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Corrosion of Copper Alloys

  • 1.  Corrosion of Copper Alloys

    Staff Liaison
    Posted 05-22-2020 14:47

    In reviewing usage statistics for ASM Handbooks in the ASM Digital Library, I noticed that Corrosion Characteristics of Copper and Copper Alloys was the article in the Metals Handbook Desk Edition, 2nd ed., that received that most usage in 2019 and also so far in 2020. It has about five times the usage of an average article in that volume. Any ideas what might be driving the interest in that particular topic?

    The article reviews the forms of corrosion and the general performance of copper in each. It discusses the effects of alloy compositions and alloy selection for specific environments. Table 4 is a very large chart that gives corrosion ratings for nine classes of copper alloys in more than 120 different media. The ratings are excellent or good in most media, but there are a few harsh environments (such as nitric acid) where it performs poorly.

     It would be interesting to know the various reasons ASM Desk Editions users turn to this article. Is it to diagnose a corrosion issue or failure, to develop a corrosion protection strategy, or to select an appropriate alloy for a given application?

     As a reminder, access to the full text of the ASM Desk Editions is provided as an ASM membership benefit. ASM members just need to log in using their ASM site credentials.



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    Scott Henry
    Senior Content Engineer
    ASM International
    Materials Park OH
    (440) 338-5401
    ------------------------------


  • 2.  RE: Corrosion of Copper Alloys

    Posted 05-26-2020 10:18
    I do a lot of failure analyses involving stress corrosion cracking in yellow brass. Many plumbing components are being made out of yellow brass these days - easy to machine (good), cheap to produce (good), susceptible to dezincifcation (bad). I'd guess that more than half of my metal failure cases involve yellow brass, specifically, as compared to copper, aluminum, iron/steel, etc.

    ------------------------------
    June Bott
    Materials Engineer
    JENSEN HUGHES
    Mountlake Terrace WA
    (425) 775-5550
    ------------------------------



  • 3.  RE: Corrosion of Copper Alloys

    Staff Liaison
    Posted 05-26-2020 19:21

    June, That's interesting. Is the relative failure rate of  yellow brass due to its higher alloy (and lower copper) content? Would the SCC failures be fewer in number if a higher copper brass was selected?






  • 4.  RE: Corrosion of Copper Alloys

    Posted 05-27-2020 17:26

    Scott,

    I also deal with this daily and agree that this is a big and fascinating issue.  From a metallurgical standpoint the solution (as you suggested) is simple - use brass with a lower zinc/higher copper content and both SCC and dezincification go away.  Unfortunately, it seems like some major plumbing code and spec decisions have already been made without serious regard for metallurgical implications and they are pretty set-in-stone, so yellow brasses are often explicitly allowed and are easier for manufacturers to work with.  All this makes it a really challenging to rebut an argument of "the code says this is OK, so how can there be an issue?"  Anyway, I'm not sure if this is related to the increase in traffic (I hope so though!), but I think it is an interesting issue to keep track of.



    ------------------------------
    Adrian Hruszkewycz
    Donan
    Simpsonville KY
    8004825611
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  • 5.  RE: Corrosion of Copper Alloys

    Posted 05-27-2020 22:12
    I am a member of ASTM A01 Steels, Stainless Steels and Related Alloys and several non-ferrous subcommittees. Manufacturers dominate these committees and their decisions to standardize alloys often will affect codes.  Although corrosion engineers like myself know that higher Zn contents in yellow brass will result in dezincification, higher Cu contents in brass can result decreased machinability.  Free-cutting brass has higher Zn and Pb content than several other brass alloys, but its machinability is so superior, that a manufacturer will choose it every time since they want lesser cost and high productivity.  Replacing corroded components also means providing replacement parts.  Our metallurgical and corrosion knowledge is unfortunately subordinate to profitability and economics...

    Christopher Hahin, MetE, CorrE, PE
    States of Illinois and California
    Springfield IL 62704

    ------------------------------
    Christopher Hahin
    Engineer of Structural Materials & Bridge Investigations
    Illinois Department of Transportation
    Springfield IL
    (217) 522-4023
    ------------------------------



  • 6.  RE: Corrosion of Copper Alloys

    Posted 05-27-2020 22:12
    Hello everyone,

    I have found that standard NSF 14 addresses these issues.

    I agree, it is a fascinating issue.





  • 7.  RE: Corrosion of Copper Alloys

    Posted 05-28-2020 08:32
    NSF 14 does recognize the issue and requires high-zinc alloys to pass the ASTM B858 test for SCC in order to be NSF certified, which is definitely better than nothing.  However - ASTM B858 only tests for whether residual stresses in a part are enough to cause SCC.  There is no explicit requirement to take into account the actual applied stresses imparted by plumber wrenching on a threaded connection out in the field or any other potential sources of stress.  So again the question arises - "NSF has certified the product, so how can there be an issue?"

    ------------------------------
    Adrian Hruszkewycz
    Donan
    Simpsonville KY
    8004825611
    ------------------------------



  • 8.  RE: Corrosion of Copper Alloys

    Posted 05-29-2020 08:23

    NSF 14/ANSI 61 does not address torque requirements for fittings; it is a standard which provides guidance on compatibility of chemicals used in water treatment and disposal.  With respect to residual stresses, there are stress relieving temperatures associated with brass alloys.  The purchaser, in most cases a large distributor, would have to specify stress relief or verify if the product manufacturer performs this process after manufacture.  I have found that many cast products, such as valves, coming in from China have no stress relief treatments, and they often split apart after sustaining pressure.

     

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  • 9.  RE: Corrosion of Copper Alloys

    Posted 05-27-2020 08:55
    Although you state that the majority of your casework is due to stress-corrosion of yellow brass, those alloys are subject to dezincification, resulting in a loss of tensile bearing section.  Stress corrosion of brass is traditionally associated with the presence of ammonia.  However, when coupled with the localized stesses of threading and the loss of tensile-bearing section caused by dezincification, this phenomenon should be best described as dezincification-induced stress corrosion of yellow brass.

    Regards,

    Christopher Hahin, MetE, CorrE, PE
    States of Illinois and California
    Springfield IL

    ------------------------------
    Christopher Hahin
    Engineer of Structural Materials & Bridge Investigations
    Illinois Department of Transportation
    Springfield IL
    (217) 522-4023
    ------------------------------



  • 10.  RE: Corrosion of Copper Alloys

    Posted 05-28-2020 11:54
      |   view attached

    Colleagues, 

    Please see attached. The material is C260 annealed temper.

    Was sent to us by our customer with following message;

    "…We bought the material in question from you in June 2017.  We sold it to a customer in May 2019.  Customer notified us of this concern in April 2020.

    Customer's quality department is claiming that both parts in attached pic came from the same shipment.  Parts were laser cut and the end use is a Fey Shield they believe."

    We asked about protective atmosphere during laser cutting. The answer is:

    " Our laser operation is not in a non-oxidizing atmosphere but we do use nitrogen as a shielding gas." 

    Please advise how to design an investigation.

     

    Thank you in advance.



    ------------------------------
    Vadim Yashchenko
    manager of process metallurgy and quality
    heyco metals, inc
    West Chester PA
    (302) 897-5272
    ------------------------------



  • 11.  RE: Corrosion of Copper Alloys

    Santa Clara Valley Admin
    Posted 05-29-2020 08:23
    I would verify that the material did meet the compositional requirements of C260 rather than some other alloy.  Mix-ups happen!
    If the alloy is correct, I'd use SEM to inspect the surface and XRF to determine the composition of the surface layer. If that layer is too thin, methods such as Auger or ESCA might be needed.

    ------------------------------
    [Dave] Himmelblau
    [Retired Materials & Processes Engineer]
    Mountain View CA
    (650) 968-1121
    CharlesRetired
    ------------------------------



  • 12.  RE: Corrosion of Copper Alloys

    Posted 05-29-2020 14:55
    Both, good and bad parts are from the same batch. Not a mix-up definitely.
    Thank you for the recommended method.

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    Vadim Yashchenko
    manager of process metallurgy and quality
    heyco metals, inc
    West Chester PA
    (302) 897-5272
    ------------------------------



  • 13.  RE: Corrosion of Copper Alloys

    Posted 06-02-2020 08:55
    I have seen and heard of mixed batches that are the result of intentional and accidental counterfeiting.  Unfortunately this occurs for more and more products each quarter. I don't suggest that is your situation, but keep an open mind to this.

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    Gary Shade
    Sr. Microelectronics Engineer
    Samtec
    Monument co
    (719) 465-6579
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  • 14.  RE: Corrosion of Copper Alloys

    Posted 05-27-2020 08:55
    I grew to love the ECO BRASS C69300 alloy during a project while at Insight Technology.
    Its a bit expensive, but I put it through two 48 hour salt fog tests with little corrosion, while 360 brass turned into a mess.
    my reason for looking at it way back when (it just became known or in production at the time) was to find a free-machining brass which could also be ultrasonically welded.   Leaded brass alloys cannnot be easily ultrasonically welded.   This alloy was able to support ultrasonic welding of a solid copper ground wire to it. Big time saving there. 


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    Wallace Woodman
    consultant engineer
    Woodman Technologies
    Merrimack NH
    (603) 341-2133
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  • 15.  RE: Corrosion of Copper Alloys

    Posted 05-29-2020 08:23
    What kind of plumbing parts are these?  Drinking or non-drinking (sprinklers, industrial etc..)?  Dezincification could be solved easily by adding 0.02% Sb or As and many standards have included in the specs (C27453, C84800) for plumbing application.  If in industrial use if it is exposed to Ammonia then the problem can arise.  Comparing common yellow brass to C360 which has 3% Pb and no Sb or As will not be beneficial.

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    Muthukumarasamy Sadayappan FASM
    Research Scientist
    Canmet MATERIALS, Natural Resources Canada
    Hamilton ON
    (905) 645-0782
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  • 16.  RE: Corrosion of Copper Alloys

    Posted 05-29-2020 10:29
    This is a big deal in home drinking water systems, though I'm sure it affects other areas as well.  All sorts of couplings, nuts, and valves made from high-zinc brass are used in modern plumbing.  If any of these things breaks, then some very serious water damage can occur to a home or building.  Dezincification-resistant ("DZR") brasses are sometimes used, but the SCC issue remains.  Trace amounts of ammonia can be present in drinking water as a result of water treatment processes, so the potential for SCC is always out there.

    ------------------------------
    Adrian Hruszkewycz
    Donan
    Simpsonville KY
    8004825611
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  • 17.  RE: Corrosion of Copper Alloys

    Posted 05-30-2020 10:01
    Sorry, but your recommendation to limit the dezincification in machinable yellow brass in potable (drinking or food grade) water by the addition of arsenic is unsafe and would probably result in some dissolution of arsenic.  The American (and possibly even more stringent in Canada) limit as established by the EPA is 0.010 mg/L, or 10 parts per billion.  Alloys with Sb or As could be used for wastewater piping/plumbing components or industrial fluids, but are not appropriate for any contact with drinking water.

    ------------------------------
    Christopher Hahin
    Engineer of Structural Materials & Bridge Investigations
    Illinois Department of Transportation
    Springfield IL
    (217) 522-4023
    ------------------------------



  • 18.  RE: Corrosion of Copper Alloys

    This message was posted by a user wishing to remain anonymous
    Posted 05-30-2020 10:01
    This post was removed


  • 19.  RE: Corrosion of Copper Alloys

    Posted 05-26-2020 10:18
    I would guess there is a lot of interest due to the antimicrobial properties of copper and COVID-19.

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    Ken Kirby
    Snap-on, Inc.
    Kenosha WI
    (262) 748-3836
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  • 20.  RE: Corrosion of Copper Alloys

    Kansas Admin
    Posted 05-29-2020 10:06
    And what corrosive affect does Chlorox dis-infecting wipes have on the copper door knobs or other handles?

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    Patrick Mizik
    Principal Metallurgical Engineer
    Haldex
    Leawood KS
    (816) 510-2458
    ------------------------------



  • 21.  RE: Corrosion of Copper Alloys

    Posted 05-30-2020 10:01

    Larry, 

    Perhaps because Copper is in the noble metals column, but maybe as a knight or bishop, rather than as a king or queen. The gap in perception versus reality may be driving the high usage of the article.

    Agree: Copper and nitric acid can produce various nitrogen oxides, only one of which is laughing gas, the others are nothing to laugh at, at all.

    You have stirred some interesting discussions.





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    Bob Foley
    Materials Engineer
    Elkay Manufacturing Company
    Downers Grove, IL
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  • 22.  RE: Corrosion of Copper Alloys

    Posted 06-01-2020 08:23
    I think one of the reasons to review that article is that there ARE so many.  Trying to understand the huge variety of copper alloys just from the naming conventions is futile.  It's still difficult enough with tables of data like in the article.  I can recall looking at a composition range, especially one with a bit if uncertainty, and having to spend quite a bit of time sorting through which alloy family that might belong to. So trying to identify a "found" material, for instance doing a failure analysis, as well as searching for what the heck "Navy M" is, as well as looking for a suitable alloy for a selection task, these are all great reasons that the article and those tables are useful. 

    In another discussion here someone is discussing whether trace elements will result in water contamination.  It reminds me of the old corrosion joke, "A drop of acid will dissolve its own weight in metal, forever."  An element like lead, or like antimony, is present in very limited amounts on the wetted surface of a component.  It either corrodes, releasing its somewhat toxic payload and disappearing thereafter, or it doesn't, and is bound up in the surface patina.  Leaded copper alloys were used for many years in home plumbing fixtures because of the huge improvement in machinability.  As I understand that usage is now not encouraged, but nobody made everyone go back and remove all of the old stuff.

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    Paul Tibbals
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  • 23.  RE: Corrosion of Copper Alloys

    Posted 7 days ago
    I agree with Ken, copper is in the press a lot right now due to its anti-bacterial and anti-viral properties. I know ASM covered this in their September Antimicrobial copper article from Northwestern University and Harold Michels has recently put together a video about this alongside a website https://www.amcopper.com/. Recent studies from Harold I believe showed a four log drop in a number of hours with 70%+ copper alloy but he could confirm this. Having been testing Monel myself and dealing with nickel silver in the conservation field, I wonder if this doesn't place the latter and other higher copper content brasses in a new light.

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    James Churchill
    Architectural Conservator
    Kreilick Conservation
    Ambler PA
    (917) 847-6267
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  • 24.  RE: Corrosion of Copper Alloys

    Posted 6 days ago
    Being a newcomer to ASM I have only recently picked up on this thread. Over the last few years I have spent a lot of time working with copper and copper alloys from shipwrecks. This gives me a perspective of about 150-250 years. One thing is clear and that the beta phase in an alpha-beta brass such as Muntz metal dezincifies very rapidly which is why it was good practice to re-sheath a hull about every three or four years. Even with a wreck where the sheathing is known  to be less than a year old the dezincification is very significant. The point with hull sheathing is that the environment is not static: erosion by the passage of the hull trhough the sea and a variety of sources for mechanical damage accelerates the loss of metal and incnreases the biocidal activity.

    I have also looked at brass tubes from the boiler of a locomotive lost in 1857 on its delivery voyage to Nova Scotia. These gave 30% zinc and have suffered some inter- and transgranular attack but in general are in remarkably good condition. 

    It is also noticeable that the Romans would tin a sheet brass vessel used for food or wine but weree less likely to tin a bronze one.

    ------------------------------
    Peter Northover
    Retired
    Department of Materials, University of Oxford
    Abingdon
    +44 1865 820543
    ------------------------------



  • 25.  RE: Corrosion of Copper Alloys

    Posted 6 days ago
    Peter, that is very interesting!  Given that metallography as an art had not been developed back then, the fine points of what was happening weren't available to those who sheathed the ships.  Though the deterioration would have been obvious on a macro level.  But there must have been some property of the alpha-beta materials that was superior to just using copper sheet, otherwise that would have been used.  Perhaps cost?  Or maybe it didn't dissolve the iron nails as quickly?
    OK, that got me to do some cursory research - you're probably much further along on this topic! - But some great details are at
    https://shipwrecks.com/muntz-metal-hull-sheathing/

    From which I quote:"According to Muntz's patent, his [60Cu, 40Zn, trace Fe] alloy can vary to 50% copper and 50% zinc. It was rolled at "red heat."  Its original application was as a replacement for copper sheathing on the bottom of ships, as it maintained the anti-fouling abilities of the pure copper at around two thirds of the price. It became the material of choice for this application and Muntz made his fortune."


    It also mentions later that Muntz later developed fasteners of his composition that did not dissolve (as would happen from a corrosion couple with iron) further enhancing his commercial gains.

    When younger I was in Sea Scouts and we had to renew the copper-bottom paint on our vessel regularly.  But those materials are starting to be banned, precisely because of the copper build-up in the environment of harbors.  One summary of this situation can be found at
    https://archive.epa.gov/region9/waste/archive/web/html/san-diego.html

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    Paul Tibbals
    ------------------------------



  • 26.  RE: Corrosion of Copper Alloys

    Posted 5 days ago
    Paul, you are asking just the right questions. What Muntz was looking for was a) something with better properties than copper so unit weight for the job was less, b) was cheaper to produce, and c) he could get patent protection. He managed with the first two because zinc was cheap and he could hot roll the alloy. He also got away with the third. He was actually not the originator of brass fastenings for ships but, when he took a competitor to court, he managed to convince the judge that his patent was valid. Actually, the first brass bolts were tried in 1781-82; it is possible we have one from the wreck of HMS Sirius lost on Norfolk Island in 1790. If it is indeed from Sirius rather than intrusive from another wreck, then alpha-beta brasses were being tried in the early 1780s. This is a reasonable conclusion because patented in 1779 was an alloy which was an alpha-beta brass with the addition of 4% iron (James Keir's alloy), a corrosion disaster waiting to happen.; there is a graphic description of what the bolts looked like when a ship where they had been used was dismantled after 25 years. 

    Muntz took out patents for his alloy un both sheathing and bolts in 1832 but take-up was very slow, only gathering pace after about 1838. When his patent expired in 1846 he tried another alloy with a percentage of lead but nobody was buying that. The Royal Navy did not switch to brass because they had a highly efficient mill recycling copper from their own ships and they had little need for new metal. The US Navy seems to have followed suit: the USS Housatonic, of 1861 certainly had copper fastenings. 

    The whole history of these topics needs revision because much of what is published is based on secondary sources which are just plain wrong. The Royal Navy had been aware of the copper/iron couple and the problems it posed as soon as they inspected HMS Alarm on heer return from her first cruise in 1763. They tried two approaches: one was to try and keep the iron an copper apart and the other to explore copper fastenings, the first experiment being Swallow of 1769. The first natch of larger ships was ordered at the end of 1776 and after that the number and size of ships sheathed and fastened with copper increased. These first bolts were produced with tilt hammer and swage. When the Navy opted to copper fasten all sizes of vessel and to retrofit all existing iron fastened vessels there was a need to ramp up production and this was when using grooved rolls to produce the bots began. With the end of the American War in 1783 British entrepreneurs promptly sold the technology to the French. I believe Paul Revere was the first to produce copper bolts  in the USA in order to resize bolts when the wrong size had been delivered from Britain.  

    There is so much history here and we are just getting to grips with it. Our present interest is texture analysis to distinguish between methods of production, forged, rolled with grooved rolls, and using the rolls to pull the copper bar through a die. That is easy to spot and at the moment we are just starting on a forged bolt. 

    If anybody is interested in further information do get in touch direct.

    ------------------------------
    Peter Northover
    Retired
    Department of Materials, University of Oxford
    Abingdon
    +44 1865 820543 peter.northover@retired.ox.ac.uk
    ------------------------------