Uncoated Wire of Iron or Nonalloy Steel

Heat treatment — typically patenting or annealing — alters the mechanical properties of wire and is commercially significant for downstream processors. The US tariff schedule uses heat-treated versus non-heat-treated as a classification criterion within several carbon-content and diameter brackets, so importers must confirm the thermal processing history with the mill to select the correct 10-digit line.

Flat wire has a rectangular or near-rectangular cross-section, while round wire has a circular cross-section. The distinction is based on the actual cross-sectional geometry of the finished wire as drawn, not the shape of the original rod. Mill certificates typically specify cross-section geometry; when the shape is ambiguous, a customs broker or CBP ruling request can provide classification certainty.