C
SECTION C — CHEMISTRY AND METALLURGY
  
METALLURGY
 C21
METALLURGY OF IRON
 C21B
MANUFACTURE OF IRON OR STEEL (preliminary treatment of ferrous ores or scrap C22B 1/00)
 C21B

Note(s)

This sub-class covers the production of iron or steel from source materials, e.g. the production of pig-iron, and apparatus specially adapted therefor, e.g. blast furnaces, air heaters (furnaces in general F27).


 C21C
PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON AND STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS (refining or in general C22B 9/00)

 C21D
HARDENING AND ANNEALING OF STEEL, IRON, OR ARTICLES MADE THEREFROM; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING MALLEABLE BY DECARBURISATION, TEMPERING, OR OTHER TREATMENTS (cementation by diffusion processes C23C)