Titanium Crafting
Titanium is one of the most common elements in the earth's crust; it is the 9th most common element in the earth's crust, or it makes up approximately .565% of the earth's crust. Iron makes up approximately 5.63%, or is only about 10 times more common. Despite this, Titanium is extremely difficult to use in machinery, due to the difficulty of extracting Titanium from Titanium dioxide, the fact Titanium reacts with air and needs to be at atmospheric pressure makes it difficult to operate under ordinary conditions, it's extremely high melting point of nearly 3000 degrees, and it's expensive substrate costs to serve as a catalyst to remove the oxygen normally present in natural titanium sources. It is also very difficult to machine, due to it's plasticity, brittleness, and likelihood to chip and fragment during maching. [1][2][3] Furthermore, in reciprocating parts, such as in a rifle or engine, the parts quickly succumb to abrasion, and galling, where the surface of the metal will flake and produce fragments, as well as produce an alloy with the other material, changing the material composition.
Despite this, Titanium has the highest natural strength-to-density ratio of any metallic element, and is incredibly corrosion resistant. In environments where even aluminum would corrode quickly, such as salt water or under high temperatures, Titanium is extremely useful. It is approximately the same strength as steel, but only has a density of 4.5 grams per cubic centimeter, compared to 7.8 grams for iron. This is approximately 58% of the weight for the same strength. It is also twice as strong as weak aluminium alloys but only 60% heavier. It is used in aircraft, specifically, due to it's high heat and corrosion resistance, as well as strength for weight (it's hard to maintain flight with something heavier), but also used in turbine engines. While ordinarily this reciprocation would produce a large volume of fatigue, particular forms of titanium have much higher resistance to these forms of operation. Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the most commonly used alloy for such purposes. It has a chemical composition of 6% aluminium, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium. It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti). Among its many advantages, it is heat treatable. This grade is an excellent combination of strength, corrosion resistance, weld and fabricability. "This alpha-beta alloy is the workhorse alloy of the titanium industry. The alloy is fully heat treatable in section sizes up to 15mm and is used up to approximately 400°C (750°F). Since it is the most commonly used alloy – over 70% of all alloy grades melted are a sub-grade of Ti6Al4V, its uses span many aerospace airframe and engine component uses and also major non-aerospace applications in the marine, offshore and power generation industries in particular."
In addition to this, various forms of surface treatment can increase the lubricity of moving parts, which allows the weapon to operate more smoothly. [1][2][3] While the exact application varies, increasing the life of the moving parts by a factor of 10 is not uncommon, especially at high RPM. Using similiar materials found in aircraft turbines, Titanium can be used effectively to create firearms, even with moving parts. It's high strength and low weight makes it ideal for weapon's where weight is a significant factor, and lighter but weaker materials aren't available, such as polymer. The M240L is an example of titanium reducing the weight of a weapon that requires it, and many similiar machine guns can end up being in the same situation.
