New Steel Alloy Body Material Coming For Cybertruck Says Musk

[TruckElectric]

Elon Musk: Tesla is going to change alloy of the Cybertruck electric pickup


Elon Musk confirmed that Tesla plans to use a different alloy for the upcoming Cybertruck electric pickup.
When Tesla unveiled the Cybertruck last year, one of the most interesting features was the fact the vehicle isn’t going to be built using a traditional automotive body system but with an exoskeleton.

The automaker wrote about the exoskeleton:

“Cybertruck is built with an exterior shell made for ultimate durability and passenger protection. Starting with a nearly impenetrable exoskeleton, every component is designed for superior strength and endurance, from Ultra-Hard 30X Cold-Rolled stainless-steel structural skin to Tesla armor glass.”

Tesla said that they were using the best steel they could make:

“If there was something better, we’d use it. Help eliminate dents, damage and long-term corrosion with a smooth monochrome exoskeleton that puts the shell on the outside of the car and provides you and your passengers maximum protection.”

At the launch, CEO Elon Musk said that it is using the same alloy as SpaceX’s next interplanetary spaceship:

“We’re going to be using the same alloy in the Starship rocket.”

Now on Twitter, the CEO of both Tesla and SpaceX confirmed that the alloy planned for the spacecraft has changed:

“We’re rapidly changing alloy constituents and forming methods, so traditional names like 304L will become more of an approximation.”

Musk then confirmed that the change will also trickle down to the Tesla Cybertruck:












Electrek previously reported that Tesla and SpaceX are partnering up to create new materials to use on Earth and in space.

They have been building material engineering teams to develop new advanced materials for their respective products.

It started in 2016 when we reported in an exclusive story that Elon Musk hired Apple’s alloy expert Charles Kuehmann to lead materials engineering at both of his companies simultaneously.

Kuehmann and his team have since been developing new alloys for both SpaceX and Tesla.

It sounds like the one planned for the Starship and Cybertruck is still evolving ahead of production.

The team also develops its own variations of existing alloys, like 304L. PSP describes 304L:

“Alloy 304L a T-300 series stainless steel austenitic, which has a minimum of 18% chromium and 8% nickel. Type 304L has a carbon maximum is 0.030. It is the standard “18/8 stainless” that is commonly found in pans and cooking tools. Alloys 304L is the most versatile and widely used alloy in the stainless steel family. Ideal for a wide variety of home and commercial applications, Alloys 304L exhibits excellent corrosion resistance and has a high ease of fabrication, outstanding formability. The austenitic stainless steels are also considered to be the most weldable of the high-alloy steels and can be welded by all fusion and resistance welding processes.”

Tesla is planning to bring the Cybertruck electric pickup to production in late 2021.

Source: Electrek

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[DMC-81]

I don't know how I feel about this. More information is needed I guess. For example, I doubt the 304L will be used in the Starship, as this article lists its maximum temperature range to below 800 degrees, unless it will be used in areas where high temperatures are not encountered.

"304L dual certified stainless sheet is a very low carbon "18-8" austenitic chromium-nickel steel with good corrosion resistance and superior resistance to intergranular corrosion following welding or stress relieving. It is a flat rolled product produced by continuous mill rolling. The low carbon content limits the formation of harmful carbides to such an extent that this grade may be safely used for most operations of welded construction, and where the service temperature is limited to 800° F. It is non-magnetic in the annealed condition and not hardenable by heat treatment. Both hardness and tensile strength can be increased by cold working, which may cause slight magnetism. The dual certified 304/304L sheet meets specifications for both 304 and 304L stainless steel, and may be interchanged and used safely for either grades application. 304/304L stainless sheet is available in the common 2B finish (cold rolled on polished rolls, annealed, pickled, and skin passed on polished rolls), and #4 finish (polished with fine abrasive finish, giving a "brushed" look), and is sheared to size for rectangular and square shapes, or can be supplied in rounds, rings, or shapes on our Speedy Metals high definition plasma cutter."

Also, 304L can be formed/stamped which is counter to the reason for the CT shape:

"APPLICATIONS
304/304L is used almost exclusively for parts requiring machining, welding, grinding, or polishing where good corrosion resistance is also required. It is a good general all-purpose stainless grade. Good in corrosive environments as in paper and chemical industries and cryogenic services. Used where corrosion resistance and good mechanical properties are primary requirements. 304/304L is widely accepted in such industries as dairy, beverage, and other food industries where the highest degree of sanitation and cleanliness is of prime importance. Parts for handling acetic, nitric, and citric acids, organic and inorganic chemicals, dyestuffs, crude and refined oils, etc., are fabricated from this material. Because of its lack of magnetism it is highly desirable for instruments. It is also widely used for architectural trim. 304 sheets are used in applications where corrosion resistance is required, but elevated temperatures are not involved. 304/304L finds particular use in applications requiring welding. 304/304L has good drawing, forming, and stamping properties"

https://www.speedymetals.com/information/Material55.html

Some questions:
1) Will The CT still be Cold Rolled and 3 mm thick?
2) Ergo, will it still be bulletproof to a 9mm round?
3) And, is the bulletproof claim just for the doors, or is the whole body bulletproof?
4) Will the shape of the Cybertruck change due to the new forming/stamping ability?
5) Will the exoskeleton be just as strong?

The DeLorean was made with Type 304 Stainless Steel, and the (albeit thinner) panels were stamped. Although even on the thinner thicknesses than the CT, British Steel had problems with the early "gas flap" hoods cracking around the fuel door during stamping. They wasted a number of hoods this way. They eventually removed the fuel door, and then the grooves, ending up with a flat hood in the final version.

Heres a picture of the hood with both the fuel door and the grooves on my early car:

Finally, "Type 30X " at the reveal of the CT seemed to be more exotic than a "good general all-purpose stainless grade" in the above description.

Don't get me wrong, a Stainless Steel vehicle is still cool, but the type was billed/suggested to be a rocket grade exotic alloy. The DeLorean is susceptible to dents.

Hopefully we'll get more information on what the metal properties are of the CT skin.

 

[Frank W]

I have complete faith in Elon in making it a better product than a worse one.

 

[Geo]

I don't know how I feel about this. More information is needed I guess. For example, I doubt the 304L will be used in the Starship, as this article lists its maximum temperature range to below 800 degrees, unless it will be used in areas where high temperatures are not encountered.

No real change to the situation. At least not of any substance at all to the manufacture of the Cybertruck.

But a little more meaningful to the manufacture and performance of the Rockets, which needs to withstand Pressures in excess of 7 bar in extremely cold and hot temperatures.

Just the Tesla fan boys without any engineering understanding selling this as a big deal,
a big advancement to the Cybertruck, it most definitely is not.

A/ Cybertruck still is an exoskeleton body. Meaning panels still need to be 3mm Cold Rolled Stainless Steel for structural purposes. The difference to 301 vs 304L is No change in density. And tensile strength greatly overlaps in its range, meaning there is zero to negligible change in strength properties. Panels still can’t be stamped, and still require scoring before bending with a break press or equivalent.

Much of the hardness comes from the “Cold rolled” process, so no change there.

B/ Elon announced steel is as per what’s used by SpaceX in the Starship Rocket, Still the case, No change there.

C/ Elon announced it is their own special recipe of 30 X Stainless Steel. No change there.

D/ Its been confirmed they were building the rocket out of 301 Stainless Steel, and now using 304L

The difference in composition is in fact less than 5% ( Slightly more Chromium, slightly less Iron, slightly more Nickel.)

E/ However as the Spacex recipe for the steel is still not settled, they may tweak the alloy ingredients further, through numerous iterations.

F/ https://www.makeitfrom.com/compare/AISI-301L-S30103-Stainless-Steel/AISI-304L-S30403-Stainless-Steel

 

[ricinro]

As I recall another difference between 301 and 304L is that 301 can achieve full hard with cold working and the other alloys not as much (half hard?).

yeah, found this as well...

https://www.meadmetals.com/metal-products/stainless-steel/physical-chemical-properties

 

[SONNYDUT]

Exciting to hear news about the CT. I remember Elon Musk said at the unveiling event, “If there was something better, we’d use it." I believed him and trust that would be true. What ever the material will be, it's going to be awesome for me.

 

[MEDICALJMP]

Exciting to hear news about the CT. I remember Elon Musk said at the unveiling event, “If there was something better, we’d use it." I believed him and trust that would be true. What ever the material will be, it's going to be awesome for me.

Agreed.

 

[Sirfun]

Also, 304L can be formed/stamped which is counter to the reason for the CT shape:

The DeLorean was made with Type 304 Stainless Steel, and the (albeit thinner) panels were stamped. Although even on the thinner thicknesses than the CT, British Steel had problems with the early "gas flap" hoods cracking around the fuel door during stamping. They wasted a number of hoods this way. They eventually removed the fuel door, and then the grooves, ending up with a flat hood in the final version.

You are correct, The 304 SS on the Delorean is 22ga. and can be stamped and formed. But, 3mm is 11ga. which is roughly 4 times as thick, definitely not something to stamp or form. The problem with cracking happens when you try to bend stiff and thick metals into too tight of bends.

 

[carrtb]

My chief concern regarding the surface steel is strong resiliency to hail, next door dings. If it’s anything like the functional prototype and passes the sledge test, no worries!

 

[Jhodgesatmb]

I have complete faith in Elon in making it a better product than a worse one.

+1

 

[Delusional]

To me the big news here is... No problem when you weld something to the body.
"The low carbon content limits the formation of harmful carbides to such an extent that this grade may be safely used for most operations of welded construction,"

Limited amount of carbon splatter making your weld look like crap, and needs to be cleaned off.
Low loss of strength in the areas heated by the weld.
Relatively easy to find stainless that is a close match for the CT body. (this is a big deal)

Now all I need to know is what's underneath the areas I plan to weld? Don't want to melt anything that shouldn't be melted.
Or...
Does the Tesla ladder rack fit my needs? (assuming there will be a Tesla ladder rack.) If the Tesla rack works for me, I probably won't be welding anything to the body.

 

[Jhodgesatmb]

Not even a winch or plow mount?

 

[PLC]

Now all I need to know is what's underneath the areas I plan to weld? Don't want to melt anything that shouldn't be melted.

At first I was thinking about welding directly to the body of the CT too, but there are several disadvanteges if you think closer. Melting other stuff is sure #1, but also the loss of the mechanical properties of the cold twisted steel and the loss of the corrosion resistance at the back of the sheet-metal is an issue. I would rather go with blind rivet nuts that are closed at the bottom and some sealant at the drilling. I guess it would be easy for tesla to define areas of the body where drillings would not weaken the structure and where serious loads could be carried (close to the bent edges).
Customizing this thing could be such a breeze...

 

[ReddykwRun]

At first I was thinking about welding directly to the body of the CT too, but there are several disadvanteges if you think closer. Melting other stuff is sure #1, but also the loss of the mechanical properties of the cold twisted steel and the loss of the corrosion resistance at the back of the sheet-metal is an issue. I would rather go with blind rivet nuts that are closed at the bottom and some sealant at the drilling. I guess it would be easy for tesla to define areas of the body where drillings would not weaken the structure and where serious loads could be carried (close to the bent edges).
Customizing this thing could be such a breeze...

I agree. I worked on aircraft structures for 20 years and that's a good description of how to safely attach something on one side of the skin and not damage what's on the backside and disperse the load over a broad area and not induce stress in the attachment point like a "Lap Patch".

 

[Delusional]

You guys are still way overthinking this stuff. It's not that complicated. It's not rocket science. It's not going to be life-or-death flying in the air and one cracked weld results in the deaths of a couple hundred people. It's not aluminum. It's cold rolled stainless steel and quite thick too. I don't even want to call it sheet metal, it's more like plate. You get a competent welder and it will hold a ladder rack with quite a few ladders, no problem whatsoever.
The location and preparation for something like a winch... I'd bet Tesla has thought of that and prepped it at least a bit.
Like I've said before, just slap a sticker, "Sanford and Son" on the door, and call it a day.