COLD ROLLED STEEL PLATE OF EXCELLENT MOLDABILITY, PANEL SHAPE CHARACTERISTICS AND DENTING RESISTANCE, MOLTEN ZINC PLATED STEEL PLATE, AND METHOD OF MANUFACTURING THESE STEEL PLATES

摘要

Disclosed is a cold-rolled steel sheet excellent in formability, panel shapeability and dent-resistance, comprising 0.005 to 0.015% by weight of C, 0.01 to 0.2% by weight of Si, 0.2 to 1.5% by weight of Mn, 0.01 to 0.07% by weight of P, 0.006 to 0.015% by weight of S, 0.01 to 0.08% by weight of sol. Al, not higher than 0.004% by weight of N (N </= 0.004%), not higher than 0.003% by weight of O (O </= 0.003%), 0.04 to 0.23% by weight of Nb, 1.0 </= (Nb% x 12)/(C% x 93) </= 3.0, and a balance of Fe and unavoidable impurities, said cold-rolled steel sheet meeting the relationship given below: <MATH> where 0.002 < epsilon </= 0.096, epsilon represents a true strain, sigma 0.2 represents a 0.2% proof stress, and sigma represents a true stress relative to epsilon .