3mm stainless steel - wow

[HaulingAss]

While 3mm is a substantial thickness of metal for the skin of an automobile, 300 series stainless is not "hardened steel". It's actually very soft.

The alloy specification does not denote the hardness specification.

Cold rolling provides different levels of hardness depending upon the pressures used and the number of passes through the rollers. For example, annealed (soft), 1/4 hard, 1/2 hard, 3/4 hard and full hard. Different mills may use different ratings.

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[firsttruck]

The alloy specification does not denote the hardness specification.

Cold rolling provides different levels of hardness depending upon the pressures used and the number of passes through the rollers. For example, annealed (soft), 1/4 hard, 1/2 hard, 3/4 hard and full hard. Different mills may use different ratings.

Yup

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Label on SpaceX stainless steel roll
304L
thickness: 3.96 mm
hardness: extra hard - cold-rolled, pickling, without final annealing

Label on SpaceX steel roll - What Exactly Is Starship Made From?
Let's dissect the new information from the supply label captured on SpaceX steel roll - Supplier, thickness, polish, length ...
How many rings can you build out of a single roll?
Sep 21, 2020
Spaceflight Explained

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[Dave Lyon]

The alloy specification does not denote the hardness specification.

Cold rolling provides different levels of hardness depending upon the pressures used and the number of passes through the rollers. For example, annealed (soft), 1/4 hard, 1/2 hard, 3/4 hard and full hard. Different mills may use different ratings.

Why don't you look up the RC of "full hard" 304SS and let me know how it compares to hardened D2.

 

[HaulingAss]

Why don't you look up the RC of "full hard" 304SS and let me know how it compares to hardened D2.

Why? You're not making any sense - that's a carbon tool steel. The Cybertruck will be made of a 300 series stainless steel that doesn't require paint. Hardened D2 is entirely unsuitable.

Diamonds are harder than either, it doesn't mean it's a good choice.

 

[Dave Lyon]

Why? You're not making any sense - that's a carbon tool steel. The Cybertruck will be made of a 300 series stainless steel that doesn't require paint. Hardened D2 is entirely unsuitable.

Diamonds are harder than either, it doesn't mean it's a good choice.

Because my argument is that 300 series stainless is not a hard steel. That was my only statement.

I agree D2 would be a poor choice for a car body.

 

[HaulingAss]

Because my argument is that 300 series stainless is not a hard steel. That was my only statement.

I agree D2 would be a poor choice for a car body.

Hardness is relative to the application. And, when dealing with 300 series stainless steels, hardness is more a function of the grade of hardness (annealed through full hard cold rolling) than it is to the specific alloy. Which is why you need to specify the grade of hardness when talking about how hard it is. If you specify a stailess steel without specifying the hardness, it's assumed it is in the unhardened state.

Do you know of any other production vehicles constructed of full hard 300 series stainless steel?

Didn't think so.

 

[cvalue13]

Which is why you need to specify the grade of hardness when talking about how hard it is.

I think the point is, any grade of hardness is relative to alloy

 

[TyPope]

I think the point is, any grade of hardness is relative to alloy

I thought that's what all those blue pill ads say...

 

[Crissa]

...You do know that the glass is technically harder than the steel, right?

Not just steel but for example 3mm cold-rolled 304L stainless steel?

Hardness is just one property of materials. Steel doesn't break not usually because of hardness, but ductility. Glass breaks when it hits its limit of ductility, although modern gas-treated glasses (like the armor glass) are a special type of matrix that is held in tension so beating its hardness is how they shatter. But the lamination of glass allows it to retain some strength and ductility as a web of interconnected material and resist penetration even when 'broken'.

-Crissa

 

[FutureBoy]

The Cybertruck will be made of a 300 series stainless steel that doesn't require paint. Hardened D2 is entirely unsuitable.

Diamonds are harder than either, it doesn't mean it's a good choice.

Oh.... Now there is an idea... Take the SS panels of the CT and use Chemical Vapor Deposition to build up an external coat of diamond. So much for EVER getting a scratch. Well, unless someone uses an engagement ring on it.

The ostentatious vehicle used to be coated in gold leaf. Just wait, there will be a day when they are coated in diamond.

 

[fritter63]

Oh.... Now there is an idea... Take the SS panels of the CT and use Chemical Vapor Deposition to build up an external coat of diamond. So much for EVER getting a scratch. Well, unless someone uses an engagement ring on it.

And put a sign on it:

"Free engagement ring tester. #IsHeCheapOrNot"

 

[PilotPete]

Hardness is not a feature for a stressed member of a vehicle. Even if you hit it with a sledge hammer. You have to take into account;

1. Compression: The structural skin experiences compressive forces when the body weight or external loads are transmitted through the stressed members to the ground or other supporting surfaces. These forces are distributed across the frame and structural elements.
2. Tension: Tensile forces arise in certain parts of the body when it is stretched or pulled by the vehicle's movements.
3. Bending: When the vehicle moves, the structural skin may experience bending forces due to the flexing of its components.
4. Shear: Shear forces are parallel forces acting in opposite directions. Two nearby attached castings exerting opposite forces.
5. Torque: The structural skin must withstand these twisting forces without deformation or failure.
6. Impact: In some scenarios, the vehicle may experience impact forces due to external factors such as collisions, falls, or contact with objects. The structural skin must have sufficient strength to absorb and distribute these forces to protect the vehicle's internal components.
7. Fatigue: Repeated use of the vehicle over time can subject the structural skin to cyclic loading, leading to fatigue forces. These forces can cause gradual degradation and failure of the materials if not properly designed for durability.

It is these forces that the alloy has to be designed to handle. And then add to that in the long term, the alloy needs to be resistant to degradation in any of these areas as a result of environmental exposure. This could include salt in ice or coastal climates, A relatively wide temperature range and possible rapid changes, and environmentally present chemicals in differing concentrations.

 

[CT19TX]

The alloy specification does not denote the hardness specification.

Cold rolling provides different levels of hardness depending upon the pressures used and the number of passes through the rollers. For example, annealed (soft), 1/4 hard, 1/2 hard, 3/4 hard and full hard. Different mills may use different ratings.

The ASTM/AISI specification does have minimum or maximum mechanical requirements. The mill produces a product to meet those specifications but they are not the ones “producing” the temper ratings. Those ratings pertain to the alloy’s specification.

 

[JBee]

The front corner of an out of control shopping trolley smashes into the side of the Cybertruck.

Will it leave a dent ?

If it's a normal undamaged trolley rolling around a flat shopping center carpark it won't dent it, but the metal corners could leave a mark or plastic parts could leave discolouration on the surface.

 

[JBee]

Let's face it... "Things that were said" four years ago are as likely as not, moot. A LOT has changed since that time, so unless you have authoritative, on the record, comments from folks from Tesla, we shouldn't dig in our heels to assert them.

The 30X cold rolled 3mm stainless steel exoskeleton "promise" is no longer gospel. The only thing in that description I'd be willing to bet 1% of my $TSLA holdings on is the stainless steel part. The rest can, and should, be adjusted if the reasoning for it initially has changed. If the chief rigidity of the body has been switched to the body in black as opposed to the outer skin, the need for heavy 3mm 30X would be more of a detriment than a benefit. It would be a shame if Tesla sticks with needlessly heavy and costly components just so Elon/Franz can avoid the appearance of lying.

I was willing to accept that non-ferromagnetic autinitic 30X steel would be used because I thought it was essential for the structural strength. If it isn't... I would prefer martensitic stainless steel so that I can adhere magnetic signs, or hooks, or lights to the sides, hood, tailgate of my truck. My magnetic numbers that I use for auto-cross only stick to the rear quarter panels of my Model 3, and nowhere at all on my Model S. It's kind of humiliating* using painter's tape on a $100k car when I have nice magnetic #s and logos in the frunk.

When working on/around your vehicle at night it's nice to be able to slap a magnetic flood light wherever you need it to illuminate the area you're working in. The limitations I've had to deal with these aluminum cars has made me long for the days of good old American steel.

Not sure if you're being ironic or not, but either way if it's ferrous metal that is magnetic you'll find it oxidises (rusts) easier than a less magnetic one.

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