Tuesday, August 3, 2010

RE: [MW:6282] Satbalising (Treatment of SA321H

Carbon in case of 321 will be dissolved in any way during solution annealing, hence generally not recommended for 321 grade (practically no C left to form CrC). Ti or Nb have stronger affinity to form carbides than Cr.
In my opinion even in case of 321 H this is generally recommended if service temperatures are low (above 1200 °F will take care of stabilization during operation) or fluid is corrosive (refer NACE RP 0170 for polythionic acid SSC) and not necessarily in all cases.
 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Sayee Raghunathan
Sent: Tuesday, August 03, 2010 11:33 AM
To: materials-welding@googlegroups.com
Subject: RE: [MW:6278] Satbalising (Treatment of SA321H

Hegde Sahib

 

i)What is the significance of stabilizing treatment at 950-980C  with soaking for 2 hrs and cool in air   even after solution annealing at 1050C followed by water quenching? Why Stabilizing treatment is necessary for H grade Ss and not in L grade SS ?

The ASM Handbook states that 'the stabilising anneal.. consists of holding at 845-900°C for up to 5h, depending on section thickness', but does not give methods of cooling or cooling rates. The Metals Handbook suggests a stabilising treatment of 2-4h at 870-900°C followed by rapid cooling to precipitate all possible carbon as Ti or Nb carbides and subsequently prevent Cr carbide precipitationThis is especially needed for H grades of stainless steels.

 

ii) Is there any  affect on properties  if we do not go for Stabilizing treatment

Yes, in effect with no stabilised treatment, you would expect that Cr carbides are formed (rather than Ti or Nb carbides) thereby reducing the corrosion resistance (primarily).

 

iii)What will be the microstructure of Stabilized 321H steel as against only Solution annealed

See above, you will have Cr carbides in the grain boundaries, leading to depletion of Cr in a narrow band around grain boundaries. Hence the requirement for IGC practice E.

 

Rgds

 
Sayee


From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of PB HEGDE
Sent: 03 August 2010 05:07
To: materials-welding@googlegroups.com
Subject: RE: [MW:6271] Satbalising (Treatment of SA321H

Dear Friends

My query was  particularly for H grade  321 i.e. 321 H

i)What is the significance of stabilizing treatment at 950-980C  with soaking for 2 hrs and cool in air   even after solution annealing at 1050C followed by water quenching? Why Stabilizing treatment is necessary for H grade Ss and not in L grade SS ?

ii) Is there any  affect on properties  if we do not go for Stabilizing treatment

iii)What will be the microstructure of Stabilized 321H steel as against only Solution annealed

 

 

Regards

 

Hegde p.B.

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Shashank Vagal
Sent: Monday, August 02, 2010 11:46 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:6262] Satbalising (Treatment of SA321H

 

I am confused-
Solution Treatment (Annealing) which involves heating to 950-1120°C and cooling rapidly is for achieving maximum corrosion resistance.
Stabilising - heating to 870-900°C for 1 hour per 25mm of thickness and air cool.
Stabilisation is recommended for most severe service conditions (above 425°C) and particularly for material annealed at the upper side of the annealing temperature range.


--- On Mon, 2/8/10, PREM SHANKARDUTT NAUTIYAL <prem_nautiyal@rediffmail.com> wrote:


From: PREM SHANKARDUTT NAUTIYAL <prem_nautiyal@rediffmail.com>
Subject: Re: [MW:6257] Satbalising (Treatment of SA321H
To: materials-welding@googlegroups.com
Date: Monday, 2 August, 2010, 9:20 PM

Sir

Grade 321H is a modification of 321 with a higher carbon content, to provide improved high temperature strength.321H has higher hot strength, and is particularly suitable for high temperature applications i.e upto 800 degree C.

Solution Treatment (Annealing) which involves heating to 950-1120°C and cooling rapidly is for achieving maximum corrosion resistance.

Stabilising - heating to 870-900°C for 1 hour per 25mm of thickness and air cool.
Stabilisation is recommended for most severe service conditions (above 425°C) and particularly for material annealed at the upper side of the annealing temperature range.

Note that these grades cannot be hardened by thermal treatment.

Regards

Prem Nautiyal


On Mon, 02 Aug 2010 16:50:20 +0530 wrote
>



Dear Friends

Request you to share information



We have a material of SA321H

Specification calls for

The plate should be Solution annealed i.e. Heat to
1040C quench in water after adequate soaking time , and followed by stabilizing
treatment like heating to 900-950C with holding for 2 hrs and cool fast need
not be quenched in water



However This plate to be tested for IGC Practice
E




II want to know

i)
What is the significance of Stabalizing treatment once
it is solution annealed by Water quenching?

ii)
Why it is recommended to cool by Air ( need not be
water quenched)?

iii)
Why it is in H grade only?

Regards



Hegde P.B.





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