Aluminum - Knife Handle Material
Aluminum is a very low-density metal used in knifemaking, and is very corrosion resistant. Since it is such a soft metal, it is primarily used in knife handles and sometimes hard annodized for aesthetics and wear resistance. Aluminum is also the most abundant metal in the earth's crust.
Most knives use a type of Aluminum Alloy called T6-6061, which means the type of aluminum is 6061, and it is T6 tempered. T6-6061 Aluminum has one of the highest yield and tensile strengths of all aluminum alloys. T6-6061 is used extensively in aircraft, and is often referred to as "aircraft aluminum", and sometimes this is seen as a gimmick, kind of like "surgical stainless steel".
Aluminum alloy is cheaper to machine and produce than Titanium, and is lighter, weaker, and less resistant to wear. For the most part, Aluminum is an inferior metal to Titainum aside from its lightness. However, when producing complex knives that require a large amount of CNC machining, such as the case with automatic knives, aluminum is much cheaper to produce and the material costs less.
Aluminum is rarely used by custom knifemakers as titanium is generally preferred.
Hard Annodized Aluminum is an annodizing technique that creates an oxidation layer on the aluminum that is up to 30% harder than some stainless steels. Annodizing Aluminum involves placing the aluminum in a bath of acid and passing electrical charges through the material. This builds up a layer of aluminum oxide on the outside of the aluminum.