The words âat least 17 years of age and *â*â* under 45 years of ageâ are substituted for the words âwho shall be more than seventeen years of age and *â*â* not more than forty-five years of ageâ.
Steel is cheaper, and brass is more expensive, and not much of a structural material. Brass is a tensile metal, and has a great ability to bend. It is used to make bearings, valves and moving parts, because it does not break easily. Steel, on the contrary, is difficult to cast, and quite difficult to work with in small machines.
Main article: Brass. A brass is an alloy of copper with zinc. Brasses are usually yellow in color. The zinc content can vary between few % to about 40%; as long as it is kept under 15%, it does not markedly decrease corrosion resistance of copper. bronze is an alloy of copper and other metals, most often tin, but also aluminium and silicon. 1  Aluminium bronzes are alloys of copper and aluminium. 2  Bell metal. 3  Phosphor bronze. 4  Nickel bronzes, e.g. nickel silver and cupronickel. 5  Speculum metal. 6  UNS C69100.