Re: [MW:20127] Reduction in % ferrite of UNS S31803 weld after Post forming HT

Hi

 

We had also faced similar problem in one of the dished ends which was solution annealed and having one long seam weld.

 

Eventually Ferrite Number check was carried out in AS WELDED condition only  after forming and before solution annealing.

There is no code reference.

 

Regards

 

Prem Nautiyal

9769316004

 

On Sunday, February 16, 2014 4:19 PM, CHINTUKUMAR GANDHI <cgandhi1975@yahoo.com> wrote:

Dear Experts,

In one of our project, one coil pipe to pipe butt weld was undergone PWHT @ 1080º C. for 12 minutes soaking period and rapid water quenching after forming a pipe in coil form. Pipe size is 21.3 mm. O.D. X 2.77 mm. W.T. SA 790 UNS S31803. We have used ER 2209 filler wire with GTAW process. 

After solution annealing, % ferrite was measured 8-10 using fisher make calibrated ferritescope instead of required 30-60%. PQR was established in the same pipe size and material Grade. In PQR, after PWHT @ 1020º C. for 10 minutes and rapid water quenching, % ferrite was coming average 38 in point counting method as per ASTM E 562.

What shall be the reason of reduction in % ferrite in production weld? What shall be the corrective action to achieve % ferrite between 30-65%. In this forum, some where I have read that heating to temperatures approaching 1100º C will dissolve some or all of the ferrite, depending on the hold time at temperature, composition of the weld metals, and the as-welded ferrite content. I need some reference book on this issue.

Thanks & regards,

C. R. Gandhi

      

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