Continuous annealing line having carburising/nitriding furnace.

摘要

A continuous annealing line for annealing a cold-rolled strip (7) of a ultra-low-carbon steel comprising a heating furnace (2) for heating the strip which is fed continuously, with or without a soaking furnace (3) following the heating furnace, a cooling furnace (5) in which the heated steel strip is cooled, and a carburizing/nitriding furnace (4) disposed between the heating furnace (2) or the soaking furnace (3) and the cooling furnace (5). The carburizing/nitriding furnace (4) may be divided into a plurality of zones, each of which is provided with control means for controlling the carburizing/nitriding atmosphere and carburizing/nitriding temperature in the zone. The continuous annealing line may further comprise a plurality of carburizing/nitriding furnaces and have an arrangement for conducting a switching between a mode in which the carburizing/nitriding furnace is used for carburizing/nitriding the steel strip and a mode in which the carburizing/cooling furnace is used for cooling the steel strip. <IMAGE>