Can Post weld heat treatment eliminate defects? uses and abuses? 2

[IJR]

Pals

I understand PWHT(around 700 degrees celsius) eliminates residual stresses and cuts down hardening in the HAZ.

But if weld was poor, say has cracks, is porous, lacks fusion etc, does PWHT eliminate any of these errors?

In other words, what are uses and abuses of PWHT?

respects
IJR

 

[metengr]

But if weld was poor, say has cracks, is porous, lacks fusion etc, does PWHT eliminate any of these errors?

No. These are defects that must be evaluated and if necessary removed to ensure structural integrity.

In other words, what are uses and abuses of PWHT?

Use;
reduces residual stresses
softens the weld deposit and base metal heat affected zone

Abuse
improper application of PWHT can result in unpredictable properties of the weld and surrounding base metal.

 

[DVWE]

But if weld was poor, say has cracks, is porous, lacks fusion etc, does PWHT eliminate any of these errors?

No, in fact, many companies specify some type of NDE before and after PWHT to ensure that no cracking occured during PWHT.

In other words, what are uses and abuses of PWHT?

Always try to keep the PWHT within an acceptable range of temperature. For example, 1275 +/- 25 F. Anything above or below that will give you results that may be unacceptable and further testing may be required.