| 摘要 |
PURPOSE:To decrease energy consumption by rationalization of a heat treatment by hardening a steel plate right after hot rolling and cooling the same quickly to prescribed temp. then cooling the steel plate slowly and tempering the same without reheating from said temp. CONSTITUTION:A steel plate 3 hot-rolled by continuous rolling mills 1, 2 is passed through a leveler 4, and is then cooled with water at about >=10 deg.C/sec cooling rate by a forced cooler 5. When the temp. of the plate 3 attains about a 400-600 deg.C range, the quick cooling by the cooler 5 is finished. After the end of the hardening treatment by the cooler 5, the steel plate 3 is conveyed to the charging side 8 of a slow cooling hearth 7 for tempering by a roller table 6 and is charged successively into the hearth 7. The plate 3 charged successively therein is transferred on the hearth 7 in the direction intersecting with the rolling line, and during this time the hot wind ascending from the plate 3 is shut off by a heat insulating cover 9; therefore the plate 3 is cooled slowly in an optimum high temp. atmosphere and is removed through a discharge port 10. |
