×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Killed vs normilized
3

Killed vs normilized

Killed vs normilized

(OP)
Spec calls for "plate steel used for pressure vessles shall be fully deoxidized (killed). Is this equal to being normilized.  

RE: Killed vs normilized

No. Killed refers to silicon or aluminum addition to deoxidize the melt. Normalized refers to heat treatment.

RE: Killed vs normilized

A lot of steel is "killed" whether it's required for your application or not.  Some checking with suppliers or mills may confirm that your regular steel is okay.

If not required by the plate specifications, normalized is a hefty extra cost, and you won't usually buy normalized plate unintentionally.

RE: Killed vs normilized

Agents added (silicon or aluminium) to killed steel aim to prevent gas evolution during the solidification phase in order to get more chemical homogeneity and reduction of segregations.

Normalizing aims to remove the internal stress, which could potentially lead to deformation or failure, throughout a thermal treatment (heating above austenitic temperature and then air cooling).
 

RE: Killed vs normilized

ione, normalizing may or may not 'remove the internal stress', what ever that is.  But that is not its purpose.   

RE: Killed vs normilized

brimstoner,

I am probably wrong but I thought the austenitization process followed by a soaking phase and then by an air cooling phase always removed internal stresses (besides the improvement of both toughness and tensile strength, throughout cementite and carbides solubilisation to get a finer and more homogenous microstructure).

RE: Killed vs normilized

I have seen some plate come out pretty warped after normalizing.  Roll flattening will only add to the internal stress.  

Normalizing is performed to refine the grain size of carbon and low alloy steels, primarily with a view to improving the low temperature fracture toughness, but it also improves other basic mechanical properties.  Any other effects, whether desirable or not, are incidental to the procedure.   

RE: Killed vs normilized

A bit off topic but:

So normalising refines grain size and general properties of the steel.  And releiving of stress is is just a possible by-product of the normalising process???

Is Post weld heat treatment opposite?  With postweld heat treatment on a weld, the purpose is to relieve residual stress and a by-product is to atleast partially normalise the heat affected zone???

RE: Killed vs normilized

Normalizing results in a more uniform grain structure (it can result in a finer grain structure) and improved mechanical properties. As a by-product of normalizing, residual stress can be removed.

PWHT is a thermal treatment to accomplish two things; reduce residual stresses from welding and temper the weld heat affected zone. There are two types of PWHT; a reheat treatment (like normalizing, or annealing, or a quench and temper) or a subcritical PWHT. The subcritical PWHT is only performed to avoid altering the original base metal properties.


No, you do NOT normalize the weld heat affected zone from a subcritical PWHT, unless you perform a separate normalizing heat treatment.
 

RE: Killed vs normilized

And no one mentioned "fine grain practice". Sounds like the original spec sould be specific and require Cv ,or whatever property they want.

RE: Killed vs normilized

There is a fine point as to what's killed steel.
In particular I refer to  ASTM  A-6 ,Paragraph 8.0.

A-6 states that  the minimum Aluminum  must be 0.020 %
MINIMUM.

This is the same language as in A - 20.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources