We often hear a lot of misconceptions about 440C Steel and we want to clear up a few of them. 440c Steel has gotten kind of a bad rap because a lot of factory knives use 440 stainless, sometimes called "surgical stainless".
It is very important to understand that not all 440 series is the same. In fact, there are different grades of 440 with VERY different properties. There is 440A, 440B, and 440C.
440A and 440B are "softer" grades of 440 Steel. While they are VERY rust resistant and will take a great looking mirror polished finish, they will not hold an edge nearly as well as 440C. Factories use the milder steels because the blades are stamped out of sheet of steel using dies. 440C is too hard and expensive for this process. Some manufactures are intentionally vague about the type of steel they use. If the blade is marked "stainless steel", "surgical stainless" of just "440 stainless" you can bet it is 440A or 440B.
440C is a considerably better and more expensive steel and if a blade is made from 440C it will almost always be described as, or marked, "440C".
This is one of the primary differences between mass produced factory knives and handmade custom knives. Factories must use the milder steels for the stamping process. A custom maker does not have this restriction since each blade is cut by hand so a custom maker will almost always use the better cutlery steels.
When someone says that 440 stainless (or any stainless) will not take or hold a good edge, they are most likely comparing to a factory knife with a lower grade of 440 stainless steel. The fact is that there are a number of excellent stainless steels that will take and hold a great edge provided they are properly made and heat treated.
What is 440C?
A martensitic stainless steel. It's composed of these major alloy elements (I don't list the minor elements since they don't play a major role) :
§ Carbon: 1.00-1.25% This increases hardenability and wear resistance, but decreases toughness in higher amounts.
§ Manganese: .45% This is added to reduce brittleness and improve forgeability, hardenability, and reducing deformation.
§ Silicon: .30% This is a deoxidizer and improves hot-forming properties.
§ Chromium: 17.00-18.00% Added in high amounts only to high alloy tool steels: this improves hardenability, high wear resistance, toughness, and corrosion resistance.
§ Molybdenum: .50% Improves deep hardening and toughness, along with wear resistance.
These basic elements (along with iron) are a simple combination that works well together, and has for many decades.
I've seen these designations as a source of confusion in the knifemaking field for decades, and it's time to set some things straight. First, there is NO "440" stainless steel. Without the letter designation, it's like claiming your car is a 20th century version (not identifying the year)! Yes, I drive a 1900's car; it's a great car; it was built in the 1900s. How ridiculous is that? Yet I've seen this again and again in not only individual knife maker's sites, but in knife manufacturer's advertisements as well. The numbers 440 without the A, B, or C designation after them are essentially meaningless. Just Google the term 440 steel and see the endless list of makers and manufacturers that are proud to spew their ignorance about this type of steel, calling it surgical stainless, dive stainless, or other terms that demonstrate their lack of knowledge about the term they are attempting to define.
440A: this is a hardenable stainless steel alloy, hardenable to a higher hardness than 420 series stainless steel (which are only hardenable to 52 HRC!). 440A has good corrosion resistance, and is used in less expensive bearings and in harder surgical tools (rare). It has 0.6 to 0.75 percent carbon, about the same carbon content as most steel springs. Its advantage is that is cheaper than 440B and slightly more corrosion resistant.
440B: this is a hardenable stainless steel alloy, hardenable to a higher hardness than 440A. It has good corrosion resistance and is used in cutlery (economy), valves, and instrument bearings, where high wear is less important than high corrosion resistance. It has 0.75 to 0.95 percent carbon.
440C: this is also a hardenable stainless steel alloy, hardenable to a higher hardness than 440B. It has good corrosion resistance, and is used in ball bearing balls and races, high pressure nozzles, valve seats and high wear components. It has 0.95 to 1.20 percent carbon. As detailed in the Machinery's Handbook: "This steel has the greatest quenched hardness and wear resistance upon heat treatment of any corrosion-resistant or heat-resistant steel."
All three of these steels have the same amount of chromium, from 16 to 18 percent. They are all high chromium martensitic standard stainless steels. All of their other alloy elements are about the same, including manganese, silicon, phosphorus, sulfur, and molybdenum. Truly, the difference in these three is the carbon content, which is substantial. The higher carbon content in 440C yields a much more wear resistant knife blade.
Collectors, investors, professional knife users, active duty military, and others will continue to specifically order fine custom handmade knives made of 440C (and other steels) based on their needs, desires, and intelligent research. 440C is a fine steel for hand knives, it's bright, beautiful, durable, and proven, when properly processed and finished. It excels in corrosion resistance, and is many times stronger than carbon steels, while being reasonably priced. It has high wear resistance, high toughness, and extremely high finish value, which is seldom mentioned, yet extremely important. It won't soon be replaced in the industrial and military complex as a fine, high grade martensitic stainless steel, and the machine tool industry will continue to rely upon it. There is no current replacement for 440C that has the same characteristics as this steel; if there were, and it was less expensive, it would disappear. This is how all products and their production works.
In knives, there are only a couple steels that can compare with its beauty while exhibiting the toughness and wear resistance that 440C has. A polished 440C blade will hold its finish for many decades with a minimum of care. It's reasonable to sharpen, it's affordably priced and machined. This is why it simply is a popular knife steel and will remain so.