Exploring metal especially as used in martial arts.

While chemistry might define a metal as an element that readily forms positive ions (cations) and has metallic bonds, the martial arts are more concerned with metallurgy (the field of materials science and engineering that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their alloys or mixtures) for the improvement of arms and armor.

In the American Iron and Steel Institute (AISI) steel grades, the first 2 digits indicate the alloy composition and the following digits or letters indicated variants. The Unified Numbering System (UNS) is an alloy designation system consisting of a letter (for the alloy) and 5 digits (the first 3 of which match older numbering systems like AISI). There are other organizations that have also named different alloys such as the Society of Automotive Engineers (SAE).

Steel alloys by type [via http://claymore.engineer.gvsu.edu/eod/material/material-4.gif]

Here are the Mohs hardness ratings of common items:

Copper (Cu, Z=29, SG=8.96, melting point=1084 C, Mohs hardness=3.0) was probably the first metal used in blades. UNS: C00001 to C99999, covers bronze and brass too.

Iron (Fe, Z=26, SG=7.86, melting point=1538 C, Mohs hardness=4.0) is harder than copper and its alloys but also more brittle. Copper and its alloys were used throughout the Iron Ages, but as iron got better and cheaper, iron overtook copper and its alloys in the Middle Ages.

Aluminum (Al, Z=13, SG=2.70, melting point=660 C, Mohs hardness=2.75) is less dense than iron but is cheaper and is commonly used for non-sharpened practice weapons. UNS: A00001 to A99999.

There are many process that affect the properties of a blade.

Lead (Pb, Z=82, SG=11.34, melting point=327 C, Mohs hardness1.5) is very dense, fairly soft and malleable, has a low melting point, is very corrosion resistant, and is a poisonous neurotoxin. Lead in the martial realm is best known for its use in guns as the bullet itself. Lead is the only metal that has a zero Thompson effect, i.e. no gradation in temperature when conduction electicity.

Uranium (U, Z=92, SG=19.1, melting point=1,132 C, Mohs hardness=6.0) is very dense, has a high melting point and hardness, and is radioactive. Uranium along with plutonium are fissile and are used in nuclear fission weapons. Depleted uranium is also used in high level armor and armor piercing.

Gold (Au, Z=79, SG=19.3, melting point=1,064 C, Mohs hardness=2.5) is very dense, fairly soft and malleable. Gold is often fought over.

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