A heat treatment applied to medium and high-carbon steel prior to cold drawing to wire.
The treatment involves austenitization followed by isothermal transformation at a temperature that produces a microstructure of very fine pearlite.
The metal is gradually heated to about 1830 (degrees) F., with subsequent cooling, usually in air, in a bath of molten lead, or in a fused salt mixture held between 800 (degrees) F. and 1050 (degrees) F.