NAICS 33111 covers production at integrated or electric arc furnace mills that smelt and cast steel into semi-finished forms such as slabs, billets, and blooms, as well as ferroalloy outputs. Downstream operations — rolling, drawing, pipe forming — are classified in separate NAICS groups like 3312, even when performed by the same corporate entity at a different facility.

Section 232 tariff liability and quota eligibility hinge on the country where the steel was melted and poured, not merely where it was last processed. Importers must obtain mill certificates and, where applicable, affidavits from the producing facility to substantiate origin claims and support any exclusion requests filed with the Department of Commerce.