The invention relates to 4Cr5MoSiV1
hot work die steel, in particular to a preparation method for improving the performance of the 4Cr5MoSiV1
hot work die steel. The preparation method comprises the steps of producing highly-clean steel ingots with the total
oxygen content being 12 ppm by adopting electric furnace
smelting, vacuum carbon deoxidizing and
slag surface diffusing and
deoxidization refining, adding the pure
rare earth La and Ce on the
oxygen control condition and carrying out
argon shield pouring; carrying out diffusing and homogenizing annealing on the steel ingots and upsetting and drawing
forging on the steel ingots in the three-dimensional directions three times, fast cooling the steel ingots through water and air alternately after
forging, carrying out the processes of fast cooling after ultrahigh-temperature austenitizing and spheroidizing annealing before
quenching, carrying out
tempering with the temperature not lower than 590 DEG C 2-3 times after
quenching, and finally obtaining the stable tempered structure of the 4Cr5MoSiV1
hot work die steel. According to the invention, the single notched
impact property KV2 of the 4Cr5MoSiV1 hot work die steel is greater than or equal to 25 J, the average notched
impact property KV2 is greater than or equal to 30 J, the single non-notched
impact energy is greater than or equal to 280 J, the average non-notched
impact energy is greater than or equal to 320 J, the ratio of the transverse non-notched
impact energy to the longitudinal non-notched
impact energy is greater than or equal to 93%, and the
isotropy is excellent.