C
CHEMISTRY; METALLURGY
C21
METALLURGY OF IRON
C21D
MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
C21D1/00
General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
C21D1/74
Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
C21D1/76
Adjusting the composition of the atmosphere