17/4PH forging 1

[MA2069]

Can anybody please advise.
I have heat-treated Condition A 17/4ph into the aged H1150 condition(621 C for 4 hours )
The parts have then been heated at 1150 C for 30 minutes prior to forge
On completion of forging the parts were then Heat-treated to Condition A -1050 C - 1 hour and Air Cool, followed by Heat-treatment to condition H900 -482 C for 1 hour.

The parts were then tested for hardness, Mechanical and Charpy test.
The Hardness produced low results- results 34 to 40 HRC
The Charpy produced very inconsistent results of between 12 J to 150 J
Mechanical test did not meet the ASTM Std

Can you please advise on the correct H/T condition for forging and the subsequent Heat-treatment to optain the required material properties for the H900 condition
Thankyou for your help

 

[metengr]

Look here at page 16 and 18;

http://www.aksteel.com/pdf/markets_products/stainless/precipitation/17-4_PH_Data_Bulletin.pdf

 

[forging82]

Are you only working to AMS 5643? Is your furnace in good condition? Usually when I run 17-4 parts I also do a stabilize in between the solution and age operations.

 

[EdStainless]

1. Did you get it cold enough for long enough between the anneal and aging?
2. Try re-heat treating a sample (both anneal and age). You will get grain refinement and it may help make up for non-optimal hot work and anneal temps.

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Plymouth Tube

 

[OGMetEngr]

The martensite finish temperature (nominal) of this alloy is just over room temperature. As Ed hinted, you may have residual austenite if the material didn't cool to below the martensite finish. This would explain results such as this. I would also expect a lower than expected yield strength, with the expected or more than expected ultimate tensile strength.