The Complete Online Guide to Knifemaking, MATERIALS
The Complete Online Guide to Knifemaking, MATERIALS
After choosing a blade design or coming up with your own concept, the next step is to pick the blade material. The qualities of a knife blade can be defined by its hardness, toughness, wear resistance, corrosion resistance, and edge retention. Hardness is the steels ability to resist deformation and is usually measured using the Rockwell C scale. Toughness is the blades ability to resist cracks and chips. Wear resistance is very similar to hardness. A hard material is less likely to wear down than a soft material. Corrosion resistance is the blades ability to resist rust. Many materials that are corrosion resistant may not have the best edge retention. Edge retention as the name applies is the blades ability to hold an edge or retain its sharpness.
The decision of which steel to use can be daunting. In addition to the above listed material qualities, the choice also has to be based on what equipment you have available for heat treating. For beginner and novice knife smiths, pick a steel that is easy to harden with a standard forge or torch. High Carbon steel like 1084, 1095 or a tool steel like O1 would be a good choice because they are inexpensive, readily available, and relatively easy to work with and harden. Knives made from these steels will also hold a great edge, so the end result can be a knife that is rugged, sharp, and with the proper care, can last forever. Listed below are some examples of types of steel commonly used by knifemakers.
High Carbon steel is probably the most common type of steel used when handcrafting knives. This steel is made up of a combination of iron, carbon, and manganese. Carbon gives the steel its hardness. The more carbon the harder the steel and the better it will hold an edge. The types available are labeled with a designation number like 1075, 1084, and 1095. The last two numbers refer to the percentage of carbon in one-hundredth of a percent. For example, 1084 is .84 percent carbon, 1095 is .95 percent carbon. Steels that range from 1075 to 1095 are all good choices for knife making. A steel like 1095 has a higher carbon content and will, therefore, be harder and hold a better edge. A steel like 1075 might not hold quite as good an edge but would be less brittle and tougher to break. Any of the high carbon steels can be hardened with a forge or even a set of torches. This material is available in small quantities and a variety of manufacturers actually offer high carbon knife blanks which are already profiled to shape. The downside to working with high carbon steel is that the material easily rusts. Finished knives must be maintained by drying them after each use and applying a protective coating of oil.
1045 is sometimes used by knifemakers, but this steel is generally used in combination with another higher carbon content steel to create multi-layered Damascus. It is usually considered too soft to be used alone for knife making as it would not hold as good of an edge as its higher carbon counterparts.
1075 is frequently used for large blades and is tough and durable.
1084 is a good choice for beginners. This is the easiest high carbon to heat treat. It does not require any precision temperature or hold time.
1095 is an excellent choice for forging or stock removal blades. A little trickier to heat treat than 1084. This steel needs to be quenched very quickly after removing it from the forge or oven.
1095 can be quenched in water or oil (with oil being recommended to avoid cracking).
15N20 is a great steel for knife making. This steel has a high nickel alloy content and is often used in conjunction with 1045 or even 1095 to create “Damascus” steel.
5160 is the material many automotive leaf springs are made of.
Tool steels contain more elements compared with High Carbon steel. Tool steel is commercially available in small quantities which is nice for the hobbyist knifemaker. Tool steels have a designation number that identifies each. The SAE (Society of Automotive Engineers) system designation starts with a letter for any steel classified as tool steel. Each letter is a different designation. For example, A stands for air hardened. W for water hardened and O for oil hardened. D designates a high Chromium content. Tool steel often offers better wear resistance than high carbon. The disadvantages are some require a more precise hold time at temperature during heat treating. Without a heat-treating oven, this can be difficult. Like high carbon, tool steel can rust without proper care.
A2 - Versatile and air hardening A2’s wear resistance is slightly better than O1 and not quite as good as D2. which gives it a nice balance between strength and edge retention.
CPM 10V & CPM M4 - CPM stands for Crucible Particle Metallurgy. This tool steel is tough and wear resistant.
D2 - Because of the high chromium content, this tool steel has good rust resistance. D2 is a good compromise between tool steel and stainless steel. It is tougher than most stainless steels, but at the same time, not quite as strong or durable as other tool steels. D2 has excellent wear resistance and edge retention. The downside is it can be difficult to polish.
O1- Similar to other tool steels, O1 has good edge retention and wear resistance. It will rust without proper care. O1 is easy to forge or grind and should be quenched in oil for hardening.
W2 - This steel is very similar to high carbon. It holds a great edge and like most tool steels can rust without proper care. W2 can produce an excellent hamon when deferentially heat treated. W2 is very malleable and easy to forge. W2 can be quenched in water as the prefix indicates. This material calls for a hold time at a temperature, so it's a little difficult to do in a forge. When heat treating W2 is very similar to 1095 because it needs to be quenched quickly.
Stainless is usually a little softer than high carbon or tool steel. The benefits are from its rust inhibiting factors. The compromise between rust prevention and edge retention have always been one of the major deciding factors when deciding on a material for a knife project. New “Super Stainless steels” have now been created and offer the knifemaker the best of both worlds between great machineability, as well as edge retention. For stainless steel, heat treating is a bit more complicated than high carbon. A heat-treating oven with precise time and temperature control is required. The beginner or novice knife smith should not be distracted from using stainless. Many companies offer heat treating services even for small quantities which allows the hobbyist knife smith to work with rust-resistant stainless while avoiding the expense of a heat-treating oven.
440C has a high carbon content and for years was one of the most common stainless steels used in knife making. It holds a great edge and is wear and rust resistant. 440-C is relatively easy to polish and is widely used in the cutlery industry.
AEB-L is another excellent stainless. It's considered one of the new “super stainless steels”. AEB-L is often used to make razor blades and kitchen knives.
CMP-154 is easy to grind and polish. It also has improved toughness and corrosion resistance.
Nitro-V is very similar to AEB-L, but by using Nitrogen and Vanadium, they created a ferroalloy that provides exceptional edge retention, hardness, and extreme corrosion resistance. This material is especially popular for use in the marine environment.
Damascus is made by hammer forging two or more different materials together. Usually, layers of flat stock are flattened, hammer welded, and then folded several times. There are variations that combine different shapes and materials into a canister prior to hammer forging. The end result is thin layers of steel that form the final product. Once a knife blade is either forged or ground from a Damascus blank, the blade is polished and then dipped in acid. Because Damascus is made from two different materials one corrodes at a faster rate than the other. Dipping in acid accelerates this process and leaves a very distinct pattern in the steel. Damascus is available from a variety of sources. Be aware of Pakistani Damascus which is marketed on the internet. Because the materials used are sometimes inferior, Damascus from this region has the reputation of looking good but not holding an edge. Today smiths have even combined different types of stainless steel to create beautiful stainless Damascus patterns. These not only offer the blade smith beautiful designs but the rust prevention of stainless steel. Damascus is not considered a beginner material. It’s harder to cut, drill, and grind.
For the beginner and experienced knifemaker alike, recycled steel offers a neat variety of options. Old automotive leaf springs are often made from quality spring steel and can be formed into beautiful knives. Other common materials like files, rasps or even saw blades can also be used. Keep in mind that most times recycled steel will already be hardened. It should be annealed to soften the steel before attempting to cut or grind the blade into shape. Annealing is a fairly simple process. Heat the steel in a forge until it is cherry red and nonmagnetic. Once at temperature, hold it in a nonmagnetic state for a couple minutes and then turn the forge off and let it cool slowly to room temperature. The annealing process will save hours of grinding and save on consumables like grinding belts.
Files and rasps - The teeth on files these must be hard enough to cut into steel. They are usually made from high carbon steel. Files can be left with some of the teeth of the file for display or function on the finished knife. One example would be a blade crafted from a rasp which when finished serves not only as a kitchen knife but also as a cheese grater.
Springs - Automotive leaf springs are generally made from 5160 high carbon spring steel.
Saw blades - Saw blades can be made from a variety of different steels. Some are excellent but others like concrete saw blades are made from mild steel and are not usable. In many areas of the country, old lumber mill blades are available and work nicely for knife material.
Railroad spikes - Railroad Spikes are usually only around .3 percent carbon. They are plentiful and great for beginners to practice forging with. This material is very soft so it will not hold a good edge. Having said that, many knife smiths are still able to combine or forge together a high carbon steel blade to a railroad spike handle and spine creating a San Mai blade. In this manner, smiths can produce a blade that is very interesting and can still hold an edge.
Lawnmower blades - These blades are easy to find but the material used is not consistent. Basically, some lawnmower blades will work well for making a knife and others will not. It is always a good idea to cut off a small test piece and harden it in a forge prior to forging a blade.
A great option for the beginner or novice knifemaker is to utilize precut knife blanks. These blanks are available in quality high carbon steel as well as stainless steel. They come in an assortment of shapes and sizes and usually have pre-drilled pin holes. Basically, the knifemaker just has to ream out each of the pinholes, grind the bevels, harden, add handles and/or bolsters, and sharpen. Starting with pre-cut knife blanks eliminates the need for some of the expensive equipment associated with knife making like a band saw or drill press.
Check out our Knife making tools, huge assortment of topic specific how-to knife making videos, our Complete Online Guide Knife Making and our New Book Introduction to Knifemaking by Dan Berg and Jason Northgard.