STEEL SHEET FOR BUILDING BOX COLUMN EXCELLENT IN CRACK RESISTANCE IN HEAT-AFFECTED ZONE AT LARGE HEAT INPUT WELDING AND ITS MANUFACTURE

摘要

PURPOSE: To inexpensively manufacture a steel sheet for building box columns excellent in crack resistance in heat-affected zone at the time of large heat input welding by hot-rolling a low carbon steel slab having a specified composition contg. small contents of Si, S, etc. ;CONSTITUTION: A continuous cast slab contains, by wt.%, 0.06-0.18% C, 0.05% Si, 0.80-1.60% Mn, 0.015% P, 0.003% S, 0.005-0.080% Al, or further 0.10-0.40% Cu, 0.10-0.40% Ni or respectively singly or compositely one or two kinds of 0.010-0.05% V, 0.005-0.05% Ti and 0.005-0.050% Nb, is heated to ≥1300°C and made to a hot rolled steel sheet by hot rolling. In the case where the box column or the like is assembled with large heat input submerged arc welding, the high-tensile steel sheet without generating hydrogen crack in the heat- affected zone in corner joint parts and having tensile strength of 490 MPa grade is easily manufactured at a low cost.;COPYRIGHT: (C)1995,JPO