Introduction 47
such as magnetite, hematite (red iron ore), limonite (brown iron ore) or the
carbonate based siderite.
Iron is melted from iron ore in a bloom in the form of pig-iron (or iron
sponge), the physical features of which are not appropriate for making tools
or weapons.183 The pig-iron contains various forms of iron microstructure like
ferrite,184 pearlite185 and cementite.186
The steel attains its final characteristic by a combination of additives and
forging. The steel is an alloy of iron including various elements but mostly car-
bon of at least 4 per cent. According to other definitions the steel is an iron-
based alloy which can be processed by forging (hammering). The majority of
steel from archaeological contexts also contains some phosphore (P) and arse-
nic (As), both of which made the steel harder but more brittle, and it reduced
its carbon-absorbing capacity. The higher carbon content of the steel results
in a hard and brittle material, however, its hardness could also be affected by
several other factors.187
The steel is heated to between 700–900°C during the forging188 resulting in
a shapeable state called the austenite phase. The ancient blacksmiths would
have recognised the appropriate temperature from the sound, the sparks and
the colour of red-hot steel.189 This hot and forged steel should be cooled by
dry ash. Various shaping processes were used during the forging which can be
divided into two groups: free hand190 and die forging. During free hand forg-
ing the artefact is shaped on an anvil, while during die forging the heated iron
183 The iron metallurgy and the production of pig iron is not included since its abundant
literature offers a good overview (Gömöri 2000).
184 The ferrite is known as α-ferrite too and used for the most stable form of iron in a body-
centered cubic structure, which is a fairly soft metal containing low percentage of carbon
or other materials.
185 The pearlite is a two-phased lamellar structure composed of alternating layers of ferrite
and cementit, which is a harder structure than ferrite.
186 Cementite or iron-carbide is a chemical compound of iron and carbon (Fe3C), it is a hard
and brittle material usually used for hardening the surface of iron artefacts.
187 According to its carbon content low carbon steel (less than 0.15% of carbon), mild steel
(0.15–0.3% C) and high carbon steel (over 0.3%) can be distinguished.
188 The temperature depends on the carbon content, the higher the carbon content of an
artefact the lower the temperature needed for forging.
189 The hard steel is forgeable in the state of red ignition, while the soft steel in the state of
white heat.
190 Szabó 2001.