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How to Identify Metals: The Importance of Knowing Your Materials

Aluminum and steel are the two most commonly used metals in manufacturing. However, despite their different properties and applications, it can be difficult to distinguish between them by appearance alone. Furthermore, aluminum and stainless steel come in countless different metals and grades, some of which look identical.

Ideally, metals come with some kind of identifying marking or documentation. However, this is not the case in most scenarios, especially when dealing with scrap metal. How do you identify metals when you’re not sure what type they are or where they came from?

When working with steel, aluminum, or any other type of metal, it’s important to know how to tell the difference between them. Depending on the metal, identification methods may be as simple as comparing colors. Many metals, though, look virtually identical. Fortunately, there are other techniques to determine what material you’re dealing with.

Below, we detail a few simple metal identification methods to help distinguish between steel and aluminum, different grades of aluminum, and other metals such as copper, bronze, and titanium.

How to Tell the Difference Between Steel and Aluminum

Aluminum and steel have significantly different mechanical properties you can use to tell one from the other. Here are some simple identification methods for aluminum and steel.

The easiest method for distinguishing steel from aluminum is by using a magnet. Ferrous materials are magnetic, while most nonferrous metals are not. Simply press a magnet to the metal—it will stick to stainless steel but not aluminum. However, it’s important to note that some stainless steels are magnetic, while some are not.

Aluminum is also much softer than steel, and this property is easy to test if you don’t mind scratching the piece of metal. Press a key into a piece of unidentified metal that may be aluminum or steel. If the piece is aluminum, it will scratch easily and deeply with light pressure. Steel grades will scratch, but they take much more pressure and won’t be as deep. This metal identification method gets easier as you practice and get used to how aluminum feels under the key versus how galvanized steel alloys feel.

How to Identify Different Aluminum Alloys

There are dozens of aluminum alloys, and some are very different from each other. There are aluminum alloys that weld easily, while others don’t. Some alloys can be heat-treated, while others can’t be. If you know you have aluminum but not what alloy, how can you identify it?

Distinguishing aluminum alloys from one another without sophisticated equipment isn’t easy, but there are metal identification methods that can provide some useful information about an alloy. For example, if you need to determine whether a piece of aluminum can be welded, look at the surface finish. In general, if it’s bright and easy to polish, it will weld, but if it’s dull, it will not.

Determining the exact aluminum alloy requires equipment that can measure the material’s composition. The equipment applies energy to a sample of the metal and measures the frequencies of the resulting emissions. The methods can be destructive, like atomic emission spectroscopy, which requires the material to be atomized or burned, or non-destructive, as in x-ray fluorescence spectroscopy, which energizes the material by scanning it with x-rays. If you need an exact answer to what aluminum alloy you have, you’ll need help from a lab or other metal professional with access to one of these metal identification methods.

Other Metal Identification Methods

What about identifying ferrous metals other than stainless steel and aluminum? Many metals have distinctive colors that can help with identification. If a metal is bright, shiny, and reddish-brown, it’s most likely either copper or red brass. Copper also forms a pale green patina over time when exposed to the elements—this is the reason for the Statue of Liberty’s color.

Bronze is an alloy of copper and tin, so it has a reddish-brown color very similar to copper. Bronze has a dull gold, darker finish, while copper has a more pinkish-orange color. Bronze is also much more brittle than copper, so if a copper-colored metal is easy to bend, it’s copper.

Gold-colored metals are usually brass. Yellow brass has a similar color to metallic gold, but gold is darker and less yellow. Gold is also heavier and is much rarer, so it’s likely your gold-colored scrap metal is brass.

Keep in mind that metals may be oxidized, coated, or painted, so trying to identify scrap metal based on color can be misleading.

Purchase or Recycle Metals with a Local Metal Supplier

Whether you’re a machine shop owner, a metalworker, or you just need to recycle some scrap metal, Industrial Metal Service can help. We have been supplying steel, aluminum, and other ferrous metals to the San Francisco Bay Area and nationwide for over two decades.

What if you need to recycle scrap metal, but you still don’t know what type it is after trying the metal identification methods above? No problem. We verify scrap metal using x-ray fluorescence technology. Our handheld Thermo-Fisher XRF analyzers can identify metals and their compositions so we can ensure that you’re getting the alloy and grade you need and you know you’re getting a fair price for your scrap metal.

Published by IMS Team

Industrial Metal Service has decades of experience and over 1.1 billion pounds of metal sold and recycled. Our founder, Jeff, has spent his life in the industry and prides himself on offering fair, efficient, trustworthy, knowledgeable, outstanding customer service. We offer metal salesmetal recycling pickup service, and other associated services, such as precise metal sawing, machinery teardown, and warehouse cleanupGive us a call and we’ll get it done.