Most people have probably heard by now that Elon is changing Starship to a complete stainless steel build. Anyways, it got me thinking, why isn't stainless steel ever used for rocket engines (nozzle, combustion chamber)?
I am in a University student rocketry club currently building a liquid engine, so this is of particular interest to me. I am on the team designing the regenerative cooling and engine structure/manufacturing.
Copper alloys and Inconel 718 (INC718) are popular choices, but what about a 300 series stainless steel?
Compared to INC718, stainless has a slightly lower density, higher specific heat, and higher thermal conductivity. Mechanical properties such as melting temp and modulus of elasticity are similar. The greatest disparity against stainless is that the tensile and yield strength are much smaller than INC718. Is this the primary factor keeping stainless from being used in rocket engines?