CN115283592A - Forging and heat treatment process of 7050 aluminum alloy large ring piece - Google Patents

Abstract

A forging and heat treatment process for a large ring piece of 7050 aluminum alloy, the steps of which are: S1. ingot size design; S2. ingot heating; S3. tool die preheating; S4. ingot forging; S5. return to furnace for heat preservation; S6. Punching; S7. Return to furnace for heat preservation; S8. Horse frame reaming; S9. Return to furnace for heat preservation again; S10. Ring rolling; S11. Machining; S12. Solution treatment; S13. Cold deformation; Machined again. The invention provides a full-process forming and heat treatment process scheme for large-scale 7050 aluminum alloy rings. The ingot is fully forged through the multi-directional forging process, and the residual crystal phase in the as-cast structure is broken. Gradually increase the solid solution temperature and prolong the solid solution time to reduce the undissolved crystal phase and increase the solid solution degree. The shape and distribution of intragranular and grain boundary precipitates are controlled by two-stage aging, so that the product has both high strength and high stress corrosion resistance.

Description

Forging and heat treatment process of a 7050 aluminum alloy large ring

technical field

The invention relates to the technical field of plastic forming and heat treatment of aluminum alloys, in particular to a forging and heat treatment process of a 7050 aluminum alloy large ring.

Background technique

Large rings are widely used in heavy machinery, aerospace and energy fields. In the field of aerospace, 2A14 and 2219 aluminum alloys are mainly used for large ring parts, but the strength of 2XXX aluminum alloys is lower than that of 7XXX aluminum alloys, which can no longer meet the service requirements of special products. Therefore, 7XXX aluminum alloys are currently the key research objects of aerospace models. 7XXX series aluminum alloys have the advantages of high specific strength, high yield strength ratio, and good stress corrosion resistance as super duralumin. Among them, 7050 aluminum alloy has high comprehensive performance and is mainly used to manufacture components that withstand high loads.

The large ring is the main load-bearing component in the tank structure of the aerospace vehicle. During service, it is subjected to multiple forces such as radial pressure, axial pressure and bending moment. The stress state is complex and the comprehensive performance requirements are high. 7050 aluminum alloy The manufacture of large rings is a key technology in the development of storage tanks for aerospace vehicles. However, there are few researches and manufactures on large rings made of 7050 aluminum alloy in China, and there is no mature and stable deformation and heat treatment process for reference.

Contents of the invention

In order to solve the above problems, the present invention provides a forging and heat treatment process of a 7050 aluminum alloy large-scale ring. The product manufactured by this process has uniform structure and high comprehensive performance.

The technical scheme adopted in the present invention:

A kind of forging and heat treatment process of 7050 aluminum alloy large-scale ring, its steps are:

S1. Ingot size design: The raw material is 7050 aluminum alloy semi-continuous ingot, and the ingot size is designed according to the size of the part, and the ratio of height to diameter is required to be L/D=2～2.5;

S2. Ingot heating: use an electric furnace to heat the 7050 aluminum alloy ingot, install the furnace at room temperature, and raise the temperature to 430±5°C with the furnace, and the heat preservation coefficient is 2.2～3min/mm;

S3. Tool and mold preheating: heat the upper and lower hammer anvils in a heating furnace, keep them warm at 250°C for 6-10 hours, and apply lubricant after installation;

S4. Ingot re-forging: The ingot is re-forged by three-upsetting, three-drawing and multi-directional forging, that is, one upsetting and drawing deformation is performed along the three directions perpendicular to each other of the ingot, and the last time is carried out along the axial direction of the ingot. Upsetting deformation, after upsetting, the cake blank is obtained, and the height of the blank is 120-500mm;

S5. Heat preservation in the furnace: keep the cake base at 430±5°C for 4-6 hours;

S6. Punching: Place the punch in the center of the cake base after preheating and lubricating, and press it down slowly several times. After pulling out the punch each time and before pressing down, you need to apply lubricant, and the final thickness of the skin is 100~ 150mm, and then the final punch;

S7. Return to the furnace again for heat preservation: heat the cake base at 430±5°C for 4-6 hours;

S8. Horse frame reaming: Carry out horse frame reaming and flat end face to the blank after punching to prepare ring blank;

S9. Return to the furnace again for heat preservation: heat the cake-shaped billet at 430±5°C for 4 to 6 hours;

S10. Ring rolling: Preheat the rolls before rolling, keep them warm at 250°C for 3-5 hours, the main roll speed of the ring rolling mill is 0.5-0.6m/s, the diameter growth rate is 2-3mm/s, and monitor during the ring rolling process Material temperature, to ensure that the final forging temperature is not lower than 380°C;

S11. Machining: process the surface of the ring after ring rolling, especially the upper and lower end faces, to ensure that there is no folding damage on the end face and inner and outer circular surfaces.

S12. Solution treatment: use graded solution treatment to carry out solution treatment on the ring, put it into the furnace when it reaches the temperature, start timing when the furnace temperature reaches 465°C, the holding time is the effective size × (1.6 ~ 1.8) min; Raise to 475°C, keep warm for 0.6-0.7min; finally raise the furnace temperature to 480°C, keep warm for 0.6-0.7min, and cool the parts in water for no less than 20min after they are out of the furnace and quenched.

S13. Cold deformation: after the parts are taken out from the quenching tank, they are cold forged in time, and deformed by cold pressing in the height direction of the ring, and the deformation is controlled at 2-3%;

S14 Aging treatment: after cold forging, the parts are aged in time, and the rings are aged by double-stage aging. As the furnace heats up, the rings are kept at 121°C for 4-6 hours, and then at 176°C for 4-6 hours, and the rings are released from the furnace. air cooling;

S15 Remachining: Machining the aged rings to the target delivery size.

In the S4 step, after three piers and three pulls, ensure that the length direction after the last elongation is the height direction of the original ingot, and ensure that the upsetting deformation in the process is 55-65%, and the elongation deformation is 40-40%. 50%.

The material temperature is monitored in real time during the reforging process of the ingot in step S4 to ensure that the final forging temperature is not lower than 380°C.

The temperature of the blank after the punching step in the step S6 is not lower than 380°C.

The material temperature is monitored in real time during the saddle reaming process in step S8 to ensure that the final forging temperature is not lower than 380°C.

In step S10, when the temperature is close to 400°C during the ring rolling process, the diameter growth rate is increased, and when the temperature is close to 440°C during the rolling process, the diameter growth rate is decreased.

The S13 cold deformation process is followed by aging in time, and the interval between the cold deformation and aging process is within 30 minutes.

Beneficial effects of the present invention: The present invention provides a full-flow forming and heat treatment process plan for large-scale 7050 aluminum alloy rings with a diameter of 5m. The ingot is fully forged through a multi-directional forging process, and the residual in the as-cast structure is broken. The crystalline phase, through multi-stage solid solution strengthening, gradually increases the solution temperature, prolongs the solution time, reduces the undissolved crystalline phase, and increases the degree of solid solution. The morphology and distribution of precipitated phases in the grain and grain boundary are regulated by double-stage aging, so that the product has both high strength and high stress corrosion resistance.

Description of drawings

Fig. 1 is the metallographic photograph enlarged 100 times of the 7050 aluminum alloy large ring of the present invention.

Fig. 2 is the metallographic photograph enlarged 500 times of the 7050 aluminum alloy large ring of the present invention.

Detailed ways

The invention relates to a forging and heat treatment process of a 7050 aluminum alloy large-scale ring, which manufactures a 5-meter-level 7050 aluminum alloy large-scale ring with uniform structure and high comprehensive performance by means of multi-directional forging, multi-stage solid solution, double-stage aging and the like.

Example 1

For a 7050 aluminum alloy 5-meter ring in a certain aerospace vehicle, the part size is Φ5030×Φ4984×80mm, considering the process consumption, machining allowance, sampling ring and other factors, the design forging size is Φ5070×Φ4885×105mm;

S1. Ingot size design: The raw material is 7050 aluminum alloy semi-continuous ingot, and the ingot size is designed to be Φ580×1230 according to the size of the part;

S2. Ingot heating: use an electric furnace to heat the 7050 aluminum alloy ingot, install the furnace at room temperature, and raise the temperature to 430±5°C with the furnace, and the holding time is 580×2.5min/mm=1450min;

S3. Tool and mold preheating: heat the upper and lower hammer anvils in a heating furnace, keep them warm at 250°C for 8 hours, and apply lubricant after coming out of the furnace for installation;

S4. Ingot reforging: adopt the method of three upsetting and three drawing multi-directional forging to reforge the ingot, first upsetting along the Z direction of the ingot to H=500mm, and then drawing along the X direction to 540×540×1115mm, Then upsetting along the X direction to H=500mm, then upsetting along the Y direction to 540×540×1115mm, then upsetting along the Y direction to H=500mm, and then upsetting along the Z direction to 540×540×1115mm, three upsetting After the third drawing, the billet axially returns to the Z direction of the original ingot, and then upsets along the Z direction to H=200mm. During the reforging process, the material temperature is monitored in real time to ensure that the final forging temperature is not lower than 380°C;

S5. Return to the furnace for heat preservation: heat the cake-shaped billet at 430±5°C for 5 hours;

S6. Punching: After preheating and lubricating the punch, place it in the center of the cake base, and press it down slowly several times. After pulling out the punch each time and before pressing down, apply lubricant. The final thickness of the skin is 120mm. Then carry out final punching to ensure that the temperature of the blank after punching is not lower than 380°C;

S7. Heat preservation in the furnace: heat the cake-shaped blank at 430±5°C for 5 hours;

S8. Horse frame expansion: Carry out horse frame expansion and flatten the end face of the punched blank to prepare a ring blank with a size of Φ2200×Φ1740×205mm. During the horse expansion process, the material temperature is monitored in real time to ensure that the final forging temperature is not lower than 380 ℃;

S9. Return to the furnace for heat preservation again: heat the cake-shaped billet at 430±5°C for 5 hours;

S10. Ring rolling: preheat the rolls before rolling, and keep the temperature at 250° C. for 5 hours. The speed of the main roll of the ring rolling mill is 0.6m/s, the diameter growth rate is 2.5mm/s, and the rolling is to Φ5090×Φ4840×150mm. During the ring rolling process, the temperature of the material is monitored to ensure that the final forging temperature is not lower than 380°C. During the rolling process, the temperature When the temperature is close to 400°C, the diameter growth rate is increased to 3mm/s, and when the temperature is close to 440°C during the rolling process, the diameter growth rate is reduced to 2mm/s.

S11. Machining: Surface processing of ring parts after ring rolling, especially the upper and lower end faces, to ensure that the end faces and inner and outer circular surfaces have no folding damage, etc., and process to Φ5090×Φ4840×130mm.

S12. Solution treatment: use graded solid solution to carry out solution treatment on the ring, put it into the furnace when it reaches the temperature, start timing when the furnace temperature reaches 465°C, and keep it for 220 minutes; then raise the furnace temperature to 475°C and keep it for 80 minutes; finally put The furnace temperature was raised to 480°C and kept for 80 minutes. After the parts are out of the furnace and quenched, the cooling time in water should not be less than 20 minutes.

S13. Cold deformation: After the parts are taken out of the quenching tank, they are cold forged in time (the process interval is controlled within 30 minutes), and they are cold-pressed and deformed in the height direction of the ring, and the deformation is controlled at 3-4.5mm.

S14. Aging treatment: After the parts are cold forged, they are aged in time, and the process interval is controlled within 30 minutes. The rings are aged by double-stage aging, and the temperature is raised with the furnace. The rings were incubated at 121°C for 6h and then at 176°C for 4h. The rings come out of the oven and are air-cooled.

S15. Machining: ring parts are processed to the target delivery size Φ5070×Φ4885×105mm.

After testing, the microstructure of the 5m ring manufactured by a 7050 aluminum alloy large ring forging and heat treatment process is shown in Figure 1. The mechanical properties are shown in Table 1,

Table 1

It can be seen from Figure 1 and Figure 2 that the 7050 aluminum alloy large-scale rings treated by this process have uniform structure and fine grains, and the grain size is about 10-20 μm. It can be seen from Table 1 that the mechanical properties of the parts are relatively high. The tangential strength is 600MPa and the elongation is 13%. The tangential strength is 546MPa and the elongation is 7.8%. The tangential strength is 580MPa and the elongation is 6%.

The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention, and cannot be considered as limiting the implementation scope of the present invention. All equivalent changes and improvements made according to the application scope of the present invention shall still belong to the scope covered by the patent of the present invention.

Claims (7)

1. A forging and heat treatment process for a large 7050 aluminum alloy ring piece is characterized by comprising the following steps:

s1, designing the size of an ingot: the raw material adopts 7050 aluminum alloy semi-continuous ingot casting, the size of the ingot casting is designed according to the size of a part, and the height-diameter ratio L/D = 2-2.5 is required;

s2, ingot casting heating: heating the 7050 aluminum alloy cast ingot by an electric furnace, charging at room temperature, heating to 430 +/-5 ℃ along with the furnace, and keeping the heat preservation coefficient at 2.2-3 min/mm;

s3, preheating a tool and a die: heating the upper and lower hammering blocks in a heating furnace, preserving heat for 6-10 h at 250 ℃, and smearing a lubricant after discharging and mounting;

s4, ingot casting and forging changing: the ingot is re-forged by adopting a three-upsetting three-drawing multidirectional forging mode, namely, the ingot is subjected to upsetting and drawing deformation once in three mutually vertical directions, then the ingot is subjected to upsetting deformation for the last time in the axial direction, and a cake blank is obtained after upsetting, wherein the height of the blank is 120-500 mm;

s5, returning and preserving heat: keeping the cake blank at 430 +/-5 ℃ for 4-6 h;

s6, punching: preheating and lubricating a punch, placing the punch in the center of a cake blank, slowly pressing down for multiple times, smearing a lubricant after pulling out the punch each time and before pressing down, and finally punching after the thickness of the continuous crust is 100-150 mm;

s7, re-melting and preserving heat: keeping the cake blank at 430 +/-5 ℃ for 4-6 h;

s8, trestle reaming: carrying out trestle reaming and end surface leveling on the punched blank to prepare a ring blank;

s9, returning again for heat preservation: keeping the cake-shaped blank at the temperature of 430 +/-5 ℃ for 4-6 h;

s10, ring rolling: preheating a roller before rolling, keeping the temperature at 250 ℃ for 3-5 h, keeping the rotating speed of a main roller of a ring rolling mill at 0.5-0.6 m/s, the diameter growth rate at 2-3 mm/s, monitoring the material temperature in the ring rolling process, and ensuring that the finish forging temperature is not lower than 380 ℃;

s11, machining: processing the surface of the ring piece after ring rolling, particularly processing the upper end face and the lower end face, and ensuring that the end face and the inner and outer circular faces are free from folding damage;

s12, solid solution treatment: carrying out solid solution treatment on the ring piece by adopting graded solid solution till Wen Rulu, starting timing when the furnace temperature reaches 465 ℃, and keeping the temperature for 1.6-1.8 min; then the furnace temperature is raised to 475 ℃, and the temperature is kept for 0.6 to 0.7min; finally, the temperature of the furnace is increased to 480 ℃, the temperature is kept for 0.6-0.7 min, and the time for cooling the parts in water after the parts are taken out of the furnace and quenched is not less than 20min;

s13, cold deformation: the part is taken out from the quenching tank and then is subjected to cold forging in time, and is subjected to cold pressing deformation in the height direction of the ring piece, wherein the deformation amount is controlled to be 2-3%;

s14, aging treatment: timely aging after the part is subjected to cold forging, performing aging treatment on the ring piece by adopting two-stage aging, heating along with a furnace, preserving the temperature of the ring piece at 121 ℃ for 4-6 h, preserving the temperature at 176 ℃ for 4-6 h, and discharging the ring piece from the furnace for air cooling;

s15, machining again: and machining the aged ring piece to a target delivery size.

2. The forging and heat treatment process of the large 7050 aluminum alloy ring according to claim 1, wherein the length direction after the three-pier three-drawing in the step S4 is ensured to be the height direction of the original ingot, the upsetting deformation in the process is ensured to be 55-65%, and the elongation deformation is ensured to be 40-50%.

3. The forging and heat treatment process for the large 7050 aluminum alloy ring piece according to claim 2, wherein the temperature of the material is monitored in real time in the ingot re-forging process in the step S4, and the final forging temperature is guaranteed to be not lower than 380 ℃.

4. The forging and heat treatment process for the large 7050 aluminum alloy ring according to claim 1, wherein the temperature of the blank after the punching step in the step S6 is not lower than 380 ℃.

5. The forging and heat treatment process for the large 7050 aluminum alloy ring according to claim 1, wherein the temperature of the material is monitored in real time in the broaching process of the trestle in the step S8, and the final forging temperature is guaranteed to be not lower than 380 ℃.

6. The forging and heat treatment process for the large 7050 aluminum alloy ring piece according to claim 1, wherein the diameter growth rate is increased when the temperature in the ring rolling process in the step S10 is close to 400 ℃, and the diameter growth rate is decreased when the temperature in the ring rolling process is close to 440 ℃.

7. The forging and heat treatment process of the large 7050 aluminum alloy ring piece according to claim 1, wherein the aging is performed in time after the step of cold deformation S13, and the interval between the step of cold deformation and the step of aging is within 30 min.

Images