New Surface Hardening Process

[JohnNabors]

I just read an article in a newsletter about a new surface hardeneing process that is being studied for stainless. I will partially quote the article:

"A recent cooperative research effort, funded in part by the Department of Energy, and involving Case Western Reserve University (CWRU), Oak Ridge National Laboratory, the Naval Research Labs and the commercial company Swagelock, produced the development of a new quite promising diffusional surface hardening process.

When applied to Stainless Steel Type 316 it provides an increase in surface hardness, improved resistance to wear, corrosion and fatigue without impairing ductility.

The uniform hardness gradient avoids any risks of delamination or peeling. The microstructure remains austenitic and non magnetic throughout the process. The treatment is performed at the relatively low temperature of 470C (878F) that does not alter dimensions or produce distortions."

The article goes on to mention that this process is also being studied for PH stainless, duplex alloys, and cobalt and nickel based high temp alloys. Does anyone have any more information about this process including any indication of when it might become commercially available?

-John

 

[TVP]

The September 2006 issue of Advanced Materials & Processes has a short article about this process. It won ASM's 2006 Engineering Materials Achievement Award. The following is an excerpt:

At present, Swagelok uses the technology for treatment of tube fitting rear ferrules, mostly manufactured in type 316 stainless steel. Swagelok intends to make the technology available commercially to third parties, and will set up a new business unit to support these efforts.

I would keep an eye on the Swagelok website or contact someone such as Dr. Sunniva Collins, who was the author of the AM&P article.

 

[EdStainless]

You could contact Sunniva, she would route you to the right person.
It is an interesting process. It has a rather complex set of limitations, but offers some great potential. Personally I can see this becoming a major force in the medical device biz.
I worked on a similar process using nitrogen many years ago. We couldn't control things tightly enough to make it work.

Applying it to higher strength substates (duplex and PH) would greatly expand it usefulness.

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[arunmrao]

How do you recommend salt bath nitriding for 304 parts. A few of my casting users are using this effectively in their machines.

 

[kenvlach]

Their technique of using an HCl gaseous mixture in situ to activate the surface (remove oxides, etc) would benefit the plasma nitriding process, although upgraded equipment materials would seem necessary.
Article in the Sept/Oct issue of Heat Treating Progress mentions having to polish away a 1-micron thick, oxygen contaminated surface layer of nitrided parts. Isn't there some way to avoid this, maybe with reverse polarity prior to nitriding (or sputter cleaning)?

 

[EdStainless]

Can you nitride without forming any nitrides? Think of this process as carbon implantation. No carbides are formed. That is why the material stays nonmagnetic and why it does not hurt corrosion resistance.

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[unclesyd]

EdStainless
Yes.
Take a look at the "SolNit-A" process by Ipsen (Europe).
There is some information at the Industrial Heating site.

http://www.industrialheating.com

arunmrao,

I have liquid nitrided many components of 304, especially SS conveying lines. I have even liquid nitrided 303 for outstanding wear resistance, probably one of the best.

kenvlach
I have used Vapor Phase Fluoride Ion cleaning prior to nitriding parts. The Kolene QPQ process uses a mechanical means to remove the skin of a salt bath nitrided part.
Over the year I tried different nitriding process but always return to liquid for SS due to thw white case problem.

 

[EdStainless]

Sorry Syd, I was trying to be clever. Yes, I know that there are nitrogen impantation methods. I really like them.

It looks like the Swagelok carbon process produces a more robust case.

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Rust never sleeps
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[castingsRus]

The process you described almost sounds like "Kolsterizing". I have heard of its use in pump housings to help prevent wear. Because it is performed at low temps, you can do it after finish machining. The treatment penetrates to a depth of .004" which is not very deep. Case carburizing of 4140 steel penetrates to a depth of .125". I have not seen any practical evidence yet that the entended life out weighs the extra cost.

 

[JohnNabors]

castingsrus-

We are already doing a trial on Kolserising. The process I described above is Low Temperature Colossal Supersaturation. Here is what I was told by a rep at Swagelok a few weeks ago:



Below is what one of our LTCSS representatives had to say about commercializing the process:

“We are getting close to having a final plan regarding LTCSS. My best guess is that we will know where we are heading by the end of January and have something commercially available (should we go in this direction - very likely) by mid-year.

We think that pump housings and impellers are a particularly attractive market for the process. We could process a prototype for them to look at (no charge). Of course, this assumes that the components would fit in the furnace and still leave room for ferrules. You may also want to make sure that they understand that this is not a typical metal treatment process and will be fairly expensive since it is high value-add”



That's what I know so far. We intend to run a trial of this process when it becomes available. I will post a new thread when we have results from the trial. I will also let you all know the results from our Kolsterising trial.

Thanks everyone for your responses!

Regards



John Nabors

"Against stupidity the very gods themselves contend in vain." - Friedrich von Schiller

 

[EdStainless]

"high value added" that reminds me of the days working with Union Carbide Coating Services. Lots of great coatings, but so expensive that few applications could be justified. But we did make some cool stuff witht the insitu TiC system.

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Rust never sleeps
Neither should your protection

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