Aircraft made in steel?

In photo processing, stainless 316 was used because of it's corrosion resistance. Any thing we had that was 308 had to be kept clean as rust would eventually appear at joints. The few things that were grade 410 would probably last centuries, but it was softer (more bendable) than 316. Grade 308 could attract/hold a strong magnet, 316 and above were non magnetic to magnets.

For the North American Aviation XB-70 Valkyrie - a sustained Mach 3 heat-soak capable design - a stainless steel 'honeycomb' method was
utilized for primary airframe construction, IIRC.