Re: [MW:15761] RE: 15748] Regarding p91 intermediate cooling

As expert said, Mf temp for this steel is around 150 degree celsius.
before taking up for PWHT, if u have not broughtdown the weldmentd
temp below 150( safely less than 100), untempered martensit present
will get tempered while while PWHT which will inferior mechanical
properties
That is why it is brought down to below 100 if pwht will take
immediate or bring down atmospheric temp

On 10/25/12, george.dilintas@gr.bureauveritas.com
<george.dilintas@gr.bureauveritas.com> wrote:
>
> That's right Pradip, lets always keep basic metallurgy in mind
>
> best regards
>
> Dr. Georgios Dilintas
>
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> "pgoswami"
> <pgoswami@quickcl
> ic.net> To
> Sent by: <materials-welding@googlegroups.com
> materials-welding >
> @googlegroups.com cc
>
> Subject
> 25/10/2012 02:25 [MW:15758] RE: 15748] Regarding p91
> intermediate cooling
> Ref
> Please respond to
> materials-welding
> @googlegroups.com
>
>
>
>
>
>
>
>
> Hi Govindaraju,
>
> This temperature corresponds to the Martensite finish temperature for this
> steel.Grade-91 is thorough hardening steel and produces martesite on air
> cooling. The best room temperature mechanical properties (tensile, impact
> and hardness) for this steel and the best high temperature creep
> properties are achieved when this steel is in fully tempered martensitic
> condition, i.e tempered @ 740-780 Deg C, following welding
>
> Cooling to this temperature ,80c-110C immediately following welding but
> prior to PWHT is strongly advisable.
>
> Thanks.
>
>
>
> Pradip Goswami,P.Eng.IWE
>
>
> Welding & Metallurgical Specialist
>
>
> Ontario, Canada.
>
>
> Email-pgoswami@sympatico.ca,
>
>
> pgoswami@quickclic.net
>
>
>
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of GOVINDARAJU RAJU
> Sent: Tuesday, October 23, 2012 4:43 AM
> To: materials-welding@googlegroups.com
> Subject: [MW:15748] Reagrdin p91 intermediate cooling
>
> Dear sir
> I am doing qc engineer in power plant construction.I have doubt regarding
> P91 welding.After completion of welding, we are doing intermediate cooling
> at 80c-110C.What is the need of intemediate cooling?
>
> Rgds
> V.GOVINDARAJU
>
>
>
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