Galling resistant stainless - proprietary alloys

[prdave00]

I've been exploring "galling resistant" stainless alloys. Nitronic 60, Gall-Tough, and Gall-Tough PLUS are all being considered. The melt chemistries of Nitronic 60 and Gall-Tough PLUS are similar with the exception of manganese limits. Data sheets also list the UNS S21800 designation for both these alloys so I assume both fall within the composition limits for that designate. The original Gall-Tough grade appears to be the only one on the market of its kind and therefore a single source material.

Anyone familiar with Nitronic 60 & Gall-Tough PLUS to comment on the equivalence (or difference) of the two in terms of galling resistance against, say, 17-4 stainless in the H900 condition. I'd like to have two sources for the UNS S21809 stainless, but only if I can convince myself that these two alloys are equivalent for all intents and purposes.

 

[blacksmith37]

I would say you need a galling test standard (I do not see one in the ASTM index)so you are not relying on mfgrs claims. You may need to develope your own test; try searching under "tribology".(Many years ago I worked for a company that developed its own galling test, but it was not published).

 

[EdStainless]

I would consider the two S21809 alloys are being equivalent. They will be closer to each other than any other two alloys that you could select, and against a hardened PH grade should perform very well (at least for a SS).
If the parts are small you might want to look at some Co based alloys (low carbon ones). They have extremely good gall resistance, and a price to go along with it.

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Plymouth Tube

 

[prdave00]

Thanks gents.

blacksmith37: Although I'm not presently interested in independently characterizing galling resistance, I did come across ASTM G98-02(2009) Standard Test Method for Galling Resistance of Materials in case anyone else is interested. It looks like the first issue was 1991, so maybe too early to use to generate the data in Carpenter's and Armco's literature for Gall-Tough (PLUS) and Nitronic 60, respectively.

I am trying to put my best foot forward in terms of stainless steel alloy selection to give be a good shot at mitigating galling without the used of lubricants. I especially want to keep my options open by avoiding single source alloys - like Gall-Tough. Turns out Nitronic 60 is the more available of the two UNS S21800 alloys, so it looks like my choice has been made up for me as to which to try first.

Ed: I'll see how Nitronic 60 performs and see if I need to cast my net out further to capture Co, Cu, or Ni based alloys. Any recommendations on a Co based alloy for future consideration?

 

[unclesyd]

The first link is to ARMCO's wear and galling data for Nitronic 60 and others. If you application will allow it you might want to consider Waukesha 88. It has excellent anti galling properties and very good corrosion resistance. It works with most SS. Waukesha has other anti galling alloys.
The third link is for information on the QPQ nitrocarburizing process. Using this process I've had outstanding results using nitrided 17/4 versus Nitronic 60. I have one application,drum and sleeve, in split case horizontal pumps used in acidic service that have been running running for 30 years. There are three pumps with two one stream 24/7/365 with one swinging to take up any slack. The pumps are are rotate yearly.
Of the Stellite alloys we use mainly alloy 6 and 12.

Will you application allow Copper based alloys?

http://www.hpalloy.com/alloys/brochures/Nitronic60book.pdf

Download the "Food Processing Brochure".

http://www.waukeshafoundry.com/#/LiteratureDownloads

http://www.burlingtoneng.com/index.html

 

[EdStainless]

I have used both L605 and Ulitmet for galling and cavitation resistance. These alloys are actually rather soft but the surface work hardens very fast and makes them very robust.

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Plymouth Tube

 

[prdave00]

Cu-based ToughMet, Ni-based WM88, and Co-based alloys such as BioDur CCM+ / Acube 100 are all on the radar, but Nitronic 60 is at the top of the list for a variety of reasons including availability. The assembly is for medical instrumentation so we are trying to stick with stainless steels suggested/covered by ISO 7153 and/or ASTM F899 standards. I'd have to think on Cu-based alloys being OK since I've never designed with them for this type of application. Surface treatments and coatings are not ideal, as it would add another processing step and yet another thing to control. This instrumentation will see no more than 10 uses before these components with sliding counterfaces are replaced, so there is an eye toward keeping things as low cost as possible.