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Nimonic 75

Nimonic 75

(OP)
How to stress relieve ring after machining.We have a problem after cutting segments from ring, they bend inward on edges.

RE: Nimonic 75

How was the stock manufactured?
What heat treatment was it given?
What final HT condition do you need it in?
The HT of these alloys is complex, you need to be careful.

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P.E. Metallurgy, Plymouth Tube

RE: Nimonic 75

Stress relieving can be done on this material between 840 to 890 deg F for between 1/2 to 1 hour. This is a Ni/Cr alloy that work hardens significantly. As far as heat treatment, it is typically 30-60 minutes at 1050°C (1920°F) followed by
air cooling. This material is basically unaffected by heat treatment.

RE: Nimonic 75

(OP)
Stock was forged ring,and i think it was HT,more thick then we would like so we had to machine more.After rough turning, ring was heat treated 1h on 1080°C ,and then final machined.Mean thing is to machine it right,we don't have any special final HT condition.I was warned that HT will not affect the part the way I would like ,but I insisted to try it anyway.
Any suggestions,are welcome.Thank you!

RE: Nimonic 75

aleksandar81
I would try the stress relief I mentioned above between 440 deg C to 475 deg C (840 to 890 deg F) for between 1/2 to 1 hour after rough machining versus 1976 deg F (1080 deg C).

RE: Nimonic 75

Good advice on the temp and let it cool gently. Differential cooling will cause a lot of residual stress.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Nimonic 75

(OP)
Thank you for advice's.

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