Temperature Range ( minimum / maximum ) for duplex/superduplex material ( F51, F53, F55)

[Luigi De Micheli]

Good days to all; I'm a question regarding the minimum/maximum temperature range of duplex/superduplex materials. I'm Considering Valves in stainless steel ( F316/CF8M ) with the stem in ASTM A 182 F51 ( or F53,F55 ) How is the range of min and max temperature?

 

[EdStainless]

The upper limit is generally taken as 300C, though some duplex alloys may be limited to 275C.
Above this temp these alloys will experience long term formation of detrimental secondary phases.
This lowers toughness and corrosion resistance.
As for the lower limit this will be largely set by toughness requirements. Different design rules set different min values.
I have seen limits of 0C, -15C, or -40C used depending the alloy and the service.

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P.E. Metallurgy, Plymouth Tube

 

Ditto.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[MagBen]

Due to ferrite phase, duplex limits to 300C (due to famous 475C embrittlement, the decomposition of ferrite)
F316/CF8M has least 475 embrittlement due to lack of ferrite. However, there exists chance to form carbide precipitates, temp better limited to 400C.