RE: [MW:6782] 9Cr-1Mo/9Cr-1Mo-V steel welds

To my limited knowledge, it is also depend on time at temperatures, there are studies demonstrated that formation of σ at 480 °C in alloy with less than 12% Cr. However it also states σ forms with long time exposure in the range of 565-980 °C. The composition of σ in austenitic stainless steels is more complex than it is for simple iron-chromium ferritic grades. Carbon also decrease σ formation by forming chromium carbides.

Source: ASM Handbook

-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Kathalingam Babu
Sent: Monday, August 30, 2010 3:29 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:6780] 9Cr-1Mo/9Cr-1Mo-V steel welds

Hi Abby

Pls note that , 9Cr-1Mo/9Cr-1Mo-V Steels are the Ferritic Steels.

Don't confuse Sigma embitterment of ASS with Ferritic Steels.

Regards,

K.Babu
Singapore

----- Original Message -----
From: "Abby Joseph" <abbyjoseph@gmail.com>
To: "Materials & Welding" <materials-welding@googlegroups.com>
Sent: Monday, August 30, 2010 4:37 PM
Subject: [MW:6775] 9Cr-1Mo/9Cr-1Mo-V steel welds

Do 9Cr-1Mo/9Cr-1Mo-V steel welds also develop sigma phase during service, like some stainless steels?
(Note- these alloys also contain substantial wt% of Cr, Fe and Mo. They are also exposed to the high temp at which sigma phase forms.)
If not, why?

Regards,
Abby Joseph

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