What is the Difference Between Ferrous & Non-Ferrous Metals?
Ferrous and non-ferrous metals are two broad classifications of metals that have significantly different properties and uses.
Ferrous Metals
Ferrous metals are metals that contain iron. Some common ferrous metals include:
- Steel - An alloy of iron and carbon, steel is the most widely used metal in the world due to its relatively low cost, high strength, and wide range of applications. Steels can be highly specialized through alloying and heat treatments to tailor their properties for specific uses.
- Cast iron - Made by melting iron and mixing in carbon and silicon, cast iron is more brittle than steel but can be cast into complex shapes. It provides good vibration dampening and excellent machinability.
- Wrought iron - Nearly pure iron containing very low carbon and other impurities. Historically used in applications like fences, railings, furniture, and architecture.
- Alloy steels - Steels alloyed with elements like chromium, nickel, manganese, and tungsten to achieve enhanced properties like corrosion resistance, hardness, machinability, and strength. Common grades include stainless steel, tool steel, and structural steel.
The key characteristic of ferrous metals is that they contain iron, are magnetic, and conduct heat and electricity well. Their main disadvantage is they readily corrode in moist conditions, so they require coatings or frequent maintenance in many applications.
Non-ferrous Metals
Non-ferrous metals do not contain any iron. They tend to be more costly than ferrous metals, but provide properties that may be desirable in applications where corrosion resistance, low weight, conductivity, or malleability are required. Some common non-ferrous metals include:
- Aluminum - Lightweight, corrosion resistant metal with good conductivity and machinability. Used extensively in transportation and electrical applications. Can be alloyed and heat treated.
- Copper - Excellent conductor of electricity and heat. Used in wiring, plumbing, coins, cookware, and many other applications. Can be alloyed with metals like zinc (brass) and tin (bronze).
- Lead - Soft, corrosion resistant metal. Formerly used extensively in plumbing, paints, ammunition, and radiation shielding applications, but is being phased out due to health risks.
- Nickel - Heat and corrosion resistant, nickel is often used in alloying other metals. Also used as coatings and for certain batteries and electronics.
- Precious metals like gold, silver, and platinum - Prized for jewelry, investments, and industrial uses like corrosion resistance. They conduct heat and electricity well.
- Tin - Used to coat and protect other metals from corrosion (tin plating). Also alloyed with copper to make bronze.
- Zinc - Coatings on steel (galvanizing) and die casting. Also used in alloys like brass.
Non-ferrous metals provide useful qualities like low weight, higher conductivity, non-magnetic properties, and corrosion resistance. However, they are typically more expensive than ferrous metals and require different manufacturing processes. Selecting ferrous vs non-ferrous metals depends on the needs of the application and the properties required. Understanding their differences allows engineers to make optimal material choices in design.
In summary, the main differences between ferrous and non-ferrous metals are:
- Ferrous metals contain iron as main constituent, non-ferrous do not contain iron.
- Ferrous metals are magnetic, non-ferrous metals are generally not magnetic.
- Ferrous metals are usually harder, stronger, and less ductile than non-ferrous metals.
- Ferrous metals tend to be less conductive and more corrosion prone than non-ferrous.
- Non-ferrous metals are usually more expensive by weight than ferrous metals.
- Ferrous metals include steel, cast iron, wrought iron, and various alloy steels. Non-ferrous metals include aluminum, copper, lead, nickel, tin, zinc, and precious metals.
- Ferrous metals are the most widely used metals globally and across industries. Non-ferrous see more specialized uses based on desirable properties.
Knowing when to use ferrous or non-ferrous metals depends on considering properties like cost, strength, ductility, corrosion resistance, weight, conductivity, and machinability for the application. Engineers combine knowledge of materials science and manufacturing processes when selecting optimal metals.