If you click the 'advanced search' link and type in 'steel' and get it to search titles only, you'll find the answers in there somewhere.
Or just wait for Don D to chime in and espouse the virtues of Columbus TSX...or something.
Just keep in mind, the tubing is just the raw material - two bikes made from the same tubes are not the same bike. I know that sounds obvious, but it's amazing how many people think that.
*edit* Okay, I found the threads. Here's what i said last time -
Steels. 3 basic categories -
4130 or Cromoly - A Steel alloy of Chromium and Molybdenum. There are various different grades of this, but it's kinda the basic performance metal. Common brands/models are Columbus Gara and Thron, and True Temper Versus. Sometimes these materials are heat treated, which improves their mechanical properties, such as with True Temper Versus HT.
Micro-Alloyed steels - Sometimes using 4130 as a base, some other elements such as Niobium, Manganese and Vanadium are alloyed with it to improve the grain structure of the material, therefore improving it's mechanical properties or post weld characteristics. Columbus Zona is probably the best well know example.
Air hardening or Thermophillic steels - These are alloys usually specifically designed to have certain reactions to the heating TIG welding emparts on a frame. The material is designed to withstand or improve at the Heat Affected Zone (HAZ). Some examples are 853, OX Platinum, and Foco/Ultrafoco.
( There's also now a version of the above with Niobium alloyed into the mix. Apparently this improves ductility or some such spiel. Typical example is Columbus Spirit and Life. )
Now, all materials are not created equal. There are many ways to improve a material that are not simply a matter of alloying it, such as heat treating it or working it mechanically by work hardening, drawing, swaging, butting etc.
More info can be found in the threads -
"Steel numbers:Translation please?"
and
"what exactly is cro-moly"