A long time ago I had to look up X-750. There were some good references, sorry I don't have those files available to me, I think the Aerospace Materials Handbook and the ASM handbook blue editions (black dust covers) were among the places I looked. You may be up on this but the alloy was initially meant for high temperature use in the creep regime. When I was looking at it, it was an alternate use that had been developed for high strength in the nuclear reactor environment. There was a significantly different microstructure and heat treatment for corrosion service than it was for creep service. The difference in properties and structure would certainly have an effect on the fatigue performance of a spring.
The only reason we were looking into using such an "obsolete" alloy, rather than 718, was that it had been more or less pre-qualified for the service we were looking at. So if you aren't tied into 750 for some really good reason like that you might want to look at 718 or A286.
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Paul Tibbals
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Original Message:
Sent: 02-17-2020 09:02
From: Richard Marques
Subject: Spring life of Inconel X-750
Hello Everyone,
Any guidelines to predict the spring life of Inconel X-750 helical coil spring? SN curves?
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Richard Marques
Senior Metallurgical Engineer
One Subsea
Houston TX
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