Introduction of Engineering Materials science
The knowledge of materials and their properties great importance for a design engineer. A design engineer must be familiar with the effect which manufacturing process and heat treatment have on the properties of the materials. The engineering materials are mainly classified as,…
1) Metal and their alloys such as iron, steel, copper, aluminum, etc.
2) Non-metals such as glass rubber plastic etc.
The metals may further be classified as:
a) ferrous metals.
b) Non-ferrous metals.
The ferrous metal is those which have iron as their main constituents such as cast iron, wrought iron, and steel.
The non-ferrous metal is those which have a metal other than iron as their main constituent such as copper aluminum brass tin zinc etc.
The important mechanical properties of the metal are as follows:-
Strength:- ability of a material to resist at the extremely applied force without breaking or yielding.
Stiffness:-. The ability of the material to resist deformation under trace. The modulus of elasticity is the measure of stiffness.
Elasticity:- is the property of a material to regain it is original shape after the permission when the external force is removed. The property is described for materials used in tools and machines. It may be noted that steel is more elastic than rubber.
Plasticity:- what is the property of a material that retains the departments and produced on the load permanently. This property of the material is necessary for forgings, in Stamping image on coins and in ornamental works.
Ductility:- it is the property of a material enabling it to be drawn into wires with the application of a tensile force. A ductile material commonly used in engineering practice( in order of dismissing ductility). Exa- mild steel, copper, aluminum, nickel, zinc, Tin, and lead.
Brittleness:- it is the property of a material opposite to ductility. It is the property of breaking of material with little permanent distortion. Cast iron is a brittle material.
Malleability:- it is a special case of ductility which permits material to be rolled or hammered into thin sheets. A malleable material should be plastic but it is not essential to be so strong. The malleable materials commonly used in engineering practice( in order of diminishing Malleaability) are lead, soft iron, wrought iron, Copper, and Aluminium.
Toughness:- it is the property of a material to resist fracture due to high impact loads like hammer blows. The toughness of a material decreases when it is heated. This property is described in parts subjected to shock and impact loads.
Resilience:- it is the property of a material to absorb energy and today’s shock and impact loads. It is measured by the amount of energy absorbed per unit volume within the elastic limit. This property is essential for spring materials.
Creep:- When a party subjected to constant stress at a high temperature for a long period of time it will undergo a slow and permanent deformation is called a creep. This property is considered in designing internal combustion engines, boilers, and turbines.
Fatigue:- when a material is subjected to repeated stresses it fails at stress below the yield point stress. Search type of failure of material is known as fatigue. The failure is caused by means of progressive crack information which is usually fine and microscopic in size. Party is considered in designing shaft, connecting rods, springs, gears, etc.
Hardness:- it is a very important property of the material and has a wide variety of meanings. It embraces many different properties such as resistance to the wire, scratching, deformation, and malleability, etc. It also means the ability of a metal to cut another metal. The hardness is usually expressed in number which has dependent on the method of making the test.