Metallurgy is a very complicated topic, comparing one steel to another can be very confusing. Reputable knife manufacturers will provide some guidelines for comparing one steel to another. Spyderco has a fairly comprehensive comparison tool on their website: https://www.spyderco.com/edge-u-cation/steel-chart/
this tool allows you to compare the percentages of certain elements within the alloy.
Generally speaking the following assumptions can be made when comparing one steel to another
Carbon: The higher the carbon content the harder the steel can be heat treated
Chromium: Chromium increases toughness and wear resistance, as well as gives the steel stain resistant properties, steels with more than 13% chromium are considered stainless
Cobalt: Increases hardness and strength
Manganese: increases hardness, makes the steel more stable in quench, increases wear resistance and tensile strength
molybdenum: increases hardness and high temperature strength, improves machinability, improves corrosion resistance, is a carbide former
Nickel: increases ductility and toughness
Niobium: Is a grain refiner, carbide former, improves strength and toughness.
Nitrogen: Can replace carbon in steels, increases stain resistance
Phosphorous: Considered an impurity in steel, can cause brittleness
Silicon: Can increase toughness and hardness, helps to remove impurities from steel
Sulfur: Considered an impurity in steel, in small amounts can improve machinability
Tungsten: Forms carbides and promotes wear resistance
Vanadium: Helps control grain growth, increases toughness and strength
There are lots of blade steels to choose from, an incomplete list includes:
Tool Steels often preferred by custom knife makers due to simpler heat treatment requirements.
1. A2 - A good all around tool steel, stain resistant but not quite stainless, wear resistance is good but not quite as good as D2
2. D2 - The standard material for metal working dies, better wear resistance than A2, but not quite as tough, somewhat corrosion resistant, but not stainless.
3. O1 - Comparable to A2 in terms of toughness and wear resistance, not as stain resistant as A2.
4. M4 - High wear resistance, can be more challenging to heat treat.
5. W1 - Common steel found in metal working files, hobbyists and beginning knife makers prefer this steel because it's easy to find and not difficult to heat treat.
I consider these every day carry steels, good knives can be found with these steels for <$100.
1. CPM 154, 154CM, ATS-34 - Essentially the same 3 steels, good corrosion resistance, good edge retention, fairly easy to sharpen.
2. 12C27m, 13C26, 14C28N - These Sandvik steels were developed specifically for use as razor blades, they have excellent edge retention and are easy to sharpen, 14C28N has nitrogen added for corrosion resistance. These steels are used by Victorinox (swiss army knife) Mora and Kershaw.
3. 440C - This was considered the best blade steel in the 70's and 80's, it's still pretty good, very stain resistant, good edge retention, can be difficult to sharpen.
4. 420HC - Low cost, stainless, good corrosion resistance, easy to sharpen, doesn't stay sharp as long as more expensive steels.
5. 8Cr14MoV - This is the "best" Chinese blade steel, it has good corrosion resistance, is easy to sharpen and holds an edge well, when it holds an edge well. Quality is hit or miss, I've had some import knives that stay sharp as long as knives that cost 3-4X as much, others dull if you look at them funny.
High end "super steel"
1. CPM S30V - was considered the best high end steel about 10 years ago, powdered metal, good edge retention, difficult to sharpen, depending on heat treat and geometry can be prone to edge chipping.
2. CPM S35VN - An incremental improvement over S30V, less prone to edge chipping, stainless, good edge retention. My current favorite knife has a S35VN blade.
3. CPM S110V - One of the toughest and most wear resistant steels available according to the data sheets, I have found that S110V is very difficult to sharpen, the one knife I owned with an S110V blade didn't stay sharp very long. A good heat treat is needed for this steel to perform well.
4. CPM 20CV, CTS 204P, M390 - Currently considered the best stainless blade steels, all three steels have essentially the same composition, but from 3 different manufacturers. In my experience Bohler Uddeholm has a superior powdered metal process and makes a slightly better blade steel, but all 3 steels hold an edge longer than any other steel I've used, they are all difficult to sharpen.
7. Elmax - This steel is somwhere between S35VN and M390, it has really good edge retention but is easier to sharpen than M390.
1. CPM 3v - Ultra high toughness, ideal for machetes and other large chopping blades, not stain resistant.
7. 52100 - Commonly used in ball bearings, good blend of toughness and wear resistance, somewhat stain resistant but not stainless.
Please share your experiences with any of these steels or others I haven't listed.