What makes one steel tougher than another is by virtue of its metallurgical composition as well as heat-treating.

Certain elements do certain things. You generally want to avoid high-alloy stainless steels if you want a real sword. After all, don't want your sword to smash apart!

Iron - Swords made according to ancient Japanese tradition - even the serious ones today, are made out of tamahagane (pronounced "ta-mah-hah-gah-neh" ). This is basically an iron-bearing sand. Iron, laced with Carbon, form the basis of steel.

Carbon - From the fires of the forge and the finest of charcoal comes carbon, which serves as the hardener of iron to form steel. A higher carbon content means that the resulting steel is harder (but too much carbon means that the steel is so hard it could be brittle). A lower carbon content gives steel a "tougher" property, but it won't hold an edge as well as higher carbon steel because it's too soft.

Chromium - Avoid at all costs. It is what makes stainless steel corrosion resistant, and in small quantities can act as a grain enhancer and yields a mirror-finish when polished, making stainless steel look very nice. But it also makes the steel brittle. In addition, chromium - at high amounts - makes it extremely difficult to create a hamon (temper line) in the sword blade.

Silicon - Silicon's presence in traditional steel gives it additional flexibility and strength.

There is no such thing as an indestructable sword or indestructable sword steel.

Traditional/Original Japanese Steel - Always the best, this contains iron, carbon, silicon and many various trace elements. Approx. 0.6-0.7% carbon. The presence of silicon increases structural strength as well as improving flexibility characteristics.

AISI/American 1050/10xx - A good choice! While not identical to medieval Japanese steel, this plain carbon steel is the closest we have today. AISI 10xx steel contains iron, manganese and carbon, thus differing slightly from traditional steel. AISI 1065 maybe closer in carbon content to Traditional than 1050, but 1050 is tougher steel, and compensates somewhat for the lack of silicon in the steel (silicon improves strength and flexibilty ). The xx in 10 xx indicates the percentage of carbon, where 1050 has .50% carbon, and 1070 has .70% carbon, etc. The higher the carbon content, the harder the steel. The lower the carbon content, the tougher the steel is. Too hard, and the blade can shatter upon impact. Too soft, and it can easily be cut through. Generally, you want a low-alloy steel for your sword. The biggest difference between 10xx and traditional Japanese steel tamahagane is the presence of manganese in 10xx but also the lack of silicon.

AISI/American 5160 - a low Chromium (0.7%) alloy tool steel, it also contains 0.2% silicon, and is considered widely to be a superior steel for swords in general, particularly European style swords, because it is so tough. Although this steel contains chromium, there is not enough to make it stainless (More than 13% is required to make steel "stainless". 440C contains 16-18% chromium) or to affect the strength of the steel. This steel has a slightly richer alloy mix than the AISI 10xx series. The steel's chromium content is enough to make it extremely difficult to create a hamon (temper line). Also, 5160 is a bit more corrosion resistant than 10xx when it comes to fingerprint oils' acidity. You could touch it without fear of instant rusting, but clean your sword still before resheathing it.

A2 Tool Steel - The "A" of "A2" means "Air Hardening" which means it can be cooled with an air blast ("slow cooling") rather than being quenched in water or oil ("fast cooling") A2 is a chromium tool steel, rated for high toughness and in a knife, very good edge holding potential. The chromium content is not enough to make the steel "stainless" or to weaken the grain boundaries significantly (like 420 and 440 Stainless). Despite its excellent properties, for use in a Japanese style blade, it cannot be clay treated (for differential hardening) in the traditional manner - which gives the katana its superiority, as traditional blades are fast cooled instead, and clay does not work to prevent hardening of the blade's back in cooling A2. Because of this, you generally cannot create a hamon (temper line) with A2. In short, A2 will make a good sword steel. A lower-alloy high carbon steel may perform better. Generally, the marketing pitch on A2 swords is that "it's a tool steel that cuts through other steels, so it's good for a sword."

D2 Tool Steel - This is a good chrome-vanadium tool steel; it has 12.5% chromium which is not enough to make it stainless, but which in other steels, would be enough to rule it out as a sword steel. However, D2 also has vanadium and tungsten which act as grain refiners and counteract some of the weakening effects of the chrome. Because of the addition of molybdenum and some nickel, it is very tough, very hard (from the tungsten) and holds a good edge (only stellite and maybe 440V come close in terms of edge holding, but 440V is much more brittle, and stellite is a cobalt alloy, not a steel). Unfortunately, like A2 and other high alloy, deep hardening steels, you cannot create a hamon on it. A sword of this material would be incredibly tough. And despite its edge holding characteristics on paper, it is said that it holds a lousy edge and will hold it forever. Like A2, it's an air-hardening steel and is hard to heat treat properly. L6 may be a better choice for high performance steel (it's not too hamon-friendly either). It is said that D2 may be a little better than high carbon stainless steels.

S-5 Steel - The "S" stands for "shock-resistant" which comes about as a result of its 2% silicon content. This might be better than 1050, but it is more difficult to find, and will most certainly be more expensive than plain carbon steels.

S-7 Steel - Another shock-resistant tool steel, air hardening, which means that unless the smith really knows what he's doing, this finnicky steel is hard to heat treat. Some may use a torch to treat the edge to give it a Japanese style temper line - such a maneuver might be okay with knives, but in swords there is almost always a total loss of control of quality. We've gotten reports of certain "Angelic" swords cracking. The marketing hype is "Shock resistance" so everyone thinks this steel that "cuts through other steels" must automatically be good for swords. Take into account the totality of the sword smithing process! Inferior heat treating can result in a poor steel. S-7 is getting very alloy-rich for use as a high-performance sword. S-5 might be a better way to go, but it's pricey.

CK55 Krupp Steel - The European equivalent of AISI 1055. "C" stands for "Carbon" and "K" for Krupp - the German company that makes it.

50CRV4 - This is a steel with very small amounts of Vandium and Chromium. Chromium in higher quantities lends to a steel's "stainless" properties. However, in 50CRV, there isn't enough to make it "stainless" - and metallurgically brittle. Thus it makes a good spring steel. It contains trace amounts of Silicon and Manganese. The tensile strength of CK55 and CK50 is about 600 N/mm2, while 50CRV4 ranks about 750 N/mm2.

420, 440A, 440B, 440C, 440V, ATS-34 - Stainless steel. Great for kitchen knives, folding knives, etc. They are unsuitable for swords and swordplay re-enactment, namely because of the weak grain boundaries caused by the presence of the chromium, which is used as a grain enhancer and gives it it's "stainless" properties and mirror finish when polished, but makes it more brittle. Chromium and other alloying elements like Vanadium, tungsten, etc. can make steels stainless, fine grained, heat resistant, etc but really add to the problem because you cannot create a beautiful hamon ("cloud pattern") line with these steels. The ones that appear on replicas are acid or electro-etched sine waves.

NEW! CPM420V Stainless Steel - Made by the Crucible Materials Corporation as an upgrade for CPM440V, this high alloy (20 percent) stainless steel was developed originally as a high-wear steel for wear and corrosion resistance (on par with most other popular stainless knife steels). For a knife blade, this steel has good things going for it. It has good edge holding capabilities (you can make a very aggressive edge on blades made of CPM440V), and you'll find some ductility and pliability with this steel. On the downside, it's difficult to get a decent finish on it due to its high alloy content. It's an excellent steel but not a workhorse like D2, 51200 (used for ball bearings), 440C, and 154CM/ATS34 (a modification of 440C). Knifemakers find CPM440V blades outcut all other steels hands down.

420J2 Stainless Steel - 420 Stainless Steel could normally produce a fair wallhanger sword. However, 420J2 has very little carbon content, so the Rockwell hardness won't be higher than 53 Rockwells. It's extremely easy to grind - almost like butter. Think of 420J2 as the stainless equivalent of mild steel - with very low carbon content and thus will not harden.

High Carbon Steel / High Carbon Spring Steel - They may use words like " Spring Steel " or " Live Steel " in their sales pitch. Spring Steel is a term that refers to any member of a group of steels that various types of springs are usually made out of (e.g, car springs are commonly made of 5160, but they can also be 1065). "Live Steel" is another euphemism for "plain carbon steel" (i.e., it can refer to any of 1050, 1065, 5160, CK55 or any plain carbon or low alloy steel). Because these are not stainless, swords made of these materials do require oiling to prevent rusting. You may want to keep Iberia swords outside of their scabbards to avoid moisture damage and corrosion from chemicals used to treat the leather. Their high carbon spring steel is from the Philippines and comes from automobile springs (typically 5160), and can flex somewhat and return true. The high carbon steel used in Indian swords is similar to 1065. In terms of "bang for the buck" you're getting an okay sword.

Damascus Steel - The original Damascus was a crucible steel with an extremely high carbon content. When forged into a blade, the carbides in the steel formed into a pattern that was visible on the surface of the steel. This material is also called "Wootz" or "Bulat". What most people think of today when they hear the word "Damascus" is actually pattern-welded damascus. Now this steel is composed of many layers of high and low carbon steel, and when etched, the high and low carbon steels are attacked at different rates by the acid, resulting in a visible pattern. Pattern-welded steels have existed since man began working with iron and steel .

The term "Replica Sword" refers to the class of swords made from of stainless steel.

Can these be considered as actual weapons? Yes, in that if you conceal it in your trench coat, you might get arrested for concealment of an illegal-length weapon - regardless of how authentic to traditional sword manufacture your sword is.

In the classic sense, the answer is no. Stainless steel contains chromium . This gives the resultant blade a nice chrome look. However, chromium makes the steel molecularly weak, and thus the sword is vulerable to deep scratches and a damageable edge - and more. Thus, manufacturers of replica swords compensate by making the swords thicker . Now, thicker also means heavier .

On the battlefield, a heavy sword is inefficient, will weigh you down, will make you tired, and get you killed.

Can you kill with a stainless steel sword? Yes, naturally. It can be used as a stabbing weapon and, to an extent, a cutting weapon, depending on its edge. Because these swords are not heat-treated in the traditional manner, the edge will not retain sharpness after you cut cardboard several times.

Remember that swords are not chopping weapons, as opposed to what you see on TV. Some swords are good for piercing, but its ultimate edge (no pun intended) is in it's ability to cut. Japanese swords feature edges with extremely high Rockwell hardness for cutting ability and a lower Rockwell hardness for its spine for impact absorbtion and toughness.

Stainless steel is not suitable for real swords, but is acceptable for short knives and decorative swords that are intended to be hung on a wall and not used.

440C stainless steel has better edge holding capabilities due to its higher carbon content (about 0.2 percent) than 420C. 420C has a lower carbon content, which makes it thus slightly tougher.

You may have heard of 420J2 - this is the equivalent of "mild steel" but in stainless. 420J2 is extremely stain resistant, but cannot be hardened - even if you heat treat it. In addition, it will not hold an edge.

Now on the more technical side, 420C has up to 1.2% carbon content. There is also a fraction of a percent difference in chromium content than 440C but the effect is negligible.

If properly heat treated, 440C could be made harder than 420 and would hold an edge better. However it is more brittle.

In general, the chromium content of stainless steel swords weakens the grain boundaries and makes the steel molecularly weaker than low alloy carbon steel (e.g. 5160, 1050, etc.).

If you have to choose between 440C and 420C, 420C is a slightly better choice because although you can't harden it as much, the lower carbon means that it's a bit tougher.

If it important to follow some basic safety guidelines. This information is true for both display and functional swords. The basics here can be summed up by the following (although this is by no means a complete list!):

• Take as many precautions with your sword as you would with a loaded weapon . Many display swords are heavy or unwieldy, and can easily slip from your hand. Even a dull sword can become extremely dangerous should it fall point first into something or someone! It would be very easy to swing your sword and lose your grip causing the weapon to fly! Do not endanger yourself or others!
• Do not swing your sword - or any weapon - around without carefully evaluating the distance of your swing. Do not carelessly swing your weapon!
• Do not hit your sword against another sword in theatrical-style duels! No matter how tough or strong the steel is in any sword, it will nick when struck against something equally hard. In stage plays or in movies, theatrical swords with wide, thick edges are used. The edges are flat and often as much as 1 1/6" wide. Such theatrical swords are designed to take the flashy looking punishment of banging edges together. Parries were made with a the flat of the blade (not the edges) or were simply avoided altogether. Real swords were never designed for the sword banging you see in the movies. You would be immediately be thrown out of your warriors guild for grossly mistreating your weapon and livelihood! :-)
• Do not chop wood or trees with your sword!  Axes and machetes were designed to concentrate the weight of the steel over the point of impact. Impacting a sword upon a tree is likely to cause the blade to bend, or if stainless steel, shatter!

We cannot be held responsible for any harm to persons, creatures, or objects caused by inappropriate sword use.