Thickness and width specification 460MPa grade steel plate with good low-temperature toughness and manufacturing method thereof

The invention provides a thickness and width specification 460 MPa grade steel plate with good low temperature toughness and a manufacturing method thereof, the manufacturing method comprises the steps of molten iron pretreatment, converter smelting, LF treatment, RH vacuum treatment, continuous casting, casting blank slow cooling, heating, rolling and cooling, steel plate slow cooling, finishing, inspection and ultrasonic flaw detection, and the steel plate comprises the following components in percentage by weight: 0.04-0.07% of C, 0.10-0.35% of Si, 1.60-1.70% of Mn, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.015-0.035% of Al, 0.030-0.045% of Nb and the balance of Fe and inevitable impurities. The alloy comprises the following components in percentage by weight: 0.20-0.35% of Ni, 0.008-0.025% of Ti, 0.20-0.35% of Cr and the balance of Fe. The wide and thick steel plate produced by the method has good low-temperature toughness and can be widely applied to engineering machinery, o