Process for avoiding adhering and scratching during recrystallization annealing of cold strips in a hood type furnace in a protective gas containing hydrogen comprises subjecting the cold strip to an atmosphere adjusted using an oxidant

摘要

Process for avoiding adhering and scratching during recrystallization annealing of cold strips in a hood type furnace in a protective gas containing hydrogen comprises subjecting the cold strip to an atmosphere having a partial pressure ratio P(carbon dioxide)/P(carbon monoxide) more than 1 which is adjusted by mixing an oxidant with the protective gas. The oxidant contains a fresh gas, hydrogen and carbon dioxide in an amount of less than 0.4 g carbon dioxide per m<2> on the cold strip surface. The partial pressure ratio of the water and hydrogen formed in the oven atmosphere is determined using an oxygen probe and regulated. The concentration of carbon dioxide in the fresh gas is at most 35 vol.%. Preferred Features: The fresh gas contains less than 0.3 g carbon dioxide per m<2> on the cold strip surface. The cold strip is further treated during the cooling phase in a carbon dioxide/hydrogen (CO2/H2) atmosphere.