| 摘要 |
PURPOSE: A preparation method of the high tensile backboard in the 500 MPa class is provided to have the good rolling productivity, the high strength, the high impact resistance and the high-temperature strength. CONSTITUTION: The preparation method of the high tensile backboard in the 500 MPa class comprises reheating slabs composed of 0.10 to 0.16 wt.% of C, 0.10 to 0.50 wt.% of Si, 1.00 to 1.60 wt.% of Mn, not more than 0.015 wt.% of P, not more than 0.010 wt.% of S, 0.015 to 0.050 wt.% of Al, 0.005 to 0.020 wt.% of Ti, 0.005 to 0.015 wt.% of Nb, 0.010 to 0.070 wt.% of V, 0.0020 to 0.0060 wt.% of N and the balance of Fe and the inevitable impurities at the temperature of 1150 to 1250 deg.C in a backboard heating furnace, followed by hot rolling with the condition having a pressing ratio of 15 to 30% per pass and a rolling finishing temperature of 900 to 950 deg.C, and then air cooling.
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