Heating 17-7Ph a little, how much softer?

[antknee]

I have some 17-7Ph stainless steel that is in the CH condition. So its been cold rolled and then had 1 hour at 480 degrees C. Now I need to heat it again for 1 hour at 120 degrees C. So how much softer will it get? I mean will i lose 1% or 10%? on the yield strength. What would you think? Regards, Ant.

 

[metengr]

Look at the publication below regarding information on consition and heat treatment;

http://www.aksteel.com/pdf/markets_products/stainless/precipitation/17-7_PH_Data_Bulletin.pdf

Review table 5 which is elevated temperature tensile properties to determine the effects of exposure temperature at 120 deg C.

So, I see two options - the first is to assume if you took CH900 and exposed it to 120 deg C you can determine how much the UTS and TS could drop at that temperature, and use the % drop as worst case scenario.

OR second option, I would expect even less of a change in the CH900 properties from option 1 above because the exposure temperature (up to 120 deg C and back down to RT) is too low to cause any appreciable changes. To prove this option, run a coupon of the CH900, expose it to the second temperature, cool and test for UTS, RA and elongation. This is the only way to know for sure.

 

[metengr]

Sorry, typos

consition

should be condition

UTS and TS

TS should be YS

 

[unclesyd]

As stated nothing will happen. We have numerous production parts made from 17/4 PH, normally condition H 1125 that run for periods of time at 285°C and then are subject to up to 6 hrs at 770°F and 1 hr at 900°F for cleaning. Even some parts at condition H 925 see no change.

Point of interest:
There is a phenomena that does manifest itself after about 100 thermal cycles and that is we start getting an increase
in hardness with some loss of elongation. We have seen a rise in from hardness from 40 Rc to around 48 Rc over time. We will normally overage them at this point.

 

[antknee]

It looks like I lose 6% and presumably on cooling I won't get any of that back.

 

[EdStainless]

If this material is CH900 and you heat it to 120C you will have slightly lower strength while it is hot, but upon cooling it will be exactly as it was before.

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Plymouth Tube

 

[antknee]

Oh good. Thanks.