Elon Musk talks about FSW

Elon Musk explains, why Space X chose stainless steel over carbon fiber for the two-stage, fully reusable, super heavy-lift launch vehicle SpaceX Starship (click onto the white-on-red arrow, please, to display the YouTube video)

© Space Studies Board and Board on Physics and Astronomy, 17 November 2021)

Elon Musk commented on 17 November 2021 that for making space craft, apart from using composites “the other two materials worth considering are a high-strengh form of aluminium, or potentially steel. So, for Falcon 9, we used  aluminum-lithium, which is the highest strength-to-weight aluminum alloy that you can use, but the problem is, it's very difficult to weld. You need to do friction stir welding, and also the material cost is quite high: Arguably on the sort of $40 a kilogram level.”

• FSW: Artemis III Orion: Friction Stir Welding of the Orion-Spacecraft for NASA's Artemis III Program to the Moon.
    
• FSW of Ariane 5 and 6 of ESA: Friction stir welding of Ariane rockets of the European Space Agency ESA