| 摘要 |
<p>PURPOSE: A high strength steel sheet having ultra low temperature toughness and a manufacturing method thereof are provided to obtain superior toughness of steel materials for a tank in ultra low temperatures environment and to obtain tensile strength over 490MPa. CONSTITUTION: A high strength steel sheet having ultra low temperature toughness is composed of 0.02-0.06 wt.% of C, 0.1-0.35 wt.% of Si, 1.0-1.6 wt.% of Mn, below 0.02 wt.% of Al, 0.7-2.0 wt.% of Ni, 0.4-0.9 wt.% of Cu, 0.003-0.015 wt.% of Ti, 0.003-0.02 wt.% of Nb, below 0.01 wt.% of P, below 0.005wt.% of S, residual iron, and inevitable impurities. High strength steel sheets having superior ultra low temperature toughness satisfy[Mn]+5.4[Si]+26[Al]+32.8[Nb]<4.3. In the equation, the[Mn],[Si],[Al], and[Nb]implies wt% unit content of the Mn, Si, Al, and Nb.</p> |
