How can I tell the wear resistance, strength, ect from the name of the steel?how could I tell the difference between 420 and 440 steel. what does the HC in 420 HC steel mean? what do the numbers and letters in s30v steel mean?
Larry gave a good answer. As for the HC, it means High Carbon.
If your question implies how to tell the differences just by looking at the actual knife then I'd say there is no real way to do that. Just about all high carbon steel's look alike. You should be able to tell the difference between a stainless steel, but which one is anybodies guess, and a carbon steel however.
So what does all that mean in the real world of knives. 420 has very low carbon by blade standards, as such it is just junk steel. There are three grades of 440, A, B and C. The amount of carbon in A is about half of what C has. (carbon is what makes steel get hard). Iron is very much like a sponge in that it can absorb and hold different alloys. These alloys give the iron different attributes, and they can magnify each other. Like a sponge iron can only hold so much, for Chromium it is around 13%. At that point the steel becomes stainless. The drawback is a loss of strength. As a bladesmith my knives are generally 59 to 60 rch, 420 and 440 at its hardest is 59 but at that it is brittle so most makers draw it down to around 57. In my test a knife made of 420 couldn't make 5 slicing cuts through rope (most couldn't make one). 440 averaged between 5 and 10. Compared to the lowest grade of carbon steel I use (5160) which average between 25 to 30 on the same rope. I have tested many stainless blades and the rule always the same, the more chromium past 13% the weaker the blade and the less edge holding ability.
