This is one of the most asked questions we get, “what kind of steel do you use to make your knives?” To be honest I’m tired of answering it because their is a lot to that question, and the usual response is “depends on the knife.”
So lets start with this odyssey of explaining knife steels and start with steel itself. Why Steel? Steel is a quite versatile blade material (no s***). But why, what makes steel the universal blade making material? Steel is basically just iron, carbon, and usually a few other elements mixed in to gain desired properties. Basic steel that say you can by and a general hardware store is what is usually called weldable, hot rolled or cold rolled steel. This is generally a low carbon steel, and tends to be a 1020-1030 steel which at best can be a case hardened steel. Its generally cheap to make and mass produce as well as still contain the strength properties of steel while still being soft enough to be worked or bent. It usually is a bit more carbon the being raw iron. Where as some of the other steels we use such as 1095 have a significance higher carbon makeup. This allows the steel to be hardened more then case hardened.
I know I am throwing a lot of terms out at this point, so were gonna pause for a minute and go over some of them. Case Hardenable steel basically means that when you heat treat the steel, the only part of the steel that creates a higher hardness is the outside layer, and that layer is very thin. So the first time your sharpen it the blade of the knife will no longer have edge retention.There is another one, Edge Retention means the ability to keep a sharp blade on the knife after use. A fully hardenable or hardenable steel is a steel that retains hardness though the entire piece of steel. This allows for the knife to be sharpened a lot before it starts loosing its edge retention. Metallurgy is another important word and in the simplicity form it is the study of metals and their material properties. Material properties are are measurable properties of materials such as Hardness, Toughness, Yield Strength, Tensile Strength, and Mass Density. Hardness is the ability, or lac there of for a material to plastically deform under force. Toughness is the measure of force a material can take, and possibly plastically deform before it fractures. Yield Strength is the measure of when a deformity is permanent or if the material will snap back into place, or the force required for the material to yield to permanent deformation. Tensile Strength is the measure of how much tension you can put on a material before it deforms or breaks. Mass density is the density of a material, or how much it ways per given size, irrelevant to the force of gravity. Is that enough terms for now? Ill try to be good about defining them as I go!
Most of the time when dealing with knives you generally want a high carbon knife because it provides the edge retention, hardness, and toughness for the ideal blade. High carbon steels generally come spheroidized, or soft and unhardened. They are then hardened after the blade is roughly ground in order to gain the ideal material properties that make a knife. The downside to high carbon steel knives is they are prone to rusting and need to be oiled to prevent this. However they do have a significantly better edge retention then most stainless steel knives. Most high carbon steel knives include 1070-1095, 52100, O1, A2, and W2 which are a number of steels we have worked with however there are many more. These steels work well for camp knives, edc knives, pack knives, and most general purpose blades. These blades can also have added coatings in order to prevent rust, as well as high polished surface finishes. We are still working on new finishes for high carbon steel knives in order to have a higher resistance to corrosion.
Stainless Steels are the next type of important knife steel. Stainless steels get tricky because in order to heat treat stainless steels, it requires a zero air environment. When heat treating if oxygen is present, stainless steel will not form the proper atomic structures in order to change the material properties of the steel. This can be good because if the knife is exposed to high heat, the steel will not become softer. On the other hand it makes it a nightmare for knife makers to work with unless you have the expensive fancy tools….. Stainless steels are great for things like kitchen or food preparation knives. This is because though you loose some edge retention and hardness, the blade is less likely to chip, as well as rust, both of which are a significant hazard to things that are consumed or ingested. We are still working on our kiln in order to be able to heat treat stainless steel knives, more on that to come.
We will probably link to a further breakdown of the chemical composition of steel types that we use as well once we find a sufficient resource.
We will also most likely have a part two of this that breaks down specific steels that we work with and the benefits, pitfalls and chemical compositions for each steel.The other thing Ill either write a post about or have a link to after more future experience is cryogenic heat treatment. Ill link to it when it is built.
If you want to know more about hardening steel, we will hopefully have a blog post about that soon and will be linked below, but that should be enough to keep talking about steel!
Hopefully this was a somewhat easy dive into knife steels and I hope you found it useful.