heat treating stainless steel

[raidoh]

My question is, if I heat treat 303 Stainless Steel, will it retain the 30-50% elongation, which is good, or its tendency to creep under load, which is bad, or both, which is still bad. Plus, I don't know anything about the process of heat treating, so I couldn't give any details on temps or quenches or the like. Any advice in that realm would be greatly appreciated.

Background information:
I have a 303 Stainless Steel block, 8" x 2" x 1.5" tall, being loaded from the top with 10 - 30 kips. Strain gages are mounting to measure the shear and bending strains. The 303 Stainless shows signs of creep and plastic deformation, so I'd like to use something harder, but still retain a good % elongation such that the output of the strain gages will still give a reasonable uE/lb resolution. It seems that the max stress on the block is around 60ksi under max load, so the block was under-designed significantly. 303 Stainless has a UTS/Yield Strength of 75/30 ksi, 30-50% elongation.

I can:
Use readily available AISI 4140 Heat Treated Steel, which should give me a UTS/Yield Strength around 125/100 ksi, 18% elongation. This will corrode, which is probably not a problem, but is yet to be agreed upon.
Heat Treat the 303 Stainless to get the Yield around 100 ksi.
Heat Treat 13-4 Stainless, which my co-worker "heard" is stronger, but I haven't had a chance to look into it.

Thanks for the info.

Chad Schneider
raidoh@yahoo.com

 

You may want to consider 17-4PH. This is a precipitation hardenable (thus the PH designation) alloy with fair to good corrosion resistance. It is used quite often in shafting and other high strength applications. However, it is rather brittle compared to the austentitic grades. 17-4PH has a UTS/YS of 150/110 and elongation of 15% in condition A material. It is available in several different heat treated conditions.

You may also want to consider a nickel alloy. Alloy C-276 has a UTS/YS of 118/50 and elongation of 60%. The nickel alloy will be considerable more expensive in material costs and machining but has outstanding corrosion resistance in some of the more severe chemical applications. Check out the Haynes website at

http://www.haynesintl.com/mini/C276s/C276.htm

Best of luck

Kayakscout

 

[mcguire]

It sounds like you could simply use an inexpensive martensitis stainless steel such as 410. it can be quenched and tempered to the same levels as the 4140.
If you don't want to heat treat, use 2205 which has about 65000 PSI yield strength as annaealed and super corrosion resistance. Consult with the people at stainlesscenter.com.
It's free and not for profit.