CN102350474B - Control method for hot forging structure property of Mn18Cr18N steel retaining ring - Google Patents

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

Mn18Cr18N 18 N steel guard ring forge hot structure property control method

Technical field

The invention belongs to stress metal manufacture field, be specifically related to a kind of Mn18Cr18N 18 N steel guard ring forge hot structure property control method.

Background technology

Retaining ring is the nonmagnetic steel loop that is contained in generator amature two ends, for lock ring end coil.In High Rotation Speed, bear huge centrifugal force, bear the alternate stress of periodic motion generation, the concentrated stress effect of erection stress, bending stress and the inhomogeneous generation of structure of complexity, force-bearing situation is extremely complicated, operating mode is special, manufacture difficulty is very big, is one of key member of thermoelectricity generating equipment.In order to guarantee the safe operation of generator, require retaining ring should there is enough intensity, good toughness, uniform structure property and minimum residual stress, thereby manufacturing technology requires very high.In tradition, organize aspect Properties Control just along with flat-die forging base is shaped and obtain tissue, namely only guarantee forging shape and uncontrollable tissue, all uncontrollable in heating times, heating schedule and deformation process in forming process, and even the structure property after distortion is very inhomogeneous, have influence on final products performance uneven.And patent ZL 200510012565.2 " a kind of method and mould of making circular cog hot forged from generator protective ring " is: mild steel jacket is heated together, be then placed in a mould, its upper surface is put drift and pressed down punching.When punch load rises to press apparatus allowable load, to change drain cap and wash out gross weight, forming process finishes.This technique is used mould constraint to be shaped, and has replaced the core bar drawing work step in traditional handicraft, and blank is in compressive stress state, has solved the problem of blank surface cracking.But because extruding force required in impact extrusion process is very large, causing can not be for rushing macropore, and blank bore area deflection is large in impact extrusion process, and external diameter surface deflection is little, causes the whole crystal grain skewness of forging.

Summary of the invention

The object of this invention is to provide a kind of Mn18Cr18N 18 N steel guard ring forge hot structure property control method, can effectively overcome the shortcoming that prior art exists.

The present invention realizes by following process:

1. the outside that mild steel jacket is sleeved on to blank is placed on together in heating furnace and is heated to 1180～1220 ℃;

2. the moulds of industrial equipment of punching being used are placed on press platform, then the blank that warmed-up outside is surrounded by mild steel jacket is put into a mould, with drift to its punching, when punch load rises to press apparatus allowable load, remove the chassis of bottom, change drain cap and carry out impact extrusion, wash out gross weight;

3. the annular blank again impact extrusion being become is put into heating furnace and is heated to 1100 ℃～1150 ℃, is incubated 1～3 hour;

4. carry out the reaming of first lap plug, deflection is controlled at 13%～18%;

5. in reaming process when temperature is reduced to final forging temperature when following, then put heating furnace into and be heated to again 1100 ℃, be incubated 1 hour;

6. carry out the second circle plug reaming deflection and be controlled at 9%～13%;

7. when temperature is reduced to final forging temperature when following, then put into heating furnace and be heated to 1100 ℃, be incubated 1 hour;

8. proceed plug reaming, until reach dimensional requirement.

Advantage of the present invention and good effect are: the phenomenon that in the deformation process that 1. can prevent from existing in prior art, forging surface cracks; 2. in plug reaming process repeatedly, suitably increase the distortion of forging outer surface, made grain refinement more even, improved the quality of forging.

The specific embodiment

1. the outside that No. 20 mild steel jackets of 20mm is sleeved on to φ 820mm * 1100mm blank is placed on together in heating furnace and is heated to 1200 ℃;

2. the blank that warmed-up, outside is surrounded by mild steel jacket is put into a mould, with drift, it is pressed down to punching, when punch load rises to press apparatus allowable load, remove chassis, change drain cap and wash out gross weight, obtain the ring base that is of a size of φ 910/ φ 400mm * 1100mm;

3. the better ring base of impact extrusion is put into heating furnace and be heated to 1100 ℃～1150 ℃, be incubated 1 hour;

4. carry out the reaming of first lap plug, deflection is controlled at 40mm;

5. when reaming process temperature is reduced to final forging temperature when following, then ring base is put into heating furnace be heated to again 1100 ℃, be incubated 1 hour;

6. carry out the second circle plug reaming, deflection is controlled at 25mm;

7. when temperature is reduced to final forging temperature when following, then put into heating furnace and be heated to 1100 ℃, be incubated 1 hour;

8. proceed plug reaming, until diffuse into size, reach φ 1000/ φ 620mm * 1100.

Adopt the method can obtain 3～4 grades of tissues uniformly.

Claims (1)

1. a Mn18Cr18N retaining ring forge hot structure property control method, comprise to blank heat, punching, heat again, plug reaming link, it is characterized in that operating procedure is as follows:

1. the outside that mild steel jacket is sleeved on to blank is placed on together in heating furnace and is heated to 1180 ~ 1220 ℃;

2. the frock of punching being used is placed on press platform, then the blank that warmed-up outside is surrounded by mild steel jacket is put into a mould, with drift to its punching, when punch load rises to press apparatus allowable load, remove the chassis of bottom, change drain cap and carry out impact extrusion, wash out gross weight;

3. again impact extrusion blank is circlewise put into heating furnace and be heated to 1100 ℃ ~ 1150 ℃, be incubated 1 hour;

4. carry out the reaming of first lap plug, deflection is controlled at 18%;

5. in reaming process, temperature is reduced to final forging temperature when following, puts heating furnace into and is heated to 1100 ℃ again, is incubated 1 hour;

6. carry out the second circle plug reaming, deflection is controlled at 9%;

7. when temperature is reduced to final forging temperature when following, then put into heating furnace and be heated to 1100 ℃, be incubated 1 hour;

8. proceed plug reaming until reach dimensional requirement.