The properties which completely define mechanical behavior under the action of external loads or force. Or in other words, those properties which are associated with its ability to resist failure as well as behavior under the action of external force.
Most of the mechanical properties of the metals are generally expressed in term of stress, stain or both stress- stain.
The following important mechanical properties area:-
- Elasticity:- Ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed.
- No material is perfectly elastic, over the entire range of stress up to rupture.
- steel and other metals have a wide range over which they appear to be elastic.
- Just an example of a rubber band experiment shown in the attached pic. there if rubber comes in over its original shape after removing the stress then the material is called elastic material. ( similar to metals)
2. Plasticity:- The property of a metal by virtue of which a permanent deformation ( without facture ).
- The plasticity of the metals depends upon its nature and the environment condition, whether the metals is shaped on red hot or in cold.
- This is important property for forming, shaping and extruding operation of metals.
3. Ductility:- It may be defined as the property of metal by virtue of which it can be drawn into wires or elongated before rupture take place.
| Sr. No. | Elongation Percentage | Consider as |
| 1. | More than 15% | Ductile |
| 2. | 5 to 15 % | Intermediate Ductility |
| 3. | Less than 5% | Brittle |
The following metals have ductility in the decreasing order
- It is depends upon the grain size of the metal crystals.
- The measure of the ductility of a metal are its percentage elongation and percentage reduction in the cross-section area before rupture.
- The best example of its property is :- The wire-making process is also the part of ductility.
4. Brittleness:- The property of metal by virtue of which it will facture without any appreciable deformation. its opposite to the ductility of a metal.
- Cast iron, glass and concrete are the example of brittle material.
- It is important for design of machine tools, which are subjected to sudden load like :-n lath machine and drill machine tools.
- In this type of material, it works like a very hard form but when any sudden load is active on that then its brake immediately.
5. Hardness:-The property of metal by virtue of which it is able to resist abrasion, indentation( or penetration ) and scratching by harder bodies.
- The hardness of a metal is determined by comparing its hardness with ten standard mineral. These minerals, in the increasing order of their hardness (as shown in above dig.)
6. Toughness:- The property of metal by virtue of which it can absorb maximum energy before fracture takes place.
- The value of toughness falls with the rise in temperature.
7. Stiffness:-The property of metal by virtue of which it resists deformation. like spring,
- Module of elasticity ( ratio of stress to the strain below elasticity limit) is measure of stiffness of a metal.
- It is of great importance which selecting it for a member or a component of a machine.
8. Resilience:- The property of metal by virtue of which it stores energy and resists shocks or impacts.
- The resilience of metal is also great important in the selection of materials used for various types of springs.
9. Creep:- The property of metal by virtue of which it deforms continuously under a steady load.
- The creep occurs in steel at higher temperatures
- It is great importance in the following case.
- Soft meals used at about room temperature such as lead pipes.
- Gas turbine working at higher temperature.
- Rockets, missiles ,supersonic jets.
- Nuclear reactor field.
10. Endurance:- The property of metal by virtue of which it can withstand varying stresses.
- The maximum value of stress, that can be applied for an indefinite times without causing its failure.
- The endurance of metal is of great importance in the design and production of parts in reciprocating machines and components subjected to vibrations
11. Strength:- next…..
Aluminium Metals 