HIGH STRENGTH STEEL PLATE HAVING SUPERIOR ELECTROMAGNETIC SHIELDING PROPERTY

摘要

PURPOSE: Provided is a high strength steel plate having superior electromagnetic shielding property of greater than 25 dB based on 1 mm and yield strength of greater than 22 kg/mm¬2. CONSTITUTION: The high strength steel plate comprises 0.0150 wt.% or less of C+N+S, Mn 0.2 to 0.8 wt.%, 0.6 wt.% or less of Al, 0.4 wt.% or less of Si, 0.1 to 0.6 wt.% of total sum of at least one elements selected from Cu and Sn, a balance of Fe and incidental impurities, wherein Mn+Cu+Sn+Si+Al is less than 1.0 wt.%; C and N are less than 0.0030 wt.%, respectively; S is less than 0.0090 wt.%. The steel plate is characterized in that a zinc coat is formed thereon; an organic resin coat is formed on the surface of the zinc coat; a powder including 17 to 99 wt.% of Mg(OH)2 is coated thereon with a specific surface area of greater than 1m¬2/g.