Preparation method of 20CrMo steel pipe

The invention relates to a preparation method of a 20CrMo steel pipe and belongs to the technical field of steel pipe preparation. The preparation method comprises the following steps that 20CrMo round steel is subjected to perforation under the condition of being heated to 1200 to 1250 DEG C to obtain a pipe blank, the perforation eccentricity is controlled, and the surface quality of the pipe blank is controlled; the pipe blank is introduced into an annealing furnace to be subjected to annealing, the annealing temperature and the annealing time are controlled, and an annealing pipe blank is obtained; the annealing pipe blank is introduced into a pipe rolling machine to be subjected to cold rolling, the number of reciprocating times of a machine head frame of the pipe rolling machine is controlled, the feeding length of the pipe blank in each time is controlled, and a rolled pipe is obtained; the rolled pipe is introduced into a heating furnace to be subjected to heating and heat insulation, the furnace discharge is carried out after the rolled pipe is cooled along with the furnace, and an annealing pipe blank is obtained; the annealing pipe blank is subjected to acid washing, phosphorization and saponification lubrication to obtain a pipe blank to be subjected to cold pulling; the pipe blank to be subjected to cold pulling is subjected to the cold pulling processing to obtain a cold pulling pipe; the cold pulling pipe is introduced into the annealing furnace to be subjected to finished product heat treatment, the finished product heat treatment temperature and the time are controlled, and the 20CrMo steel pipe is obtained. The preparation method has the advantages that the process steps are short, the hardness is high, and the energy source consumption is saved.