Titanium sponge — the porous primary metal produced by the Kroll process — is classified as unwrought titanium under 810820, along with titanium powders. It is the feedstock for melting into ingots and billets, which are also unwrought and fall in the same subheading. Wrought mill products such as sheet, plate, bar, and tube are classified under 810890.

Aerospace-grade titanium must generally be accompanied by material test reports (MTRs) certifying compliance with AMS or ASTM specifications, traceability documentation back to the melt, and often first-article inspection records. These requirements are imposed by the purchasing aerospace manufacturer or their quality system, not by CBP, but they effectively constrain which foreign mills can supply the US aerospace market.