Austenitic light-weight high-strength steel with excellent properties of welds, and method of manufacturing the same

A method of manufacturing an austenitic steel, the method comprising:

• hot-rolling a steel including 20 wt % to 30 wt % of manganese (Mn), 6 wt % to 12 wt % of aluminum (Al), 0.6 wt % to 1.5 wt % of carbon (C), 0.3 wt % to 0.95 wt % of vanadium (V), and a remaining amount of iron (Fe) and other unavoidable impurities;
• homogenizing the hot-rolled steel;
• and
• aging the homogenized steel,
• wherein hot-rolling the steel comprises:
• hot-rolling the steel under a finish rolling temperature ranging from 900° C. to 1000° C.;
• and
• cooling the steel to 600° C. or less, wherein cooling the steel comprises cooling the steel at an average cooling rate ranging from 10° C./sec to 50° C./sec, and
• wherein aging the homogenized steel comprises:
• aging the homogenized steel at a temperature ranging from 540° C. to 560° C. for 10 minutes or more;
• and
• cooling the steel to a temperature of 200° C. or less, at an average cooling rate of 10° C./sec or less.