[MW:2802] RE: 2797] Heat treatment of low alloy steel plates SA387 material

Check the TT (tempering temperature) in QT steel and NACT steel, the higher TT will increase toughness, but reduce the strength. Generally TT lower in NACT steel in comparison with QT steel.

And when you need PWHT temp below TT, it is difficult to maintain required PWHT below TT when NACT steel are used, ask mill specifically for the temperature(TT) and simulated treatment of test coupons for the specified PWHT temp , include two additional cycles of PWHT.

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Agrawal Sunil (Mumbai -Stequ)
Sent: 24. juli 2009 09:57
To: materials-welding@googlegroups.com
Subject: [MW:2797] Heat treatment of low alloy steel plates SA387 material

As per ASME Sec II Part A, following is heat treatment requirement about SA 387 (plate material):

 

“Except for Grades 91 and 91 1, all plates shall be thermally treated either by annealing, normalizing- and - tempering, or, when permitted by the purchaser, accelerated cooling from the austenitizing temperature by air blasting or liquid quenching, followed by tempering”

 

Code is requesting that plates shall be normalized and tempered, or it shall be normalized-accelerated cooled and tempered (NACT) condition when agreed by the purchaser.

 

Can anyone guide me what is the difference between “normalizing- and – tempering” plates and “NACT” plates? How it will make difference to the properties of the plates.

 

For our running project, one of the bidder has said that none of the mill is offering plate in normalizing- and – tempering condition so he has considered NACT condition. Can we accept the plate is NACT condition?

 

Request to guide me on this topic.

 

Thanking you,

Sunil Agrawal

Static Equipment Department (STEQU)

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