Variations in 304 from suppliers

[Gorpomon]

Hi,

I've noticed as I shop for 304 and 316 there are many small variations in the materials.

For instance, I have noticed:
- Variations in the upper nickel content, between 10.5 and 12.00
- Some suppliers have 304 with up to .75% Cu while others don't even list Cu as a constituent
- Some suppliers only list low Carbon variants
- Some have up to .10% Nitrogen

These are examples of what we've seen and wondered about. Obviously I don't expect you all to address these specific issues, what I am instead wondering is if there is any big picture thing I'm not seeing?

Are there common variants I should expect? Is it just accepted in industry some minor constituents will vary?

Any illumination on this would be greatly appreciated!

 

[metengr]

Gorpomon;
First question –
How are you shopping for material (do you have a request for quotation based on product form and specification)?

Second question-
Do you have a specific material specification based on some recognized standard like EN or ASTM or ???

If the answers above are I don't know or no, I would suggest you have some type of material specification provided to suppliers as a RFQ so you know exactly what is being supplied. Simply shopping for material quotes means you get what is available and what other knowledge customers don't want to purchase.

 

[EdStainless]

If the Cu is not deliberately added then it is not controlled by the specifications. It actually comes from poor scrap segregation. The only time to worry about Cu is if you need very smooth welds in material with a good surface finish.
For some product forms the N is not a controlled element either. It is the one exception to you not being able to make an alloy that has been adjusted to become another grade and still calling it both. (304L and 304LN)
In the US and EU there is very little 304. It is either L or H. There is no reason to make another variation. Especially since the L material meets the requirements for 304 in both chemistry and strength. There used to be a added charge for L but not any more.
I would be worried about someone making 12% Ni. Either they can't do a proper analysis or they can't control their melt practice. I haven't seen a value over 11% in high quality sheet ever.

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Plymouth Tube

 

[sreid]

EdStainless,

I recall that you were writing a book on Stainless Steel. Is it now published?

 

[EdStainless]

Right idea, wrong guy.
You are thinking of this:

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

http://www/menuitem.2b9d1953d012ee1...fbb68ddb0b110VgnVCM100000621e010aRCRD&itemId=

Stainless Steels for Design Engineers
Publish Date: 01-01-08
ISBN 10: 0-87170-717-8
ISBN 13: 978-0-87170-717-8
Number of Pages: 296

About the Author(s) or Editor(s)
Michael F. McGuire, Ph.D. is a consultant with extensive steel industry experience in executive and manufacturing research positions. As Vice President of Technology at J & L Specialty Steel, he was responsible for developing new markets for stainless steels especially in the architecture and household appliance segments. During his tenures at J & L Specialty Steel, LTV Steel, and Gould, Inc., he led projects for improving manufacturing processes and has numerous patents. He is a leading expert on stress corrosion cracking and hydrogen embrittlement, areas he continues to research as an adjunct professor at Carnegie Mellon University. Dr. McGuire moderates an online forum on stainless steels at eng-tips.com.
Dr. McGuire is a graduate of Case Western Reserve University (M.S., Ph.D. Metallurgy and M.S. Management) and the University of Notre Dame (B.S. Metallurgy).

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Plymouth Tube

 

[arunmrao]

ed,brilliant idea,perhaps some of you like metengr,corypad,tvp,unclesyd and other like minded can pool in and write a book.That would be excellent. Can we start a discussion,about how the book could be.


If you think education is expensive, try Ignorance.
- Andy McIntyre


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[mcguire]

Hi guys
Thanks for the plug, EdStainless. The book is selling well; up in the top 200,000 on Amazon.
304 chemistries are not accidental. The idea of producers is to minimize alloy cost and they do it to a very fine degree. 0.1% nickle reduction is $30/ton which can be well over $1,000,000 per year savings. N is high to counter low carbon, because both act like nickel in stabelizing austenite. Cu is high to minimize nickel. (Yes, it is done deliberately.)
P is steady and not controllable. S is deliberately added to help weldabiility for some customers. Mn is kept near the maximum (nickel substitute). Some producers deliberately add Ti to help hot working. If you ever get nickel far above the minimum, it is probably a left-over from a customer's heat for which a premium was paid for higher nickel, such as is done for deep drawing applications.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[arunmrao]

welcome,good to see you Sir,in this forum after a long time.


If you think education is expensive, try Ignorance.
- Andy McIntyre


_____________________________________

 

[EdStainless]

If I ever catch a mill deliberately adding Cu or Ti to 304 and not reporting it I'll do my best to make sure that every authorizing body knows that they have deliberately violated the ASME certification rules. We rely on alloys having specific creep and stress rupture properties, mucking with chemistry can have serious consequences.
If they add enough to make it another grade (321) then they can't call it 304.
Nitrogen is allowed, but it still has to be reported.

Many of the grade variations are actually designed for specific end applications.
The ones that you have to watch out for are the guys just trying to cut corners.

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Plymouth Tube

 

[mcguire]

In the case of Ti, there is no residual amount measureable because it's used as a deoxidizer, like silicon and manganese, except stronger. If it were present you would notice on the GTAW tube line as slaggy welds.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/