Ferrous and Non-Ferrous Metals – All You need to know

What Defines Ferrous and Non-Ferrous Metals?

The term “ferrous” originates from the Latin word for iron, “ferrum,” symbolized as Fe. Ferrous metals contain iron, while non-ferrous metals do not. Although technically, non-metallic materials like wood or plant fibers also fall under the non-ferrous category, the term is generally reserved for metals and alloys in the field of metallurgy.

Iron: The Backbone of Ferrous Metals

Iron is one of Earth’s most abundant elements, forming roughly 5% of the planet’s crust and constituting much of the core. It has played a crucial role in human history as an essential material for weapons, tools, and infrastructure. Iron’s versatility stems from its ability to form alloys with other elements, allowing it to achieve diverse properties suitable for various applications. Among the most significant ferrous materials are cast iron and wrought iron, each valued for specific characteristics based on their carbon content and structural properties.

• Cast iron contains higher levels of carbon, making it hard and brittle but suitable for compression-heavy applications like engine blocks and pipes. Its high carbon content makes it different from wrought iron, which contains lower carbon levels.
• Wrought iron is known for its malleability and toughness, attributed to its low carbon content and fibrous structure. This material is widely used in decorative work and structural applications requiring bending and shaping.

Key Properties of Ferrous Metals

All ferrous metals contain iron in some form, making them widely used and highly versatile. Steel, the most common ferrous metal, exists in numerous varieties with more than a thousand types. Common ferrous metals include:

• Mild Steel
• Stainless Steel
• Tool Steel
• High-Strength Low-Alloy (HSLA) Steel
• Alloy Steel
• Carbon Steel

Are All Ferrous Metals Magnetic?

Contrary to popular belief, not all ferrous metals are magnetic. Magnetic properties depend on the metal’s structure rather than the mere presence of iron. For example, while cast iron generally exhibits magnetism, certain stainless steels (like austenitic grades) are non-magnetic or only weakly magnetic due to their atomic structure. Moreover, materials like cobalt and nickel are ferromagnetic without containing iron.

General Characteristics of Ferrous Metals

Although ferrous metals vary widely, they share a few common characteristics:

• Density and weight: Ferrous metals tend to be heavier than non-ferrous metals, with iron’s high density contributing to this.
• Corrosion resistance: While most ferrous metals are prone to rust (iron oxide formation) when exposed to oxygen, alloying elements such as chromium and nickel can enhance corrosion resistance, as seen in stainless steel.
• Strength and hardness: Ferrous metals generally exhibit high yield and tensile strength, making them suitable for applications requiring durability and load-bearing capabilities.
• Magnetic properties: The presence of iron often endows ferrous metals with magnetic properties, making them suitable for electromagnetic applications in motors, generators, and transformers.

Applications of Ferrous Metals

The strength and durability of ferrous metals make them ideal for heavy-duty applications, including:

• Railroad tracks
• Shipping containers
• Automotive components

Key Properties of Non-Ferrous Metals

Non-ferrous metals contain little to no iron, making them generally more resistant to rust and corrosion. These metals are typically more expensive than ferrous metals due to their relative scarcity and unique properties. Common non-ferrous metals include:

• Aluminum
• Copper
• Nickel
• Zinc
• Titanium
• Precious metals like gold, silver, and platinum

Mechanical Properties of Non-Ferrous Metals

Non-ferrous metals are highly diverse, meaning their properties vary significantly. For example, titanium is one of the hardest elements, while gold is among the softest. Similarly, some non-ferrous metals are more affordable, while others, like precious metals, are highly valued and costly.

Popular Applications of Non-Ferrous Metals

Due to their light weight and corrosion resistance, non-ferrous metals are often chosen over ferrous metals in applications where weight is a factor. Examples include:

• Aerospace and Automotive: Aluminum is widely used in aircraft and car manufacturing for its low weight and durability.
• Jewelry: Precious metals like gold and silver are used for high-end jewelry, while ferrous metals are less common due to rust and durability concerns.

Comparing Ferrous and Non-Ferrous Metals

Both ferrous and non-ferrous metals offer advantages depending on the application. Here are some distinctions to consider:

1. Corrosion Resistance: While stainless steel has excellent corrosion resistance, non-ferrous metals like aluminum naturally form a protective oxide layer, making them ideal for exposure to the elements.
2. Cost: Non-ferrous metals tend to be more expensive than ferrous metals, though this varies widely depending on the metal.
3. Weight: Non-ferrous metals are generally lighter than ferrous metals, an essential factor in industries like aerospace and automotive.
4. Workability: Non-ferrous metals are often more malleable, with softer metals like gold and copper easier to shape, making them popular for intricate designs in jewelry and electronics.

Hardening of Stainless Steel with the BORINOX® Process

Stainless steel is favored for its high corrosion resistance and strength. However, it is not typically hardened without compromising its corrosion resistance. The BORINOX® process addresses this issue by providing a way to harden stainless steel without diminishing its corrosion-resistant properties. This low-temperature diffusion process introduces carbon and nitrogen into the surface, creating a hardened layer that is up to five times harder than untreated stainless steel.

Advantages of the BORINOX® Process:

• Retained Corrosion Resistance: The process maintains stainless steel’s protective layer, unlike traditional methods that compromise this aspect.
• Dimensional Stability: The BORINOX® treatment does not cause significant changes in shape or size, even in complex components.
• Durability: BORINOX® hardening improves resistance to wear and fatigue, making stainless steel suitable for high-wear applications.

For advice on whether the BORINOX® process suits your material, Bortec’s specialists are available to provide expertise.