Dear Pradip:
Delayed cracking is caused by Hydrogen embrittlement. They are typically transverse to the weld but in your case it runs with the weld, which is unusual. By close observation, the crack mostly offsets the centerline and near HAZ. Because you mentioned that the joint preparation has "little beveling", I am wondering if the crack originates from under the surface where lack of fusion occurred at the fusion line.
To solve the problem, you may consider the following approach:
1. After welding and weld metal cooled to room temperature (to finish Martensitic transformation), immediately do PWHT within 5 ~ 6 hours.
2. If this is not feasible, conduct a Hydrogen baking heat treatment at 600 F ~ 650 F for 1 hour.
3. Increase the bevel angle or train and enhance the welder's skill to avoid Lack of Fusion problem
Thanks!
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| Feng Lu, Ph.D., NDE Level III | ||
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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of pradip kumar Sil
Sent: Sunday, February 11, 2018 4:38 AM
To: materials-welding <materials-welding@googlegroups.com>
Subject: [MW:27331] P-22 plate welding ...6-MM plate
Dear Everybody,
We are doing P-22 plate welding, thickness is 6 mm with E-9018B3 ( Dia 2.5 mm) electrode. Preheat is 150 to 200 degree centigrade with little beveling. Site is near the sea area.
We found lot of delayed crack generally after 12 hours. Crack is coming middle of the weldment.
Can anybody inform me cause & corrective action for the same.
Pic attached for your ready reference.
Thanks in advance.
Regards,
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