Free-cutting (or free-machining) steel contains deliberate additions — typically sulfur, lead, bismuth, or selenium — that improve chip breakage during machining. The chemical composition on the mill certificate will reflect these additions, and that composition governs whether the bar falls under 721510 (free-cutting) or 721550 (other cold-formed).

Heading 7215 covers iron and nonalloy steel only. If the bar's chemistry meets the alloy steel definition under the Section XV notes — for example, chromium, nickel, or molybdenum content above the specified thresholds — it is classified in the alloy steel bar headings rather than in 7215, regardless of the cold-finishing process.