08-08-2012, 05:01 PM
Making copper alloys like brass and bronze was well understood, so I presume you are refering to iron objects.
I will try to explain something about iron and steel, along with alloys. Starting with the alloys; to make an iron alloy you will have to melt the iron. There is some discussion on whether or not the Romans could cast iron iow melt iron to a liquid. There are certainly shapes I have seen in tools that would imply iron casting, as forging these would have been highly impractical. Mind you, casting an object in iron does not make the object of castiron, as that has a very high carbon content of over 2 % and is notoriously brittle. But ... the metalurical knowledge was very limited in respect to the effects of additives like nickel and chroom, should these have been available in pure form. What I think happened is that natural alloys from a specific ore-site and their superior performance was noticed by the craftsmen. Iron ore contains a good number of assorted metals in small quantities, but certainly sufficent to create a natural alloy. Medium alloyed iron contains between 1,5 en 5% alloying elementens (excluding carbon). Manganese and silicium (yep, sand!) are the most commom elements for alloys (Si = 0,7 % Mn = 1,6 %) The raw material from a specific mining location could thus be recognised as being of superiour quality and traded as such. A trained craftsman could certainly tell the difference, using things like a scratch test with a tool of known hardness.
Then there is the difference between iron and steel. Steel is basicly iron with a higher carbon content or an iron alloy with other metals. Mind you, the carbon content is not above 2 %! Steel may be hardened and tempered, low carbon, unalloyed iron cannot be hardened at all. There were methodes available to the Romans to add carbon to the iron, like the very slow smouldering in a burning charcoal bed with little oxygen. This would cause a slow diffundation of carbon into the iron (case hardening). Reworking the iron in the forge and then repeating the proces caused more carbon to be absorbed and created a homogenious steel.
Mild or construction steel(max. carbon 0,17 % Mn 1,40% Si 0,045%) as we have available these days is really top range stuff compared to the materials the Romans would have had by and large. Great stuff for making swords and a lot more accurate then EN45 spring steel blades (Carbon 0.55% Mn 0.75% Si 1.75%).
I will try to explain something about iron and steel, along with alloys. Starting with the alloys; to make an iron alloy you will have to melt the iron. There is some discussion on whether or not the Romans could cast iron iow melt iron to a liquid. There are certainly shapes I have seen in tools that would imply iron casting, as forging these would have been highly impractical. Mind you, casting an object in iron does not make the object of castiron, as that has a very high carbon content of over 2 % and is notoriously brittle. But ... the metalurical knowledge was very limited in respect to the effects of additives like nickel and chroom, should these have been available in pure form. What I think happened is that natural alloys from a specific ore-site and their superior performance was noticed by the craftsmen. Iron ore contains a good number of assorted metals in small quantities, but certainly sufficent to create a natural alloy. Medium alloyed iron contains between 1,5 en 5% alloying elementens (excluding carbon). Manganese and silicium (yep, sand!) are the most commom elements for alloys (Si = 0,7 % Mn = 1,6 %) The raw material from a specific mining location could thus be recognised as being of superiour quality and traded as such. A trained craftsman could certainly tell the difference, using things like a scratch test with a tool of known hardness.
Then there is the difference between iron and steel. Steel is basicly iron with a higher carbon content or an iron alloy with other metals. Mind you, the carbon content is not above 2 %! Steel may be hardened and tempered, low carbon, unalloyed iron cannot be hardened at all. There were methodes available to the Romans to add carbon to the iron, like the very slow smouldering in a burning charcoal bed with little oxygen. This would cause a slow diffundation of carbon into the iron (case hardening). Reworking the iron in the forge and then repeating the proces caused more carbon to be absorbed and created a homogenious steel.
Mild or construction steel(max. carbon 0,17 % Mn 1,40% Si 0,045%) as we have available these days is really top range stuff compared to the materials the Romans would have had by and large. Great stuff for making swords and a lot more accurate then EN45 spring steel blades (Carbon 0.55% Mn 0.75% Si 1.75%).
