304 stainless 1/4 to 1/2 hard plate availability?

[ktgottfr]

Greetings all - I have recently started a project for a prototype engine. There are some papers in the literature that suggest 304 stainless hardened to 1/4-1/2 hard (125ksi UTS 80ksi yield) will have the fatigue properties we want for UHCF. However, I am having a hard time sourcing this material.
Does anyone know where I might be able to source 1/2" thick 304 plate/sheet that has been work hardened? Every potential source I have contacted so far has turned out to only stock the annealed plate even if they advertised work hardened plate.
Am I on a wild goose chase here? Is 1/4 hard 304 plate even something that anyone has ever offered? Will I need to order it straight from the mill to get this material? Does anyone know if a common rolling machine can do this sort of 25% thickness reduction on a 5/8" thick plate to get it down to 1/2" thick - or is this beyond the capability of a typical rolling machine a shop might have. Any suggestions or advice would be appreciated! Thanks everyone!
-Kristjan

 

[EdStainless]

The spec is ASTM A666 for as-cold-rolled stainless.
That said, finding this in 1/2" may be next to impossible.
If you wanted a lot of it then you could get it, but small amounts aren't going to happen.
The other options would be to see if a duplex SS would be strong enough, after that a PH grade (17-7 or 15-5, not 17-4) aged to a med strength condition might be an option.

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P.E. Metallurgy, Plymouth Tube

 

[ktgottfr]

Thanks Ed,
Have you ever heard of anyone rolling small quantities of stainless steel like this in a normal machine shop? Or is this the type of operation that would only be done at the mill? Its not critical we use 304 stainless here, but if we do it will need to be work hardened... Its starting to look like this is not something we can readily get our hands on. Thanks again!
-Kristjan

 

[metengr]

I would suggest you find an industrial fabrication shop that can do this to your project requirements. There are many industrial fab shops that can easily handle it.

 

[EdStainless]

Rolling the plate takes a large rolling mill.
There are some re-roll houses out there (Ulbrich) but I don't know if they go this thick.
You should get similar properties out of any austenitic stainless (201, 204, 301, and so on).
And remember that these will be magnetic when cold worked.
These materials will also begin stress relieving at about 700F. At first the yield strength will drop but not the UTS, at higher temps the UTS will begin to decline.


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P.E. Metallurgy, Plymouth Tube

 

[metengr]

http://www.jorgensonrolling.com/platesheetrolling.html

 

[ktgottfr]

Thanks Ed,
So it would seem that Natural Resources Canada has a pilot rolling mill that they provide to companies for just this sort of problem. So at the moment we will likely be getting them to set up some test runs of small amount of cold rolled material to see if its practical to get to the thicknesses we need, and to look at the properties of the final product to see if they are good enough. Its really just what we needed as we can't afford to do a full mill run and then find out that the material is not suitable.
Thanks again for everyone's comments - they were a big help!
-Kristjan

 

[EdStainless]

What properties are you most interested in?
You do need to be careful cold working SS plate, you can end up with hard surfaces and a soft core.
If fatigue is one of your primary concerns I would suggest using S21904 (XM-11, 21-6-9, Nitronic 40) and not 304.
It will stay more ductile when cold worked. We make aircraft hydraulic tubing in this alloy, cold worked to 120ksi min yield, 142-162ksi UTS and 20% min elongation (thicker material will be a bit lower).


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P.E. Metallurgy, Plymouth Tube