The invention discloses a manufacturing technique of a heavy piece-weight thick steel plate used for an offshore wind
turbine tower tube. The chemical components of the used
continuous casting slabs are as follows: 0.08-0.16% of C, 0.20-0.50% of Si, 1.10-1.60% of Mn, less than or equal to 0.010% of S, less than or equal to 0.010% of P and less than or equal to 0.50% of micro-alloyed elements; and at least two
continuous casting slabs are provided with grooves, overlapped and welded into a big-thickness
continuous casting blank by using a combined
welding technique of gas shielded
welding, submerged-
arc welding and
electron-bombardment
welding, and then, the blank is arranged in a
bogie-type furnace or a soaking pit furnace for heating, rolled by a
thick plate rolling
machine after being discharged from the furnace, cooled under control and subjected to heat treatment so as to obtain the heavy piece-weight thick steel plate used for the offshore wind
turbine tower tube. The technique has the following characteristics that the maximum piece weight of the steel plate used for the offshore wind
turbine tower tube is 40t, the requirement of reducing welding lines in the tower tube manufacturing process is satisfied, the manufacturing technique is simple in production process, high in yield, high in ultrasonic flaw
detection rate of more than 98% and excellent in each factor such as low-temperature roughness, Z-direction performance and the like.