| 摘要 |
The present invention relates to a method for manufacturing a high manganese hot-dip galvanized steel sheet having excellent coatability and ultra-high strength, and a hot dip galvanized steel sheet manufactured by the method. An embodiment of the present invention provides a high manganese hot dip galvanized steel sheet and a method for manufacturing the hot-dip galvanized steel sheet, the method comprising the steps of: obtaining a cold-rolled steel sheet by cold-rolling a hot-rolled steel sheet by the reduction ratio of 30-60%, wherein the hot-rolled steel sheet includes, 0.3-1 wt% of C, 8-25 wt% of Mn, 0.1-3 wt% of Si, 0.01-8 wt% of Al, 0.1-2 wt% of Cr, 0.01-0.2 wt% of Ti, 0.0005-0.01 wt% of B, 0.01-2 wt% of Ni, 0.06-0.2 wt% of Sn, and a remainder of Fe and inevitable impurities; heating the cold-rolled steel sheet under the conditions of a dew point temperature in the range of -30 to -80°C and a heating temperature in the range of 450-500°C; cooling or maintaining the heated steel plate at a temperature in the range of 450-500°C; and performing a hot dip galvanizing process by dipping the cooled or maintained steel sheet into the hot dip galvanizing bath which comprises 0.13-0.25 wt% of aluminum and has a temperature in the range of 450-500°C. According to the present invention, the high manganese hot-dip galvanized steel sheet having ultra-high strength equal to or more than 1200 MPa and having excellent coatablity can be provided since surface thickening of alloy elements and formation of an oxide film can be suppressed by a low temperature heat treatment without additionally adding expensive alloy elements or performing a high temperature annealing. |
