Steel: The Ultimate Guide to Types, Properties & Uses

Steel is all around us, from the buildings we work and live in, to the cars we drive, to the mobile devices we use every day, steel is involved in all of them in some way. This is down to its low cost, high versatility and an abundance of the natural materials needed to make it.

But to make use of this material, we first need to understand all about it, including the different types and alloys available, their properties, and uses.

Understanding the Different Types of Steel: A Comprehensive Guide

In essence, steel is an alloy of Iron and Carbon. However, it can also be very readily combined with many other elements to modify its properties in ways that range from increasing strength to making it corrosion-resistant.

The different types of steel are often categorised as:

• Mild steel
• Alloy steel
• Stainless steels
• Tool steel

Mild Steel

A commercial type of steel used in everything from building structures to car body panels. Mild steel is also known as low-carbon steel. It is strong and ductile, but with relatively low hardness and corrosion resistance.

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Alloy Steel

The term alloy steel often refers to a more specialised steel that might have higher hardness, strength, or corrosion resistance through exotic alloying elements. Alloy steels often contain molybdenum, chromium, vanadium, cobalt, and more.

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Stainless Steel

As the name suggests, stainless steels are a group of metals that resist corrosion. They typically do this by containing a large amount of chromium, at least 10.5%. This chromium forms an oxide layer when exposed to the corrosive environment and protects the material from rusting.

A range of stainless steel grades is available, from regular 304/316 for corrosion resistance, to high-strength duplex or high-nickel grades.

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Tool Steel

Tool steels are used to cut, drill or otherwise work other metals. They are made to be extremely hard by way of alloying them with high levels of carbon, cobalt, tungsten, and more.

These steels are typically heat-treated to get the hardness level correct.

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Key Properties of Steel: Strength, Durability, and More

To understand which steel is best for a certain application, one must understand the defining qualities:

• Tensile Strength: This is the measure of how much load a material can withstand until it yields and deforms permanently.
• Hardness: Harder materials resist localized/micro deformation, which gives abrasion and indentation resistance.
• Toughness: Toughness is a measure of impact resistance and is linked (though not directly) to malleability. The tougher a material is, the more energy it can absorb without fracturing.
• Corrosion resistance: stainless steels typically do not require any kind of paint or other coating to resist corrosion, mild steels will however, rust if left untreated
• Ductility: This is a material’s ability to deform without cracking, a useful property for bending and forming material during manufacture.

Steel Applications Across Industries: Construction, Automotive, and Beyond

The applications of steel are without limit; it can be found in every walk of life, from heavy industry to domestic products, and everything in between.

Construction

Steel beams, columns, ties, and brackets are used extensively in constructing all sorts of things, from homes to bridges and high-rise buildings. You’ll also find steel components doing the small jobs too, screws, nails, straps and staples are all made of some form of steel product.

Reinforcement bars (rebar) are vital to creating solid and robust concrete products. Without it, the size and load-bearing capacity of concrete structures such as bridges and buildings would be significantly reduced.

Automotive Industry

About 60% of the average car is steel by weight. Whilst many modern engines utilise aluminium, and exotics such as carbon fibre are becoming more common, steel still provides the backbone to almost all vehicles’ structure.

Most vital components, such as the bodywork, frame, radiator, suspension arms, are made of steel, and even the bits that don’t appear to be, such as steering wheels, seats, etc, still use it internally to provide structure and strength.

In performance vehicles, stainless steel exhaust manifolds and systems are common, although titanium may be a better option if cost is not an issue.

Choosing the Right Steel: Factors to Consider for Your Project

Selecting the correct material has a large impact on both manufacturing cost and performance of the product. Here are some things to consider:

• Budget: Stainless steel is significantly more expensive than mild steel, and tool steel can take extra steps such as normalising, hardening and tempering to machine, adding cost
• Strength: High-strength materials are typically harder to work with, increasing cost
• Corrosion needs: if the part is to experience a corrosive environment, not using a suitably resistant material could mean it fails prematurely
• Weight: whilst steels are relatively close in density, if high-strength materials are used, less metal will be required, reducing weight.

Steel Maintenance and Longevity: Tips for Preserving Your Investment

Steel can and will rust, given the chance. Care should be taken to avoid corrosion in all circumstances, as it not only looks bad but can seriously affect a part or structure’s strength. These are some ways to mitigate corrosion:

• Coatings: Paints and powder coating are often used when a part can be made of mild steel, but needs to look good. They offer a reasonable shield against corrosion, but are not extremely long-lasting or durable
• Galvanising: coating the part in zinc gives a durable and long-lasting coating, typically giving 25-50 years of protection
• Maintaining Stainless: Should you choose to use stainless steel to prevent corrosion, be sure to maintain the surface correctly, using a mild cleaner to remove tarnishing