Compare 304SS and duplex SS 2

[deepsok]

Can anybody guide me for comparing pro/cons/cost for 304SS and duplex.I am into cooking appliance industry looking for cost reduction in 304SS parts.i also need if cladding can be useful for cost reduction in high volume SS parts.

 

[stanier]

http://www.nidi.org

is a good starting point.

Duplex such as SAF 2205 provides an alloy designed to prevent stress corrosion cracking. It may cost a 10% premium over 304ss.

You would expect that in your industry there will be temepratures above 50C and chlorides will possibly be used in the cleaning of such parts. This is a perfect environment for stress corrosion cracking.

 

[deepsok]

Thanks Stanier.I need to be more specific by saying cooking appliances,those are not actually utensils but ovens and Ranges.We are using 304SS for doors where two fuctions are important (appearance and surface temp not to exceed more than 60c when oven is in use).We have started using 201SS as an alternatie but then corrosion resistance is a big setback we may have over a period of time.So we just want to use 304SS and try reducing cost by using duplex or cladding technology.I am looking for more information of duplex/clad steel costing when it comes to high volume parts.

 

[TVP]

You should review the archives of this site, especially for any responses from mcguire, who has a great deal of experience working on stainless steel for consumer applications, including conversions of Type 304 to other grades (duplex like 2205 & LDX 2101, ferritics, etc.). He even wrote a book recently published by ASM International called Stainless Steels for Design Engineers that would be an excellent reference for you. Here is a link to the ASM site for this book:

http://asmcommunity.asminternational.org/portal/site/

http://www/AsmStore/ProductDetails/?vgnextoid=da0fbb68ddb0b110VgnVCM100000621e010aRCRD

 

[EdStainless]

each of the steel makers web sites have such info. Why are you replacing 304? Need better corrosion resistance? cracking resistance? strength?
First you need to be aware that there are about a dozen different duplex grades available and they cover a wide range of corrosion resistance.

If 304 is failing then moving to a duplex may be the lowest cost way of getting a better part.
If you want to reduce total cost then you will need to use the higher strength in order to make the parts thinner/lighter. On a $/lb basis the lean duplex alloys are more expensive than 304 by 5-10%. But if you can cut thickness by 20% you can save money.
The prices of the duplex alloys will also be more stable since they contain so little Ni and Mo the surcharges don't fluctuate much.

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Plymouth Tube

 

[deepsok]

TVP nad Edstainless ,thanks for the valuable suggestions.
Yes I do agree that Ni prices have fluctuated so much to destabilze SS part cost.That is why I am opting for alternative to 304SS.I am looking for better dent resistance,formability, with the corrosion resistance to be like 304SS.
I think the thickness avalibility (may be .020 to .026 range)may drive the cost.

Can you suggest me some steel makers for starting point.
I know winox and otokumpu offer speciality duplex grades.

Edstainless,I really admire your knowledge in this field.Thanx again.

 

[EdStainless]

Outokumpu LDX2101
Allegheny AL2102
These are the two that I like the best.

Don't bother with 19D, it has poor corrosion resistance



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Plymouth Tube

 

[Flesh]

In your application (indoors, surfaces cleaned regularly) , I believe the 201 material should work just fine. Have you reviewed corrosion test data for this alloy? I've tested 201, 201LN, and 304L side-by-side in ASTM B117 chamber and they all look phenonmenal after 1000 hrs (painted, scribed, and bare). I think this test environment is pretty harsh compared to your application. If 201 performs this well, the next lowest cost approach in my mind would be to investigate using a ferritic grade with a clear coating.