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[MW:844] RE: 835] Re: Clarification on Heat treatment / PWHT -Reg.

By Materials & Welding

Dear Friends,

Staying with the subject line of heat treatment, I wanted to know (since long ) --------

 

What should be done if the temperature while doing PWHT exceeds the range mentioned in WPS ??

 

For example lets say-

A weld between A335 P11 ( P 4   Gr 1) , thickness 17mm.  WPS ( & B 31.3  ) has the PWHT temp as 704-746 deg C.

If the temp of  PWHT cycle exceeds the higher value by 40deg. Centigrade, what should be done?

Can the joint be accepted based on the hardness value?

 

Please also provide references with your answer.

 

Best Regards,

Rishi Raj Singh

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Prabhakar h
Sent: 09 June 2008 16:25
To: materials-welding@googlegroups.com
Subject: [MW:835] Re: Clarification on Heat treatment-Reg.

 

Dear Shabbir,

 

Thanks a lot for your prompt response and sorry even i cud not catch up quite a while as i was held up with my ASME Audits.

 

Your Explanation was usefull and it would be better if you cud tell us at what conditions we go for the HT and how the same is selected???

 

Prabhakar.H

 

On 5/4/08, shabbir ahmad <shabbir.ahmad7@gmail.com> wrote:

Dear Prabhakar,

 

Nortmalizing: The steel is heated 50 deg. cent grade beyond the upper critical tempreture( generally 900 to 940), once the calculated soaking time has elapsed the steel is removed from the furnce to cool in still air, This produce smaller n fine grain structure that has high toughness n strength.In short u can say normalizung makes steel tougher n strong.

 

Stress Reliving: Steel heated upto 550-650 d.c..The plastic flow of sresses increased as tempr. rises, relieving locked in elastic residual welding stress.

 

Tempering: The steel is re-heated after hardening and the balance of hardness & toughness is adjusted as the temp range 200 - 723deg. cent.

 

at 723 d.c. all the martensite has been tempered removing the brittleness 7 returning the toughness and some ductility. Normally tempering carried out to rebalance the propertied of thermally hardened steels.

 

solution Annealing : generally carried out on Stainless steel, this produces large n coarse grain.Heating the steel above 1040 deg.centi grade and quench in oil.

 

Thanks

 

shabbir

 

On 5/3/08, Prabhakar h <hb.prabhakar@gmail.com> wrote:

Dear all,

 

Can anyone let me know what is the difference bet'n Normallising/Stress releiving/Tempering/Solution anneling..

 

I always get confussed and cudnt get a better idea....

 

Is there anyone to help it out....?

 

Prabhakar.H

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