Preparation method of nitrogen-containing beta titanium alloy

The invention relates to the technical field of titanium alloy preparation, and provides a preparation method of a nitrogen-containing beta titanium alloy, which comprises the following steps: S1) carrying out rough rolling on a nitrogen-containing beta titanium alloy forged blank to obtain a rough rolled plate; the rough rolling is rolling in the length direction or rolling in the width direction; (S2) forward finish rolling is conducted on the rough rolling plate, and a nitrogen-containing type beta titanium alloy thin plate is obtained; and S3) the nitrogen-containing beta titanium alloy sheet is subjected to double heat treatment, and the nitrogen-containing beta titanium alloy is obtained. The rolling technology of rough rolling and finish rolling is adopted, the problems of finished product defects such as edge cracking and warping of the nitrogen-containing beta titanium alloy sheet are effectively solved, and the forming rate of the alloy sheet is increased; and by carrying out a large number of heat