PWHT vs Normalizing vs Stress Relieving

[staticmh]

Hi All,

This became an big misconception while we are dealing with pressure vessel in daily routine.

Can anybody differential in between Post weld heat treatment / Normalizing / Stress relieving.

It will be more better that if its application can also be depicted, when , what, how and why...

Pls. dont refer to code (ASME SEC VIII Div.1) ,even i've already read all the clause but just want to make some understanding with the people round the globe that what they are doing and what we are doing.

 

ASME Code refers to and regulates these operations, but it is not an educational source.
These concepts are basic to ferrous metallurgy and welding, so I suggest someone at your organization take a basic course of study.
There is also the classic 'Metallurgy for the Non-metallurgist' by Harry Chandler.
Is there an AWS chapter in your neighbourhood?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[DriveMeNuts]

How much detail do you want?
A 16 lecture course will give you an introduction.
I'm not convinced you will learn much from a five line post on an online forum.

 

[gtaw]

Post weld heat treatment includes the heat treatments you listed plus a few others. As the name suggest, PWHT is simply performed after welding. The same heat treatments can be applied to materials formed by a process other than welding. Cold formed dished heads can be heat treated after forming to reduce the residual stresses associated with forming operations, we call it stress relief. Steels can be normalized to ensure a uniform microstructure before forming. Annealing can be performed between cold forming operations to reduce strain hardening and hardness and to ensure there is sufficient ductility for subsequent forming operations.

Limiting the conversation to carbon and high strength low alloy steel; if the heat treatment is performed after welding, it is a PWHT. Simply stating that it is PWHT isn't sufficient, one must know whether it is subcritical or super critical. Subcritical would include tempering and stress relief. Super critical can include normalizing and annealing. It depends on whether the temperature of the PWHT is below the lower temperature of transformation (subcritical) or above the lower temperature of transformation (super critical).


Best regards - Al

 

[0707]

The links below maybe useful to annswer your questions

good luck

luis

https://www.cliftonsteel.com/knowledge-center/anneal-normalize-stress-relieve

https://www.sciencedirect.com/topics/engineering/post-weld-heat-treatment

 

[Dhurjati Sen]

Buy a Physical Metallurgy book, maybe by Avner.

DHURJATI SEN
Kolkata, India

 

[staticmh]

0707,

Your provided links are quite helpful to me. I got clear the all my question by self upon reading the article..

Really appreciated.

 

[weldstan]

Review the ASM Meyals Handbook Vol. 2.