Tungsten carbide — a compound of tungsten and carbon — is not classified here; it falls under the chapter covering carbides and other hard metals. Heading 8101 covers metallic tungsten and its alloys. Cutting inserts and tool tips made of cemented tungsten carbide follow a different classification path, and a binding ruling is advisable for composite tooling.

Sintered tungsten bars and rods — produced by powder-metallurgy pressing and sintering without full melting — are specifically placed under 810194 as unwrought forms. Tungsten wire drawn from sintered rod is classified under 810196 as a wrought product. The distinction matters because the two subheadings may carry different duty rates and trade-remedy exposure.