| 摘要 |
<p>PURPOSE:To manufacture steel structure with excellent hydrogen embrittlement resistance with good efficiency by a procedure in which at the time of continuous curve casting, impurities are made spherical by the addition of Ca, Ce, etc. to molten steel and floated to the upper side, and the upper side of slab and steel plate is controlled so that the upper side is not a fluid side containing wet H2S. CONSTITUTION:Impurities in molten steel are made spherical by the known method using Ca-Ce treatment by the addition of Ca and Ce to molten steel in a turndish. When the molten steel is sent to the cast mold 3 and then drawn out in the form of slab 2', the impurities 4 made spherical in the molten steel go up to the upper surface of the liquid phase 2b in the mold 3 by means of buoyancy but are dragged into slab because slab surface becomes solid phase 2a and drawn out continuously. In the case of continuous curve casting however, the impurities 4 center on the inside (upper side 2c) of curve. Thus, a mark 7 showing the upper side is put on the cut slab 2' and also on the rolled steel plate of the slab 2' for control and then steel structure is manufactured.</p> |
