Process for coating a hot- or cold- rolled steel strip containing 6 - 30 by weight of MN with a metallic protective layer

摘要

A method for coating hot-rolled or cold-rolled steel strip containing 6-30 wt %. Mn with a metallic protective layer, includes annealing the steel strip at a temperature of 800-1100° C. under an annealing atmosphere containing nitrogen, water and hydrogen and then subjecting the steel strip to hot dip coating. The method provide an economical way of hot dip coating a high manganiferous sheet steel in that, in order to produce a metallic protective layer substantially free from oxidic sub-layers on the steel strip, the % H₂O/% H₂ ratio of the water content % H₂O to the hydrogen content % H₂ in the annealing atmosphere is adjusted as a function of the respective annealing temperature TG as follows: % H₂O/% H₂≦8·10⁵·T_G^3.529.