Metals can be sorted into a manageable set of groups, and understanding these groups is the foundation for working with metal grades. Physically, a metal is a substance with a bright luster that conducts heat and electricity well, and metals vary in hardness, density, malleability, and ductility. They can be bent, stretched, drilled, cast, riveted, welded, cut, twisted, and folded, all with great accuracy. Broadly, metal grades fall into three groups: ferrous metals, non-ferrous metals, and alloys.
The ferrous group is composed mainly of iron. Small amounts of other metals or elements, such as carbon, manganese, nickel, chromium, and tungsten, may be added to achieve the required properties. Most, though not all, ferrous alloys are slightly magnetic and offer little resistance to corrosion. For example, ferrous alloys tend to exhibit some degree of oxidation, known as rust, which has a distinct reddish color. While most ferrous metals are only slightly magnetic, a few, including iron, nickel, cobalt, and their alloys, display pronounced magnetic properties, a phenomenon known as ferromagnetism.
Non-ferrous metals are those that contain no iron. They are not magnetic and are usually more resistant to corrosion than ferrous metals. Common examples include aluminum, copper, lead, zinc, and tin.
Some non-ferrous metals are pure metals, meaning they consist of a single element and therefore contain only one type of atom. The common pure metals are aluminum, copper, iron, lead, zinc, tin, silver, and gold.
An alloy is a new metal formed by mixing two or more metals, and sometimes other elements, together. The range of possible alloys is effectively endless, with each combination offering its own individual properties. This ability to tailor properties is one of the main reasons metal grades are so versatile.
Metals are an especially suitable material for mass production, appearing in buildings, bridges, cars, ships, aluminum pans, coins, and countless other products. By contrast, precious metals such as gold and silver are often crafted by skilled individuals into rings, goblets, and other objects of great beauty.
Some metals have highly specialized uses. Radioactive metals such as uranium and plutonium are used in nuclear power plants to produce energy through nuclear fission. Mercury, which is liquid at room temperature, is used in switches, where it completes a circuit as it flows over the switch contacts. Shape memory alloys are used in applications such as pipes, fasteners, and vascular stents.
The most widely used metals include iron, aluminum, copper, titanium, zinc, and magnesium.
Figure 1: Common Uses and Applications of Metal Grades
Grouping metals into ferrous, non-ferrous, and alloy families is a useful starting point, but it is only one lens on how materials are described and chosen. The rest of our Metal series looks at the others. Metal Composition gets underneath the grades to show how the mix of elements shapes what a material can do, while Metal Properties explains the mechanical and physical behaviour that determines where each grade earns its keep. Once you are working from real documents, Metal Specifications covers the paperwork that defines a material precisely, and Metal Standards explains the wider frameworks those documents sit within. And when a grade needs to be matched to its counterpart in another system, Metal Equivalents and Cross-Referencing shows how that is done.
Metal grades are generally classified into three groups: ferrous metals, which are based mainly on iron; non-ferrous metals, which contain no iron; and alloys, which are formed by combining two or more metals or elements.
Ferrous metals are composed mainly of iron, are usually slightly magnetic, and tend to corrode or rust. Non-ferrous metals contain no iron, are generally non-magnetic, and are usually more resistant to corrosion. Aluminum, copper, lead, zinc, and tin are common non-ferrous examples.
A pure metal consists of a single element and therefore contains only one type of atom. Common pure metals include aluminum, copper, iron, lead, zinc, tin, silver, and gold.
An alloy is a new metal created by mixing two or more metals, and sometimes other elements, together. Alloying makes it possible to produce an almost endless range of materials, each with its own individual properties.
The most widely used metals include iron, aluminum, copper, titanium, zinc, and magnesium, each valued for a particular combination of properties and applications.