Stainless Steel is used in almost all imported swords. It used to be that every sword on the market was made from Stainless Steel because it did not rust. This made it easy to take care of and easy to sell but did not make for a good quality sword whatsoever.
Stainless steel is 'stainless' because of its high Chromium content (over 11%). When a blade gets over 12" long and is flexed it starts to weaken because of the grain boundaries between the chromium and the rest of the steel, creating stress points. This will eventually lead to cracking and breaking on the harder stainless steels (440c) or will just bend in the case of the softer stainless steel such as (420c).
For a sword to be functional, at the very least, it must be a (properly tempered) 'High Carbon steel sword'. But what does this mean exactly?
Generally, The American Society of Automotive Engineers (SAE) scale is the one most commonly used by sword manufacturers. And the most commonly used steel for functional swords is plain carbon steel. It is designated by the first two digits 10 - and a number from 01 to 99 afterwards, with each point signifying that .01% of that steel is carbon.
For example, steel classified as AISI 1045 has 0.45% carbon content, 1060 is 0.60 carbon.
Steels with a carbon content between 0.05 to 0.15 are considered to be low carbon steel and 0.16 to 0.29 mild steel, neither of which are suitable for a functional sword (as any sword with a carbon content of less than 0.40% can’t really be hardened). The most popular three types of carbon steel used in swords are 1045, 1060 and 1095, starting with the most inexpensive (1045). Most sword experts agree that the ideal range for a durable and sharp sword is somewhere between 0.5 and 0.7 carbon content.
1045 CARBON STEEL
1045 Carbon Steel is relatively soft and easy to work with in its unheated state. We use it for my maces and battleaxes because these weapons require a lot of hole drilling and do not require much flexibility when in use. After it is properly tempered, 1045 is surprisingly strong, and is considered to be the minimum acceptable steel for a functional blade.
1060 CARBON STEEL
1060 Carbon Steel is a great compromise between hardness (edge holding ability) and pliability (strength). Consequentially, 1060 Carbon Steel swords are very popular. Although the steel is harder than 1045, it is more difficult to forge, shape and polish, thus almost always resulting in a higher price tag. A great all round, durable steel that keeps a good edge.
1095 CARBON STEEL
1095 Carbon steel is very hard. Unless it is properly heat treated, this hardness can sometimes be problematic when used on harder targets where the blade would be subject to a great amount of flexing. The main advantage to swords made from 1095 carbon steel is that they can take and keep a much keener edge than swords with a lower carbon content. The disadvantage is that they can sometimes be a little on the brittle side - so durability is compromised for edge retention. It doesn't mean that a sword made from 1095 carbon steel is exceptionally fragile, but it is simply nowhere near as tough as the lower carbon content swords.
ALLOY SPRING STEEL
There are basically two types of Alloy steels that are best for swords - 5160 and 9260. As with the plain carbon steel swords, the last two digits represent the carbon content - so both have .60% carbon the first two digits stand for the type of alloy that is in the steel. Therefore, 5160 and 9260 are like the 1060 carbon steel swords (a great compromise between hardness and durability) because of the carbon content. The alloy which is represented by the first two numbers means that these steels contain percentages of other steels and compounds such as chromium, nickel, and silicon manganese. These alloys allow objects made of spring steel to return to their original shape despite significant bending or twisting, thus giving 5160 and 9260 spring steel superior strength, flexibility, durability and edge retention.
5160/6150 SPRING STEEL
5160 Spring Steel is a low Chromium alloy steel, with around 0.7 Chromium - which is not enough to make it stainless (which requires a minimum of 13% Chromium) - but combined with a small amount of silicon (0.2%) results in an extremely tough and durable sword and is favored by some of the best custom sword makers. 5160 is a carbon-chromium spring steel. It exhibits excellent toughness and high corrosion resistance, with a high tensile-yield ratio. For this reason, it is commonly employed in heavy spring applications primarily in the automotive field for leaf springs. We use 5160 in all my swords over 1 foot in length.
9260 SPRING STEEL
9260 Spring Steel is a Silicon Manganese alloy it has a 2% silicon content, giving it an even more dramatic resilience against lateral bends and allowing it to spring back to true even after being bent almost to 90 degrees. This steel is most commonly used in rapiers because they require extreme flexibility. 9260 Spring Steel is an exotic steel making it quite expensive. It has a reputation for durability and strength having a tensile strength almost double that of 5160.
T-10 Tool Set
There are three primary properties of T-10 tool steel: toughness, wear resistance and hardness. T-10 has superior ability to resist cracking, chipping or breaking.
T10 Tool Steel is a Tungsten alloy steel with a very high carbon content (around 0.9 to 1.0%) with a little bit of silicon (around .35% maximum) and is often referred to as 'High Speed Steel'.
This stuff tends to be very hard (above HRC60 when properly tempered) and the Tungsten means that it is also more resistant to scratches and abrasions than most other types of steels, plus considerably tougher than other steels with a similar level of carbon content.
L6, also known as band saw steel, is an alloy steel. There is little argument that it is one of the toughest steels commercially available for swords. L6 is prone to rust and requires extra care and maintenance. It can be hard to work with and heat treat. Because of this, swords made from this type of steel can be quite expensive, but when properly heat treated, has the reputation of being one of the toughest steels with regard to durability and flexibility.
Damascus steel can be any of those listed above folded together for the purpose of beauty. Many have been misinformed about folded blades, thinking it is the best steel for swords - but in reality, what we currently call 'Damascus Steel' is just different grades of the steel folded together.
Almost all questions about Damascus steel swords are referring to the Katana - historically this technique produced Japanese iron ore (which was pretty poor quality) into a higher quality steel. They did this by folding steels of different properties together to get the desired effect of hardness and flexibility something which, with the quality of modern steel, is no longer required. However, the artistry and beauty of folded steel can be amazing. This is not to take anything away from the traditional Japanese sword makers who are among the best in the world.