The invention belongs to the field of preparing steels and in particular relates to a thick steel plate with excellent rack arrest property and a preparation method of the thick steel plate. The thick steel plate is prepared from the following chemical components including a plain
carbon steel or a microalloy steel. The preparation method comprises the following steps:
water cooling while carrying out rolling deformation on a billet after being discharged out of a furnace, ensuring the temperature of the surface of the billet to be cooled to 400-800 DEG C during each rolling, ultra rapid cooling to 600-700 DEG C with the
cooling speed to be larger than or equal to 15 DEG C / s after rolling is finished, and finally,
air cooling to
room temperature. According to the thick steel plate and the preparation method disclosed by the invention, the tissue of the thick steel plate takes ferrite as a parent phase and a second phase as a
pearlite, the upper and lower surface
layers of the thick steel plate are both an ultra-
fine grain layer, the thickness of a single-sided ultra-
fine grain layer is larger than or equal to 0.1 times of the thickness of the thick steel plate, the ferrite average grain size of each ultra-
fine grain layer is smaller than or equal to 3 microns, and the
grain boundary density of a large angle boundary is larger than or equal to 0.676 microns<-1>. The thick steel plate is excellent in rack arrest property and improved in core
toughness and can be used for shipbuilding, in particular to structure materials of large container ships, offshore platforms,
crude oil,
natural gas conveying pipelines and the like.