What exactly is an alloy? How are alloys made? Where are they used? This is everything you need to know in a simple guide.
When people outside the engineering and forging community hear the term “metal alloy,” they might be tempted to scrunch up their faces, say “huh?” and move on to something more interesting, like the Patriots’ fifth Super Bowl win. But we encounter metal alloys every day – in everything from jewelry to cookware to dental fillings to door locks to flatware and medical devices.
So, let’s take a few minutes to dive into the wonderful world of alloys. Even you may be surprised at just how much interesting stuff there is to learn!
What is an Alloy?
Let’s start with the basics.
An alloy is simply a metal that, in order to make it better suited to what it is going to be made into or used for, has been combined with one or more other elements. Think of it sort of like a recipe. You can’t use just flour or just eggs to make a cake, but when you mix the two together (and a few other things), you get batter.
Traditionally, alloys were made by melting the metal and other constituents into a liquid, mixing them, and then letting them harden into a “solid solution” (a scientific, technical term for the solid equivalent of a solution, a term you should remember from eighth-grade science).
Other times, the metals and constituents will be reduced to a powder and then fused together through high temperature and pressure. This process is called “powder metallurgy.” Depending on the intended use of the metal, called the “application,” numerous different component combinations, forging-heat treating processes, and other decisions must be made by the production company to ensure the best metal with the right properties for the job.
Aluminum is not an alloy in itself. In fact, because it is a naturally very soft metal (think of how easy it is to manipulate aluminum foil!), it is usually made into an alloy by combining it with copper, magnesium (at least the 6000 and 7000 series), and silicon—all metals that, when combined, are very lightweight but also quite strong.
Sometimes these additional elements may comprise fifteen percent of the total weight! Individual aluminum combinations (alloys) are given a four-digit number, with the first digit identifying its “series” (the unique combination of metals it has), and the last three denoting particular uses for distinct combinations.
For example, Weldaloy stocks and forges aluminum in four different alloy series:
And here you thought aluminum was boring! Think again!
Chromium Copper (e.g. C18200)
There are many varieties of copper alloys. Chromium copper contains about 99% copper, with the chromium comprising only about 0.6 to 1.2%.
Most metals used in building and vehicle design are expected to be strong and resistant to corrosion, and copper chromium is no exception. Moreover, because of its combination with chromium, this metal is actually more resistant to corrosion because the chromium amplifies the copper’s natural protective oxide film.
The fast-cooling process frequently used in making chromium copper creates an “age-hardening” effect, which means that the combination of very high melting temperatures and the quick cooling during the anneal process makes the metal extremely hard and durable.
Because of this, age-hardened alloys are often used in cable conductors, parts for circuit breakers, and electrical and thermal conductors needing a high degree of strength.
Weldaloy stocks a vast line of copper alloys, including copper chromium. It is available for multiple parts integral to the electronics industry, including backing plates, discs, rods, and more. It is also used in the bearing industry for thrust pads and slip rings.
Copper Nickel (e.g. C18000, C70600, and C71500)
The addition of nickel makes this alloy fantastically resistant to corrosion and macrofouling (a process whereby various slimy macroorganisms adhere themselves to the metal and create layer after layer of adhesion).
Because of this, it is very common to see copper nickel used in anything marine-related, from ship building to boardwalk-reinforcing, as they aren’t susceptible to quick rust or erosion by sea critters and the elements.
The most common copper alloy is called 90-10 copper nickel, which refers to it being made up of 90% copper and 10% nickel. (Depending on what it is used for, the nickel percentage can range from anywhere from 2 to 30%.)
Nickel enhances the copper’s natural strength and durability, while also retaining ductility (the ability for a metal to endure stress in opposite directions without breaking; an example would be pulling the copper into long thin strands to make rods).
Higher degrees of nickel, as well as other elements, can be added to the copper to create even greater durability and corrosion-resistance, especially in marine contexts where heavy exposure to saltwater, sand abrasion, and high winds make high endurance necessary.
Copper nickel goes into many products Weldaloy creates for the material processing and OEM industries. Applications include weld wheels, backing plates, superconductor wire, and a few others.
Manganese Bronze (e.g. C67000 series)
This is one of the most wear-resistant metals available. Manganese bronze is usually made by combining bronze with manganese, iron, and aluminum, and lead (the latter is a lubricant; otherwise, the metal is very brittle, and even with the lead it’s not able to be heat-treated).
This metal is ideally suited for anything needed to operate under high loads and speeds, so it’s often used in machinery parts (think brackets, electrical components, gears, hydraulic cylinder parts).
Its massive durability and resistance to erosion make it perfect for marine-related pieces (rudders, covers for hardware, various parts of boats and ships). Many types of manganese bronze are very machinable so it can be crafted into many different things (i.e., it’s versatile) very easily at low cost.
Manganese bronze is used by Weldaloy predominantly for equipment in the steel processing industry, in custom machines that deoxidize hot steel slabs.
Naval Brass (e.g. C46400)
Brass is itself an alloy, comprised of copper and zinc. Naval brass, as you might expect, is a subcategory designed specifically for marine usage.
Generally, it contains 60% copper, 0.75% tin, and 39.2% zinc. These combine to create a brass that is extremely hard, corrosion-resistant, and highly durable. Moreover, it works well in both salt and freshwater contexts.
Different naval uses include propeller shafts, decorative fittings, turnbuckles, and marine hardware.
Tin enhances the natural corrosion-resistance of the metal, and lead is often added to enable machinability. The presence of tin also prevents something called “dezincification,” which is when one of the components of an alloy disintegrates because of corrosion.
However, the durability and strength of this kind of alloy make it a natural choice for all different kinds of parts and pieces, such as metal bushings (which are often used in cars, SUVs, and trucks), valve stems (used in vehicle tires), and wear strips (a kind of guardrail frequently used under conveyer belts in bottling and packaging machinery).
Weldaloy’s forged naval brass is predominantly used in the electronics industry for backing plates and similar applications.
Obviously, alloys are used in all kinds of ways, especially in the building, transporting, sustaining, and creation of all kinds of products and industries!
Especially because so many projects and applications require endurance, strength, and stability, ensuring the precise chemical combination and the quality of the metal is the most basic first step in choosing a manufacturer.