The invention discloses a hot-rolled structural steel ST52 medium-
thick plate with the thickness of 15-60mm. The
thick plate comprises the following chemical components by weight percent (wt%): 0.10-0.16wt% of C, 0.25-0.45wt% of Si, 1.20-1.50wt% of Mn, less than or equal to 0.017wt% of P, less than or equal to 0.003wt% of S, 0.015-0.055wt% of Als, 0.020-0.040wt% of Nb, 0.010-0.020wt% of Ti and the balance of Fe and residual elements, wherein C equivalent amount [Ceq=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15] is less than or equal to 0.41. According to the invention, through KR molten iron pretreatment, converter
smelting,
argon blowing treatment, LF (
ladle furnace) refining, VD (vacuum degassing) refining,
continuous casting, heating, controlled rolling and controlled cooling and piling cooling processes and on the basis of ensuring the ST52 components, the contents of harmful elements such as P, S and the like, influencing the
plasticity and
toughness of the steel plate, in steel are strictly controlled, and simultaneously, the
heating system of rolled steel is strictly controlled; and in the rolling process, final rolling temperature, red returning temperature and
cooling speed are rigidly controlled, and methods such as steel plate stacking and
slow cooling and the like are adopted, the various properties of the ST52 steel plate with the thickness of 15-60mm reach standard requirements.