SpaceX SHS Rocket Switching to 304L Steel and Then Custom Alloy

The SpaceX Super Heavy Starship (SHS) will switch from 301 steel alloy to 304L steel alloy for some parts and then a new custom steel alloy.

The 304L steel is a lower carbon version and it will reduce welding issues.

Marcus House indicates that there are a lot of Raptor engines coming through.

The third prototype version of the Starship (SN3) is rapidly being stacked.

SOURCES- Elon Musk Twitter, Marcus House Video
Written By Brian Wang,

12 thoughts on “SpaceX SHS Rocket Switching to 304L Steel and Then Custom Alloy”

  1. Musk is a computer programmer. One such always tries the easiest/cheapest thing first, just in case! He sez *some* replacement, not all, so he (we as species) are learning. Many issues at once! Cost of steel for thousands of rockets is a big deal, unless you are building for gov.

  2. I wonder if the private alloy type might still have something to do with low entropy alloys still…

  3. I agree. Tricky indeed. And fixturing will be elaborate. It would be a custom-designed piece of unique equipment, and the IP would be valuable.

  4. Kind of tricky on that scale, given how thin the material is. But they should certainly be able to limit the welds to one seam weld per ring, and then welds between them.

    I’d been wondering if they could revive that sputtered film welding technique. No heat effected zone!

  5. I think they should try to find a friction welding solution to segments. That would speed things up a lot, and result in a better weld. May even be able to butt weld each segment sheet.
    Automate the crap out of it.

  6. Personally, I’m a deep draw tooling designer. By “work with it” I don’t mean I pound on it myself, just that I design the production tooling for a lot of parts made of it. Solenoid tubes, fuel rail components.

    304L is a very well behaved and forgiving material. 301 has some nice properties, and the price is right, but it’s not very forgiving. It is very deceptive, though: You can think you’ve gotten a good result, and it fails days later. Due to the delayed stress cracking.

  7. I didn’t do the welding, just the cutting and bending, but the result was excellent. We used 304 for an exhaust header on a SCCA race car. It turned out nice visually, and it worked, and sounded quite well.

  8. To be fair, it isn’t like it would be impossible to use 301. People make products out of 301 all the time. Usually products that are made in huge quantities, where the lower cost of the alloy outweighs the learning curve you have to traverse to get away with using it.

    It might even make sense for Musk to have a team continue working with it, while they build the flight prototypes out of 304L. (My favorite stainless, work with it all the time.) Then they can try switching to it once they have the bugs worked out.

    But only for cargo flights, please.

  9. Makes me wonder how much faster they could have started getting crews into orbit if they had used that other steel to begin with.

  10. Sheesh, they could have asked me, and saved a lot of time! So many customers are seduced by the lower price of 301, and just don’t realize how much heartache they’re signing on for.

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