3CR13: A Chinese Stainless steel that is similar in quality to 420J2 stainless steel. The following formula is a break down in the steel: Around 13% chromium and 3% carbon. It has a HRC of 52-55 making it relatively soft.

5CR13: A Chinese Stainless steel that is similar in quality to 420HC (AUS 6) stainless steel. The following formula is a break down in the steel: Around 13% chromium and 5% carbon. It has a HRC of 54-57 making it relatively soft.

7CR17MoV: A Chinese Stainless steel that is similar in quality to AUS6 stainless steel. The follwoing formula is a break down in the steel: 7CR part means it is 7% chromium and the 17MoV means .17% molybdenum  and .17% Vanadium 

8cr13MoV: A Chinese Stainless steel that is similar in quality to AUS8 stainless steel. The follwoing formula is a break down in the steel: 8CR part means it is 8% chromium and the 17MoV means .17% molybdenum  and .17% Vanadium 

10 Series Carbon Steel:  Also known as 10XX.  10 is an SAE designation for plain carbon steel.  (1 means carbon, 0 denotes no other major element in the steel) The numbers following the ten give the amount of carbon added to the steel alloy.   For instance 1070 would equal 0.70% or 7/10 of 1% of carbon added to the steel.  1050 equals ½ of 1% or 0.50%.   More carbon produces a harder, tougher blade but increase the potential for staining (rust).  See also 1095.

12C27:  A Steel with .6% carbon that originated in Scandinavia.  It is roughly equivalent to 440 A. It is often called Norwegian Steel 

15N20: Essentially the same as L6 or Band Saw Steel. is an oil-hardening tool steel that is characterized by very good toughness.  It contains approximately 1.25-2.0% Nickel, 0.65-0.75 % Carbon,   0.6 - 1.2% Chromium and  0.25 - 0.8% Manganese.  It has a maximum of 0.5%  Molybdenum. 15N20 is often used along with 1095 Carbon steel for the production of Damascus steel

154CM: Known as a crucible stainless steel, it os one of the newer stainless steels which, depending on manufacturer is about the same quality as 440c or ATS 34 stainless steel. The Rockwell test is around HRC 58-61. A popular use for 154CM is in survival knives that may be exposed to salt water for long periods of time. 154CM stainless steel contains: Carbon 1.05%, Chromium 14.00%, Manganese 0.50%, Molybdenum 4.00%, and Silicon 0.30%

304 Stainless Steel: Grade 304 is the standard "18/8" stainless; it is the most versatile and most widely used stainless steel. The steel contains 18% chromium and 8 % nickel. The steel is austenitic (non-magnetic) due to the high chromium content but is used in surgical instruments due to it high stainless content. They use it mainly for pans and throw away blades. It would make an absolutely lousy knife blade due to the softness of the metal yet in theory it is a Surgical Steel.  The steel is often used for dining sets.

316 Stainless Steel:  Grade 316 is the standard molybdenum-bearing grade stainless steel, second in importance to 304 amongst the austenitic (non-magnetic) stainless steels.  It is a surgical stainless steel. The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments. The steel is non magnetic and makes a lousy knife blade.  However, 316 is often used for other knife materials where edge retention is not required but corrosion resistance is highly valued. For this reason, it is a U.S. Military standard for marlin spikes on folding rigger knives used by the Navy and Coast Guard.

400 Series Stainless:  A term almost as misleading as “Surgical Steel”   This can be any 400 series stainless from 403 or 440F.  The smart consumer will assume it is a lesser grade steel.

420 Stainless Steel: A low carbon content (less than .5%) stainless steel which is extremely stain resistant but soft, making it a poor choice for every day or rough use.  It is, however a good choice for knives used around salt water (diving) and for decorative knives because of its rust resistant qualities.  It is often used in cheap imports.  This is probably the steel they are referring to when a company advertises “Surgical Steel.” It dulls quickly and is easily nicked, bent, blunted or broken due to being a soft steel. It is some times used as the liners on pocket knives instead of the more popular brass.

420F:  A stainless Steel with 12-14 Chromium and .15% carbon, used mostly in dental instruments.

420HC: A 420 stainless modified with more carbon, and normally a better heat treatment.  It is said to be roughly comparable to 440A. There is debate about this claim. Buck uses this in its Chinese imports. It is probably used by others.

420J Stainless Steel: Is a low carbon stainless steel which is used in lot of inexpensive imports, Some knife makers use it in the liners of their folding knives but not for blades. 420J is often  called quality surgical steel or Japanese steel. (The J has nothing to do with Japanese made steel).  420J has a high chromium content that gives it great corrosion resistance but is has lousy edge retention and is very soft meaning it will knick and dull quickly.  It is often used in Novelty and Art/Decorative knives

420J2 Stainless Steel: 420J Stainless with a little more carbon.  It is sometimes used in dive knives because of its corrosion resistance.  It is used in surgical instruments due to ease of machining and corrosion resistance.  With proper heat treating can achieve a Rockwell test of 56.   And makes it comparable to 420HC. It is often used in scissors. It is not a true "tool steel" however because it is used on making certain surgical tools some people will call it "420J2 tool steel" in a less than scrupulous sales pitch.

425M:  A stainless steel used by Buck Knives with about .5% carbon, It is about the same as 440a Stainless Steel.

440 Razor Sharp Steel:  A Rough Rider Trademark blade etch normally found on the reverse side of the main blade.  While not specified, these knives usually have a Rockwell hardness rating of around 56-58HRC.

440 Stainless Steel: Any of the 440 series Stainless Steel.  When not specified it should be considered 440 A.

440 Series Stainless Steel: A term used to specify any of the 440 Stainless Steels. (440A, 440B, 440C)  Companies use the vague term for a number of reasons but it is probably used so that different types of 440 steel with varying heat treatments can be used on different blades without having to be specific.  This can be good or bad. Assume that the steel will be 440A unless it is verified otherwise.

440 Tested Sharp (Anvil): Another Rough Rider Trademark blade etch used on their 440 series stainless steel. It is normally found on the obverse side of the main blade. While not specified, these knives usually have a Rockwell hardness rating of around 56-58HRC.
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440A Stainless Steel:   Stainless Steel with a minimum of 0.75% carbon and considered a good all around steel for an every day use knife. It has good rust resistance, and holds a reasonable edge. It is also easy to sharpen. It will not take a lot of abuse. When a knife is marketed as 440 Stainless, this is the steel they mean.  440A has a maximum hardness of 56HRC.

440B: Stainless Steel: Stainless Steel with a minimum of 0 .9% carbon.  440Bis tougher and will handle more abuse than 440A but will rust more easily. 440B has a maximum hardness of 58HRC. You normally do not see blades made with 440B steel. Most often they are made with the Japanese equivelent steel AUS8 steel.

440C: Stainless Steel: Stainless Steel with a minimum of  1.2% carbon This is the hardest of the 440 series  It takes more abuse however it also rusts more easily than the other 440 series stainless steels.  440C can achieve a 60 HRC.

4116 Krupp Stainless Steel: 4116 is a fine grained, stainless steel made by ThyssenKrupp in Germany It was developed for the medical industry but is now used in food preperation. The balance of carbon and chromium content give it a high degree of corrosion resistance and also impressive physical characteristics of strength and edge holding. Edge retention is said to be on par with 440C Stainless Steel but corrosion resistance is much better. Carbon: 0.45-0.55; Si: 1.00 Mn: 1.00; P:0.040; Cr: 14.0-15.0, Mo: 0.50-0.80, V: 0.10-0.20

1045 Tool Steel: Same as C45 Steel, a steel used in axes and hammers.

1060: A steel commonly used for Swords. It is often compared to 5160 steel with 5160 normally being considered the better of the two As this is a series 10XX steel, its carbon conten is around .60% giving it great toughness but poor edge retention.

1070, 1075: 1070 and 1075 are common carbon steels used in machetes and large cutting blades such as Kukris. the 70 and 75 refers to the amount of carbon (.70 or .75%) used in the blade construction. The steel will dull faster than 1095. On the other hand, it is tougher and thus can absorb more hacking punishment than 1095.

1080, A carbon steel blade used on survival combat knives and some of the better quality Kukris.

1095: 1095 is the steel used in many US Military fighting knives and is the de-facto industry standard for combat knives. It is one of the 10-series steels.  The 95 stands for .95% carbon content in the steel. (See also Cro-Van and CV) 

5160: A carbon-chromium steel alloy, often refered to as Spring Steel because it is used in car springs. It is a common sword steel, especially for European style swords but is also common among survival knives due its tougness. The compostion of 5160 is: Carbon - 0.56 - 0.64; Chromium - 0.7 - 0.9; Manganese - 0.75 - 1; Phosphorus - 0.035 max; Silicon - 0.15 - 0.35; and Sulphur - 0.04 max.