You have to allow martensite to formally and at the same time avoid cold cracking. Therefor keep the 200 degC for 2 hours and then proceed as you propose
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-------- Original message --------
From: 'Mostafa Kamel Hussein' via Materials & Welding <materials-welding@googlegroups.com>
Date: 17/01/2017 11:40 (GMT+02:00)
To: Materials-welding <materials-welding@googlegroups.com>
Subject: [MW:25910] PWHT Cycle Of P335-P5B (P9)
Dear Sir
Really now we are in critical situation regarding PWHT of A335 - P5B (Grade P9). The cycle in brief as attached. first preheat at 200°C then cooling to ambient temperature (20-80°C) for minimum 30 minutes as holding time. after that PWHT cycle starts by heating rate of maximum 100°C /hr till reaching to soaking temperature (704-760°C) for 2hrs. finally, cooling rate of maximum 100°C /hr.
My question is: it this PWHT cycle for P335-P9 true specially cooling to ambient temperature (20-80°C) as i know it's may cause delay crack?
and if this cycle wrong, can you provide me with the correct one which i can built PQR on it?
Your quick reply is highly appreciated.
Regards,
Mostafa K
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