Control method for hot forging structure property of Mn18Cr18N steel retaining ring

Abstract

The invention relates to a control method for the hot forging structure property of a Mn18Cr18N steel retaining ring, belongs to the technical field of a metal pressure machining. The operation method of the invention comprises the following steps: (1) sheathing a soft steel sleeve outside blanks and putting the soft steel sleeve and the blanks together into a heating furnace to be heated to 1180-1220 DEG C; (2) putting the heated blanks wrapped with the sleeve externally into a cylinder die and punching the blanks by utilizing a plunger chip; when the plunger chip load is increased to the load allowed by a press machine, replacing a chassis by a drain cap to carry out extrusion and losing the gross weight; (3) putting the annular blanks which is extruded into the heating furnace to be heated to 1100-1150 DEG C and keeping the temperature for 1-3 hours; (4) carrying out the broaching on a mandrel at the first circle and controlling the deformation amount between 13-18%; (5) when the temperature in the broaching process is reduced below the final forging temperature, putting into the heating furnace and heating to 1100 DEG C as well as keeping the temperature for 1 hour; (6) carrying out the broaching on a mandrel at the second circle and controlling the deformation amount between 9-13%; (7) when the temperature in the broaching process is reduced below the final forging temperature, putting into the heating furnace again and heating to 1100 DEG C as well as keeping the temperature for 1 hour; and (8) continuously carrying out the broaching on the mandrel until the dimension requirements are met. The method has the advantages that the phenomenon of generating cracks on the surface of a forge piece in the deformation process in the prior art can be prevented; and the deformation on the external surface of the forge piece is increased in the multiple broaching processes of the mandrel, thereby refining grains more uniformly and improving the quality of the forge piece.

Description

technical field [0001] The invention belongs to the field of metal pressure processing, and in particular relates to a method for controlling the microstructure and properties of Mn18Cr18N steel retaining ring hot forging. Background technique [0002] The retaining ring is a non-magnetic steel ring installed at both ends of the generator rotor to tighten the end coils. It bears huge centrifugal force during high-speed rotation, alternating stress caused by periodic motion, complex assembly stress, bending stress and concentrated stress caused by uneven structure. The stress situation is extremely complicated, the working conditions are special, and the manufacturing is extremely difficult. It is one of the key components of thermal power generation equipment. In order to ensure the safe operation of the generator, it is required that the retaining ring should have sufficient strength, good toughness, uniform structure and minimum residual stress, so the manufacturing techn...

AI Technical Summary

Problems solved by technology

However, due to the large extrusion force required in the extrusion process, it cannot be used for punching large holes, and the surface deformation of the inner hole of the billet is large during the extrusion process, while the deformation of the outer diameter surface is small, resulting in the overall crystallization of the forging. Uneven grain distribution