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.
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Peter Northover
Retired
Department of Materials, University of Oxford
Abingdon
+44 1865 820543
peter.northover@retired.ox.ac.uk------------------------------
Original Message:
Sent: 01-09-2021 14:55
From: Paul Tibbals
Subject: Corrosion of Copper Alloys
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
Original Message:
Sent: 01-09-2021 10:16
From: Peter Northover
Subject: Corrosion of Copper Alloys
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.
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Peter Northover
Retired
Department of Materials, University of Oxford
Abingdon
+44 1865 820543
Original Message:
Sent: 01-08-2021 16:07
From: James Churchill
Subject: Corrosion of Copper Alloys
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
Original Message:
Sent: 05-22-2020 13:36
From: Scott Henry
Subject: Corrosion of Copper Alloys
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
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