| 摘要 |
PROBLEM TO BE SOLVED: To provide a high toughness thin steel sheet by making crystal grain submicron.SOLUTION: There is provided a high toughness thin steel sheet for toughening submicron austenite having high strength and plasticity and manufactured by (1) casting an ingot with smelt a steel containing C:0.19±0.02%, Mn:1.5±0.2%, Al:1.5±0.1%, Si:0.3±0.02% and the balance Fe, (2) holding a temperature at 1150±10°C for 1 to 3 h, then hot rolling and cooling to 750±10°C and holding the temperature for 0.5 to 1 h and water cooling to a room temperature, (3) cold rolling with 40 to 55%, (4) heating at 80 to 120°C/s to 750 to 850°C, holding the temperature for 120 to 180 sec. and then super high speed cooling at 80 to 100°C/sec. to 420±10°C and holding the temperature for 4 to 6 min. with controlling parameters such as a heat treatment and cooling.SELECTED DRAWING: Figure 1 |
