METHOD FOR COATING A HOT-ROLLED OR COLD-ROLLED STEEL STRIP CONTAINING 6 - 30 WT%. MN WITH A METALLIC PROTECTIVE LAYER

摘要

The present invention relates to a method for coating hot-rolled or cold-rolled steel strip containing 6 - 30 wt%. Mn with a metallic protective layer, in particular a protective layer based on zinc, wherein the steel strip to be coated is annealed at a temperature of 800 - 1100°C under an annealing atmosphere containing nitrogen, water and hydrogen and is then subjected to hot dip coating. With the method according to the invention high manganiferous sheet steel can be hot dip coated in an economical way. This is achieved 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 T G as follows: %H2O/%H2 <= 8.cndot.10 -15.cndot.T G3.529