SpaceX will use 3XX stainless steel for their Starship and Super Heavy rocket booster due to better performance compared with carbon fiber over the spectrum of operating temperatures and conditions encountered. @ElonMusk shows he has more than just a passing awareness of materials and manufacturing in his recent interview with @PopMech. In it, Musk describes how material selection affects stiffness, fracture toughness, and of course cost. He talks about a novel approach to cooling the metal surface by transpiration, where cryogenic fuel evaporates after seeping through micro-pores in the outer layer of a double-walled shell. Novel in aerospace, that is. The evaporation of water from plant leaves is another example of transpiration.
The interview is in Popular Mechanics.
The feasibility of transpiration is covered in Teslarati.
-Danny Schaeffler, www.EQSgroup.com and www.Learning4M.com