Production method of ultra-thin and ultra-wide low-temperature steel LT-FH32

The invention relates to a production method of ultrathin and ultra-wide low-temperature steel LT-FH32. The steel comprises the following chemical components in percentage by weight: 0.05%-0.07% of C, 0.10%-0.50% of Si, 1.30%-1.40% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.010%-0.015% of Nb, 0.008%-0.02% of Ti, 0.015%-0.05% of Al and the balance of Fe and inevitable impurities. The method comprises the key process steps of cogging, rolling and pre-straightening, the ultra-wide steel plate with the thickness of 6-10 mm and the thickness of 3800-4300 mm is produced through a heavy and medium plate rolling mill, the metallographic structure of the ultra-wide steel plate is ferrite and pearlite, and the grain size is 10-12 grades. The low-temperature steel has good obdurability and low yield ratio, the strength grade is LT-FH32, the impact energy at-60 DEG C is larger than or equal to 60 J, the yield ratio is smaller than or equal to 0.8, the unevenness of the steel plate can