Lorica Hinge Durability

[QVINTVS ARTORIVS CORVINVS]

Salve,

I have made a new prototype hardware set for my new lorica and used solid brass door kickplate from a hardware store. Just wondering about the durability of the thickness... guessing it is in the vicinity of about 22-24 gauge.
Just don't want to go through all the work of fabricating these only to have them pull apart under stress. They will be annealed to work and hardened after all shaping is completed especially on the pin-barrel.

Have any of you done the same with any amount of success?

[Magnus]

Mine are made from 0.015" brass sheet...Though mine aren't work hardened and didn't require annealing. They're fine after about 6 years.

[QVINTVS ARTORIVS CORVINVS]

Hmmm... a quick google search reveals:
0.015â€

[Matthew Amt]

Most kickplates I've seen run 18 to 20 gauge. Even 24 gauge is thicker than the .020" that I tend to use, and I haven't had any problems with it. And even .020" is thicker than what the Romans used! Granted, on my own lorica I used .015" and .010" brass, and after 17 years of abuse 5 of the 8 main hinges have broken and their plates riveted together, just like the Corbridge originals. Still works like a charm.

Vale,

Matthew

[Hibernicus]

Try to work the brass cold. It is very difficult to work harden the brass after it's been annealed and then shaped without seriously reshaping the fitting.

You can see the scorch marks from annealing on Britannicus's seg. Note the replacement/repair hinge on his right shoulder, the squarish blocky lobate hinge.. not annealed btw. I think these are .025

Note the blood right by the crease and on the upper back plate, somebody else's not his.

War: Estrella

[QVINTVS ARTORIVS CORVINVS]

Is it ok to anneal the pieces before chisel work, then once done, re-harden it? I.e. heat it and let it cool very slowly in sand?

[Marcus Mummius]

Is it ok to anneal the pieces before chisel work, then once done, re-harden it? I.e. heat it and let it cool very slowly in sand?

This will not harden your brass... Where did you hear or read that?

[Magnus]

I thought that did in fact harden brass...to soften it you heat then quench. Unlike ferrous metals which is the opposite.

[Marcus Mummius]

I thought that did in fact harden brass...to soften it you heat then quench. Unlike ferrous metals which is the opposite.

When brass is heated until it reaches the anneal point and you let it cool slowly it gets softer and becomes more maleable.

If you heat it to the anneal point and then quickly quench it it's also soft but a bit less so than when you let it cool slowly.

Either way, brass, that reaches it's anneal point and then cools (quickly or slowly) will get softened.

If you work brass hot it will break.

Vale,

[QVINTVS ARTORIVS CORVINVS]

Yes I think Magnus is correct sir.
Brass' metallurgical reactions are much the inverse of steel.

[Matt Lukes]

My understanding is the same as Jef's- that brass cannot be hardened save for by working. Heating just softens it- no matter how slowly it's allowed to cool again: [url:3w0oqwq7]http://www.ganoksin.com/orchid/archive/200406/msg00225.htm[/url]

And as for the hinges Phil, real ones were made from about 0.5mm (0.020") brass (doubled), so if that thickness did the Romans in real battle, it should be considered sufficient for everyday (non-SCA) use for sure.

[marsvigilia]

If you work brass hot it will break.

Ah, this is true of common yellow brass. Roman brass or orichalcum (15 to 20 percent zinc) is much closer to red brass. Red brass is wonderful stuff, and can be worked hot. It tends to crack less than yellow brass when worked cold.

[QVINTVS ARTORIVS CORVINVS]

Hmmm. I stand corrected.
By work hardening I would take that to mean the same as with steel work... as in the case of mild steel you can harden it by planishing the piece which fractures the fibres and creates martensite... or a more tightly woven structure.

[Marcus Mummius]

By work hardening the deformation of the structure is meant. The grains are pushed together in a 'dense packet' with little space between them. this makes for a very hard but also more brittle structure.

While working you will reach the point were the metal looses it's plasticity and will break, crack etc. when you try to deform it. I don't know the correct term for this state. Translated literally from the dutch term it would be 'metal-tirednes'.

When you reach this point the metal has to be annealed. This is heating it to a certain point that is specific for each metal. When this point is heated a recristalisation finds place and the thight dense structure get's rearanged into a looser structure that is plastic again.

The recristalisation will begin in the points in the metal were the stress is greatest. This is because in this places the most energy is already present. So you'll see that a piece that has been worked a lot and already contains a lot of energy 'hammered into it' needs less energy when you anneal it than a piece that is almost unworked.

@marsvigilia: The romans used many different kinds of brass. It is incorrect to say that aurichalcum was more like what we know as red brass/tomback. For rivets brass that consisted out of Copper (Cu) with only a slight ammount of Zinc (Zn) was used. This is just because it's easier, as this metal is softer than yellow brass (=brass with a higher Zn content). But more decorative things such as florettes on helmets and loricae were made out of brass with a high Zn content, to have a nice golden colour.
The name 'aurichalcum' consists out of aurum (gold) and chalcum (copper). And can be translated as 'golden copper'.

Vale,

[AntonivsMarivsCongianocvs]

Ave,

Here are multiple examples of original hinges that might help you out a bit.

LINK: [url:13cvdhlg]http://www.romancoins.info/MilitaryEquipment-Body-Armour.html#BodyArmour[/url]

One of many examples: