A nickel-aluminum bronze alloy semi-solid extrusion die and casting method

Abstract

The invention discloses a semi-solid extrusion die and casting method of a nickel-aluminum bronze alloy, and belongs to the technical field of semi-solid forming. The semi-solid extrusion casting method of the nickel-aluminum bronze alloy comprises: melting the original nickel-aluminum bronze ingot, and keeping it warm to obtain liquid nickel-aluminum bronze; then lowering the temperature of the liquid nickel-aluminum bronze to 40-70°C above the liquidus to obtain a semi-solid slurry; injecting the semi-solid slurry into a preheated mold and keeping it warm, and then squeezing the semi-solid slurry from a barrel into the mold cavity of the mold for extrusion casting, and removing the mold after pressure maintenance to obtain a nickel-aluminum bronze alloy casting. The invention adopts semi-solid rheology technology to prepare semi-solid slurry, refines the morphology of the iron-rich phase in nickel-aluminum bronze, and makes the alloy material have the advantages of high strength and high wear resistance. In addition, through the bottom injection extrusion technology, the filling is more stable, the pore defects in the filling process are reduced, and the compactness of the alloy structure is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semi-solid forming, and in particular relates to a nickel-aluminum bronze alloy semi-solid extrusion die and a casting method. Background Art

[0002] Semi-solid technology refers to a material molding technology that processes a solid-liquid mixture containing a non-dendritic solid phase within the solidification temperature range. It has the advantages of low shrinkage, low molding temperature, and fine grains. Semi-solid molding technology is divided into rheoforming and thixoforming technology according to different processing methods. Because rheoforming is to directly mold semi-solid slurry, the production process is short and the cost is much lower in industrial applications.

[0003] Nickel aluminum bronze is widely used in aerospace, construction, ocean and other fields due to its excellent wear resistance, corrosion resistance, high strength, hardness and other excellent properties. However, as a complex alloy with iron, nickel, manganese and other elements added to aluminum and copper, nickel aluminum bronze has been widely used in industrial production, but its manufacturing process is prone to defects such as component segregation, shrinkage and shrinkage, and the appearance of second phase particles has a certain impact on the properties of the alloy. As a unique intermetallic compound in nickel aluminum bronze, the iron-rich phase mainly has petal-shaped, block-shaped and spherical morphologies, but the petal-shaped and block-shaped iron-rich phases are easy to split the matrix, thereby weakening the strength and plasticity of the material.

[0004] The existing methods for preparing nickel-aluminum bronze are mainly sand casting, centrifugal casting, additive manufacturing, etc. However, the nickel-aluminum bronze prepared by sand casting and centrifugal casting still has coarse petal-shaped and blocky iron-rich phases, and the mechanical properties of the material are low, which cannot meet higher requirements. Although the production of nickel-aluminum bronze by additive manufacturing technology can refine the iron-rich phase, it has the disadvantages of complex process and certain requirements on part size, which limits its industrial development. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a nickel-aluminum bronze alloy semi-solid extrusion die and a casting method.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for semi-solid extrusion casting of a nickel-aluminum bronze alloy comprises the following steps:

[0008] (1) By operating the extruder operating table, the slider drives the upper mold of the mold to move and open the mold, remove the residues in the barrel, the upper mold, and the lower mold, and evenly spray the release agent on the upper and lower molds of the mold;

[0009] (2) The mold is opened and heated to 450-600°C by a heating rod and kept warm for 2-3 hours;

[0010] (3) The original nickel aluminum bronze ingot is heated to 1300-1400° C. using a medium frequency induction furnace, kept warm for 30 minutes, taken out and left to stand to form liquid nickel aluminum bronze; when the temperature of the liquid nickel aluminum bronze drops to 40-70° C. above the liquidus, a semi-solid slurry is prepared, and then the prepared semi-solid slurry is introduced into a barrel;

[0011] (4) The upper die and the lower die are closed, and the extruder push rod squeezes the semi-solid slurry from the barrel into the mold cavity at a speed of 17-25 mm / s and a pressure of 100-250 MPa. After the extrusion is completed, the pressure is maintained for 20 seconds. After the casting is formed, the mold is opened, and the upper die moves upward with the slider, and the nickel-aluminum-bronze alloy casting remaining in the lower die is ejected by the thrust of the push rod.

[0012] As a preferred embodiment of the present invention, when cooling the liquid nickel aluminum bronze to prepare the semi-solid slurry, a cooling circulating water channel is used for cooling, the water flow rate of the cooling circulating water is 100-200L / h, the angle between the water channel and the horizontal plane is 45°, and the length is 300-400mm.

[0013] The die for semi-solid extrusion casting of nickel-aluminum bronze alloy of the present invention comprises an upper die, an upper heat insulation board, an upper cushion block, an upper mold plate, a lower die, a lower heat insulation board, a lower cushion block, a lower mold plate, a barrel and a push rod;

[0014] The upper heat insulation board is arranged above the upper mold; an upper pad is arranged between the upper heat insulation board and the upper mold, and through holes are arranged on the upper heat insulation board and the upper pad; a connecting rod connects the upper mold with the upper mold through the through hole;

[0015] A lower heat insulation plate, a lower cushion block and a barrel are provided between the lower die and the lower template; the lower heat insulation plate is located between the lower die and the lower cushion block, and through holes are provided on the lower heat insulation plate and the lower cushion block; a connecting rod connects the lower die and the lower template through the through hole; a through cavity is provided at the center of the lower die, the lower heat insulation plate, the lower cushion block and the lower template, and the outer wall of the barrel contacts the cavity wall of the lower die, the lower heat insulation plate and the lower template.

[0016] As a preferred embodiment of the present invention, a guide column is provided on the upper surface of the lower mold, corresponding to a guide sleeve provided on the lower surface of the upper mold, to play a role in positioning and fixing.

[0017] The present invention arranges the guide pin on the lower die to prevent metal chips from entering the guide sleeve and causing the die to be stuck.

[0018] As a preferred embodiment of the present invention, the upper and lower mold plates of the mold are made of hot working mold H13 steel; the upper mold, upper insulation board, upper pad, lower mold, lower insulation board, lower pad and barrel are made of 45# steel.

[0019] As a preferred embodiment of the present invention, the upper template and the lower template are both provided with four U-shaped grooves, the U-shaped grooves of the upper template are fixed to the extruder slide by connecting nuts, and the U-shaped grooves of the lower template are fixed to the extruder workbench by connecting nuts.

[0020] As a preferred embodiment of the present invention, the upper mold plate of the mold moves up and down with the slide block of the extruder, the upper mold, the upper cushion block, and the upper insulation board move with the upper mold plate, and the lower mold plate is fixed.

[0021] As a preferred embodiment of the present invention, 40 heating holes are arranged around the upper mold and the lower mold for placing heating rods to heat the mold; the heating hole has a diameter of 10 mm, a length of 100 mm, and is 5 mm away from the cavity.

[0022] As a preferred embodiment of the present invention, an overflow groove and an exhaust groove are provided between the upper mold and the lower mold.

[0023] As a preferred embodiment of the present invention, the nickel-aluminum bronze alloy semi-solid extrusion casting mold also includes a push rod, which contacts the outer surface of the bottom of the barrel, and utilizes the thrust of the push rod to squeeze the semi-solid slurry from the barrel into the mold cavity of the mold.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention adopts semi-solid rheological technology to prepare semi-solid slurry. On the one hand, the large iron-rich phase in the alloy liquid phase is refined, and the high-temperature iron-rich phase is induced to form spherical particles. By regulating the morphology of the iron-rich phase in nickel-aluminum bronze, the alloy material has the advantages of high strength and high wear resistance. On the other hand, the preparation process is shortened and the economic benefits are improved.

[0026] (2) The present invention adopts bottom injection extrusion technology, which can make the filling more stable, reduce the pore defects formed by air entrainment during the filling process, and improve the density of the alloy structure. In addition, by preheating the mold, the segregation of elements is reduced, volume solidification is achieved, the diffusion of solute atoms is accelerated, the formation of equilibrium phase is promoted, and the microstructure of the alloy material is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a process flow chart of the method for semi-solid extrusion casting of nickel-aluminum bronze alloy.

[0028] Figure 2 It is a schematic structural diagram of the mold for semi-solid extrusion casting of nickel-aluminum bronze alloy according to the present invention.

[0029] Figure 3 It is a schematic cross-sectional structure diagram of a die for semi-solid extrusion casting of nickel-aluminum bronze alloy according to the present invention.

[0030] Figure 4 It is a schematic structural diagram of the nickel-aluminum bronze alloy casting of the present invention.

[0031] Figure 5 In the figure, (a) (c) are the microstructure diagrams of the sand-cast nickel-aluminum bronze described in Comparative Example 1; (b) (d) are the microstructure diagrams of the nickel-aluminum bronze alloy casting described in Example 1.

[0032] In the figure: 1-barrel, 2-lower template, 3-lower cushion block, 4-lower insulation board, 5-lower mold, 6-upper insulation board, 7-upper cushion block, 8-upper template, 9-upper mold, 10-guide sleeve, 11-guide column, 12-elevator rod. DETAILED DESCRIPTION

[0033] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] The die for semi-solid extrusion casting of nickel-aluminum bronze alloy of the present invention comprises: 1-barrel, 2-lower template, 3-lower cushion block, 4-lower heat insulation board, 5-lower mold, 6-upper heat insulation board, 7-upper cushion block, 8-upper template, 9-upper mold, 10-guide sleeve, 11-guide column, 12-pushing rod; upper heat insulation board 6 is arranged above upper mold 9; upper cushion block 7 is arranged between upper heat insulation board 6 and upper template 8, and through holes are arranged on upper heat insulation board 6 and upper cushion block 7; connecting rod connects upper template 8 with upper mold 9 through through hole.

[0036] A lower heat insulation board 4, a lower pad 3 and a barrel 1 are provided between the lower die 5 and the lower mold plate 2; the lower heat insulation board 4 is located between the lower die 5 and the lower pad 3, and through holes are provided on the lower heat insulation board 4 and the lower pad 3; a connecting rod connects the lower die 5 and the lower mold plate 2 through the through hole; a through cavity is provided at the center of the lower die 5, the lower heat insulation board 4, the lower pad 3 and the lower mold plate 2, and the outer wall of the barrel 1 is in contact with the cavity wall of the lower die 5, the lower heat insulation board 4 and the lower mold plate 2.

[0037] The ejector pin 12 contacts the outer surface of the bottom of the barrel 1 , and the semi-solid slurry is squeezed from the barrel 1 into the cavity of the mold by the thrust of the ejector pin 12 .

[0038] The middle layer of the mold of the present invention is provided with an upper heat insulation board 6 and a lower heat insulation board 4, which can reduce heat loss and shorten the preheating time.

[0039] Preferably, a guide post 11 is provided on the upper surface of the lower mold 5, corresponding to a guide sleeve 10 provided on the lower surface of the upper mold 9, to play a role in positioning and fixing; the present invention arranges the guide post 11 on the lower mold 5 to prevent metal chips from entering the guide sleeve 10 and causing the mold to get stuck.

[0040] Preferably, the upper mold plate 8 and the lower mold plate 2 of the mold are made of hot working mold H13 steel; the upper mold 9, the upper insulation board 6, the upper cushion block 7, the lower mold 5, the lower insulation board 4, the lower cushion block 3 and the barrel 1 are made of 45# steel.

[0041] Preferably, the upper template 8 and the lower template 2 are both provided with four U-shaped grooves, the U-shaped grooves of the upper template 8 are fixed to the extruder slide block by connecting nuts, and the U-shaped grooves of the lower template 2 are fixed to the extruder workbench by connecting nuts.

[0042] Preferably, 40 heating holes are provided around the upper mold 9 and the lower mold 5 for placing heating rods to heat the mold; the heating hole has a diameter of 10 mm, a length of 100 mm, and is 5 mm away from the cavity.

[0043] Preferably, an overflow groove and an exhaust groove are provided between the upper mold 9 and the lower mold 5. Figure 3 Shown in the enlarged portion.

[0044] The present invention adopts the nickel-aluminum bronze alloy semi-solid extrusion casting mold to prepare the nickel-aluminum bronze alloy, including the following steps:

[0045] (1) Turn on the power supply, operate the extruder operating table to drive the slide to move the upper mold 9 to open the mold, remove the residues in the barrel 1, the upper mold 9, and the lower mold 5, and evenly spray the mold release agent on the upper mold 9 and the lower mold 5;

[0046] (2) Mold opening: The mold is heated to 600°C by a heating rod and kept warm for 2 hours. Then the mold is opened. The upper mold plate 8 of the mold moves up and down with the slider of the extruder. The upper mold 9, the upper cushion block 7, and the upper insulation board 6 move with the upper mold plate 8, while the lower mold plate 2 is fixed;

[0047] (3) using a medium frequency induction furnace to heat the original nickel aluminum bronze ingot to 1300° C., keeping the temperature for 30 minutes, taking it out and letting it stand; when the temperature drops to 70° C. above the liquidus, preparing a semi-solid slurry, and then introducing the prepared semi-solid slurry into the barrel 1;

[0048] (4) The upper mold 9 and the lower mold 5 are closed, and the extruder push rod 12 squeezes the semi-solid slurry from the barrel 1 into the mold cavity at a speed of 25 mm / s and a pressure of 250 MPa. After the extrusion is completed, the pressure is maintained for 20 seconds. After the casting is formed, the mold is opened, and the upper mold 9 moves upward with the slider. Since the material head and the overflow groove are in the lower mold 5, the casting will be left in the lower mold 5; finally, the casting is ejected by the thrust of the push rod 12, and then the next casting is formed.

[0049] Compared to Figure 5 (a)(c) Compared with the microstructure of nickel-aluminum bronze cast in sand mold, Figure 5The alloy structure of the nickel-aluminum bronze alloy casting in (b) and (d) is still composed of α phase, β' phase and κ phase. The iron-rich phase is in the form of fine spheres and is evenly distributed in the matrix. No coarse iron-rich phase is found. The average size of the iron-rich phase of the nickel-aluminum bronze alloy prepared in Example 1 is 2.64nm.

[0050] Example 2

[0051] The nickel-aluminum-bronze alloy semi-solid extrusion casting mold used in this embodiment is the same as that in Example 1.

[0052] This embodiment uses the nickel-aluminum bronze alloy semi-solid extrusion casting mold to prepare the nickel-aluminum bronze alloy, including the following:

[0053] (1) Turn on the power supply, operate the extruder operating table to drive the slide to move the upper mold 9 to open the mold, remove the residues in the barrel 1, the upper mold 9, and the lower mold 5, and evenly spray the mold release agent on the upper mold 9 and the lower mold 5;

[0054] (2) Mold opening: The mold is heated to 450°C by a heating rod and kept warm for 3 hours. The upper mold plate 8 of the mold moves up and down with the slider of the extruder. The upper mold 9, the upper cushion block 7, and the upper insulation board 6 move with the upper mold plate 8, while the lower mold plate 2 is fixed;

[0055] (3) using a medium frequency induction furnace to heat the original nickel aluminum bronze ingot to 1400° C., keeping the temperature for 30 minutes, taking it out and letting it stand; when the temperature drops to 40° C. above the liquidus, preparing a semi-solid slurry, and then introducing the prepared semi-solid slurry into the barrel 1;

[0056] (4) The upper mold 9 and the lower mold 5 are closed, and the extruder push rod 12 squeezes the semi-solid slurry from the barrel 1 into the mold cavity at a speed of 17 mm / s and a pressure of 100 MPa. After the extrusion is completed, the pressure is maintained for 20 seconds. After the casting is formed, the mold is opened, and the upper mold 9 moves upward with the slider. Since the material head and the overflow groove are in the lower mold 5, the casting will be left in the lower mold 5; finally, the casting is ejected by the thrust of the push rod 12, and then the next casting is formed.

[0057] The alloy structure of the nickel-aluminum bronze alloy casting described in this embodiment is composed of α phase, β' phase and κ phase. Compared with the microstructure of the sand-cast nickel-aluminum bronze, the iron-rich phase is in the form of fine spheres and is evenly distributed in the matrix, and no coarse iron-rich phase is found. The density of the nickel-aluminum bronze alloy prepared in Example 2 is that the average size of the iron-rich phase of the prepared nickel-aluminum bronze alloy is 2.68nm.

[0058] Comparative Example 1

[0059] This comparative example adopts the nickel-aluminum bronze alloy sand casting mold to prepare the nickel-aluminum bronze alloy, and the steps are as follows:

[0060] (1) Place the pattern into sand to make a mold;

[0061] (2) Joining sand and prototype in the casting system;

[0062] (3) Remove the pattern;

[0063] (4) injecting the molten metal into the mold gap to fill it;

[0064] (5) Wait for the metal to cool;

[0065] (6) Knock off the sand mold and take out the casting.

[0066] according to Figure 5 (a)(c) It can be seen that the microstructure of the sand-cast nickel-aluminum bronze described in Comparative Example 1 is an iron-rich phase κ phase, and the average size of the iron-rich phase of the nickel-aluminum bronze alloy prepared in Comparative Example 1 is 12.52nm.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for semi-solid extrusion casting of a nickel-aluminum bronze alloy, characterized in that: The steps include: (1) By operating the extruder operating table, the slider drives the upper mold of the mold to move and open the mold, remove the residues in the barrel, the upper mold, and the lower mold, and evenly spray the release agent on the upper and lower molds of the mold; (2) The mold is opened and heated to 450-600°C by a heating rod and kept warm for 2-3 hours; (3) The original nickel aluminum bronze ingot is heated to 1300-1400° C. using a medium frequency induction furnace, kept warm for 30 minutes, taken out and left to stand to form liquid nickel aluminum bronze; when the temperature of the liquid nickel aluminum bronze drops to 40-70° C. above the liquidus, a semi-solid slurry is prepared, and then the prepared semi-solid slurry is introduced into a barrel; (4) The upper die and the lower die are closed, and the extruder push rod squeezes the semi-solid slurry from the barrel into the mold cavity at a speed of 17-25 mm / s and a pressure of 100-250 MPa. After the extrusion is completed, the pressure is maintained for 20 seconds. After the casting is formed, the mold is opened, and the upper die moves upward with the slider, and the nickel-aluminum-bronze alloy casting remaining in the lower die is ejected by the thrust of the push rod.

2. The method for semi-solid extrusion casting of nickel-aluminum bronze alloy according to claim 1, characterized in that: When cooling liquid nickel aluminum bronze to prepare semi-solid slurry, a cooling circulating water channel is used for cooling. The flow rate of the cooling circulating water is 100-200L / h, the angle between the water channel and the horizontal plane is 45°, and the length is 300-400mm.

3. A die used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy as claimed in claim 1 or 2, characterized in that: include: Upper die, upper heat insulation board, upper pad, upper template, lower die, lower heat insulation board, lower pad, lower template, barrel and ejector pin; The upper heat insulation board is arranged above the upper mold; an upper pad is arranged between the upper heat insulation board and the upper mold, and through holes are arranged on the upper heat insulation board and the upper pad; a connecting rod connects the upper mold with the upper mold through the through hole; A lower heat insulation plate, a lower cushion block and a barrel are provided between the lower die and the lower template; the lower heat insulation plate is located between the lower die and the lower cushion block, and through holes are provided on the lower heat insulation plate and the lower cushion block; a connecting rod connects the lower die and the lower template through the through hole; a through cavity is provided at the center of the lower die, the lower heat insulation plate, the lower cushion block and the lower template, and the outer wall of the barrel contacts the cavity wall of the lower die, the lower heat insulation plate and the lower template.

4. The mold used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy as claimed in claim 3 is characterized in that: The upper surface of the lower die is provided with a guide column, which corresponds to the guide sleeve provided on the lower surface of the upper die and plays a role in positioning and fixing.

5. The mold used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy as claimed in claim 3 is characterized in that: The upper mold plate and the lower mold plate of the mold are made of hot working mold H13 steel; the upper mold, the upper heat insulation board, the upper cushion block, the lower mold, the lower heat insulation board, the lower cushion block and the barrel are made of 45# steel.

6. The mold used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy as claimed in claim 3 is characterized in that: The upper template and the lower template are both provided with four U-shaped grooves. The U-shaped grooves of the upper template are fixed to the slide block of the extruder through connecting nuts, and the U-shaped grooves of the lower template are fixed to the workbench of the extruder through connecting nuts.

7. The mold used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy as claimed in claim 3 is characterized in that: The upper mold and the lower mold are surrounded by 40 heating holes for placing heating rods to heat the mold; the heating holes have a diameter of 10 mm, a length of 100 mm, and are 5 mm away from the cavity.

8. The mold used in the semi-solid extrusion casting method of nickel-aluminum bronze alloy as claimed in claim 3 is characterized in that: An overflow groove and an exhaust groove are provided between the upper die and the lower die.

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