Technology and our changing world high Technology

METAL MATERIALS
Many kinds of metals are used in industry to make the hundreds of different metal products we use. Metalworkers must know the properties of th ese d ifferen t metals.
There are two major types of metals, ferrous and nonferrous. Metals with high iron content are called ferrous metals. These are metals such as galvanized iron, tin plate, iron sheet, and iron bars. Metals containing little or no iron are called nonferrous metals. These include copper and its alloys, aluminum,pewter, and nickelsilver.
Metals for projects must be chosen carefully. Each metal is different in color, properties, and ease of working. Metal properties are very important. For example, copper is ductile, or can be hammered thin. It also is malleable, which means it can be stretched easily. However, as it is worked it becomes very brittle. It must be annealed (softened), or it will crack. Copper is annealed by heating it red hot and dipping it in water to cool it.

Property	Mean ing
Ductility	Metal easily drawn or stretched into wires.
Malleability	Metal easily stretched or formed
Brittleness	Metal hard to work, cracks easily
Conductivity	Heat and electricity move easily through metal.
Hardness	Metal not easily scratched or nicked.

Nonferrous Metals