At Tesla, HFS Is Short for Stainless Steel

Tesla

QuickTakes:

• HFS is a proprietary type of stainless steel
• HFS is particularly difficult to work with
• The benefits and drawbacks of Tesla's HFS

The recently introduced Tesla Cybertruck battery-electric pickup truck made headlines for its stainless steel construction, which hasn't been used in a production vehicle since the 1980s DeLorean DMC-12. Tesla's proprietary version is called HFS, or Hard Freaking Stainless.

There are a few interesting points to consider about the creation of this material and its use on the Cybertrucks.

Tesla

HFS Is a Proprietary Type of Stainless Steel

Stainless steel is produced by adding chromium to steel's traditional mix of iron and carbon. "Stainless" refers to the metal's ability to resist corrosion when exposed to oxygen. It's possible to tweak the characteristics of stainless steel by adding and varying the ratio of other materials.

Tesla's HFS is a derivative of 300-series stainless steel, previously used in limited automotive applications such as the DeLorean.

Tesla says HFS is 3 millimeters thick, but other details are unknown. The processes by which it gains its strength are related to the cold-rolling production technique, which adds martensite and austenite to its microstructure.

Tesla

HFS Is Particularly Difficult to Work With

The additional strength of Tesla's HFS makes it much more challenging to work with as a material. Because it is a cold-formed alloy, too much pressure when forming can add extra tensile hardness to the metal, making it impossible to bend into the shapes required to create the Cybertruck's angular body panels.

The process for manipulating the Cybertruck's stainless steel involves unrolling it, flattening it, cutting it into panels using lasers, and then using a process called air bending, where high-pressure air forms a protective barrier between the bending tool and the metal itself. Extra care is taken in order to avoid scuffing the vehicle's panels.

The Cybertruck is also assembled using gigantic hot stamping machines, further adding to the number of techniques required for Tesla to make this stainless steel vehicle a reality.

Tesla

The Benefits and Drawbacks of Tesla's HFS

Initially, the Cybertruck's use of HFS was intended to support an "exoskeleton," where the welded-together body panels could form the vehicle's structure. The production model is much closer to a traditional unibody design than originally proposed, with the stainless steel skin not performing any meaningful load bearing.

Still, the stainless steel construction is rigid enough to forgo the need for side-impact-protection beams in the doors. The panels can also stop a certain range of handgun and rifle rounds but aren't certified as bulletproof. Tesla further claims HFS is more durable than the standard steel and aluminum used in existing pickup trucks.

There are downsides to stainless steel when it comes to maintenance. Tesla says owners can repair minor scratches in its HFS via buffing. However, online news site InsideEVs reports that, as with stainless steel DeLoreans, taking the Cybertruck to a body shop to fix dents or cracks in its panels is next to impossible. The amount of time and work it would take to repair a panel would be cost prohibitive, meaning any damaged panels would likely have to be replaced.