A High Strength Steel Plate Having Superior Electric and Magnetic Shielding Property

PURPOSE: A high strength steel plate having superior electromagnetic shielding property of greater than 20 dB based on 1 mm and yield strength of greater than 25 kg/mm¬2. CONSTITUTION: The high strength steel plate comprises 0.012 wt.% or less of C+N; Mn 0.1 to 1.0 wt.%, Si 0.2 to 1.0 wt.%, Si+Al 0.2 to 1.2 wt.%, a balance of Fe and incidental impurities, wherein the steel plate is characterized in that Al content in the steel plate is 0.4 to 1.0 wt.%; a zinc coat is formed on the surface thereof; an organic resin coat is formed on the surface of the zinc coat; a powder including 17 to 99 wt.% of Mg(OH)2 with a specific surface area of greater than 1m¬2/g is coated thereon in the thickness of 15 to 60 micrometers. 전자기장 차폐성이 우수한 고강도 강판이 제공된다 본 발명은, 중량%로, C+N:0.012%이하, Mn:0.1~1.0%, Si:0.2~1.0%, Si+Al:0.2~1.2%, 잔부 Fe 및 불가피한 불순물로 조성되고, 그 항복강도가 항복강도 25kg/㎟이상이고 연신율이 35%이상인 전자파 차폐능이 우수한 고강도 강판에 관한 것이다. 본 발명의 강판은 전자파 차폐를 요하는 고강도 건축용 소재등으로 활용될 수 있다.