Hot rolled from low, medium and high carbon or alloy steel billet, wire rod is delivered as coil, most commonly at 5.5mm dia, but in sizes up to 60mm dia. Close control of final cooling is a critical part of production.
Low carbon rod is used for undemanding applications like fencing wire and concrete reinforcing mesh, while medium and high carbon rod goes into higher performance uses like steelcord for car tyre reinforcement.
Some rod (cold heading carbon and alloy grades) is used to make fasteners (bolts, screws, nails, rivets), and alloy rod is commonly machined into products like engineering bearings. Some rod provides filler metal in welding operations. For more information check this article.