About PROPERTIES OF METAL

About Properties of Metals 

1- Properties are the characteristics of any material indicating its behavior and performance under different conditions of working on it or during its use. 

2- Properties of metals can be broadly categorized as follows.

   i • Physical properties 

   ii • Mechanical properties 

  iii • Chemical properties

Physical properties 

1- Physical properties are those properties which remain unchanged when metals are heated, electrical current is passed, the metal is melted or magnetized.

2- Important physical properties include,

    • Color 

    • Weight/Specific gravity 

    • Structure • Conductivity 

    • Magnetic property 

    • Fusibility

Color 

1- Different metals have different colors. For example, copper is of a distinctive red color. 

2- Mild steel is of a blue/black sheen. Weight 

1- Metals differ based on their weight. 

2- A metal, like aluminum, weighs lighter (specific gravity 2.8) than many others and a metal, like lead, is heavy (specific gravity 9). 

Structure

1- Generally metals can also be differentiated by their internal microstructure. 

2- Metals like wrought iron and aluminum will have a fibrous structure, and metals like cast iron and bronze will have a granular structure. 

Conductivity 

1- Thermal conductivity and electrical conductivity are the measure of the ability of a material to conduct heat and electricity. 

2- Conductivity will vary from metal to metal. 

3- Copper and aluminum are good conductors of heat and electricity. 

Magnetic property 

1- A metal is said to possess magnetic prop if it is attracted by a magnet. 

2- Almost all ferrous metals, excepting some types of stainless steel, can be attracted by a magnet and all non ferrous metals and their alloys will not be attracted by a magnet.

Fusibility

1- It is the property possessed by a metal by virtue of which it melts when heat is applied. 

2- Many materials are subject to the transformation in shape from solid to liquid at different temperatures. 

3- Tin has a low melting temperature (232° C) and tungsten melts at a high temperature (3370° C).

Mechanical properties 

1- Mechanical properties of a metal characterize its capacity and capability to withstand the action of variety of external loadings. 

2- Mechanical properties include, 

    • Ductility 

    • Malleability 

    • Hardness 

    • Brittleness 

    • Toughness 

    • Elasticity Tenacity 

2- These depend on its crystal structure, alloying elements, cold and hot working of the metal, heat treatment, geometry and shape of the product and working conditions, like working at higher temperatures.

Ductility 

1- A metal is said to be ductile when it may be drawn out in tension without rupture. 

2- Wire drawing depends upon ductility for its successful operation. 

3- A ductile metal must be both strong and plastic. 

4- Copper and aluminum are good examples of ductile metals.

Malleability 

1- Malleability is the property of permanently extending in all directions without rupture by hammering, rolling etc., to change its size and shape. 

2- Lead is a very malleable metal.

Hardness 

1- Hardness is a measure of a metal's ability to withstand scratching, wear, abrasion and penetration.

Brittleness 

1- Brittleness is that property of a metal which permits no permanent distortion before breaking. 

2- Cast iron is an example of a brittle metal and it will break rather than bend under shock or impact.

Toughness 

1- Toughness is the property of a metal to withstand shock or impact. Toughness is the property opposite to brittleness. 

2- Wrought iron is an example of a tough metal.

Elasticity 

1- Elasticity of a metal is its power of returning to its original shape after the applied force is released. 

2- Properly heat treated spring is a good example of elasticity.

Tenacity and specific gravity 

1- Tenacity of a metal is its ability to resist the effect of tensile forces without rupture. 

2- Mild steel, wrought iron and copper are examples of tenacious metals. 

3- Tenacity is used to express the resistance which the body opposes to the separation of it parts.

Specific gravity 

1- It is the ratio between the weight of the metal and the weight of equal volume of water. 

2- Specific gravity = mass of the object / mass of water.