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Jean Henri Chandler




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PostPosted: Thu 19 Nov, 2020 10:51 am    Post subject:         Reply with quote

I hadn't seen that Mark, thank you.

Yeah I am not a metallurgist, but I noticed, when I was trying to sort of 'summarize and dismiss' bronze and brass for a short essay about weapon-metallurgy I did in one of my game books, that as I was double checking my theory, I kept finding more and more exceptions on the range of possible properties of the bronze. The gist being, answering the question 'why is iron better than bronze?' The more I looked into it the murkier the answer seemed to be. Most Bronze (or "Latten") alloys seem to be a bit (around 10%) heavier than iron, and certainly heavier than steel for the same given strength. But on the other hand "Latten" alloys seem to have existed which had almost every property we can find in ferrous metals today: springiness, hardness, toughness, resistance to corrosion... especially in certain places like China where the development was very advanced, but not only there.

"Latten" metals remained popular with the Romans for armor, helmets especially, for a long time and as we have already noted, they remained the go-to metal for cannon and firearms throughout the medieval period, the only apparent downside being higher cost.

I came away with the idea that the most significant advantage of iron was that it didn't require any other rare elements to add to it in order to make it. Maybe the right kind of heat resistant clay. Some kind of source of carbon and maybe a bit of phosphorus for certain purposes, some charcoal to burn, and you were in business.

The whole question of the Bronze Age collapse comes into question somewhat. Some modern narratives claim it was due to the discovery of iron by the uncouth barbarians and nomads, who fell upon the settled civilizations. Probably more complicated than that, and maybe some significant climate change involved such as were occasionally caused by volcanic activity or celestial objects crashing and blowing up.

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T. Kew




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PostPosted: Thu 19 Nov, 2020 12:11 pm    Post subject:         Reply with quote

Regarding bronze vs iron for firearms, a big factor seems to have been the ability to cast it. Making a pressure vessel from iron staves and hoops does work, but it's a difficult and error prone process.
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Jean Henri Chandler




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PostPosted: Fri 20 Nov, 2020 5:55 am    Post subject:         Reply with quote

Yes but

1) they did seem to have more or less perfected the forged gunbarrel and
2) they were casting iron cannon barrels by the later 14th Century

And yet bronze remained in favor for both firearms and cannon well into the 18th Century, IIRC. You certainly see them all through the 16th Century. Both types existed side by side but it seems like the the latten made ones were usually more expensive and considered better, at least until it became commonplace to make steel gunbarrels.

Interesting that what became 'gunmetal' was a latten metal which had both zinc and tin

https://en.wikipedia.org/wiki/Gunmetal

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Andrew Gill





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PostPosted: Wed 25 Nov, 2020 6:13 am    Post subject:         Reply with quote

Hi there everyone, an interesting discussion

Regarding the use of copper alloys in making gun barrels, I have a highly speculative suggestion:
The properties of iron and steel can be quite drastically altered by a relatively small change in the carbon content (a fraction of a percent - 0.18% carbon is mild steel which won't keep a good edge, 0.6% carbon will just about make a usable blade, if still a little soft, 1.2% or more and you have brittle cast iron...

Bronze, on the other hand, has much larger quantities of tin relative to copper - British admiralty gunmetal was apparently 10% tin and 2% zinc, according to a quick google.

If you're making alloys using relatively primitive methods, its much easier and more forgiving to work with larger quantities, because the measurement is so much easier.

So whereas a relatively small error in the amount of carbon introduced via smelting would result in a brittle or over-ductile gun-barrel, you have to make quite a large error with the amount of tin introduced before you get a correspondingly bad alloy(and the tin is less likely to be accidentally introduced by the smelting process than carbon is with iron!).
Ergo, bronze would seem to give a more consistently reliable product for a lower level of metallurgical technology.

I'd love to hear from those engaged in making bronze for weaponry whether my idea holds any water.

As for the original question:
If the "brass arablests" aren't hand-cannons (which they plausibly may have been), perhaps it refers to the trigger-mechanisms being cast in bronze? I seem to recall that the trigger mechanism components of ancient chinese crossbows were cast to surprisingly high precision, and moisture, etc would affect them less than either organic materials or iron. I know some people in historical sources referred to a "silver sword" when they meant that there was silver inlay in the hilt...
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Jean Henri Chandler




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PostPosted: Wed 25 Nov, 2020 9:08 am    Post subject:         Reply with quote

Well i see a couple of problems with those theories, I wouldn't rule them out but these immediately come to mind

Regarding the quality of steel - they were able to produce rather vast quantities of swords, armor, and other steel military artifacts throughout the 15th Century. Augsburg for example became a center for tempered steel armor by the early 1400's. Milan had been making (untempered) steel armor since the mid-14th Century The armor would be 'proofed' and if it failed the test (being shot with a powerful crossbow or a handgun) it couldn't be sold, and obviously if it failed in the field that would reflect badly on the maker.

Outfits like the Stromer metalworks outside of Nuremberg or the Venetian arsenal could produce arms of consistent quality at a very large scale. Venice was able to build a warship in a single day and could churn out impressive quantities of firearm and cannon gunbarrels (of both bronze and iron) of sufficient quality that they were in high demand from European and Middle Eastern polities. These kinds of places had large partially automated blast furnace and bloomery forge complexes and had the science of producing metal and metal artifacts of consistent quality down pretty well, if not quite to modern industrial standards. It was hardly a caveman beating out iron over a campfire the way they show you in movies.



A lot of the comments we used to read about inconsistent metallurgy in medieval swords is due to A) not filtering for the source of the weapon, and B) not understanding the way medieval swords were intentionally made with different ferrous compounds.


Personally I think the single biggest advantage of bronze for firearms and cannons is that it doesn't make sparks.

As for the metal grips - they already knew how to weatherproof iron or ferrous metals sufficiently by the 14th Century that they routinely made all kinds of things which sat out in the weather indefinitely. In fact this knowledge goes back many centuries before the late medieval (see the Iron Pillar of Delhi which has sat in the Tropical rain and heat for 1600 years without a drop of rust on it)

For crossbows, by far the bigger issues with weather inevitably are the prods, which would be either steel, or composite / horn - (the latter usually covered with some kind of waterproofing like parchment, but not necessarily truly weatherproof) and the strings.

And why would brass grips be sufficiently noteworthy in the description of a battle for Dlugosz to mention it? Even if you assume that it's better than having iron fittings, is it better enough to make a difference in battle?

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Andrew Gill





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PostPosted: Thu 26 Nov, 2020 9:13 am    Post subject:         Reply with quote

Hi Jean, thanks for the reply

I certainly don't regard the metal workers of the renaissance as cavemen; I've seen and read enough to know that their metallurgical knowledge and industrial processes were pretty advanced. But even today, with our knowledge of the crystal structures of alloys and eutectic phase diagrams, getting the ratios of alloying elements (and avoiding impurities) is not a straightforward matter. The carbon content of many commonly available steels apparently varies considerably between batches (and even for high quality engineering materials, it is always specified within a range, not as a single number).

There is a definite difference in being able to produce steel consistently enough to manufacture sword blades or armour of an acceptable quality, to being able to reliably produce a metal tube capable of containing an explosion - a very energetic, high-temperature event that takes place in a very short period of time. A flaw that may be inconsequential in a sword blade could render a gun barrel dangerous and unfit for use. "Uniform" is a relative term (my old postgrad supervisor drilled a strong mistrust of vague, non quantitative comparisons into me).

Could they make good iron or steel gun barrels in that period? Absolutely - there are enough extant examples in museums, many which have survived undamaged to this day, so some of them worked very well. However my point is that quality control is slightly more difficult when you are dealing with minute quantities of one substance, relatively speaking, having a large effect on the properties of an alloy. There's simply more chance for error, so iron or steel guns would have been slightly more prone to fail. I can't say that it is the main reason for the perceived greater reliability of brass or bronze gun barrels - there are many variables.

Also, humans are risk-averse and conservative, especially regarding weapons on which their life may depend. Having established a reputation for slightly greater reliability (for whatever reason), copper alloy gun barrels would remain favoured even after steel gun barrel manufacturing techniques had caught up. After some point, the perceived superiority may well have been illusory.

Your suggestion about not sparking is interesting and does hold a lot of merit. I wouldn't have thought of this.

There's another factor that may well be important. Whereas sufficiently heated steel, when quenched is almost invariably hardened (and thus embrittled) to some degree, quenching many copper alloys actually anneals them, making them less brittle. Some degree of quenching can happen accidentally - even by exposure to cool air (air-quenching).

As for the brass crossbows, I tried to indicate that I suspected they were actually early firearms, but my main point was that if they were crossbows, it was dangerous to assume which parts were brass - not necessarily the largest parts, at any rate. I certainly didn't suggest that the grip would be cast in brass, but rather the moving parts of trigger mechanism. I believe crossbow nuts were often made of horn or bone?
The nut and trigger lever were the most complex parts of the crossbow (excluding perhaps cranequins or windlasses), and which certainly needed to have the finest tolerances in order to function. Organic materials tend to be more sensitive to moisture than brass and would wear more quickly, while iron or steel would need more maintenance (because a relatively small amount of corrosion would potentially cause tolerance problems). Consider that bushes (solid bearings) and small gear mechanisms are often still made of copper alloys today - they are good choices for high-precision, rubbing moving parts.

But whether the people of the time considered this to be a sufficient advantage to distinguish the entire weapon based on the material used in the trigger mechanism, I don't know, and I lean decidedly towards the idea that they meant firearms instead.

Cheers

Andrew
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Jean Henri Chandler




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PostPosted: Thu 26 Nov, 2020 1:02 pm    Post subject:         Reply with quote

All reasonable points. And I didn't mean to imply that you were describing medieval metalworkers as cavemen so much as it is a general cultural assumption we kind of all carry with us because it's so ubiquitous in the media and popular entertainment.

My only caveat would be that I think today most of the metal manufacturing we do is for relatively low-risk purposes (washing machines and rebar), and even then it fairly often fails, seemingly with impunity. Especially given the way the regulatory environment has changed in recent years. In the late medieval world, they were indeed making swords and other types of hand weapons, armor, crossbow prods, and firearm barrels, all of which bore a makers mark and all of which potentially controlled the fate of whoever bought them.

If the military kit you bought from say Brescia got a reputation for failing in battle, you would quickly switch to Milan, or Augsburg or go to some other option. Meanwhile back in Brescia they will be scrambling to figure out what went wrong. By contrast today if a defense contractor fails in some spectacular manner, those responsible may never be held to account. Look at early deployment of the M-16 in Vietnam.

Another reason to use brass for firearm and cannon barrels is that so much combat in the medieval period was done in a riverine or marine context, and if you bring iron weapons on board a ship the maintenance requirements go up a lot as do the risks associated with rust. I suspect that is the other reason why the British Admiralty stuck with "brass" gunmetal for so long.

J

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Andrew Gill





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PostPosted: Fri 27 Nov, 2020 7:45 am    Post subject:         Reply with quote

Hi Jean

Quote:

If the military kit you bought from say Brescia got a reputation for failing in battle, you would quickly switch to Milan, or Augsburg or go to some other option. Meanwhile back in Brescia they will be scrambling to figure out what went wrong.

Absolutely, yes. I suspect this did occur at some point with iron firearms when the technology was in its infancy, and it took a while for the customers to realise that the iron-using gunsmiths had long-since got their stuff right.
As you'll probably agree, the myths and half-truths that laymen often believe about weapons are often quite surprising and frustrating to those who know a little more...

And the use of these weapons in naval context is quite well illustrated in art of the period, so you're probably right about the corrosion aspect. As an aside, the Royal Navy was also often incredibly conservative up until the turn of the 20th century, when they suddenly showed a flurry of spectacular innovation (the Dreadnought, aircraft carriers and armoured cars, to name a few examples). They held onto big muzzle-loading shipboard artillery into late in the 19th century because of some unfortunate accidents involving early breach-loading guns decades before, and long after most of their rivals had changed over.

One last possibility might just be that because copper alloys were more expensive and therefore reflected on the owner's wealth (they were actually used for low-denomination coinage in earlier eras, I think?) Conspicuous consumption, and all that.

Anyway, a rather interesting discussion that's making me think, thanks!

Andrew
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Jean Henri Chandler




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PostPosted: Fri 27 Nov, 2020 10:58 am    Post subject:         Reply with quote

Likewise!

One question I have, which I've never been able to figure out, is why did copper alloys continue to be so much more expensive for so long? Was copper expensive more or less continuously through history or were there circumstantial reasons which drove the price up over time? I would have expected with wider global trade in the Early Modern period they would be able to get all of the alloying metals more easily and price should go down but it never really seemed to do enough, until maybe the 20th Century.

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