"Hot finished" vs "Normalized"

[ElCidCampeador]

Hello, I've just finished surfing through this forum, looking for threads about the differences between "Hot finished in normalizing temperature range" vs "Normalized" of carbon steel, but I still don't understand what the point is.

Example: SA 106 Gr.B carbon steel pipe, certificated as "Hot finished in normalizing temperature range". My client wants it "Normalized", hot finished is not enough. I could suggest SA 333 Gr.6 which has by code normalization required.

BUT.

Is there a REAL (mechanical/metallurgical) difference between something just "hot finished" and something "Normalized", even if they are both above Ac3?

Thanks

 

There is a big difference.
Normalizing of carbon steel refines the grain size, which raises impact toughness as well as tensile strength. (No other strengthening mechanism simultaneously improves impact toughness.)
The applicable ASTM standard will prescribe the required heat treatment, although if there is more than one option the condition is decided by agreement between purchaser and vendor.

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

 

[SJones]

https://www.eng-tips.com/viewthread.cfm?qid=325888

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

This is somewhat analogous to the Stainless steel 'process anneal' where they finish hot work above the min anneal temp and quench from there.
In both cases if you finish well above the min temp, and allow some dwell time then the results are indistinguishable from a separate HT.
However in most cases the temperature is not very uniform, and it is very close to the minimum, and the parts have little to no dwell, and then you end up with a lot more variability in properties than you should.

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P.E. Metallurgy, Plymouth Tube

 

[MagBen]

Depends, may or may not work. From metallurgical viewpoint, "Hot finished in normalizing temperature range" is a dynamic process, including recrystallization, while Normalization is "static", might be easier to control.

 

[ElCidCampeador]

Thank you all, now it's more clear.

Let's see from another point of view.

Supposing we have a SA 106 Gr.B pipe. It's used as a shell for vessel, so it will be drilled for nozzles, welded to caps/head, etc...

For static application, with no impact test required and no fatigue cycle applied: could be "hot finished" enough"? What could be its weak point?

 

[weldstan]

Non normalized A-106B has been used for countless small diameter vessels through the years.