The invention relates to a dendritic
structure control method for a high-strength and
toughness steel
forging, which comprises the following steps of: performing
electrode blank
rare earth treatment on the
forging produced by 4 percent Ni-Cr-Mo-V high-strength and
toughness steel; the method comprises the following steps of: mixing a
molten steel ingot with an electroslag remelting
slag system, melting speed and cooling into a whole, refining a uniform as-cast structure, reducing the secondary dendritic
crystal spacing of the as-cast structure, reducing dendritic
crystal segregation of elements such as Cr, Mo, V, Mn, Si and Ni, performing closed
extrusion on the high-temperature homogenized steel
ingot, increasing the transverse and
longitudinal deformation degree, breaking transverse and longitudinal columnar crystals, changing the direction of the columnar crystals, refining the uniform structure, and obtaining the high-temperature homogenized steel
ingot. The intermediate refined annealing blank is uniformly forged by a precision
forging machine to further smash secondary dendritic crystals and refine the structure, in application detection, the high-strength and high-
toughness forging manufactured by the method has macroscopic dendritic
crystal residue of less than 5%, the actual grain size of 8.5 grade, the normal-temperature yield strength of 1375Mpa-1401Mpa, the low-temperature
impact of-40 DEG C of 29.3 J-33.6 J, and the
impact difference value of the same test piece is below 6J.