Bright anneal stainless in a Carbon steel annealing oven

[Hercules28]

Ok, before you start throwing ingots at me here is the question in detail:

I have an oven that I routinely anneal carbon steel parts. There is smut all over the inside of it. Guessing Fe and oils from parts that where not ideally cleaned.

Can I burn off the smut with a few high T cycles and then try to bright anneal stainless?

I need some votes here. ... I am already saying no.

Thanks,

Herc

 

[antknee]

I don't think some high T cycles would make much difference. You could wrap them in some spare foil.

 

[Hercules28]

Aluminum foil??

 

[MikeHalloran]

Stainless steel foil, typically .002" thick.

You'll want some heavy leather gloves to protect your hands while you're cutting or folding it; it makes a nasty deep cut that bleeds freely.



Mike Halloran
Pembroke Pines, FL, USA

 

[TVP]

What kind of atmosphere does the furnace usually have? What gases are used? Bright annealing usually entails a small amount of Hydrogen. Do you have this available?

 

[metengr]

The bright anneal is a reducing atmosphere so existing oxides within the furnace will be reduced and could result in surface contamination of stainless steel. If I was a client I would not permit it on my stainless steel products.

 

[Hercules28]

TVP, It is an atmosphere furnace that pulls a vaccuum and quenches with Nitrogen.

There has been done bright annealing of stainless in this furnace in the past but results where not consistent.

Yes I don't like the idea either....!

 

[EdStainless]

Vacuum is not a bright anneal, it may be shinny but it is not chemically reducing.
SS that is vacuum annealed will always have some residual surface oxides.
This material will not have optimal corrosion resistance unless it is further treated.

That said, if you ran a cycle hotter than your SS anneal temp on the furnace with a dummy load I don't see any reason why the SS that you ran after would be any worse than stuff run in a SS only furnace.

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Plymouth Tube

 

[Hercules28]

I need to doublecheck with that.
So for Bright anneal you would need Argon/Nitrogen or Hydrogen?

We do have a pickle/pass step afterwards.

 

[TVP]

Bright annealing means a reducing atmosphere, which requires hydrogen. At annealing temperatures, nitrogen diffuses into stainless steels, so even argon/nitrogen is not used. The following link, especially Table 4 on page 7, should be helpful:

http://heattreatment.linde.com/Inte...sf/repositorybyalias/wp_annlg_13/$file/13.pdf

 

[EdStainless]

People often use the term bright anneal to cover inert gas or vacuum annealing.
In some alloys (which cannot anneal in hydrogen) this definition is fine.
In SS it is not. Without hydrogen you will not reduce the Cr oxides on the surface and be able to achieve optimal corrosion resistance.
When we vacuum anneal SS we follow it with pickle and passivation.

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Plymouth Tube

 

[Hercules28]

OK, I see, so if I pickle and passivate I should be all set then. Thanks that was an eye opener.!!