17-7PH vs 17-4PH Stainless Steel

[harrisiqbal]

Greetings,

I want to know how 17-4PH and 17-7PH compare in terms of corrosion in SUBSEA application.

We have always mostly used 17-4PH with H 1150 treatment and Stainless Steel 316 and 316 L for our applications but now I'm looking at a valve (to be used subsea) where the spring material is 17-7PH and I don't have much experience with this material.

Any help is appreciated.

 

[EdStainless]

There will be no significant difference between the two.
They are both 17% Cr and no Mo, so their pitting resistance will be the same (and for that matter the same as 439 or 304).
The HT processes are different for the two alloys so make sure that that won't cause you any issues.

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Plymouth Tube

 

[metengr]

Go here and review the information;

http://www.aksteel.com/markets_products/stainless_precipitation.aspx