Metals: Types, Properties, and Uses Every Fabricator Should Know

Bronze, Iron, Steel, and others have played a significant role in the development of humankind, in everything from food gathering to sanitation.

Nowadays, the range of metals on offer is vast, with numerous versions (alloys) of each metal, each one having slightly different properties and benefits. In this article, we’ll take a look at the key metals every fabricator should know.

Understanding Metal Properties: A Comprehensive Guide

Metals have a few key characteristics that set them apart from other elements, their luster, their hardness, and their ability to conduct electricity and heat. However, the extent to which these things are true varies greatly from metal to metal.

Physical properties:

• Strength, both tensile and yield strength, is a measure of a metal’s ability to withstand force without breaking
• Malleability, the amount a metal can be deformed without fracturing
• Density, the weight per unit volume
• Melting point, the melting point of metals ranges from Mercury at -38.2°F to Tungsten at 6191.6°F
• Electrical and thermal conductivity, the ability of the material to conduct electricity or heat

Chemical properties:

• Oxidation/corrosion resistance, certain metals, such as iron rusts readily, whereas non-ferrous metals do not

Common Types of Metals and Their Application

Several metals are commonly fabricated, each with many different variations – known as alloys.

• Steel, the most commonly found metal in industry, is an alloy of Iron and Carbon, and has great strength with relatively low cost
• Stainless steel, Steel with more than 11% chromium, is considered to be stainless steel, a version that does not readily suffer corrosion
• Aluminum, a lightweight metal that offers a high strength-to-weight ratio and is corrosion resistant
• Copper, revered for its high thermal and electrical conductivity, as well as its appealing color and ease of working

Metal Alloys: Enhancing Properties for Specific Uses

There are very few metals we use in their pure form; almost all metals used in engineering and fabrication are alloys. This means they have several additional elements added, which can make up anything from 0.1% to over 40% of the resultant material by weight.

There are numerous reasons for alloying metals, such as:

• Increasing the strength, adding carbon to iron to make steel, increases its strength by a significant amount
• Corrosion resistance, as we’ve discussed, stainless steel in its most basic form is normal carbon steel with at least 11% Chromium added. This chromium forms an oxide layer that gives corrosion resistance.
• To improve workability, there are many grades of steel made for machining, they often have elements such as lead or sulfur added to machine turning and milling easier.
• To allow heat treating, with various grades of steel, aluminum and other metals, the alloying elements enable heat treatment processes to work, giving more flexibility with manufacturing and post-processing

Metalworking Techniques: Shaping and Joining Metals

Being able to shape and join metals is one of their biggest strengths. Unlike materials such as wood or concrete, most metals can be welded, forged and bent with ease.

Welding

Before welding was invented, processes such as riveting and bolting were used to make complex structures. This was effective, but slower and less efficient.

Welding allows two pieces of metal to be permanently joined together, with the resultant joint being stronger than the base material if done correctly. Various processes are available, allowing most thicknesses and metal types to be welded.

Cutting

Before any sheet, box section, tube, or solid bar is welded, it is usually cut to shape or length. In the past, saws and hand thermal cutting were the only options. Now we have multiple choices, all highly precise and efficient.

These methods include Laser cutting, waterjet cutting, CNC sawing, punching, shearing and cropping. Each one has its own merits and drawbacks, depending on the accuracy and cost limitations.

Forming

Deforming metal to change its shape in an exact way is an incredibly efficient method to create parts. Processes such as bending, rolling, forging and extruding can produce repeatable, accurate components at high speeds.

Machining

Without being able to make highly precise parts, things such as cars and machinery would not be possible. This is where machining comes in, it uses hardened cutting tools to accurately remove material.

Processes such as turning and milling are commonly computer controlled, also known as CNC. Modern machining can produce parts to micron accuracy and at a fraction of the time of manual machines.

Finishing

Finishing covers any process that changes the surface finish and or appearance of a part. This can be for aesthetic or protective reasons. For large steel components, paint or zinc galvanizing is commonly used.

On smaller or more precise parts, processes such as electroplating and anodizing are often used, depending on the base metal.

Selecting the Right Metal: Key Considerations and Uses

With so many options to choose from, selecting the right metal for the task can seem daunting. Here are some key considerations.

• Cost, this is often the first deciding factor, steel is generally the cheapest metal to fabricate from, as it is so much cheaper to buy than stainless to aluminum, but it will require protecting from corrosion
• Availability, a particular high-performance alloy may offer better strength or weight saving, but be sure to check that the section sizes you need are readily available in that grade
• Manufacturing, some metals are harder and take longer to make parts from. For instance, certain grades of aluminum can crack when bent too tightly
• Corrosion resistance, consider not only rust, but also galvanic corrosion. For instance, stainless steel and aluminum can oxidize in such a way that they can be very difficult to separate

Conclusion

Hopefully, this guide has given you some critical information needed to progress your project. Whether that be an ornate copper piece or some structural steelwork. For more information on the metals and processes discussed, check out our other blog posts.