Is Stainless Steel Suitable for Swords?

By WarAngel and Motoyasu

The mass market has been flooded with an onslaught of stainless steel decorative imitation swords, often made in Spain, but there are numerous swords (even copycats of the swords made in Spain) from Taiwanese companies. It's not surprising to find the words "440 STAINLESS STEEL" imprinted on the blades of imitation Japanese swords. Aside from the construction, how suitable is stainless steel for swords?

Coming to popularity only in the mid-20th century, Stainless steel is an alloy of steel (steel is a product of iron and carbon) which contains the element Chromium of approximately 13-16 percent.

Chromium added to steel helps prevent rust because the chromium forms a protective oxide layer on the surface of the steel. In smaller amounts, Chromium generally makes the steel deep hardening and helps to refine the grain size. However, in larger amounts, the grain boundaries are weakened, which affects the overall performance of the steel. How much performance is affected increases with the length of the blade. Blades under 12 inches may not notice any problems. Stainless steel knives can excel in performance, are low-maintenance, and find use in underwater applications or diving operations. The trade-off between steel toughness and edge-holding capabilities, however, is far more noticable in longer lengths such as that of a sword, whereby one is forced to choose between two extremes: either a sword that can hold a good edge for a long time,but will break as soon as you stress it, or a sword that is very soft and tough, but dulls very easily.

Mass-manufacturers decorative replica/imitation swords made out of stainless steel generally aim for toughness - they are tempered softer but lose the "bite" of their edge after some use. For a sword to be both tough and to have the sufficient hardness that can retain an edge, the solution is to use low-alloy steels with very little chromium; for Japanese swords in particular, in addition to being low alloy, they should be free of "grain refiners" and should be "shallow hardening", otherwise it would be near to impossible to create real temper line (known in Japanese as "hamon") Why do decorative replica sword mass-manufactureres use stainless steel? Well, stainless steel allows for low-maintenance care, as opposed to real swords made of a low- or simple-alloy high carbon steel which require constant oiling to prevent rust.

In the production sword industry, stainless steel is obtained as bar stock and are ground to shape (howbeit crudely, sometimes) rather than hand-forging or forge-welding (forge-folding) the steel. The blades are then subjected to minimal heat treatment, normally to about 46-48 Rockwells of hardness to keep it softer - and thus somewhat tougher - in case people want to use these swords to, say, chop wood or attack the backyard tree. However, the lower Rockwell hardness of the sword results in an edge that loses sharpness-retention. In the cases of some of the US$80 range Japanese-style swords made in Taiwan, the steel used is "420 J2 Stainless Surgical Steel" which, most often, is not even heat treated and is so easy to shape at the belt grinder that it is often remarked as a steel that grins "like butter."

On occasion, some companies may claim their stainless steel swords are either forged or forge-folded. (Forging is the process of hammering a steel billet to shape, and forge-folding/forge-welding is the process of hammering out, and then folding the steel to create layers, which was historically done to purify the steel). Technically speaking, stainless steel is "forged" at the manufacturing plants. However, statements that factory replica swords are forged by hand are generally inaccurate, as stock removal allows for a lower cost of production.

Another reason why stainless steel is generally not forged by production sword companies is the time and energy required to do so. Stainless steel exhibits a quality known as "red hardness" which means that it remains quite hard to forge even when red hot.

As for forge-welding (or folding) steel, this remains a practice almost exclusive to pattern-welding. Again, this is a more expensive and time-consuming process that increases the cost of production.

What's most amusing is that the sales pitch some companies employ runs along the lines of the ancient Samurai would have wanted such a stainless steel swords - even calling the swords "tree splitters"! The Japanese sword is a product of - first and foremost - functionality and secondly beauty. Such beauty comprises not only the geometry and artistic architecture of the blade but also surface details such as the temper line ("hamon") and forge-folding wood-like patterning or "grain" ("hada") - which are qualities that cannot be accomplished on stainless steel. Thus, the temper lines on imitation Japanese swords are either acid etched or machine ground.

Aesthetics aside, the performance of a stainless steel imitation sword cannot best a traditionally made katana blade. Occasionally, blades will be made softer for toughness, or made thicker to compensate for the brittleness of stainless steel at high Rockwell hardnesses. A thicker sword generally means a heavier sword. However. the thickness of imitation swords are not necessarily done to compensate for the lack of strength between the grain boundaries of stainless steel. Sometimes it's just merely a lack of skill to create a distal taper which lightens the sword along its length, creating a more maneuverable and manageable weapon.

Thus, the next time you consider a sword for your purchases - whether it's from a mail order catalog - or a special ops "katana" made by someone at a Knife or Gun Show boasting various Rockwell hardness readings, aside from the construction of the sword, keep in mind the inherent weaknesses of stainless steel due to the chromium content of the metal!

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