Is intergranular corrosion test required for duplex steel

[mrmalcolm]

Dear Sir,
Duplex stainless steel can easily pass the intergranular corrosion test in ASTM A262 actual E. If the duplex stainless steel has already undergone ASM G48 pitting corrosion test, is intergranular corrosion test required for duplex steel?
Thank you

 

[EdStainless]

No, you don't do A262 on a duplex.
You do a A923 on duplex to check for detrimental phases.
Similar to a G48, but different.
It requires full cross sections and freshly ground surfaces.
Or low temperature impact toughness.
Don't allow passing based on microstructure.

 

[mrmalcolm]

No, you don't do A262 on a duplex.
You do a A923 on duplex to check for detrimental phases.
Similar to a G48, but different.
It requires full cross sections and freshly ground surfaces.
Or low temperature impact toughness.
Don't allow passing based on microstructure.

Thank you. For type approval tests of duplex stainless steel, including chemical composition, mechanical properties, detecting detrimental intermetallic phase according to ASTM 923, pitting corrosion test according to ASTM G48.However, intergranular corrosion according to ASTM A262 is not required. Is it correct?

 

[EdStainless]

Correct.
The other thing that you want is to verify the A:F ratio.

 

[SJones]

This may help: ISO 17781

 

[Vahid.A]

As EdStainless and SJones mentioned, sigma phase formation in duplex stainless steels should be evaluated. For quality control of duplex materials, we refer to ISO 17781 and A923. Note that this phase can lead to localized depletion of alloying elements, a phenomenon known as sensitization. To assess the extent of depletion, an electrochemical test called DLEPR (Double Loop Electrochemical Potentiokinetic Reactivation) is used, as outlined in ISO 12732.

 

[EdStainless]

And just as a note you can measure sensitization of austenitic SS with electrochemical testing also.
For duplex I prefer to use low temperature impact testing.
It is straightforward and well understood.

 

[mrmalcolm]

And just as a note you can measure sensitization of austenitic SS with electrochemical testing also.
For duplex I prefer to use low temperature impact testing.
It is straightforward and well understood.

Thanks very much for your early reply.
In ISO 17781, the qualification tests for duplex stainless steel include:
-Microstructural examination, may be interpreted as detecting detrimental phase in austenitic-ferritic(duplex) stainless steels similar to ASTM A923
-Ferrite content measurement
-Charpy V-notch impact toughness test
-Pitting corrosion test in accordance with ASTM G 48, Method A
(1)Do the above qualification test requirements apply to both raw material (base material) and welding of duplex stainless steel?
(2)Is the above qualification tests sufficient, without the need for intergranular corrosion testing?
Your promote reply will be greatly appreciated.

 

[SJones]

Look at the scope of ISO 17781 in the link above