Based on the many different processes that can be used to make knives, there are many different materials that can be used. Early knives would have used primitive materials like bronze, copper, brass, iron, obsidian, or flint, but now we use more advanced compounds like carbon steel or stainless steel.
To understand the necessity for different materials, first you must understand the basic process by which knives are made. Generally all knives made these days are fashioned from steel, so the first step is the initial forging.
In the initial forging, the knife is shaped by heating the steel up to a very high temperature and then using a hammer and anvil to mold it into the desired shape. This shape will be very similar to the final design, but very little stock removal occurs in this phase of the process.
Next, the grinding will occur. Power tools like a belt grinder are generally the best bet for these, but it can also be done with files. The goal here is to shape it and take off any unnecessary material.
Heat treatment will then be used to temper the knife into a hardened state. This is done by employing both heat and cold to the knife. The cool is often applied by using oil, water, animal tallow, or brine.
Finally, the knife maker will engage in a finishing grind to polish the knife to its end state. Each of these processes requires countless hours of practice and require numerous decisions to be made along the way.
Types of Steel in Use
As with everything, there are tradeoffs when it comes to choosing what type of steel to use. Hardness, corrosion resistance, and edge retention are all qualities to strive for, but each material has its own property.
Carbon steel is one of the most commonly used substances, due to its availability and tensile strength. The edge tends to hold a lot better with higher carbon, and the resistance to wear and tear is notable.
Knives made with carbon steel will often exist on a continuum, where the highest carbon blades are easily broken but very hard, and the lower carbon blades are difficult to break, but very malleable.
Chromium is another commonly used substance that is resistant to corrosion, and also has lots of hardness and tensile strength. Stainless steel contains a high amount of chromium, but also tends to have plenty of carbon to help maintain the hardness of the blade.
Other potential substances are molybdenium, vanadium, nickel, manganese, or silicone, each with their own advantages. For example, manganese tends to be used in modern industrial settings because it is easier to work with and cheaper to produce.
It is possible that a non-metallic material is used, but you end up with a very brittle edge when you use something like obsidian or ceramic. The plus side is that your knives never corrode and are very sharp in the beginning.
Fashioning the Handle
The tang is the part of the knife that extends into the handle, so the choice of how the handle will be designed depends largely on the tang of the knife. The handle is almost as important as the blade, as it must protect the user’s hands and be comfortable.
The materials used for the handle tend to range from something natural like wood or elk to synthetic materials, such as plastic or polymer. Depending on the tang of the knife, the handle may be either screwed or pinned on, or in the case of not having a full tang, it could be inserted into a solid handle.