303 SS Vs 17-4
303 SS Vs 17-4
(OP)
We're looking at switching to 17-4 SS in place of 303 SS. What are the pros and cons. Material compatibility, machining, surface finish and cost?
Thanks.
Thanks.
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RE: 303 SS Vs 17-4
Why are you changing from the common 303 (austenitic with added sulfur and phos to aid machining) to the rarer 17-4 (semi austenitic precipitation hardening grade)?
nick
RE: 303 SS Vs 17-4
We're currently pressing a 303 SS insert into a 303 SS body, of course we're seeing galling. We thought using a deferent grade of SS would work better.
Wayne
RE: 303 SS Vs 17-4
You can try Nitronic alloys such as Nitronic 60 or Carpenter NO gall alloys.
RE: 303 SS Vs 17-4
RE: 303 SS Vs 17-4
All 18-8 stainless steels can be purchased in the annealed, 1/4 hard, 1/2 hard. 3/4 hard and hard condition which is achieved by cold work but it will not avoid galling.
See the other post for the gold plating suggestion.
RE: 303 SS Vs 17-4
I just tried liquid nitrogen, .0001 shrinkage. I like your suggestion for Nitronic alloys, is it hard to machine, costly, hard to find?
RE: 303 SS Vs 17-4
RE: 303 SS Vs 17-4
(900degF @ 1hr; +15 min. /-0.00 min). 15 minutes into the soak, power goes out for 10-15 min. When power returns operator cooks parts for additional 45 minutes. Operator's rationale: TOTAL soak is 60 minutes, (though not continuous. The result is that parts exhibit Rc42, right where they should be. Need to pass shear test also. Assuming they shear correctly, are they good, or must they be re-solution annealed and harened all over again? I.e. Are there any delayed maladies that might surface "down the road" though
the parts may test properly today?
RE: 303 SS Vs 17-4
RE: 303 SS Vs 17-4
You are pressing stainless into stainless.
Why? What purpose does the insert serve? Why isn't this monlithic?
Presuming that you need an insert, why can't you shrink fit this? If you heat the part with the hole you can get a lot of gowth, room temp to 400F the CTE is 9.6ppm/F. If you cool the insert to LN temps you will get shrinkage of 7.5ppm/F.
If this is a 1" insert, by heating and cooling you will open up 0.006" clearance, if the hole and insert were the identical size to start with.
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Corrosion, every where, all the time.
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