[MW:7724] MW: 7714] Re: Chemical properties of SA 213 Gr. 304H

Hi Mr. Sindhe,

I presume your query about chemical properties  after solution annealing  is on "corrosion resistance". Solution annealing will improve corrosion resistance of SA 213 304H. 304H contains more "C"(0.04- 0.10% ) as compared to 304(0.08% max ) and 304L(0.035% max). As this alloy is unstablized, it does not contain other stronger alloying elements e.g Mo,Ti, Nb, which have more affinity for "C" to form preferential carbides.Welding and any other heat induced fabrication such as forming will cause some precipitation of  "Cr" as Cr-carbides, which reduce corrosion resistance through sensitization.

Solution annealing  will revert "Cr" back into solid-solution and will lessen any precipitation of "Cr-carbides".

However as pointed out by Mr. Herman Pieper, solution anneal will not change chemical composition. Also solution annealing will improve mechanical properties, e.g better % elongation and reduction of hardness.

Thanks


Pradip Goswami,P.Eng.
Welding & Metallurgical Specialist

Email-pgoswami@sympatico.ca,
pgoswami@quickclic.net

-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of hpi001
Sent: Friday, October 22, 2010 6:25 AM
To: Materials & Welding
Subject: [MW:7714] Re: Chemical properties of SA 213 Gr. 304H

Dear Shinde,

I don't agree with Mr. Kesavamoorthi his answer. There is a difference between chemical composition and chemical properties. Chemical composition won't change but chemical properties at the other hand will, and that is what you are asking for in my opinion.
Because of materials production process and/or welding activities Chromium carbides can / will be present in the material at the grain boundaries, especially in case of H quality (higher Carbon content).
The formation of Chromium carbides will cause a lower Chromium content near the boundaries of the grains, even less than 12% which makes these parts of the structure no longer Corrosion Resistant. This can cause Inter-crystalline corrosion. Due to the solution heat treatment these carbides will be solved and Chromium will be devided over the microstructure again. Therefore the chemical properties of 304H material will always be better in the solution annealed condition.

Best Regards,

Herman Pieper

On 21 okt, 09:39, "agstes" <ags...@gmail.com> wrote:
> Dear All,
>
> Is there any change in chemical properties prior to solution annealing and after solution annealing of SA 213 Gr. 304H ( solution annealing temp 1040 degree centigrade) e.g. % of carbon specifically.
>
> Thanks well in advance.
>
> Regards,
>
> Shinde

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