AISI 304 SS TTT DIAGRAM

[BMccarthy81]

I'm tying to find a TTT diagram for AISI 304 stainless. I've beed given the task to streamline a annealing/heat treating operation, and at this moment, I am unable to find one. Can anyone direct to place where I may find it? Thank you very much.

 

[arunmrao]

Atlas of Isothermal Transformation and Cooling Transformation Diagrams
Price: $50.00
Boyer, Howard E. / Gray, Allen G. - Editors: American Society for Metals x + 422 pp, preface, diagrams in 2 sections - isothermal & cooling. 7" x 10.2" red cloth boards in blue DJ (45 oz) H METALLURGY Jacket Condition:Good Hard Cover 1977 Book Condition:Very Good LCCC No. 76-58536, Cooling Curves - Steel Heat Treatments First Edition / First Printing 009551
Merchant: aabooks

 

[Metalguy]

304 SS doesn't have a TTT, because it doesn't transform to anything during cooling.

 

[EdStainless]

The data that you need is the time required for homogenization of the structure, and the cooling rate to supress carbide formation. The latter is very common, we have a copy in the back of our alloy handbook.
The first part of the requirement you will have to determine experimentally.
Remember that temperature is your friend. 3 min at 2100F will be as good as 30 min at 1950F.

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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[BMccarthy81]

Actually we're stress relieving/softening the material that we're given. The 304 is in wire form, anywhere from .125" to .005". As of now there's very limited knowledge about the proper heat treatment of material. We were "stress relieving" the steel at 1200F, while the actual stress relieve temp is around 400F-750F. This shouldn't have any affect because of its low carbon content? am i correct in that assumption?

 

[Metalguy]

1200 deg F is just about the worst temp. to use for SR *IF* you have any concerns with corrosion--which is usually the case w/SS's. You are likely to cause carbide precipitation at the grain boundaries unless the C is extremely low-say ~.01% or lower. The time/temp curve is extremely steep vs C, such that a few seconds at 1200 F are all it takes w/.07-.08 C, to a few minutes at ~.05. The effect on mech. props. is low-it's really a corr. issue.

 

[swall]

For 304 SS spring wire, the stress relief temp is 450-950F.

 

[EdStainless]

You need to find a copy of the sensitization curves and check against your carbon level.
I don't know why you would ever need to go above 750F. If you want to check you can start corrosion testing samples that you ran through different treatments. A262 Practice E is a good place to start.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm