Steel material for brake disc of motor vehicle having excellent wear resistance and high temperature strength and method of manufacturing the same

A method of manufacturing a steel material for a brake disc of a motor vehicle having excellent wear resistance and high temperature strength, the method comprising:

• heating a steel slab in a temperature range of 1050 to 1250° C., the steel slab including, by weight:
• 0.02 to 0.07% of carbon (C), 0.1 to 0.5% of silicon (Si), 0.2 to 0.7% of manganese (Mn), 0.05% or less (excluding 0) of phosphorus (P), 0.02% or less (excluding 0) of sulfur (S), 0.07% or less (excluding 0) of aluminum (Al), 0.1 to 0.5% of chromium (Cr), 0.3 to 1.0% of molybdenum (Mo), 0.05% or less (excluding 0) of vanadium (V), 50 ppm or less (excluding 0) of boron (B), 0.01 to 0.5% of nickel (Ni), 0.5% or less (excluding 0) of copper (Cu), 0.02% or less (excluding 0) of titanium (Ti), 0.05% or less (excluding 0) of niobium (Nb), and 2 to 100 ppm of calcium (Ca), with a balance of Fe and other unavoidable impurities and satisfying the following Relational Expressions 1 and 2;
• roughly rolling the heated steel slab in a temperature range of 950 to 1050° C. to obtain a roughly rolled bar;
• subjecting the roughly rolled bar to finish hot rolling in a temperature range of 850 to 950° C. to obtain a hot rolled steel plate;
• air-cooling the hot rolled steel plate to room temperature, and reheating the steel plate in a temperature range of 880 to 930° C. for a residual time 1.3t+10 minutes (t:
• plate thickness (mm)) or more;
• and
• cooling the reheated hot rolled steel plate to 150° C. or lower at a cooling rate of 10° C./s or more:
• 260≤1589×[C]+228≤340 [Relational Expression 1]
• [C]/[Mo]≤0.250 [Relational Expression 2]
• wherein [C] and [Mo] are in % by weight.