The grand plan for SpaceX's starship Starship is to build a reusable transportation system that will send people, satellites and cargo weighing more than 220,462 pounds into space. It's equipped with the Raptor, a reusable Methalox internal combustion engine designed to colonize Mars or perform any mission that might go beyond the ultimate frontier.
In January 2019, Elon Musk was interviewed by the veteran technology magazine "Popular Mechanics". In the interview, he explained that the Starship's hull will be made of stainless steel rather than carbon fiber, mainly because it's cheaper. But it also has some additional benefits.
According to Musk, carbon fiber is very expensive, at about £120 per kilo (or 2.2 pounds). Not only that, but through cutting and shaping alone, up to 35% of the material is wasted and thrown into the trash. In the end, each kilogram of carbon fiber material actually cost SpaceX nearly £180. Stainless steel costs less than a coffee pod for a Starbucks brewer at only £2.66 per kilo (via Space). Additionally, stainless steel has a higher melting point, making it a more resistant material to the heat encountered during re-entry. According to Musk, carbon fiber has a "steady-state operating temperature" of about 300 degrees Fahrenheit, with some forms as high as 400 degrees. You can surpass it, but only for a short time, and even then it will start to deteriorate and weaken. Stainless steel can withstand temperatures up to 1,600 degrees Fahrenheit (through space).
Anyway... Learning about stainless steel and space all day is exhausting... we need a launch break.