I just made a summary of metallurgical data on iron swords from "The prehistory of metallurgy in the British Isles" by R.F. Tylecote. Feel free to add more examples (especially on Hallstatt swords if anyone has it).
Iron age:
Isleham, UK, 50BC-50AD
- carbon contents: variable
- phosporous contents: 0.01%
- manganese contents: -
- hardness: 320-450 HV (cutting edge 370-450 HV)
Notes: sandwich of three layers, with a higher carbon central layer. Hardness suggests fast aircooling.
Waltham Abbey, UK, ?
- carbon contents: 0-0.25%
- phosporous contents: 0.075%
- manganese contents: 0.0035%
- hardness: 170-250 HV
Notes: 24 piled layers of 0-0.25 %C. 250 HV at edge, 170 HV at core
Other blades: examination of 5 blades from Llyn Cerrig Bach showed 4 piled blades with wrought iron with various degrees in carburization, and one piled at right angle to the axis of the cross-section (linear pattern), with alternating higher and lower carbon contents. All five blades have hardnesses in the 140- 265 HV range, usually higher at the edges and lower at the core.
Other notes: edges sometimes workhardened on the iron age swords.
Roman period:
'N' type Nydam sword, Denmark, first half of 3rd century AD
-Edges: one side 0.29% C, other 0.43% C
-Core: 0.5% C
-Thin iron strips on either side of core: 0.1% C
-Three twisted billets either side of core: 0.1-0.6% C
-Phosphorous contents: 0.16-0.21%
Note: A sword from South Shields, UK (197-205AD) has twist damast as well, with similar bronze inlays as Nydam sword.
Possibly spatha, Whittlesey, 2nd-4th century AD
Section shows well diffused structure of ferrite and pearlite with a higher carbon zone running through its centre, varying from 0.3% C at cutting edge to 0.25% C at center. The carbon contents of the center decreases to about 0.1% C at surfaces. Hardness varies from 120-150 HV.
Early medieval period:
Ulfberht sword, Donnybrook, Dublin, Ireland, ?
Centre:
- carbon contents: 0.2%
- phosporous contents: 0.02%
- manganese contents: 0.1-1.0%
Fine grained ferrite with spheroidal pearlite
Edge:
- carbon contents: 0.3-0.4%
- phosporous contents: trace
- manganese contents: 0.1%
Quench-hardened to 520-550 HV
Notes: piled layout.
French pattern-welded swords:
M. 7 core:
- carbon contents: 0.12%
- phosporous contents: 0.21%
- manganese contents: 0.01%
M. 10 core:
- carbon contents: 0.09%
- phosporous contents: 0.30%
- manganese contents: 0.05%
M.11 core:
- carbon contents: 0.08%
- phosporous contents: 0.16%
- manganese contents: nil
M.11 edge:
- carbon contents: 0.2%
- phosporous contents: 0.14%
- manganese contents: nil
Luneville sword, core:
- carbon contents: 0.01-0.05%
- phosporous contents: 0.18%
- manganese contents: nil
Luneville sword, edge:
- carbon contents: 0.02-0.03%
- phosporous contents: -
- manganese contents: -
Three Norwegian pattern welded swords: 0.414% C, 0.401% C and 0.52% C
Ulfberht sword from Norway, 10th century AD: 0.75% C (not patternwelded)
Frankish sword, Canwick Common, 9th-10th century AD:
Piled in 2mm thick layers
Structure varies from high-carbon martensite to lower-carbon structure throughout the structure
Hardness 306-630HV
Pattern-welded sword of Palace of Westminster, UK, 9nd century AD:
Patternwelded areas down the center consist of 0.2% C iron together with fine and coarse grained ferrite and small globules of slag. Hardness 186-188 HV. The edges consist of fine-grained mild steel with a ferrite + pearlite structure, but surprizingly only a hardness of 136- 145 HV. Patternwelded areas are possibly harder due to higher phosphorous contents.
Note:
Story of the batlle at Swanfirth against Snorri and his folk shows that good and bad swords were used concurrently. Steinthor found that "the fair-wrought sword bit not whenas it smote armour, and oft he must straighten it under his foot"
General note: Phosporous adds slightly more hardness to non-quenched, non-workhardened steel then carbon does. So in none heat treated iron, you can replace phosphorous by carbon to get a blade of similar hardness. Phosphorous makes the steel more brittle though.
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