by Larry Connelley
Titanium is an abundant chemical element discovered by an amateur Cornish geologist William Gregor in 1791 and named after the Titans of Greek mythology. A universal substance, titanium has been detected in the chemical composition of the sun and in meteorites. It is a "transitional metal" because of the special layout of the electron orbits in its atom. In recent decades, titanium alloys have been used with increasing frequency in the aerospace, marine, automotive and manufacturing industries because of its incredible strength and durability. But is a titanium knife the way to go the next time you're looking for a new blade? We look at the properties of this element and what has to offer EDC and tactical users.
The Working Titanium Alloy: Ti4Al4V or Ti6Al4V (Grade 5)
The large majority of titanium used on high-end knives, rugged pens and assorted everyday carry gear is an aerospace grade titanium alloy. An alloy is a collection of various elements combined into a metal. Ti4Al4V breaks down to be 89 to 90 percent titanium, 6 percent aluminum, 4 percent vanadium and trace amounts of - at a maximum - 0.25 percent iron followed up by 0.2 percent oxygen. Carbon, nitrogen and hydrogen are also present in small quantities. Ti6AL4V has a similar composition, but slightly higher variances in the content of each element - for example, the titanium quantity varies between 88 and 91 percent.
Grade 5 titanium is considered the "workhorse" of the Ti alloys and the most frequently used. It has a wide use in the aerospace industry, high-end sporting goods (like knives), fasteners, jewelry, medical implants, the automotive industry and the marine industry just to name a few. For example, the Boeing 787 uses a number of parts constructed with Ti6AL4V, and many elite auto racing teams use titanium parts for their engines and chassis.
Pros of Titanium Alloy
- Strength - Titanium is ideal for high-end, high-performance knives and gear because it is light and strong. Titanium alloy has a very high tensile strength, meaning it is less likely to break under stress.
- Low Weight - Titanium alloy has a very low density. This characteristic strength-to-weight ratio is absolutely key when considering the selection of an everyday carry item such as a knife, wallet, ring, watch or pen.
- Temperature Stability - Titanium has a very large thermal range, meaning it will work in freezing cold and boiling hot temperatures equally well without breaking or cracking. A titanium alloy knife can be used in more weather conditions as a result.
- Bio-Compatible - Another key characteristic of titanium is that it is very bio-compatible when touching human skin and tissues. This feature is especially useful in medical implants and fasteners to help reduce a reaction or irritation. Titanium knives, pens, watches, rings and other everyday carry items also enjoy this benefit.
- Corrosion Resistance - Titanium alloy is highly resistant to corrosion even in saltwater environments. This resistance is due to a continuous oxide outer layer when exposed to air.
- Non-Magnetic - Titanium alloy has a very low amount of iron and is generally considered to be non-magnetic.
Drawbacks of Titanium Alloy
- Poor Cutting - Titanium alloy is NOT a good substitute for a working knife blade because it is not hard-enabled to adequate levels. In addition, it does not hold an edge for repeated use because of the lack of carbides. A titanium blade knife can be used as a last ditch material for short-term cutting or used in marine environments as a dive knife, but is generally not recommended for an everyday carry knife.
- Relative Softness - A grade 5 titanium knife is softer (Rockwell Hardness C of 36) than hardened steel knife blades (Rockwell Hardness C range of 56-61) and this difference of hardness can cause titanium lock wear over long periods. The wear reduces tolerances and can cause lock interface issues. This negative feature of titanium is a major reason that hardened lock interfaces/inserts were developed for frame locking knives. The lock interfaces/inserts greatly enhance the life of an integral bar lock knife, while taking advantage of the light strong titanium frame.
- Galling - Titanium alloy can have poor surface-to-surface wearing properties called galling. Galling is seizing or friction at the molecular level. This is particularly an issue for owners of knives with titanium frame locks and knives with moving parts (like a pivot) where they come in contact with certain other metals. This galling is often manifest in knives with "lock stick".
- Expensive - Titanium alloy is considerably more expensive than aluminum alloys and resin composites that are generally used for the handles of cheaper knives. You could end up paying a pretty penny for a knife that contains significant amounts of titanium, which is not in the budget of many users and collectors.
- Marking Confusion - Blades marked "Titanium" can be in reference to the titanium coating or just a trade name. If you want a titanium blade or handle, make sure it specifically mentions what is made from titanium.
Titanium alloy is here to stay for knife manufacturers. It is best used as a handle material for its characteristics of strength, corrosion resistance and relatively light weight. Consider what you are going to be using your titanium knife for and whether the benefits are worth the additional upfront cost. If you work on a boat or in another environment known for its corrosiveness, titanium knives can be well worth the expense in the long run.
For collectors, cost is going to be the only major concern. So if you see a titanium blade folding knife or a custom titanium knife blade that you just have to have and can afford it, then take the plunge. These artistic knives will look beautiful in your display and pair well with other titanium collectibles such as watches and pens.
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Even More Information on Titanium
Ti - A Temperamental Element
Titanium alone is a temperamental element. It is relatively expensive in spite of its abundance; this is because the process of extraction from the ore, now called the Krull process, is more demanding than the extraction of other metals. Due to the special properties of titanium, welding and high-temperature manufacturing have to be done outside the presence of oxygen in an inert argon or helium atmosphere. Commercial flat sheets of titanium are available, but titanium has a "memory" and tends to spring back when bent.
A Look at the Atomic Level of Titanium
Where do the characteristics of titanium come from? Titanium atoms are relatively light because its electron shell is relatively wide, which means that fewer atoms can be packed into a given solid volume. It weighs about 4.5 times more than water. Lead weighs 11 times more than water and iron weighs over 19 times more than water. The iron atom is only slightly heavier than titanium, but iron atoms are relatively small and more material is packed into a volume.
Titanium has the tensile strength and hardness of most steel variations but is much lighter because of its spacious molecular structure. It is 60 percent more dense than aluminum but more than twice as strong.
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