on A286 shaft. constraints: UTS 220ksi, oxygen compatibility (difficult to ignite in liquid oxygen), reasonable ductility at cryogenic temperatures. Will 15-7 CH900 or RH 900 do against an A286 component? or does anyone see a problem with using it?

 

[TVP]

Under high contact stresses, such as a bearing on a shaft, I have some concerns about galling. Even 15-7 PH against A286 will have a high propensity for galling, just due to the inherent oxide film on the surfaces. Any chance that you could make one of the parts out of a high strength copper alloy like ToughMet 3TS from Materion?

http://materion.com/Products/Alloys/ToughMetCopperNickelTinAlloys/ToughMet3TS.aspx

 

[tbuelna]

kevlar49-

If you need a corrosion resistant alloy with good strength (Fbru>220ksi) and toughness that is also suitable for LOx service (<-297degF), a better choice might be 718 Inconel in a solution treated/aged condition. If galling is still a concern with 718 there are a couple of LOx compatible coatings you can apply to the surface of one or both parts. You can use thin dense chrome which is extremely hard. Or you can consider using Vitrolube, which provides some amount of lubricity but also has limited (around 50ksi) surface contact pressure capability. Vitrolube is commonly used to coat the sliding contact surfaces of components (balls, sockets, bushings, shafts, etc.) inside the LOx ducts on space launch vehicles.

Hope that helps.
Terry

 

[kevlar49]

TVP,
don't see promoted combustion or impact testing in MAPTIS for ToughMet 3TS. Do you know where I could find data on this?

 

[TVP]

I am not aware of any data in the public domain. I would contact Materion to discuss the application. Otherwise, I think Terry's suggestion is a reasonable one.