Aftermarket performance parts are made from a wide variety of different metals compared to stock parts because they’re designed to stay in the vehicle longer, withstand the different pressures of other new aftermarket parts and usually to improve performance. Part websites always sell parts by naming the metal they’re made of, but don’t define what it is or why it’s important. In this blog post we’ll explore a of couple different metals such as, Chrome-Moly, Billet Aluminum, Magnesium Aluminum and Forged Steel seen on and other aftermarket websites.


Chromium-Molybdenum , otherwise known as Chrome-Moly is an alloy steel made for high temperature and high pressure services. It’s used because of its overall strength combined with corrosion resistance and its ability to retain strength in high temperatures. Chrome-Moly isn’t as light weight as aluminum alloys, but the corrosion resistance and strength make it well worth the added weight.

Chrome-Moly is called many different things in different markets, which can make it hard to figure out what people are talking about. Some call it Cro Mo, others call it Chromoly, but no matter what they call it, everyone is talking about a strong, corrosion resistant metal.

Billet Aluminum

A billet is a bar of metal and a billet of aluminum is a solid block of aluminum with its size dependent on your needs. Billet parts are created by removing the excess material from around the billet; basically the part is carved out of a solid chunk of metal. Think of whittling, you shave off pieces of wood until you have your shape; it’s the same with making a part out of a billet.

Billet Aluminum is created with a high degree of precision and structurally it’s stronger than cast aluminum. Billets do have one drawback, they can be expensive because they need to be computer cut and since they’re not folded or molded, the left over pieces are discarded and recycled.

Magnesium Aluminum Alloy

An alloy is a mixture of metals or a mixture of a metal and another element, in this case magnesium and aluminum. Magnesium by itself is a very light-weight metal, even lighter than aluminum, but it can be soft in its original state. When you put the two metals together you get a strong and light metal.

Many automakers are adopting magnesium alloys because of the increasingly strict environmental standards being handed out by various governments across the globe. The automotive industry is being forced to make vehicles lighter to get better fuel economy, and Magnesium is seen as one of the ways forward. “Magnesium is 33% lighter than aluminum, 60% lighter than titanium, and 75% lighter than steel,” according to Lillian Wong from CD International Enterprises, INC, a company that sources and distributes industrial commodities in China and the Americas. Because of those market conditions, we’ll definitely be seeing more Magnesium alloys in the future.

Forged Steel

When something is forged, it’s physically forced into a shape while remaining in a solid state. Forged steel is generally stronger and more reliable than cast steel and plate steel due to the fact that the grain flows of the steel are altered, molding to the shape of the part. Forged steel has a high initial investment for the design and construction of the die to stamp the parts, but after that, it has a fairly low ongoing cost for every part made afterwards. Forged steel is three times stronger than aluminum, but is also much heavier and largely used for parts that need an incredible amount of strength.

Those are only some of the metals you might see on part websites, they’re all found on ours. We hope this information helps you choose the right parts to buy. Stay tuned for our blog next month for more information on aftermarket parts materials!

Are you really passionate about one metal over another? Let us know in the comments.


  1. Chromium-Molybdenum Alloys:
  2. Cast Vs. Billet:
  3. Magnesium is Called the Metal of the Future for a Reason:
  4. Forging Vs. Casting Which is Better:
  5. The Difference Between Casting and Forging:
AftermarketBillet aluminumChrome-molyChromolyForged steelMagnesium aluminum

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