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Presence of Cu in SS 316L

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franklin55

franklin55

Mechanical
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We have procured SS 316L pipe (4" Sch. 160)for our Urea plant. We have now tested some random lengths of the pipe and the result of one of them is as follows:
Cr = 16.78 %
Mn =1.39 %
Mo = 2.19 %
Ni = 10.59 %
Cu = 0.8 %
Fe = 68.25 %

The above composition seems perfect except the presence of Copper. Can anyone advise if the presence of Cu is acceptable?
Please note that the alloy analyzer cannot detect Carbon therefore the reading of Carbon is not given.

Regards

 
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A quick trolling of Google results seems to indicate some increasing hardness, ductility and corrosion resistance attributed to copper, as well as a reduction in surface porosity when it is added to some stainless steels. I can't say, but it doesn't sound like its always a bad thing. With that much "other stuff" in there, its probably hard to add all those and still keep all the copper out. Time for you to find a metalurgist.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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franklin55,

Copper shouldn't be there as already written by others. The manganese content seems to be rather low, too. Where did you buy it, in the US or abroad? Keep in mind that the AISI code fits to various DIN or ISO material codes and some may allow some copper content. But at the end of the day it depends upon what code your supplier had confirmed.
 
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I checked the composition in ASTM A 182 for type 316L. Copper was not mentioned. Copper is not listed on the table of expected elements. Other alloys mentioned copper in the notes. The manganese shows 2% for most similar alloys.

The composition listed did not look like anything that I saw in A 182 when searching for copper.
 
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I don't know what its doing there, but it is sometimes added to steel.
------------------------------------------
Steel is considered to be carbon steel when no minimum content is specified or required for chromium, cobalt, columbium [niobium], molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 per cent; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60. Carbon steels are normally classified as shown below.
`````
High-strength low-alloy (HSLA) steels, or microalloyed steels, are designed to provide better mechanical properties than conventional carbon steels. They are designed to meet specific mechanical properties rather than a chemical composition. The chemical composition of a specific HSLA steel may vary for different product thickness to meet mechanical property requirements. The HSLA steels have low carbon contents (0.50 to ~0.25 weight percent C) in order to produce adequate formability and weldability, and they have manganese contents up to 2.0 weight percent. Small quantities of chromium, nickel, molybdenum, copper, nitrogen, vanadium, niobium, titanium, and zirconium are used in various combinations.
----------------------------------------------------------
Some uses are given here,

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Is the pipe certified as ASTM A316 or not? If so, then I would worry about if it is suitable to your process or not.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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0.8 % copper is not a negligible portion and sould therefore be mentioned in the composition of AISI 316L. As far as I know it is not. And manganese must be > 2 % for 316L. At least that's what I remember from a job where we had to supply material certificates.
 
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Yes, but can it be classified as A316 with that 0.8% copper in it??? Those 316 composition don't specifically limit copper content, if they don't even address it.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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If there were limits for copper, they would be mentioned. If no limits are mentioned, there should not be any copper in it. At least that's how I see it for a 0.8 % content. I wouldn't care about 0.1 % but 0.8 % is too high to ignore it. I'm sure if copper was common in 316L, there would be limits for it.
 
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I'm pretty sure its not common in A316, so normally wouldn't be addressed. The question I still have is, can it be there and still be given an A316 cert.?


**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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If copper was not addressed in the purchasing documents, the material may be given an inspection document in accordance with ASTM A312 TP316L, if that was the designated purchase specification, since copper is not required to be analysed or reported.

Steve Jones
Materials & Corrosion Engineer
 
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The pipe has been purchased from a stockist and the manufacturer for some of the lengths is Nippon Steel Japan and others are Made in Korea. The Copper content is detected in Korean Pipe only.
 
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Unless a range is shown, the ASTM standards indicate that the % listed is a maximum. Where a range is shown then there is both a maximum and a minimum. Where "..." is shown this is an unspecified element and as such the element is "not controlled to a specified minimum, maximum or range, in accordance with the requirements of the applicable product specification". Note: this definition of an unspecified element comes from ASTM A941.

Since we are talking about 316L pipe, I'm assuming that the applicable specification is ASTM A312 "Standard Specification for Seamless and Welded Austenitic Stainless Steel Pipes".

According to ASTM A312, for Grade 316L, Manganese is listed as 2% and Copper is shown as "...". Consequently, any value for Manganese not greater than 2% if permissible and there is no specified minimum or maximum for Copper.

As a result (as already indicated by SJones), the material you were supplied would be in accordance with ASTM A313 Grade 316L and could not rightfully be rejected on the basis of the chemistry unless you had provided supplemental requirements with the purchase order.

As to the question of whether the Cu is a good thing or a bad thing, I'll leave that to the qualified metallurgists.
 
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quote.. As a result (as already indicated by SJones), the material you were supplied would be in accordance with ASTM A313 Grade 316L and could not rightfully be rejected on the basis of the chemistry ........ unquote

For me I can't agree this thinking, accepting 0.8% Cu means you are prepared to accept any other contaminant that has been introduced during manufacture. I believe that if it is not listed it is excluded.

 
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That's the impression that I had too, but I wasn't sure. So then, if its not addressed, it doesn't necessarily mean that it CAN'T be there.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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Check to see if the purchase order reflected either an ASTM or ASME specification such as A 312 (SA 312) A 182 (SA 182) type 316L stainless steel. Please clarify the spec if such material specification was listed.

Checking ASTM A 312, Table 1 Chemical Requirements includes a column for copper. The composition percentage includes a note B that reflects the value is the maximum unless otherwise indicated. Type 316L is blank under copper. This would suggest that any copper is out of specification for ASTM A 312 type 316L. See comments in this and another post about ASTM A 941, Steel Alloy Terminology.

This may be my first look at ASTM A 941 in a while. The definition for stainless steel only addresses the mass percent with a minimum chromium content and a maximum carbon content. With a column for copper it would not be an unspecified element.

I don't have ASTM A 313.
 
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ASTM A 313 if for wire. A 182 applies to forged or rolled pipe fittings. A 312 is seamless SSt pipe.
 
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I would venture to guess that the listed copper content probably accounts in some part for the better corrosion resistance in many environments of those pipe specs (304 and others) that do list copper contents then to what 316 has.

I don't think you'd want to spec 304 in projects carrying or storing jet fuel and the likes, so what Artisi says makes sense too.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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Not that stainless of any kind is typically used in pipeline jet fuel applications.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
 
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