Torsion Techniques

Many of the most admired patterns in the present-day are based on torsion techniques. Normally these twists show a very regular, self-repeating pattern. Many splendorous historical weapons are decorated with twisted patterns, although the twist is rarely found in the cutting edge of costly historic combat weapons. This is due to the poor mechanical properties of these patterns.

In twisted patterns it is inevitable to have welds perpendicular to the cutting edge. This favors the progression of cracks, often with fatal results. While hardening, high tensions can occur between the twisted bands, weakening the blade. Often simpler steels are used in twisted patterns to overcome the risk of defects. As a general rule a twisted pattern cannot produce the performance in the cutting edge that non-twisted layered steel can.

Torn twist

Torn blade of twisted strips

A torsion band is made either from layered or stacked pattern-welded steel. This band is then twisted. When twisting, tensions are generated inside the band, having peak values at the edges. To prevent the edge from cracking, it is advisable to forge the band to an octagonal shape. This affects most patterns only slightly–only when forging a turkish twist or inscription patterns will this be noticeable.

Development of the twisted pattern (animated)

The typical twisted pattern, the star-pattern, is revealed by removing material from a twisted band. The pattern-style depends on how much material is removed from the sides. It is not uncommon to remove up to 70% to show a clear star-pattern on both sides of the blade.

Simple Twist

When only a single twisted band is forged to a blade, this is called a simple twist. The star-pattern covers the whole width of the blade. This is a very popular pattern, even if the mechanical performance of theses blades is very poor. Since the welds are always weaker than the homogenous material, hundreds of potential crack starting-points are found in the cutting edge. A crack is most likely to break the whole blade and not just a section breaking out of the edge. The very common argument for the twisted pattern–superb cutting ability caused by alternating hard and tough layers–does not withstand any serious study of the cutting edge.

Turkish Twist

If three or more twisted bands are stacked, the resulting pattern is called Turkish twist. Sometimes an eye-shaped ornament is formed by adjacent patterns, the so-called cyclops-eye. In very evenly twisted patterns this eye is more common.

Turkish Twist

Turkish twist

© 2005 G.v.Tardy