Excuse me, the difference between round steel, screw steel, steel, plate material, steel wire, hope professional answer
Anything you say can be called steel bar, except steel wire. Round and round is a name, and wire coil, general line.
The 2 plate and steel hot rolled steel plate, it is hard to know, the difference between rebar and rod easily screwed, clear, thread steel by chemical factory is a very deep rib.
Disk and rebar with rib, have all the same, basically can not see, rebar size is more than Phi 9, a lot of hardness than wire reinforced strong general, so the steel strip is usually linear, bluntly, steel disc is not up, disc. The size can be intercepted, so can be screwed up disc.
