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Swords, Cutting and Military History

Background and metallurgical analysis of a ducal Renaissance blade from Racibórz

Background and metallurgical analysis of a ducal Renaissance blade from Racibórz

Jan Van Boendale (c.1280-1351)

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In 1996, during an archeological dig in a form nunnery church in Racibórz, Poland, a broken iron sword was discovered in one grave.  This grave was located in the choir area of the church, indicating the deceased was of some importance;  the grave contained the bodies of two people, a male and female.

The broken sword blade was originally placed diagonally on wooden coffin, at chest height for the deceased.  It was commonly believed that the sword was broken before being placed in the grave, and the bodies those of Walentyn, the last Duke of Racibórz and Opava (died 1521).  In Silesian tradition, a broken sword was the sign of the extinction of a dynasty or family.

This blade was extensively reviewed and analyzed in the paper:   A Renaissance Sword from Racibórz:  by Marcin Biborski, Janusz Stepinski, Grzegorz Zabinski, which is our focus today.

Below is an image from the paper, with the pieces of the broken sword outlined:

 

Grave and sword parts

 

The blade was in extremely poor shape due to corrosion.  It was defined as an Oakeshott Type XVII sword, but with a much newer style of pommel and crossguard.  Type XVII blades were used mainly between 1350 – 1450, while the pommel and hilt styles were common only after 1500 (16th century).

In the images below, the left show the sword pieces before restoration, the right after all corrosion was removed and the pieces stabilized.  You’ll note the ball hilt and the curved crossguard with ball finials, which are of a style much later than than blade itself.   This made researchers believe an old weapon had been refitted in a more modern style.

 

The sword before and after restoration

 

Drawing of blade partsThe image to the right is a drawing of the blade,  providing an accurate scale of size, and more clearly showing the style of the ball pommel and the curved crossguard.  Note that the black triangle marks where a piece of the blade was removed for destructive metallurgical analysis.

 

Blade Dimensions

Total length 133.2 cm
Total weight – 0.75 kg
Blade length 97.7 cm
Hilt length 35.5 cm
Crosspiece length and stretch 23 cm; 19.5 cm
Crosspiece diameter (square cross-section) 1.5 mm
Pommel height 75 mm
Pommel diameters (base and broadest) 22 mm; 45 mm
Tang diameter at pommel and crosspiece 15 mm; 22 mm
Blade breadth and thickness at the shoulder 45 mm
Blade breadth and thickness at the point of breaking 40 mm
Blade breadth and thickness at the point 15 mm

In cross-section, the blade is hexagonal, though slightly rounded.  There is no fuller or rib apparent.  The corrosion of the blade was so extensive, researchers were unable to determine the sword edges were sharpened or not.  If not sharpened, this would likely have been a ceremonial sword, perhaps a sign of  rank or sovereignty.

The crossguard is a stretched “S” design, with ball endings.  The pommel was roughly pear-shaped, riveted to the tang.  Under Oakeshott’s typology, they are classed as types T5 and 12.

The paper’s authors go into a detailed discussion of their analysis of the sword typology, using comparisons to known sword types from that period.  Students  of sword typology may find this very academic discussion highly enlightening.

In summary, they summarize that the blade’s parts display a “certain temporal incoherence”, best explained (though, as they note, not proven) that this is an older blade refitted in a later period style.

Another possibility which they do not discount this that the blade itself was made in the 16th century, but according to an older pattern, at the taste of the noble.

 

Archeometallugical analysis

The edges of the blade were tested and showed signs of hardening, while the core showed no obvious signs of tempering.

Microstructures of partially tempered martensite were seen on the edges and flat sections of the blade (case exterior).  Moving inwards, the interior of the blade core was a combination of pearlite and ferrite, suggesting the blade has a well-design softer steel core, with a fairly hard (edge-holding) steel exterior and cutting edges.    The paper contains a number of images of the microstructures of the various blade sections.

The steel contains numerous slag inclusions, to the point that they comprise 2.33% of the material.  A chemical analysis of the slag suggests the large percentage of the inclusion material is calcium, which was used during the refining of iron as a flux material.  Impurities in the iron would bind and float as a liquid residue on the surface of the molten metal, which could then be scooped or poured off.

The carbon content of the tempered exterior ranged between .6 – .7, making this a fairly high carbon steel.  The core contained only .1 – .3% carbon, reinforcing the softness of the core steel.  This would have resulted in a flexible blade with excellent cutting edges.

Hardness tests were made on the blade section removed for destructive testing.  Exterior / edge hardness rated between 450 and 504 Vickers (46-48 Rockwell C).  The interior core tested at 142-151, again showing a much milder steel.

 

Blade cross section showing blade shape and penetration of carbonization and tempering

The researchers interpreted the above information to mean the blade was likely forged from one piece of relatively soft iron, roughly carbonized to improve its quality, with the exterior subjected to further carbonation and tempering.

It was likely heated to around 900-950 degrees Celsius, then quenched in wet sand or oil, which allowed the exterior to harden significantly while leaving a softer core.   This form of forging has been known in Europe since the early middle ages, and was very popular in late Medieval Europe.  In the hands of an expert smith, this was a fairly simple method of production which resulted in excellent quality swords.

 

Sources

A Renaissance Sword from Racibórz:  Marcin Biborski, Janusz Stepinski, Grzegorz Zabinski, Bladius XXIV (2004)