The design of Starship and its Super Heavy booster is based on the reported fact that 301 stainless steel is advantageous to advanced carbon fiber composites and Aluminium-Lithium alloys at both cryogenic temperatures and re-entry temperatures.

How exactly do the mechanical properties of these three materials compare over the temperature range from, say, -180 °C to 1500 °C?

I think the most important properties are the yield strength and the Young's modulus. A plot of these properties over the whole temperature range would be very illustrative. Any other relevant characteristic is welcome, too.

For 301 stainless steel, please consider the hardened condition (cold rolled). For the carbon fiber material and the Aluminium alloy, I am not exactly sure how to specify further. Both should be certified or proven for aerospace applications.

A couple of search queries did not lead to the desired plot. Most scientific papers and industrial specifications seem to only state the material properties at certain discrete temperature values.

  • 1
    $\begingroup$ At the high end of your range, Al-Li is a liquid and carbon fiber has burned away. Both of these materials have to be protected from entry heating. $\endgroup$ Oct 2, 2019 at 21:50
  • 1
    $\begingroup$ Maybe to inform this question a bit more, compare 301 SS to Al-Li 2196/2198 (External Tank / Falcon 9) and standard modulus carbon fiber? Maybe to add to add to Organic Marbles beginning, at 1500 F your steel is starting to anneal and soften. $\endgroup$
    – mothman
    Oct 3, 2019 at 0:54
  • $\begingroup$ He said C not F. $\endgroup$
    – Roko Mijic
    Oct 4, 2019 at 9:49
  • 1
    $\begingroup$ @RokoMijic Yes. But that's not so important, the range was just a suggestion and can be discussed. $\endgroup$ Oct 5, 2019 at 19:20
  • 1
    $\begingroup$ I think plotting this versus yield strength is what you are looking for. No one designs to ultimate tensile strength because it will have highly non-linear effects. $\endgroup$ Oct 8, 2019 at 22:25

1 Answer 1


This is not an answer since it does not deal with the temperature range part of the question, but the graphic can't be presented in "comments"

For aerospace design, specific modulus (stiffness per mass) offers more insight into materials choice than Young's modulus or yield strength. Many materials fail due to deformation before they yield.

enter image description here

In the diagram, carbon fiber reinforced plastics CFRP are shown having both a higher specific modulus and higher specific strength than aluminum alloys.

In the real world, many other factors such as cost, corrosion resistance, manufacturing scalability, etc also need to be considered.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.