| 摘要 |
Production of a hot strip having a tensile strength of at least 800 N/mm<2> comprises casting a steel into a pre-material, such as thin slabs or cast strip; hot rolling the pre-material at a final temperature lying above the Ar3 temperature to form a hot strip; cooling in a first cooling step at a cooling speed of at least 150 K/s to 500-700 degrees C; and cooling in a second cooling step after a 3-10 seconds cooling pause to a coiling temperature. The coiling temperature is more than 580 degrees C for hot strips having a yield point of more than 690 MPa and a tensile strength of less than 900 MPa. The coiling temperature is 580 degrees C or less for hot strips having a yield point of not more than 690 MPa and a tensile strength of less than 900 MPa. The coiling temperature is not more than 250 degrees C for hot strips having a tensile strength of less than 900 MPa. <??>The steel contains (in wt.%): 0.03-0.10 C, not more than 0.8 Si, 1.2-2.0 Mn, 0.02-0.06 Al, not more than 0.5 Cr, not more than 0.2 Ti, not more than 0.08 Nb, less than 0.005 Ca, less than 0.05 Cu, less than 0.05 Ni, less than 0.02 P, less than 0.005 S, less than 0.01 N and a balance of Fe. <??>Preferred Features: The steel contains 0.05-0.07 wt.% C and 0.3-0.8 wt.% Si. |
