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01-06-2009, 03:41 PM #1
Machining 17-4 SS, H1150 vs. H900 vs. "A"
I am looking to make a couple of small home use parts on my SB10L lathe, and am considering using 17-4 stainless steel. The parts are 5/16" to 3/8" OD, and involve some tapered ID turning, and both internal and external threading.
Any of the 17-4 options would be quite a bit higher yield than the 316 that I used before, so strength is not my prime consideration when shopping for the right heat treatment. But any practical advice on the differences in machining H1150, H900, or Annealed 17-4 would be very much appreciated.
01-06-2009, 09:56 PM #2
The selling literature makes a flat statement:
Do Not Use In The Annealed Condition
H1100(or H1150) machines nicely and you can actually buy it
H900 is hard - like 44 Rockwell C, and I have never heard of it being for sale, but only getting to that condition by heat treat. I don't think I would try to machine H900 on a 10L.
Ordinarily with 17-4, you make something from A and then send it off to get it to H900, or whatever other hardness you need and can't readily buy like that.
01-06-2009, 10:43 PM #3
McMaster has it available in all three conditions (H900, H1150, and annealed). I didn't see a caution on their site against using it in the annealed condition, though I did later see that warning elsewhere. Why?
01-06-2009, 10:47 PM #4Why?
01-06-2009, 10:51 PM #5
Definitely an H1150, cuts much much easier than annealed(solution treated), not as gummy and a higher machinability rating. Even though an H900 is up in the mid 40's C scale, its pretty darn easy to machine also.
On the never use in the annealed condition, I hadn't heard that until recently either. In fact we do a lot of 17-4 castings and do the assemblies also. Annealed condition, no heat treat. Ground support equipment, not critical, I'm just saying... I prefer it heat treated myself.
By far and away my favorite stainless, well maybe its a tie with 303, but 17-4 is so much more functional.
01-06-2009, 11:31 PM #6
I thought not using 17-4 in condition A had something to do with susceptibility to stress corrosion cracking. Or maybe that was another alloy.