A hexagonal cross-section is non-circular, so the bar falls under subheading 722219 (hot-rolled, non-circular cross-section) or 722220 (cold-formed or cold-finished), depending on the finishing process. Circular cross-section bars go under 722211.

Cold-formed refers to shaping at room temperature (e.g., drawing through a die to change the cross-section), while cold-finished typically means a surface treatment such as cold drawing or grinding applied after hot rolling to improve tolerances and surface quality. Both fall under 722220, but the distinction matters for specifications in aerospace and medical procurement.