What is a Non-Ferrous Metal?
When a metal is defined as non-ferrous it means that it does not have a significant amount of iron in its chemical composition. Note the word “significant”; nearly all metal alloys have some trace, or non-significant, amount of iron in their composition. This does not make them ferrous alloys though. Non-ferrous alloys generally have iron compositions of less than one percent as measured by weight. If iron constitutes a large percentage of a metal, such as if it is the first or second most abundant element in the metal’s chemical composition, then the metal is considered ferrous.
What are the Common Properties of Non-Ferrous Metals?
It is nearly impossible to define the common properties of non-ferrous metals simply because there is such a large variety of metals that fall into the non-ferrous category. Some non-ferrous metals are hard and brittle, some soft and ductile. Some non-ferrous metals are made for cryogenic applications, others are made to withstand extremely high temperatures. There are far more differences than there are similarities among the different types of non-ferrous metals.
However, non-ferrous metals all do have one thing in common: They do not rust. That is not to say that they don’t corrode. Several non-ferrous materials can be quite vulnerable to corrosion. When it is said that they don’t rust, that means they will never form the red flaky metal that is ubiquitous among pieces of steel and iron that are not protected from corrosive environments. That is because rust is iron oxide. Since non-ferrous alloys have no significant amount of iron, no iron is available to form iron oxide, and therefore no rust formation can occur. Another characteristic of non-ferrous metals is that they are not magnetic.
Examples of Non-Ferrous Metals
There are a variety of non-ferrous metals in use in the industry today. Listed below are a variety of the more popular ones:
Aluminum
Aluminum is a very widely used type of non-ferrous alloy. In its unanodized form, it has a silvery color. Without the addition of alloying elements, it is more ductile and not quite as strong as many steels. However, through the addition of alloying elements and heat treating or work hardening, aluminum can achieve very high strengths. Aluminum is lighter than steel. It forms a protective oxide layer that helps it reduce the risk of detrimental corrosion. Common applications of aluminum include marine equipment such as boat lifts and docks; aerospace equipment such as airplane body material; construction material such as beams and rails; and certain types of cookware.
Copper
Copper is another very popular non-ferrous alloy. Copper is a metal that is somewhere between red and brown in color. In its unalloyed state, it too is softer, more ductile, and not as strong as carbon steel. However, similar to aluminum, copper can be alloyed with a variety of elements to give it improved mechanical properties. When copper is alloyed with tin it is considered bronze. When copper is alloyed with significant amounts of zinc, it is called brass. Common applications of pure copper and its alloyed forms include electrical components such as wires, terminals, and other types of connectors; currency such as the United States or Canadian penny (although just as a coating); pipe for plumbing, tooling, and decorative work.
Nickel
Nickel is another popular non-ferrous alloy. Nickel is known for its toughness, ability to perform in high temperature and low temperature environments, and corrosion resistance. Nickel is not often used in its pure form, and like copper and aluminum, it is often alloyed with other elements to gain superior chemical and mechanical properties. Common applications of nickel and nickel-based alloys include cryogenic equipment such as tanks; hot-section aerospace equipment such as combustion chamber components; and marine equipment.
This is not an exhaustive list of non-ferrous metals. There are many more such as tungsten, titanium, zinc, silver, gold, platinum and lead.