How common lorica segmentata actually was?

[Caballo]

If you have the technology and production facilities, to mass-produce long thin sheets of metal then it is surely faster to make.

There is research going on at the moment to establish whether this and other sheet metals used water mills to hammer out the sheet metal. Such water mill driven hammering technology was also used in the Austro Hungarian Empire.

[rrgg]

What about punched rings then? Unless you made them one at a time you'd already need the technology to create sheets of metal in order to produce them. That makes it sound as though the segmentata is simply skipping steps.

[Crispvs]

I thought that the jury was still out on whether the punched rings were actually punched or were actually forge welded and simply looked 'punched' when dug up from archaeological deposits.

Whatever the case, you don't necessarily need a huge sheet of metal to punch such rings. Iron arrived at the blacksmith's in the form of billets. Any blacksmith would be capable of beating a billet into a flat sheet or pieces of flat sheet from which rings could be punched. To make plate armour though, you need to have a high level of purity in the iron, which has implications for the production process of the bloomery iron from which billets would be made. In all reality, most iron which was produced in ancient times probably contained too much slag for the production of strong plate armour. Therefore, it may have been easier to make reliable mail armour than reliable plate armour.

As a related point, many helmets appear to have been very thin. I wonder whether this might have had anything to do with the extra working it would take to remove slag from the iron, which would also strengthen the iron by the process of work hardening. Perhaps if Claudia Crisis is watching this thread she might like to comment.

Crispvs

[Dan Howard]

Williams lists plenty of munitions breastplates with slag content as high as 7.5% due to the iron being puddled rather than bloomsmithed. So no you don't need high quality iron to make plate armour. In any case I'd be surprised if any of the iron produced by the Romans had a slag content much higher than 2%. This would be too high to draw into wire for mail, but would be more than adequate for a segmentata.

[Cerco 21]

I have a great interest in archeo metalurgy, and from all I've read and digested (combined with a healthy dose of modern day steel processing knowledge) I believe that Romans did not achieve the temperatures needed to produce steel as we know it.

I don't see why you would need to have a higher quality metal for sheets than for rings. Soft rings would collapse very easily, as well as "hard" rings would crak due to being too brittle.

Don't know if anyone has done it but it would be interesting to smelt and forge with "roman" technology.

[mcbishop]

I have a great interest in archeo metalurgy, and from all I've read and digested (combined with a healthy dose of modern day steel processing knowledge) I believe that Romans did not achieve the temperatures needed to produce steel as we know it.

Well they could, as metallurgical analysis of original material shows. I gather you can achieve the necessary temperatures quite easily with Roman technology. The bog-standard steel of lorica segmentata plate was tougher and thinner than the finest plate armour made for Henry VIII by Emperor Maximillian's craftsmen. How they did it remains unclear, but doesn't alter the fact they did. David Sim's forthcoming book provides details.

Don't know if anyone has done it but it would be interesting to smelt and forge with "roman" technology.

David Sim has certainly done so and I don't think he is the first. I have stood and watched him make a pattern-welded sword blade. A modern smith's techniques and tools differ little from those of the Roman period (except in the use of coke).

Mike Bishop

[D B Campbell]

... except in the use of coke.

Thirsty work? :wink:

[Crispvs]

You might also want to take a look at Rob Travis' work on the use of coal by the Romans.

John Robert Travis, Coal in Roman Britain, BAR British Series 468, 2008 (especially pp166-172).
http://www.oxbowbooks.com/bookinfo.cfm/I...tion/Oxbow

Crispvs

[Cerco 21]

David Sim has certainly done so and I don't think he is the first. I have stood and watched him make a pattern-welded sword blade. A modern smith's techniques and tools differ little from those of the Roman period (except in the use of coke).

Mike Bishop

Excelent, when does it come out?

Did he use modern tools? Not power or such, but modern steel hammer and anvil.

Could you really reach the needed temperature without a blast furnace? For example Ferrite is a high temperature phase, can't be found at lower temperatures than 1485ºC, as well as cementite which occurs at 1148ºC.

Would they have some sort of water powered bellows along with coke?

[M. Demetrius]

I am a very neophyte smith, but with a hand cranked coal forge (rotary, not a bellows, though either would work) I am able to get mild steel hot enough to melt. Of course, that's not what I really want, and perhaps I could keep that heat up for long enough to melt small crucibles and cast the tiniest of things, but more than that, I can't sustain. If the fire is hot enough to weld, that's really all that's needed for "carbon steel", isn't it? Layering charcoal powder between the folds of a billet as it's beaten is the oldest way of getting steel, if I've read correctly.

The limiting factor in my forge is the size of the air hole, not the heat of the coal. And coal becomes coke, right? After the sulfur is burned out, coal yields coke which yields ash and clinkers. Somewhere along that line, burned fingers seem to be pretty much inevitable, too.

[Crispvs]

"Could you really reach the needed temperature without a blast furnace? For example Ferrite is a high temperature phase, can't be found at lower temperatures than 1485ºC, as well as cementite which occurs at 1148ºC."

I am reliably informed that this is possible with coal of the right type, examples of which have been found on Romano-British furnace sites.

Crispvs

[Cerco 21]

"Could you really reach the needed temperature without a blast furnace? For example Ferrite is a high temperature phase, can't be found at lower temperatures than 1485ºC, as well as cementite which occurs at 1148ºC."

I am reliably informed that this is possible with coal of the right type, examples of which have been found on Romano-British furnace sites.

Crispvs

On an scale consistant with the needs of the army? That would be amazing.

Do you know if there has been metalurgic analysis done? Has it been published? If you have such data can I have a copy?

If they could produce steel with ferrite phase and quench it, the romans would have reached a steel manufacturing level that was only re-gained in the 19th cent. And if so without a doubt rolled plates for the lorica wouldn't be hard at all to produce.

[Dan Howard]

I am a very neophyte smith, but with a hand cranked coal forge (rotary, not a bellows, though either would work) I am able to get mild steel hot enough to melt. Of course, that's not what I really want, and perhaps I could keep that heat up for long enough to melt small crucibles and cast the tiniest of things, but more than that, I can't sustain. If the fire is hot enough to weld, that's really all that's needed for "carbon steel", isn't it? Layering charcoal powder between the folds of a billet as it's beaten is the oldest way of getting steel, if I've read correctly.

The limiting factor in my forge is the size of the air hole, not the heat of the coal. And coal becomes coke, right? After the sulfur is burned out, coal yields coke which yields ash and clinkers. Somewhere along that line, burned fingers seem to be pretty much inevitable, too.

Increasing the carbon content lowers the melting point.

[Gaius Julius Caesar]

M.C.Bishop wrote-

How they did it remains unclear, but doesn't alter the fact they did. David Sim's forthcoming book provides details

Thanks for that info, one to add to the list!

[Cerco 21]

I am a very neophyte smith, but with a hand cranked coal forge (rotary, not a bellows, though either would work) I am able to get mild steel hot enough to melt. Of course, that's not what I really want, and perhaps I could keep that heat up for long enough to melt small crucibles and cast the tiniest of things, but more than that, I can't sustain. If the fire is hot enough to weld, that's really all that's needed for "carbon steel", isn't it? Layering charcoal powder between the folds of a billet as it's beaten is the oldest way of getting steel, if I've read correctly.

The limiting factor in my forge is the size of the air hole, not the heat of the coal. And coal becomes coke, right? After the sulfur is burned out, coal yields coke which yields ash and clinkers. Somewhere along that line, burned fingers seem to be pretty much inevitable, too.

Increasing the carbon content lowers the melting point.

It can also turn you carbon steel (which is a redundancy since all steel has a carbon content 0,7%-2%) into cast iron, one of the reasons metal was pretty much crap in the middle ages.