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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