METALLURGY: THE SCIENCE OF METALS
A INTRODUCTORY LESSON ON CHARACTERISTICS AND PROPERTIES OF METAL
METALLURGY
Metallurgy is a branch of science and technology concerned with
the properties of metals, their production and purification.
CLASSIFICATIONS OF METAL
Metals can be classified into three categories:
Ferrous
Non-ferrous
Precious / pure metals
FERROUS METALS
Ferrous metals contain iron as a base material. Other elements are added to produce a
desired effect.
Ferrous metals are the most useful metals known to man.
They are generally magnetic.
Examples include wrought iron, cast iron, steel, carbon steels, alloy steels, stainless
steels.
NON-FERROUS METALS
Non-ferrous metals contain no iron as their base element.
This family of metals is not magnetic.
Non-ferrous metals are very resistant to corrosion (rust).
Examples include aluminum, copper, brass, tin, nickel, pewter and lead.
PRECIOUS / PURE METALS
They contain no other elements.
Highly valued, meaning they are more expensive.
Non-ferrous and non-magnetic.
Can be mixed with other metals to create different effects: silver with a small amount
of copper added becomes sterling silver.
Examples include silver, gold, and platinum.
HIGH-TEMPERATURE METALS
Unique ability to maintain their strength over long periods of time under high
temperature.
Sometimes referred to as super alloys.
Were created with nuclear and aerospace uses in mind.
Examples include columbium, tantalum, nickel-based alloys, and tungsten.
RARE METALS
These metals are only available in very small quantities.
Used mostly for experimental purposes.
Not found in commercial applications.
More expensive than gold.
Examples include yttrium, cerium, and europium.
PROPERTIES OF METALS
Mechanical properties: related to the material’s response to mechanical forces:
Tensile strength: Resistance to a load pulling apart the material. Each type of loading is specialized
and will result in different tensile strength numbers.
Compressive: Resistance to being pushed together when loads are applied at both ends of the
material.
Fatigue: Resistance to loads being applied in a variety of ways, called cyclic loading.
Impact-toughness: Resistance to rapid application of a load.
Flow: Under constant load the material will begin to move and deform.
Ductility: Measurement of deformation before failure occurs.
Hardness: The ability to resist scratching of the surface
CHARACTERISTICS OF METALS
Characteristics: Indicate how a material is affected by non-mechanical factors.
Thermal: How the material responds to hot and cold.
Thermal conductivity: The ability to transfer heat through the material.
Electrical: Material has the ability to conduct electricity.
Chemical resistance to environment: Protective qualities of the material.
Optical: The ability of a material to absorb or reflect light.
Density: The compactness of the molecules relative to their mass. This allows for the correct
selection of a material for the job.
METALLURGY - METAL IDENTIFICATION
There are several ways to identify metals:
Spark testing
Visual inspection: colour/appearance
Hardness testing
Magnetic/non-magnetic
Weight
Electrical conductivity
