hardheart said:
S7 and H1 are pretty clear, but what are the differentiating tasks among the other 3?
M2 has a high edge stability for its wear resistance. It works well in knives which are made to cut well and stay very sharp and still offer high edge retention for those who use knives with significantly worn edges. If you don't need the latter ability then you are better off with a W series steel because the edge stability will be higher plus they are much cheaper and easier to heat treat and grind. M2 will also of course have higher corrosion resistance so works better for butchers. It is also available for very low cost in the form of power hacksaw blades so it is ideal to make knives out of because all you need is an angle grinder and you can make a knife which basically defines a standard of performance.
AEB-L basically is a stainless version of the W series tool steel and offers similar characteristics; a very high edge stability and thus extreme initial sharpness and strong high sharpness edge retention. It has slightly lower hardness and much higher corrosion resistance. Thus it would make a much better kitchen knife than a W series steel in most cases because corrosion tends to take the fine edge of W series steels very quickly. I can put a fine shaving edge on such a knife for example and after preparing just one meal the fine shaving edge is gone due to corrosion from acidic foods.
AEB-L however has a relatively low wear resistance (compared to high wear steels) and thus if you sharpen infrequently or use your knives rougher (statically, not dynamically) and thus prefer thicker profiles you can gain better edge retention with ZDP-189 which has a very high wear resistance for a stainless steel.
There are many alternatives to those steels, the ones I listed are easy to obtain in current high quality knives and they all are so balanced so as to sharpen very well when used for their types of knives. However S90V isn't an alternative to S90V for several reasons; sharpening, heat treatment, hardness and CPM-154CM/RWL34 is in no way an alternative to AEB-L. Those steels would be a low wear alternative to ZDP-189.
There are also many steels which are inbetween the extremes of those steels, or offer superior performance in one way for a decrease in another, but these gains are usually small and as Cashen is fond of noting, very significant in a lab, not likely to be noted by a user. The differences in those five steels steels I listed however are very large and you would never confuse one for another. I have been meaning to add some of this to the knife materials page and regroup the steels by the class of knife they work well in, as right now they are basically by family name which isn't overly useful and it presents a much too complicated picture.
In reality there are only a few small groups of knife steels/materials and just alternatives in those groups or inbetweens. For example, A2 is tougher than M2 but more brittle than S7, and has a lower hardness and wear resistance than M2 but is harder and more wear resistant than S7. So if your M2 blades are chipping then you would first try A2 before jumping all the way to S7. Similar if your S7 knives were rolling or just seeing excessive wear than you might want to try A2 before moving to M2. There are also steels which can jump classes depending on how they are hardened. For example bandsaw steels can reach 66 HRC and thus work well similar to M2 for a high cutting sharpness steel, but then be bainite hardened to 56/58 HRC and compete with S7 for a tough utility steel.
In general, though this isn't a good idea because if you try to mangle the heat treatment so the steel jumps class then you usually have to give up way too much of everything else to get the desired properties. Though you can usually move the steel around in its class to optomize them a little one way or the other. Generally though again you are talking about small changes which are far smaller than the class changes.
-Cliff
154CM could probably go away without leaving a hole either. A little more bothersome would be to choose a carbon steel we don't need, I don't use them much. Though I don't know if we need more than 52100 and L6.
I could ALMOST get rid of all stainless and just go with carbon blades. Note... I said almost:foot:
