WHAT ARE THE MECHANICAL PROPERTIES OF METALS?

These are the properties that express the behavior of metals when subjected to stresses or loads that tend to alter their shape.

Strength: The ability to withstand an external load; the metal must bear it without fracturing. This is referred to as the ultimate load, and failure can occur by tension, compression, torsion, or shear. There is an ultimate strength (kg/mm²) for each of these stresses.

Hardness: The property that expresses the degree of permanent deformation a metal undergoes under the direct action of a given load. The most important tests for determining the hardness of metals are indentation tests, in which an indenter (ball, cone, or diamond) is applied to the metal surface at a specified pressure and for a set time, leaving an impression that depends on the hardness of the metal. The most widely used methods are Brinell, Rockwell, and Vickers.

Elasticity: The ability of an elastic material to recover its shape once the deforming load is removed. The elastic limit is defined as the maximum load a metal can withstand without undergoing permanent deformation. Its determination is of great importance in the design of all types of mechanical components, since parts must always operate below the elastic limit. It is expressed in kg/mm².

Plasticity: The ability of a metal to undergo permanent deformation without fracturing.

Toughness: Resistance to fracture under impact stresses that deform the metal. Toughness requires both strength and plasticity.

Brittleness: The property that indicates a lack of plasticity and, therefore, of toughness. Brittle materials fracture at the elastic limit, meaning failure occurs spontaneously once the load corresponding to the elastic limit is exceeded.

Impact toughness (Resilience): The resistance of a metal to fracture by impact, determined by the Charpy test. (The ability of a metal to absorb impact energy.)

Creep: The property of certain metals to deform slowly and spontaneously under the action of their own weight or very small loads. This slow deformation is also known as creep.

Fatigue: When a part is subjected to cyclic loads (alternating or intermittent), fracture can occur at loads lower than those that would cause permanent deformation.