The invention belongs to the technical field of
metallurgy, and in particular relates to a spheroidizing annealing method for Cr and Mo steel with a sheet type
microstructure. The spheroidizing annealing method comprises the steps of putting a Cr and Mo steel rolled product sample into a
heating furnace, heating to 700-720 DEG C, preserving the temperature for 4-5 hours, then performing furnace cooling to 580-600 DEG C, taking out the Cr and Mo steel rolled product from the furnace, and cooling to
room temperature, wherein the microhardness of the Cr and Mo steel rolled product subjected to spheroidizing annealing is 162.20-175.35HV, and the
microstructure of the Cr and Mo steel rolled product consists of granular carbides dispersed on a
ferritic matrix; the granular carbides have spheroidized structures in the level 5-6. According to the method, sub-medium temperature is preserved for certain time, and then the furnace
cooling time is controlled, so that spheroidizing-annealed steel with high performance is obtained. The high preserved temperature is lower than the preserved temperature of the original technology, and the heat preservation time is shortened by almost three times, so that the
energy consumption is obviously reduced, and the spheroidizing annealing efficiency is improved; the
hardness of the steel subjected to the spheroidizing annealing technology is obviously reduced, the structure of a spheroidal
pearlite is dispersive and fine, and the spheroidizing rate is high; the Cr and Mo steel subjected to spheroidizing annealing is high in cold heading performance and has a good application prospect.