Hi, I'm interesting in how fabrication and alloys have changed over the years to make stronger and lighter steel frame tubes and wondered if anyone has put something together on this or has opinions on the changes in steel technology from the 60s to present (or earlier). Also, love to hear opinions on the quality of different tube manufacturers.

All modern (1945-present) butted tubing by the major manufacturers is very high quality. Reynolds 531 chrome-manganese-molybdenum, and Columbus chrome-molybdenum in all the various dimentions were superbly finely made steel tubing. Both were/are made by piercing a forged piece of steel and then drawing over a mandrill.
To be fair though, all good quality steel tubing makes a pretty reasonable bike frame. Even standard chromemolybdenum structural tubing.
True Temper tubing starts out as flat stock, is formed into a tube, and welded at the seam, and then worked and drawn to remove any funtional traces of the seam. It also is good stuff.

Waterford is using True Temper tubing on their super light weight R33 frameset. It's almost as light as AL.

https://www.materialsengineer.com/E-Alloying-Steels.htm
https://www.anvilbikes.com/index.php?...atList&catID=3
https://columbustubi.com/eng/1.htm
https://www.reynoldsusa.com/english.html
https://www.reynoldstechnology.biz/do...ialcompweb.pdf
https://desperadocycles.com/The_Lowdo...g_frameset.htm
https://bulgier.net/pics/bike/Articles/SteelShootOut.pdf
https://www.truetemper.com/performance_tubing/tubing.asp