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Classification of Stainless Steel 316 or 316L

2006

We ordered stainless steel 316 to the material supplier.
Enclosed material certificate says that the carbon content is 0.016%.
The cert doesn't mention its material designation like 316 or 316L.
I know that the difference between 316 and 316L is the amount of carbon that is in the material. 316 has .08 Max carbon content while 316L has a .03 Max carbon content.
Are there no minimum amount of carbon in the material to distinguish 316 with 316L?
How can I say what this material is, 316 or 316L?

Soon Lee
- Lemont, Illinois

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First of two simultaneous responses --

The reported carbon content satisfies both 316 and 316L simultaneously. All the other specified elements have the same ranges for both grades.

Neither 316 nor 316L have a specified minimum carbon, only maximum, because that's what is metallurgically significant.

If you want 316, you've got it. If you want 316L, you've got it. Call it whichever you wish to.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
2006

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Second of two simultaneous responses -- 2006

Hi Soon!

Yeah, a lot of steelmakers are doing that. By lowering the carbon to 316L levels, which isn't that difficult to do in the AOD vessel, they can sell the material as either 316 or 316L. It's both, since there is no minimum carbon content.

Such will only be a problem if you have a need for higher strength, since higher carbon content gives higher strength. Then, however, you generally order a quarter hard, half hard, or full hard condition. These kinds of things are explained in the specifications commonly used for stainless steels- check out ASTM A666 for sheet, strip & plate, and ASTM A276 for bar.

Lee Gearhart
metallurgist - E. Aurora, New York

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June 28, 2010

I have a similar dilemma as in the original post. The customers SOW for the parts I need to mfg states that they will not except 316L material. After reading this I realize I would need a carbon content from .03 to .08, but none of the material I can find goes above .025C.
What are the typical carbon content values for 1/4, 1/2 hard or full hard 316. I don't have access to the referenced ASTM specs/standards... Is there a metal supplier known for selling this classification of SS as large diameter (5.5-6.5") rounds?

Matt Jones
- Seattle, Washington, USA