9 MECHANICAL PROPERTIES OF METALS - CHEMISTRY - 2025

The mechanical properties of metals include plasticity, brittleness, malleability, hardness, ductility, elasticity, toughness, and stiffness. All these properties can vary from one metal to another, allowing their differentiation and classification from a mechanical behavior perspective.

These properties are measured when a metal is subjected to a force or load. Mechanical engineers calculate each of the values ​​of the mechanical properties of metals depending on the forces applied to them.

Similarly, materials scientists are constantly experimenting with different metals under multiple conditions in order to establish their mechanical properties.

Thanks to experimentation with metals, it has been possible to define their mechanical properties. It is important to note that, depending on the type, size and strength that is applied to a metal, the results obtained by it will vary.

This is why scientists have wanted to unify the parameters of experimental procedures, in order to be able to compare the results obtained by different metals when applying the same forces.

Main mechanical properties of metals

1- Plasticity

It is the mechanical property of metals completely opposite to elasticity. Plasticity is defined as the ability of metals to retain the shape they were given after being subjected to stress.

Metals are usually highly plastic, for this reason, once they are deformed, they will easily retain their new shape.

2- Fragility

Brittleness is a property completely opposite to toughness, since it denotes the ease with which a metal can be broken once it is subjected to stress.

On many occasions, metals are alloyed with each other to reduce their brittleness coefficient and to be able to tolerate loads more.

Brittleness is also defined as fatigue during mechanical strength tests of metals.

In this way, a metal can be subjected to the same stress several times before breaking and giving a conclusive result on its brittleness.

3- Malleability

The malleability refers to the ease that a metal has to be rolled without this representing a break in its structure.

Many metals or metallic alloys have a high malleability coefficient, this is the case of aluminum, which is highly malleable, or stainless steel.

4- Hardness

Hardness is defined as the resistance of a metal to abrasive agents. It is the resistance of any metal to being scratched or penetrated by a body.

Most metals require some percentage to be alloyed to increase their hardness. This is the case with gold, which alone would not be as hard as it is when mixed with bronze.

Historically, hardness was measured on an empirical scale, determined by the ability of one metal to scratch another or withstand the impact of a diamond.

Today, the hardness of metals is measured with standardized procedures such as the Rockwell, Vickers or Brinell test.

All these tests seek to give conclusive results without damaging the metal that is being studied.

5- Ductility

Ductility is the ability of a metal to deform before breaking. In this sense, it is a mechanical property completely opposite to brittleness.

Ductility can be given as a percentage of maximum elongation or as a maximum reduction in area.

An elementary way of explaining how ductile a material is may be by its ability to be transformed into wire or wire. A highly ductile metal is copper.

6- Elasticity

The elasticity defined as the ability of a metal to regain its shape after being subjected to an external force.

In general, metals are not very elastic, for this reason it is common for them to have dents or traces of bumps that will never recover.

When a metal is elastic, it can also be said that it is resilient, since it is capable of elastically absorbing the energy that is causing it to deform.

7- Tenacity

Toughness is the concept that is parallel to brittleness, since it denotes the ability of a material to resist the application of an external force without breaking.

Metals and their alloys are generally tough. This is the case of steel, whose toughness allows it to be suitable for construction applications that require to withstand high loads without causing ruptures.

The toughness of metals can be measured on different scales. In some tests, relatively small amounts of force are applied to a metal, such as light impacts or shocks. At other times, it is common for greater forces to be applied.

In any case, the toughness coefficient of a metal will be given to the extent that it does not present any type of rupture after having been subjected to stress.

8- Rigidity

Stiffness is a mechanical property of metals. This takes place when an external force is applied to a metal and it must develop an internal force to support it. This internal force is called "stress."

In this way, stiffness is the ability of a metal to resist deformation during the presence of stress.

9- Variability of properties

The tests of mechanical properties of metals do not always produce the same results, this is due to possible changes in the type of equipment, procedure, or operator used during the tests.

However, even when all these parameters are controlled, there is a small margin in the variation of the results of the mechanical properties of metals.

This is due to the fact that many times the manufacture or extraction process of metals is not always homogeneous. Therefore, the results when measuring the properties of metals can be altered.

In order to mitigate these differences, it is recommended to perform the same mechanical resistance test several times on the same material, but on different samples selected at random.

References

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