Steel Away

Despite the fact that my grandfather was a pretty good blacksmith, I really know very little about various types of steel and which are best for different jobs.  The obvious thing is that stainless steel uses chromium to discourage corrosion.  More carbon forged into steel helps make it harder and more wear-resistant.  The A.G.Russell site gives some specifics on the make-up of some common steels.

For non-stainless steels, one of the more popular for a knife blade is 1095 which generally has a carbon content of between 0.90 and 1.03%.  While 1095 takes and retains an edge well, it can be more brittle than some of the other carbon steels commonly used for bigger blades.  Sword steel is often 1060 with a carbon content of 0.55-0.65%.  Both 1070 (carbon 0.65-0.75%) and 1055 (0.48-0.55%) are also used in machetes and swords.  1095 is typically in the Rockwell hardness range of 56-58, while something like 1055 is going to be softer, often tempered as spring steel to lessen the likelihood of breakage.

That’s really the key when thinking about steels.  It all depends on where and how a person intends to use a blade or tools.  I would say that 420J stainless, for instance, is not a good steel for retaining an edge.  It is cheap, has a low carbon content of around 0.15% and a typical hardness of around 50 on the Rockwell scale.  For decades, though, I have had a very inexpensive hardware-store, 6-inch fixed blade made of 420J or some similar steel.  I have used this knife as a yard and garden tool.  It is left laying out in the weather, used to clean grass out of the mower deck, dig out weeds and any other rough application you can think of.  It has shown no sign of rust or corrosion despite the abuse.  I can put a reasonable edge on it in a couple of minutes, hose it off, and it will function as a decent tool to prepare vegetables.  What can you say?  It works. 

Add a little more carbon to 420 stainless, making it what is called 420HC (0.40-0.50% carbon, along with some vanadium and molybdenum), and you get a decent factory knife blade with a typical hardness of 56-58.  This is the steel used by Buck in most of their blades. 

By way of comparison, one of the higher-end stainless steels often used in custom knives over the last forty years or so is 154CM.  It has a carbon content of 1.05% with 14% chromium and 4% vanadium.  Typical hardness of 154CM varies from 58 to 62.  To get a knife with a 154CM steel blade you’re going to have to pay a premium.  Is it worth it?  If your life depends on it, it probably is. 

However, you can get a blade in something like 440C (or the slightly tougher AUS-10), 8Cr13MoV, AUS-6 (similar to 440A), or AUS-8 (similar to 440B) for less money to serve much the same purpose and hold up, in most cases, quite well.  AUS-6 is what I have in my CRKT Crawford Kasper.  I am happy with the way it has sharpened up and with the way it holds up.  The Rockwell on AUS-6 is 55-57, carbon is 0.55-0.65%, manganese 1.0, chromium 13.0-14.5, nickel 0.49, and vanadium in the 0.1 to 0.25% range.  Like 440A is has good corrosion resistance, appears to be fairly resistant to breakage, and is relatively inexpensive.    It is easier to sharpen than some steels but, understandably, requires touching up more often. 

I see that SOG uses a lot of AUS-8 for their blades.  While the carbon percentage is higher than AUS-6, at 0.70-075, the only other difference is that AUS-8 and AUS-10 (0.95-1.10% carbon) add a little molybdenum to the mix.  Carbon makes a big difference in edge retention.  Lower carbon edges have more “give” – they bend, which is why they are inferior in terms of remaining sharp.  Conversely that means they are less brittle and less likely to chip than the higher carbon, more glass-like steels.  Ninety-five times out of a hundred breaking a piece out of the edge is not an issue, and the higher carbon percentage is preferable.  But there is nothing like hearing a grown man weep and curse when he knocks a crescent chip out of the edge of his $250 Benchmade. 

The three rules of choosing knife steel might be said to parallel the three rules of real estate:  application, application, application.

By the way, my CRKT Folts Minimalist has 8Cr13MoV – hardness 58-59, carbon 0.80, manganese 0.4, chromium 13.0, nickel 0.20, vanadium 0.10, and molybdenum 0.15%.  It is standing up very well and cut like a razor.  Some of that knife’s utility is blade geometry.  The straight Wharncliffe configuration on the version of the Minimalist I have works better at cutting cordage and tape or opening bags and boxes -- for example, than a blade with more curve might.  A blade with a belly is going to skin more readily than the Wharncliffe.  A longer, flatter grind is easier (for me) to sharpen and maintain, but it can also be weaker in some situations. 

It is important to look at all the factors, do your research and do not be swayed by review blurbs or by statements of so-called experts.   The knife that works for me may not be right for you.  Our environments may differ substantially.  We may use a knife differently with widely different expectations.  Sharpening a blade after use may not be a big consideration for me; it might be for someone else.  I may place a higher value on toughness and durability; someone else might want low maintenance.  

So, once more,  the type of steel in a blade is an important consideration, but a lot will depend on where and how you intend to use that tool.