Re: [MW:7230] Heat treatment Butt joint of SA-210 Gr.A1 and SA-312 TP 304H

Dear Shinde,

 

The carbon content in TP 304H is 0.04% to  0.10%. When we heat (above 500degC) unstabilized austenitic stainless steel that have carbon content more than 0.03%,its intergranular corrosion resistance decreases significantly. This is because of precipitation of chromium carbides in grain boundries (i.e. Sensitization) while  slow cooling in the range of 450 to 650 degC.

 

As per ASME Sec VIII Div I, PWHT for SA 210 GrA-1 (P.No. 1 & Gr. No.1) shall be carried as follows:

Heating&Cooling rate: 100degC/Hr

Soaking Temperature: 595degC

 

So PWHT temperature may lead to sensitization of 304H. So it is better to butter the carbon steel with stabilized stainless steel electrode like E309Nb or low carbon fillers like ER309L/LMo and then do the PWHT. Finally the weld the buttering to the TP304H using E/ER 308H.

 

Or else, use SA 312 TP 347H/321H tubes & weld it with E/ER 347H to carbon steel and straight away do the PWHT as above.

 

Because TP 321 is titanium stabilised and TP 347 is niobium stablised stainless steel. Ti an Nb is having more affinity towards carbon. Titanium carbide/ Niobium carbide will form instead of Chromium carbide. Hence sensitization can be avoided.

 

 

On Sun, Sep 26, 2010 at 3:17 PM, agstes <agstes@gmail.com> wrote:

Dear Sudharsan S,

 

This particular joint is one of the joint from the heat recovery steam generator (unfired) constructed as per ASME Section VIII Div.1. As per UW-2 (c) this particular steam generator needs to be heat treated.

Thickness involved 12.7 mm.

In my opinion there should not be any problem for the SS material like carbide precipitation.

Please suggest the heat cycle.

 

Thanks in advance.

Regards

Shinde

----- Original Message -----

From: sudharsan s

To: materials-welding@googlegroups.com

Sent: Sunday, September 26, 2010 1:55 PM

Subject: Re: [MW:7199] Heat treatment Butt joint of SA-210 Gr.A1 and SA-312 TP 304H

Shinde,

 

SA 210 Gr A1 is a seamless medium carbon (0.27% max) steel tubes. If you weld this to SA 312 TP 304H (18% Cr 8% Ni) with fully austenitic electrode like AWS E/ER 309LMo, from metallurgical point of view , there is no need for PWHT.

 

Can you just tell me why you need PWHT, is it from process point of view or for any other reason? What is the thickness as well.

 

On Fri, Sep 24, 2010 at 6:25 PM, agstes <agstes@gmail.com> wrote:

Dear All,

 

I want to know the post weld heat treatment procedure/cycle for the butt joint of SA-210 Gr.A1 (P1) and SA-312 TP 304H (P8).

 

Thanks in advance.

 

Shinde A.G.

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.