Properties of Metals

The Basics

Brittleness

• A property of a metal that does not allow movement of material or distortion before it will break.

Tensile Strength

• A measurement of how much a metal can stretch before breaking or failing.

Toughness

• A property required for many tools, as it allows materials to withstand impacts without breaking or chipping.

Hardness

• A material’s resistance to permanent deformation after facing a force exerted by another object.

Malleability

• A property that allows materials to be continuously reshaped and formed without breaking.

Ductility

• A property that allows materials to be easily formed after experiencing a force via another object.

Elasticity

• A material’s ability to return to its original shape after a force acting upon it has been removed.

Hardening

• A process in which metals increase their resistance to penetration by an object imposing a force upon them.

• Hardening can be achieved by cold working or most commonly by heating a material by various means to a given temperature and rapidly cooling it to form a finer internal grain structure.

Tempering

• A process of heat treating, which is used to increase the toughness of iron-based alloys.

• Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to a much lower temperature than was used for hardening.

• The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product

Annealing

• A heat treatment wherein a material is altered, causing changes in its properties such as hardness and ductility

• Annealing is used to induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous and improve cold working properties.

Annealing Cont’d….(Normalizing)

• An annealing process in which a metal is cooled in air after heating in order to relieve stress.

• It is used to refine grains which have been deformed through cold work, and can improve ductility and toughness of the steel.