[MW:16375] RE: 16361] PWHT TEMP.RANGE IN CODES

Krishna,

 

The significance of lower and upper transformation temperature is explained in this diagram.

 

For C.S & LAS:-

1. 723 Deg C is typically the lower critical temperature  (denoted by A1 &  A2)-- Applicable Post Weld Heat Treatment Operations in and Around this temperature "Annealing".
2. For  C.S stress relieving is always done well below the annealing temperature range in order to avoid excessive softening of the weld and HAZ. For LAS  depending on the alloy content, the weld metal could be have high hardness, thus PWHT in the  range of 650-675-730 Deg C, for P4-P5A-P5B is  typically advisable as per SecVIII, DIV-1.
3. 910 Deg C typically is the upper critical temperature (denoted by A3)-- Appropriate PWHT operations Normalizing or Quench & Tempering (Q&T).

 

 Note Q&T operations are  often used for  plates, seldom specified  following welding. Q&T steels are advisable to weld with controlled heat input not to disturb the fine balance of microstructures & mechanical properties  obtained by Q&T operations.

 

Thanks

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist

Ontario, Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of krishna
Sent: Saturday, December 29, 2012 2:23 AM
To: materials-welding@googlegroups.com
Subject: [MW:16361] PWHT TEMP.RANGE IN CODES

Dear team,

Could one please explain the upper transformation/critical temp. and lower
transformation/critical temp of PWHT given in ASME.SEC IX.

Where the range of these temperatures is given in international codes.For example which is the
lower transformation temp. and from where the upper transformation starts and ends.

Please share some supporting documents for the temperatures ranges.

Thanks in advance,
krishna

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