| 摘要 |
PURPOSE:To obtain a high tension steel having superior toughness at low temp. in the welding heat-affected zone by reducing the amount of Al in a boron steel, also reducing the amount of N to a very low value without adding Ti, and adding a very small amount of Nb. CONSTITUTION:The composition of a steel is composed of, by weight, 0.01- 0.15% C, <0.6% Si, 0.5-2.5% Mn, <0.005% S, 0.005-0.05% Al, 0.003-0.1% Nb, 0.0003-0.003% B, <0.002% N and the balance Fe with inevitable impurities. One or more among <0.004% Ti, 0.05-4% Ni, 0.05-0.5% Cu, 0.05-0.5% Cr, 0.05- 0.5% Mo, 0.005-0.1% V, 0.001-0.05% REM and 0.0005-0.005% Ca may be further contained in the composition.
|
