Method for forming large-size QCr0.8 alloy tapered cylindrical ring

A method for forming a QCr0.8 alloy tapered cylindrical ring, comprising:

• (S1) heating a raw material to 750-850° C. followed by upsetting and stretching at least twice to obtain a primary blank;
• wherein the raw material is a standard cylindrical part made of QCr0.8 alloy;
• (S2) heating the primary blank to 750-850° C. followed by upsetting and chamfering to obtain a secondary blank with a top end and a bottom end;
• wherein a diameter of the top end of the secondary blank is greater than a diameter of the bottom end of the secondary blank;
• (S3) subjecting the secondary blank to backward extrusion to process the top end and the bottom end of the secondary blank to obtain a preform;
• (S4) machining the preform to remove a flash and a bottom residue of the preform;
• (S5) subjecting a bottom end of the preform to local bulging to enable a shape and a size of the bottom end of the preform to match a shape and a size of a drive roller in a forming tooling, so as to form a profiled ring blank;
• and
• (S6) rolling the profiled ring blank by using a radial-axial ring rolling machine in combination with the forming tooling to form a tapered cylindrical ring;
• wherein the step (S3) is performed through steps of:
• heating the secondary blank to 750-850° C. at a heating coefficient of 0.4-0.6 min/mm;
• subjecting the secondary blank to one-step extrusion molding on a press machine;
• and
• performing air cooling after forging to form the preform with a cone angle of 40-90° and a bottom diameter of Φ330-480 mm;
• wherein a final forging temperature is not less than 650° C.