Sleeve and method for improving hot isostatic pressing buckling deformation of powder metallurgy part

Abstract

The invention relates to the technical field of hot isostatic pressing, in particular to a sheath and a method for improving hot isostatic pressing buckling deformation of a powder metallurgy part. The sheath comprises a top surface, a bottom surface, an inner side wall and an outer side wall, the top surface, the bottom surface, the inner side wall and the outer side wall are enclosed to form an annular sheath inner cavity; the wall thicknesses of the top surface, the bottom surface, the inner side wall and the outer side wall are gradually increased from the middle part to two side corners; and a control mold core is arranged on the inner side wall. The method for improving the hot isostatic pressing buckling deformation of the powder metallurgy part comprises the following steps that after alloy powder is put into the sheath, hot isostatic pressing is conducted; in the hot isostatic pressing process, the top surface of the sheath is subjected to pressurization treatment, and the bottom surface and the outer side wall are subjected to constraint forming. According to the method, the wrapping sleeve with different wall thicknesses, thick corners and thin middle is adopted, and local pressurization and constraint forming are combined, so that buckling deformation of the powder metallurgy part in the hot isostatic pressing process is reduced, the utilization rate of an alloy powder material is increased, and the subsequent machining cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of hot isostatic pressing, in particular to a sheath and a method for improving the warping deformation of a powder metallurgy part under hot isostatic pressing. Background Art

[0002] In the field of modern powder metallurgy, hot isostatic pressing is an effective densification method and is widely used in the manufacturing process of various metal powder products. Hot isostatic pressing promotes the diffusion of the interface between metal powder particles by applying uniform pressure under high temperature and high pressure, thereby eliminating internal pores and increasing material density. This technology can improve the mechanical properties of materials, such as strength and toughness, and is therefore widely used in many high-end manufacturing fields such as aerospace, automobile manufacturing, and mold industry.

[0003] At present, hot isostatic pressing often uses a uniform wall thickness package, which is subjected to leak detection, cleaning, casing, degassing, and sealing welding before hot isostatic pressing to obtain powder metallurgy parts with no component segregation and uniform structure. Due to the uneven particle ratio inside the package after degassing and casing, and the unreasonable shrinkage of the uniform wall thickness package, powder metallurgy has problems of edge warping and deformation during hot isostatic pressing, resulting in poor part forming accuracy, low powder material utilization, and high subsequent processing costs.

[0004] In view of this, this invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a sleeve with different wall thicknesses at different locations, thick edges and corners, and thin middle portions, thereby facilitating the reduction of warping deformation of powder metallurgy parts during hot isostatic pressing.

[0006] The second purpose of the present invention is to provide a method for improving the warping deformation of powder metallurgy parts during hot isostatic pressing. By adopting the above-mentioned sheath and combining local pressurization and restraint forming, the warping deformation of powder metallurgy parts during hot isostatic pressing is reduced, the utilization rate of alloy powder materials is improved, and the subsequent processing costs are reduced.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a sheath, comprising a top surface, a bottom surface, an inner side wall and an outer side wall; the top surface, the bottom surface, the inner side wall and the outer side wall enclose an annular sheath inner cavity having a convex surface;

[0009] The wall thickness of the top surface gradually increases from the middle part to the two side corners; the wall thickness of the bottom surface gradually increases from the middle part to the two side corners; the wall thickness of the outer wall gradually increases from the middle part to the two side corners; the inner wall is provided with a control core, and the wall thickness of the inner wall gradually increases from the middle part to the two side corners.

[0010] Furthermore, the wall thickness of the corners of the sleeve is 4 to 12 mm;

[0011] And / or, the wall thickness of the middle portion of the top surface, the wall thickness of the middle portion of the bottom surface, the wall thickness of the middle portion of the inner wall and the wall thickness of the middle portion of the outer wall are each 1 to 10 mm.

[0012] Further, it includes at least one of the following features (1) to (3);

[0013] (1) The maximum height of the inner cavity of the annular sheath having a convex surface is 50 to 500 mm;

[0014] (2) The maximum inner diameter of the inner cavity of the annular sheath having a convex surface is 50 to 550 mm;

[0015] (3) The maximum outer diameter of the inner cavity of the annular sheath having a convex surface is 100 to 800 mm.

[0016] In a second aspect, the present invention also provides a method for improving the warpage deformation of a powder metallurgy part during hot isostatic pressing, comprising the following steps:

[0017] The alloy powder is loaded into the bag as described above and then hot isostatically pressed;

[0018] During the hot isostatic pressing process, the top surface of the package is subjected to a pressurization treatment; and the bottom surface and the outer side wall of the package are subjected to restraint molding.

[0019] Furthermore, the wall thickness of the sleeve satisfies the following relationship:

[0020] Δ=K×(F 1 -F 2 ), where Δ is the wall thickness of the package, K is the deformation coefficient, and F 1 is the hydrostatic pressure inside the hot isostatic pressing furnace, F 2 is the deformation resistance of the sleeve.

[0021] Furthermore, the pressure of the pressurization treatment is 1 to 50 MPa.

[0022] Further, the pressurization treatment includes: placing a pressurization block on the top surface of the package close to the outer peripheral corner;

[0023] And / or, the contact area between the package and the boost block accounts for 30% to 80% of the top surface area of ​​the package.

[0024] Furthermore, the contact area between the sleeve and the boost block satisfies the following relationship:

[0025] S 接触 =π(R 外 2 -(h(R 外 -R 内 )) 2 );where S 接触 is the contact area between the sleeve and the boost block, R 外 is the outer diameter of the sheath, R 内 is the inner diameter of the sheath, h is a constant, and h is 0.3 to 0.8;

[0026] And / or, the weight of the booster block satisfies the following relationship:

[0027] Where M 增压 is the weight of the booster block, P 增压 is the pressure of the pressurization treatment, and g is the gravitational acceleration.

[0028] Further, it includes at least one of the following features (1) to (4);

[0029] (1) The restraint molding comprises: placing a molding mold on the bottom surface and the outer side wall of the package;

[0030] (2) the molding die is in contact with the bottom surface and a portion of the outer wall surface of the sleeve;

[0031] (3) The height of the contact portion between the outer wall of the sleeve and the molding die is 30% to 70% of the total height of the sleeve;

[0032] (4) The thickness of the molding die is 10 to 20 times the thickness of the sleeve wall.

[0033] Furthermore, the portion of the molding die that contacts the sleeve is provided with graphite and / or glass powder.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The package of the present invention reasonably controls the package wall thickness at different positions, making the edges and corners thicker and the middle thinner, thereby helping to reduce the warping deformation of the powder metallurgy parts during the hot isostatic pressing process.

[0036] 2. The method of improving the warping deformation of powder metallurgy parts during hot isostatic pressing of the present invention achieves the purpose of controlling the uniform deformation of powder metallurgy parts to the target shape by adopting the above-mentioned sheath with different wall thicknesses in various places, as well as local pressurization and restraint molding, thereby reducing the warping deformation of powder metallurgy parts during hot isostatic pressing, improving the utilization rate of alloy powder materials, and reducing subsequent processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a schematic diagram of the structure of the hot isostatic pressing of the present invention.

[0039] Figure 2 It is a schematic diagram of the structure of hot isostatic pressing of comparative example 1 of the present invention.

[0040] Figure 3 This is a schematic diagram of the dimensional deviation of the hot isostatically pressed part of Example 1 of the present invention.

[0041] Figure 4 This is a schematic diagram of the dimensional deviation of the hot isostatically pressed product of Comparative Example 1 of the present invention.

[0042] Reference numerals:

[0043] 11-top surface; 12-bottom surface; 13-inner side wall; 14-outer side wall; 15-annular sleeve inner cavity with convex surface; 2-controlling core; 3-boosting block; 4-forming mold. DETAILED DESCRIPTION

[0044] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0045] The following is a detailed description of a sheath and a method for improving the warpage deformation of a powder metallurgy part during hot isostatic pressing of the present invention.

[0046] See also Figure 1 In some embodiments of the present invention, a sheath is provided, comprising a top surface 11, a bottom surface 12, an inner wall 13 and an outer wall 14; the top surface 11, the bottom surface 12, the inner wall 13 and the outer wall 14 enclose an annular sheath inner cavity 15 having a convex surface;

[0047] The wall thickness of the top surface 11 gradually increases from the middle part to the two side corners; the wall thickness of the bottom surface 12 gradually increases from the middle part to the two side corners; the wall thickness of the outer wall 14 gradually increases from the middle part to the two side corners; the inner wall 13 is provided with a control core 2, and the wall thickness of the inner wall 13 gradually increases from the middle part to the two side corners.

[0048] In some embodiments of the present invention, the wall thickness of the top surface 11, bottom surface 12, inner wall 13 and outer wall 14 of the sleeve is thin in the middle and thick at both ends; wherein, the inner wall 13 is close to the control core 2, and the control core 2 has the function of resisting shrinkage, so the wall thickness change is not as obvious as other surfaces; each surface of the annular sleeve inner cavity 15 with convex surface is convex and arc-shaped. The sleeve of the present invention sets different wall thicknesses at different positions of the sleeve, with a thin middle part and thick corners; the shrinkage of the corners of the sleeve is small, and the shrinkage of the middle part is large, and the alloy powder in the middle part transitions to the corners through particle rearrangement and other methods during the hot isostatic pressing process; thereby, it is beneficial to reduce the warping deformation of powder metallurgy parts during the hot isostatic pressing process.

[0049] In some embodiments of the present invention, the wall thickness of the corners of the sleeve is 4 to 12 mm; typically but not limiting, for example, the wall thickness of the corners of the sleeve can be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm or a range of any two thereof.

[0050] The corners of the package refer to the right angles formed by the inner wall and the upper and lower surfaces (top and bottom surfaces), and the outer wall and the upper and lower surfaces (top and bottom surfaces) after assembly and welding; there is a static shielding effect at the corners, which will hinder the shrinkage and deformation of the package here.

[0051] In some embodiments of the present invention, the wall thickness of the middle part of the top surface 11, the wall thickness of the middle part of the bottom surface 12, the middle part of the inner wall 13 and the middle part of the outer wall 14 are each 1 to 10 mm thick; typically but not limiting, for example, the wall thickness of the middle part of the top surface 11, the wall thickness of the middle part of the bottom surface 12, the middle part of the inner wall 13 and the middle part of the outer wall 14 can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or a range of any two of them. The thickness of the thinnest point in the center of each surface is the same or different, and the thickness can be calculated by CAE.

[0052] In some embodiments of the present invention, the maximum height of the annular sleeve inner cavity 15 with a convex surface is 50 to 500 mm; typically but not limitatively, for example, the maximum height of the annular sleeve inner cavity 15 with a convex surface can be 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm or a range of any two thereof.

[0053] In some embodiments of the present invention, the maximum inner diameter of the annular sheath inner cavity 15 with a convex surface is 50 to 550 mm; typically but not limitatively, for example, the maximum inner diameter of the annular sheath inner cavity 15 with a convex surface can be 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm or a range of any two thereof.

[0054] In some embodiments of the present invention, the maximum outer diameter of the annular sheath inner cavity 15 with a convex surface is 100 to 800 mm; typically but not limitatively, for example, the maximum outer diameter of the annular sheath inner cavity 15 with a convex surface can be 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 800 mm or a range of any two thereof.

[0055] In some embodiments of the present invention, the material of the sheath includes any one of rolled steel, glass, ceramic and rubber.

[0056] In some embodiments of the present invention, the shape of the sheath comprises a donut shape.

[0057] In addition to the above-mentioned shapes and sizes, the sheath with wall thickness variation of the present invention may also be of other shapes and sizes, and may or may not be provided with a controlled core; for example, it may also be at least one of square, cylindrical and stepped shapes; the height of the sheath is 50mm to 1000mm, the outer diameter is 50mm to 1850mm, and the inner diameter is 0mm to 1550mm (for example, the inner diameter of the cylindrical sheath is 0, there is no inner wall, and there is no controlled core).

[0058] In some embodiments of the present invention, a method for improving the warpage deformation of a powder metallurgy part during hot isostatic pressing is also provided, comprising the following steps:

[0059] The alloy powder is loaded into the above-mentioned bag and then hot isostatically pressed;

[0060] During the hot isostatic pressing process, the top surface 11 of the package is subjected to a pressurization treatment; the bottom surface 12 and the outer side wall 14 of the package are subjected to restraint molding.

[0061] The method for improving the warping deformation of powder metallurgy parts during hot isostatic pressing of the present invention achieves the purpose of controlling the uniform deformation of powder metallurgy parts to a target shape by adopting the above-mentioned sheath with different wall thicknesses at different locations, as well as local pressurization and restraint molding, thereby reducing the warping deformation of powder metallurgy parts during hot isostatic pressing, improving the utilization rate of alloy powder materials, and reducing subsequent processing costs.

[0062] In some embodiments of the present invention, the wall thickness of the sleeve satisfies the following relationship:

[0063] Δ=K×(F 1 -F 2 );where Δ is the wall thickness of the package, K is the deformation coefficient, F 1 is the hydrostatic pressure inside the hot isostatic pressing furnace, F 2 It is the deformation resistance of the package.

[0064] For packages with different parameters and target shapes, K takes different values. According to practical experience, it is generally 1 to 7×10 -8 ; F 1 F is the hydrostatic pressure inside the hot isostatic pressing furnace; 2 is the deformation resistance of the package, F 2 It is a function related to temperature, jacket wall thickness and structural strength. When the hot isostatic pressing pressure, temperature and jacket structural strength are determined, the jacket wall thickness is determined.

[0065] During the hot isostatic pressing process, the package is subjected to the interaction between the hydrostatic pressure and deformation resistance from the inside of the hot isostatic pressing furnace. When the hydrostatic pressure is greater than the deformation resistance, the package shrinks and deforms.

[0066] In some embodiments of the present invention, the pressure of the pressurized treatment is 1 to 50 MPa; typically but not limiting, for example, the pressure of the pressurized treatment can be 1 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa or a range of any two thereof.

[0067] In some embodiments of the present invention, the pressurization treatment includes: placing a pressurization block 3 on the top surface 11 of the package near the outer peripheral corner.

[0068] The booster block can be a single booster block or multiple booster blocks. The booster block and the sleeve have different contact areas and are made of different materials. The booster block only needs to meet the increased pressure requirements to overcome corner warping.

[0069] In some embodiments of the present invention, the contact area between the sleeve and the boost block 3 accounts for 30% to 80% of the area of ​​the top surface 11 of the sleeve; typically but not limiting, for example, the contact area between the sleeve and the boost block 3 accounts for 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% of the area of ​​the top surface 11 of the sleeve, or a range of any two thereof.

[0070] In some embodiments of the present invention, the contact area between the sleeve and the boost block 3 satisfies the following relationship:

[0071] S 接触 =π(R 外 2 -(h(R 外 -R 内 )) 2 );where S 接触 is the contact area between the sleeve and the booster block, R 外 is the outer diameter of the sleeve, R 内 is the inner diameter of the sheath, h is a constant, and h is 0.3~0.8.

[0072] In some embodiments of the present invention, the weight of the booster block 3 satisfies the following relationship:

[0073] Where M 增压 is the weight of the booster block, P 增压 is the pressure of the pressurization treatment, and g is the acceleration due to gravity.

[0074] The present invention places a boost block at the outer peripheral corner of the top surface of the sleeve. Taking the annular sleeve as an example, it starts from the outer circle of the ring and ends at 30% to 80% of the width of the ring. The boost block provides additional pressure for the shrinkage of the corners of the sleeve to reduce the corner shielding effect. The role of the boost block is equivalent to the downward pressure in isothermal forging, and the additional pressure required for sleeves of different shapes and materials is different. The weight of the boost block can be calculated based on the contact area between the sleeve and the boost block and the pressure required to overcome the warping of the corners.

[0075] In some embodiments of the present invention, the material of the booster block 3 includes at least one of steel, alloy and non-metallic material.

[0076] The present invention does not impose strict restrictions on the material of the booster block, and generally the booster block is made of a material with high specific gravity, high melting point and good thermal conductivity; for example, the booster block is made of 45# steel, H13 steel, JG4246A or TZM.

[0077] From a macroscopic point of view, the sleeve and the boost block are in planar contact; however, due to processing deformation and welding deformation, the upper surface of the sleeve becomes an uneven plane. Therefore, from a microscopic point of view, the contact between the upper surface of the sleeve and the boost block is point contact.

[0078] As the hot isostatic pressing process progresses, the contact area between the package and the booster block will become larger and larger; and the additional pressure decreases with the increase in the contact area. As the hot isostatic pressing process proceeds, the additional pressure provided by the booster block is different. During the entire hot isostatic pressing process, the booster block can provide an additional pressure of 1 to 50 MPa.

[0079] In some embodiments of the present invention, the portion of the boost block 3 in contact with the sheath is provided with a high temperature resistant coating; the high temperature resistant coating comprises a silicate or phosphate coating; the thickness of the high temperature resistant coating is 150-250 μm, which can prevent diffusion connection between the boost block and the sheath.

[0080] In some embodiments of the present invention, the restraint molding includes: placing a molding mold 4 on the bottom surface 12 and the outer side wall 14 of the package.

[0081] The sleeve is deformed under the combined pressure of hot isostatic pressing and the pressurizing block. The role of the forming die is equivalent to the die in the isothermal forging process, ensuring that the sleeve is deformed according to the target shape.

[0082] In some embodiments of the present invention, the forming die 4 contacts the bottom surface 12 and a portion of the outer wall 14 of the package.

[0083] In some embodiments of the present invention, the height of the contact portion between the outer side wall 14 of the sleeve and the forming mold 4 is 30% to 70% of the total height of the sleeve; typically but not restrictively, for example, the height of the contact portion between the outer side wall 14 of the sleeve and the forming mold 4 can be 30%, 40%, 50%, 60%, 70% of the total height of the sleeve, or a range of any two thereof.

[0084] In some embodiments of the present invention, the thickness of the molding die 4 is 10 to 20 times the thickness of the sleeve wall; typically but not limiting, for example, the thickness of the molding die 4 is 10 times, 12 times, 14 times, 16 times, 18 times, 20 times the thickness of the sleeve wall or a range of any two thereof.

[0085] The bottom surface and outer side wall of the sleeve are provided with forming molds. Taking the circular ring-shaped sleeve as an example, the entire bottom surface of the sleeve is flat on the forming mold, and part of the outer circumference is surrounded by the forming mold; the thickness of the forming mold located below the bottom surface is 10 to 20 times the thickness of the sleeve wall; the inner diameter of the forming mold located outside the outer side wall is the same as the outer diameter of the sleeve, the outer diameter does not exceed the inner diameter of the hot isostatic pressing furnace, the height is 30% to 70% of the height of the sleeve, and the thickness is 10 to 20 times the thickness of the sleeve wall.

[0086] In some embodiments of the present invention, the material of the forming die 4 is the material of the isothermal forging die, such as JG4246A, TZM, etc.

[0087] In some embodiments of the present invention, the portion where the molding die 4 contacts the sheath is provided with graphite and / or glass powder; high-temperature lubricant graphite and / or glass powder are placed at the portion where the molding die contacts the sheath to facilitate demolding.

[0088] The present invention does not limit the alloy powder, and any alloy powder that can be used for hot isostatic pressing can be used.

[0089] In some embodiments of the present invention, hot isostatic pressing includes: heat preservation treatment at 1000-1200° C. and 100-160 MPa for 1-6 hours; the present invention does not strictly limit the conditions of hot isostatic pressing and can be adjusted according to actual needs.

[0090] The present invention calculates the wall thickness of the sleeve according to the above method, and assembles and connects the optimized sleeve with the control core, the boost block and the forming mold in the hot isostatic pressing furnace, and then performs hot isostatic pressing, which is beneficial to the uniform deformation of the sleeve; taking the ring-shaped part as an example, compared with the hot isostatic pressing using only a sleeve with uniform wall thickness, the warping deformation of the upper and lower surfaces of the ring-shaped part is reduced by 14% to 17%, and the warping deformation of the inner and outer diameters is reduced by 50% to 78%; the utilization rate of the alloy powder material is increased by 5% to 15%, and the processing cost is reduced by 12% to 18%.

[0091] Example 1

[0092] The method for improving the warpage deformation of a powder metallurgy part by hot isostatic pressing provided in this embodiment comprises the following steps:

[0093] The sheath is in the shape of a ring; the sheath is welded from a 6.0 mm rolled low-carbon steel plate; the sheath comprises a top surface 11, a bottom surface 12, an inner wall 13 and an outer wall 14; the top surface 11, the bottom surface 12, the inner wall 13 and the outer wall 14 enclose a sheath inner cavity with a convex ring shape; the wall thickness of the top surface 11 gradually increases from the middle part (1.8 mm) to the two side corners (6.0 mm); the wall thickness of the bottom surface 12 gradually increases from the middle part (2.0 mm) to the two side corners (6.0 mm); the wall thickness of the outer wall 14 gradually increases from the middle part (1.2 mm) to the two side corners (6.0 mm); the wall thickness of the inner wall 13 gradually increases from the middle part (5.0 mm) to the two side corners (6.0 mm); the maximum height of the inner cavity of the ring-shaped sheath with a convex surface is 180 mm, the maximum inner diameter is 320 mm, and the maximum outer diameter is 530 mm;

[0094] The alloy powder (Ti 2AlNb) is loaded into the package, and then the control core 2 is assembled with the package, and the control core 2 is in contact with the inner side wall 13 of the package; the control core 2 is cylindrical, with a diameter of 308mm and a height of 192mm;

[0095] The boost block 3 is placed at the outer peripheral corner of the top surface 11 of the sleeve. The boost block 3 is annular, with an inner diameter of 420 mm, an outer diameter of 542 mm, a height of 350 mm, a material of molybdenum alloy, and a weight of 360 kg. The sleeve and the boost block are in contact at several points rather than surface contact, which can provide an additional pressure of 1 to 30 MPa for the sleeve. The portion where the boost block 3 contacts the sleeve is provided with a high-temperature resistant coating; the high-temperature resistant coating includes a silicate or phosphate coating with a thickness of 150 to 250 μm.

[0096] The forming mold 4 is placed on the bottom surface 12 and the outer side wall 14 of the sleeve, the entire bottom surface 12 of the sleeve is flat on the forming mold 4, and part of the outer circumference is surrounded by the forming mold 4; the thickness of the forming mold 4 is 120 mm, the inner height of the forming mold 4 (the height of the contact portion between the outer side wall 14 of the sleeve and the forming mold 4) is 60% of the sleeve height, that is, 116 mm, and the material is JG4246A alloy; the contact portion between the forming mold 4 and the sleeve is provided with glass powder;

[0097] Then put it into the hot isostatic pressing furnace and heat-treat it at 1000-1200℃ and 100-160MPa for 1-6h. After taking it out, the sheath is peeled or the sheath is put into the pickling tank for pickling to obtain a hot isostatic pressed part.

[0098] The target size of the hot isostatically pressed parts is: an inner diameter of 322mm, an outer diameter of 476mm, and a height of 140mm (the shrinkage size of the sleeve is larger than the size of the finished product, and the size of the finished product should be included in the shrinkage size range of the sleeve. A margin needs to be left for subsequent testing and heat treatment, and this margin needs to be reserved regardless of the method used to process the sleeve).

[0099] The method for improving the warpage deformation of a powder metallurgy part by hot isostatic pressing provided in this embodiment comprises the following steps:

[0100] The sheath is in the shape of a ring; the sheath is welded from a 6.0 mm rolled low-carbon steel plate; the sheath comprises a top surface 11, a bottom surface 12, an inner wall 13 and an outer wall 14; the top surface 11, the bottom surface 12, the inner wall 13 and the outer wall 14 enclose a sheath inner cavity with a convex ring shape; the wall thickness of the top surface 11 gradually increases from the middle part (1.8 mm) to the two side corners (6.0 mm); the wall thickness of the bottom surface 12 gradually increases from the middle part (2.0 mm) to the two side corners (6.0 mm); the wall thickness of the outer wall 14 gradually increases from the middle part (1.2 mm) to the two side corners (6.0 mm); the wall thickness of the inner wall 13 gradually increases from the middle part (5.0 mm) to the two side corners (6.0 mm); the maximum height of the inner cavity of the ring-shaped sheath with a convex surface is 180 mm, the maximum inner diameter is 320 mm, and the maximum outer diameter is 530 mm;

[0101] The alloy powder (Ti 2 AlNb) is loaded into the package, and then the control core 2 is assembled with the package, and the control core 2 is in contact with the inner side wall 13 of the package; the control core 2 is cylindrical, with a diameter of 308mm and a height of 192mm;

[0102] The boost block 3 is placed at the outer peripheral corner of the top surface 11 of the sleeve. The boost block 3 is annular, with an inner diameter of 420 mm, an outer diameter of 542 mm, a height of 350 mm, a material of molybdenum alloy, and a weight of 360 kg. The sleeve and the boost block are in contact at several points rather than surface contact, which can provide an additional pressure of 1 to 30 MPa for the sleeve. The portion where the boost block 3 contacts the sleeve is provided with a high-temperature resistant coating; the high-temperature resistant coating includes a silicate or phosphate coating with a thickness of 150 to 250 μm.

[0103] The forming mold 4 is placed on the bottom surface 12 and the outer side wall 14 of the sleeve, the entire bottom surface 12 of the sleeve is flat on the forming mold 4, and part of the outer circumference is surrounded by the forming mold 4; the thickness of the forming mold 4 is 120 mm, the inner height of the forming mold 4 (the height of the contact portion between the outer side wall 14 of the sleeve and the forming mold 4) is 60% of the sleeve height, that is, 116 mm, and the material is JG4246A alloy; the contact portion between the forming mold 4 and the sleeve is provided with glass powder;

[0104] Then put it into the hot isostatic pressing furnace and heat-treat it at 1000-1200℃ and 100-160MPa for 1-6h. After taking it out, the sheath is peeled or the sheath is put into the pickling tank for pickling to obtain a hot isostatic pressed part.

[0105] The target size of the hot isostatically pressed parts is: an inner diameter of 322mm, an outer diameter of 476mm, and a height of 140mm (the shrinkage size of the sleeve is larger than the size of the finished product, and the size of the finished product should be included in the shrinkage size range of the sleeve. A margin needs to be left for subsequent testing and heat treatment, and this margin needs to be reserved regardless of the method used to process the sleeve).

[0106] Example 2

[0107] The method for improving the warpage deformation of a powder metallurgy part by hot isostatic pressing provided in this embodiment comprises the following steps:

[0108] The sheath is in the shape of a ring; the sheath is welded from a 4.0 mm rolled low-carbon steel plate; the sheath comprises a top surface 11, a bottom surface 12 and an outer side wall 14; the top surface 11, the bottom surface 12, the inner side wall and the outer side wall 14 enclose a sheath inner cavity having a convex ring shape; the wall thickness of the top surface 11 gradually increases from the middle part (1.8 mm) to the two side corners (4.0 mm); the wall thickness of the bottom surface 12 gradually increases from the middle part (2.0 mm) to the two side corners (4.0 mm); the wall thickness of the outer side wall 14 gradually increases from the middle part (1.2 mm) to the two side corners (4.0 mm); the wall thickness of the inner side wall 13 gradually increases from the middle part (3.0 mm) to the two side corners (4.0 mm);

[0109] The alloy powder (FGH4096) is loaded into the package, and then the control mold core 2 is assembled with the package, and the control mold core 2 is in contact with the inner side wall 13 of the package; the control mold core 2 is cylindrical;

[0110] The boost block 3 is placed at the outer peripheral corner of the top surface 11 of the sleeve. The boost block 3 is annular, with an inner diameter of 100 mm, an outer diameter of 208 mm, a height of 300 mm, a material of molybdenum alloy, and a weight of 81 kg. The sleeve and the boost block are in contact at several points rather than surface contact, which can provide an additional pressure of 1 to 30 MPa for the sleeve. The portion where the boost block 3 contacts the sleeve is provided with a high-temperature resistant coating; the high-temperature resistant coating includes a silicate or phosphate coating with a thickness of 150 to 250 μm.

[0111] The forming mold 4 is placed on the bottom surface 12 and the outer side wall 14 of the sleeve, the entire bottom surface 12 of the sleeve is flat on the forming mold 4, and part of the outer circumference is surrounded by the forming mold 4; the thickness of the forming mold 4 is 80 mm, the inner height of the forming mold 4 (the height of the contact portion between the outer side wall 14 of the sleeve and the forming mold 4) is 50% of the sleeve height, that is, 200 mm, and the material is JG4246A alloy; the contact portion between the forming mold 4 and the sleeve is provided with glass powder;

[0112] Then put it into the hot isostatic pressing furnace and heat-treat it at 1000-1200℃ and 100-160MPa for 1-6h. After taking it out, the sheath is peeled or the sheath is put into the pickling tank for pickling to obtain a hot isostatic pressed part.

[0113] Comparative Example 1

[0114] join Figure 2 The hot isostatic pressing method provided in this comparative example refers to Example 1, with the only difference being that a sleeve with a wall thickness of 6 mm, an outer diameter of 550 mm, and a height of 195 mm is used; the diameter of the control core 2 is 308 mm and the height is 195 mm; and no booster block and molding mold are placed.

[0115] The target size of the hot isostatically pressed parts is: an inner diameter of 322mm, an outer diameter of 476mm, and a height of 140mm (the shrinkage size of the sleeve is larger than the size of the finished product, and the size of the finished product should be included in the shrinkage size range of the sleeve. A margin needs to be left for subsequent testing and processing, and this margin needs to be reserved regardless of the method used to process the sleeve).

[0116] Test example

[0117] The hot isostatic pressed parts obtained after pickling in Example 1 and Comparative Example 1 were sized and measured, and the difference between the maximum outer diameter and the minimum outer diameter of the parts was the outer diameter deviation; similarly, the difference between the maximum inner diameter and the minimum inner diameter was the inner diameter deviation, the difference between the highest dimension and the lowest dimension of the upper surface was the upper surface deviation, and the difference between the highest dimension and the lowest dimension of the lower surface was the lower surface deviation; the results are shown in Table 1; the dimensional deviations of the hot isostatic pressed parts in Example 1 and Comparative Example 1 are shown in Table 1. Figure 3 and Figure 4 As shown, the unit of each dimension in the figure is mm.

[0118] The degree of optimization is the degree of optimization of Example 1 compared to Comparative Example 1.

[0119] Table 1

[0120] Comparative Example 1 Example 1 Optimization level Inner diameter deviation / mm 1.1 0.54 50.91％ Outer diameter deviation / mm 7.47 1.61 78.45％ Upper surface deviation / mm 7.82 6.71 14.19％ Lower surface deviation / mm 8.02 6.65 17.08％ Powder loading / kg 88 83 5.68％ Processing fee / yuan 3643 2980 18.20％

[0121] As can be seen from Table 1, since the inner diameter of the sleeve is originally core-controlled, the original deviation is small; since the thickness of the outer wall of the sleeve changes the most, the outer diameter deviation is reduced most significantly; since the bottom of the sleeve is completely supported by the forming mold, the degree of optimization of the deformation deviation is greater than that of the upper surface.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A package, characterized in that: It comprises a top surface, a bottom surface, an inner side wall and an outer side wall; the top surface, the bottom surface, the inner side wall and the outer side wall enclose an annular sheath inner cavity with a convex surface; The wall thickness of the top surface gradually increases from the middle part to the two side corners; the wall thickness of the bottom surface gradually increases from the middle part to the two side corners; the wall thickness of the outer wall gradually increases from the middle part to the two side corners; the inner wall is provided with a control core, and the wall thickness of the inner wall gradually increases from the middle part to the two side corners.

2. The package according to claim 1, characterized in that: The wall thickness of the corners of the package is 4 to 12 mm; And / or, the wall thickness of the middle portion of the top surface, the wall thickness of the middle portion of the bottom surface, the wall thickness of the middle portion of the inner wall and the wall thickness of the middle portion of the outer wall are each 1 to 10 mm.

3. The package according to claim 1, characterized in that: The method comprises at least one of the following features (1) to (3); (1) The maximum height of the inner cavity of the annular sheath having a convex surface is 50 to 500 mm; (2) The maximum inner diameter of the inner cavity of the annular sheath having a convex surface is 50 to 550 mm; (3) The maximum outer diameter of the inner cavity of the annular sheath having a convex surface is 100 to 800 mm.

4. A method for improving the warpage deformation of powder metallurgy parts by hot isostatic pressing, characterized in that: The steps include: The alloy powder is placed in the can according to any one of claims 1 to 3 and then hot isostatically pressed; During the hot isostatic pressing process, the top surface of the package is subjected to a pressurization treatment; and the bottom surface and the outer side wall of the package are subjected to restraint molding.

5. The method for improving the warpage deformation of powder metallurgy parts by hot isostatic pressing according to claim 4, characterized in that: The wall thickness of the sleeve satisfies the following relationship: Δ=K×(F1-F2); wherein Δ is the wall thickness of the sheath, K is the deformation coefficient, F1 is the hydrostatic pressure inside the hot isostatic pressing furnace, and F2 is the deformation resistance of the sheath.

6. The method for improving the warpage deformation of powder metallurgy parts by hot isostatic pressing according to claim 4, characterized in that: The pressure of the pressurization treatment is 1 to 50 MPa.

7. The method for improving the warpage deformation of powder metallurgy parts by hot isostatic pressing according to claim 4, characterized in that: The pressurization treatment includes: placing a pressurization block on the top surface of the package near the outer peripheral corner; And / or, the contact area between the package and the boost block accounts for 30% to 80% of the top surface area of ​​the package.

8. The method for improving the warpage deformation of powder metallurgy parts during hot isostatic pressing according to claim 7, characterized in that: The contact area between the sleeve and the boost block satisfies the following relationship: S 接触 =π(R 外 2 -(h(R 外 -R 内 )) 2 );where S 接触 is the contact area between the sleeve and the boost block, R 外 is the outer diameter of the sheath, R 内 is the inner diameter of the sheath, h is a constant, and h is 0.3 to 0.8; And / or, the weight of the booster block satisfies the following relationship: Where M 增压 is the weight of the booster block, P 增压 is the pressure of the pressurization treatment, and g is the gravitational acceleration.

9. The method for improving the warpage deformation of powder metallurgy parts by hot isostatic pressing according to claim 4, characterized in that: The method comprises at least one of the following features (1) to (4); (1) The restraint molding comprises: placing a molding mold on the bottom surface and the outer side wall of the package; (2) the molding die is in contact with the bottom surface and a portion of the outer wall surface of the sleeve; (3) The height of the contact portion between the outer wall of the sleeve and the molding die is 30% to 70% of the total height of the sleeve; (4) The thickness of the molding die is 10 to 20 times the thickness of the sleeve wall.

10. The method for improving the warpage deformation of powder metallurgy parts during hot isostatic pressing according to claim 9, characterized in that: The portion of the molding die that contacts the sleeve is provided with graphite and / or glass powder.

Images