Complex thin-wall beryllium-aluminum alloy casting and precision casting method thereof

Abstract

The invention discloses a complex thin-wall beryllium-aluminum alloy casting and a precision casting method thereof, belongs to the technical field of alloy manufacturing, and solves the problems that beryllium-aluminum alloy parts, especially complex thin-wall beryllium-aluminum alloy parts, prepared by an existing casting technology have the defects of poor internal quality, high possibility of generating shrinkage porosity / cracks and the like and are uneven in performance. The method comprises the steps that S1, beryllium-aluminum pre-alloy is prepared; s2, cerium is added into the beryllium-aluminum pre-alloy for remelting; and S3, the remelted alloy melt is cooled to the pouring temperature and injected into the mold shell in the rotating motion state. According to the method, the cerium is added into the beryllium-aluminum alloy for remelting, the temperature of the melt is reduced to be close to the beryllium melting point for pouring, and the mold shell is rotated in the pouring process, so that the compactness of the internal structure of the complex thin-wall beryllium-aluminum alloy casting is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy manufacturing, and in particular, relates to a complex thin-walled beryllium aluminum alloy casting and a precision casting method thereof. Background Art

[0002] Beryllium aluminum (Be-Al) alloy has low density (density 2.14g / cm 3 ), with the characteristics of light weight, high specific strength, high specific stiffness, good thermal stability, high toughness, high modulus, corrosion resistance, etc., and at the same time has many excellent properties such as low density of beryllium and easy processing and high toughness of aluminum. In addition, beryllium aluminum alloy also has excellent thermal and optical properties, and has been widely used in aerospace electronic equipment and high wave mode frequency equipment.

[0003] At present, the production processes of Be-Al alloy mainly include: powder metallurgy and precision casting. The alloys prepared by different preparation methods have significant differences in their structure, resulting in different properties of the alloys. The Be-Al alloy prepared by powder metallurgy is complex and has high processing costs. The production process of cast beryllium aluminum alloy using precision casting is simple, low-cost, and can produce products with complex structures.

[0004] However, due to the very limited solubility between Be and Al, the two materials separate from each other during the solidification process, and the melting points of Be and Al are very different (Be is 1287°C, Al is 660°C), so the two have a wide solid-liquid two-phase region (solidification interval), which is easy to cause metal shrinkage problems during the solidification process, and also causes shrinkage defects, pores, and macroscopic and microscopic segregation of the structure in the final product. Therefore, at present, Be and Al can only be made into alloy ingots first, and then processed by other processes. Product parts. Even when preparing alloy ingots, it is often difficult to obtain beryllium aluminum alloys with good performance. For example, Chinese patent document CN106756372A discloses a method for preparing beryllium aluminum-rare earth alloys. This method can only be used to prepare ingots, and is not suitable for complex thin-walled castings. When used for casting complex thin-walled castings, it is very easy to produce casting defects such as hot nodes and shrinkage cavities, and the melting temperature is difficult to control. Summary of the invention

[0005] The purpose of the present invention is to provide a complex thin-walled beryllium aluminum alloy casting and a precision casting method thereof, so as to solve the problems that beryllium aluminum alloy parts prepared by existing casting technology, especially complex thin-walled beryllium aluminum alloy parts, have poor internal quality, are prone to defects such as shrinkage / cracks, and have uneven performance.

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

[0007] In a first aspect of the present invention, a method for casting a complex thin-walled beryllium aluminum alloy casting is provided, the method comprising:

[0008] S1. preparing beryllium aluminum pre-alloy;

[0009] S2, adding cerium to the beryllium aluminum pre-alloy for remelting;

[0010] S3, cooling the remelted alloy melt to a pouring temperature, and injecting the melt into a mold shell in a rotating state;

[0011] Among them, the temperature rises to 1400-1550°C during remelting; the pouring temperature is 1220-1250°C.

[0012] In one embodiment, the amount of cerium added is 0.1-10% of the total mass.

[0013] In one embodiment, the composition of the beryllium aluminum pre-alloy is: 45-80 wt.% metal beryllium, 10-45 wt.% aluminum

[0014] In one embodiment, the added amount of cerium is 6% of the total mass.

[0015] In one embodiment, the mold shell rotates alternately forward and reverse in a predetermined cycle.

[0016] In one embodiment, the mold shell rotates alternately forward and reverse at a speed of 100 to 150 r / min and a period of 0.2 s.

[0017] In a second aspect of the present invention, there is provided a complex thin-walled beryllium aluminum alloy casting, comprising the following components:

[0018] Beryllium, 45-80wt.%;

[0019] Aluminum, 10-45wt.%;

[0020] Cerium, 0.1~10wt.%.

[0021] The third aspect of the present invention provides a beryllium aluminum alloy consisting of the following components:

[0022] Beryllium, 45-80wt.%;

[0023] Aluminum, 10-45wt.%;

[0024] Cerium, 0.1~10wt.%.

[0025] The present invention solves the problem of shrinkage / cracks and uneven performance during the preparation of beryllium aluminum alloy by adding cerium to beryllium aluminum alloy for remelting, lowering the melt temperature to near the melting point of beryllium for pouring, and rotating the mold shell during the pouring process, thereby improving the compactness of the internal structure of complex thin-walled beryllium aluminum alloy castings. Beryllium aluminum alloy castings with good performance can be directly obtained to meet the performance requirements of beryllium aluminum alloy parts in the aviation and aerospace fields. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0028] According to an embodiment of the present invention, a method for precision casting of a complex thin-walled beryllium aluminum alloy casting is provided, the method comprising the following steps:

[0029] S1, preparing beryllium aluminum pre-alloy;

[0030] Take metallic beryllium and aluminum as raw materials, put them into a clean crucible, and pre-alloy them through vacuum induction melting.

[0031] The beryllium raw material is a beryllium ingot refined and purified by a medium frequency induction melting furnace, with a purity higher than 98.5wt.%. The purity of the aluminum block is higher than 99.9wt.%.

[0032] The obtained beryllium aluminum pre-alloy has the following components: 45-80 wt.% of metal beryllium and 10-45 wt.% of aluminum.

[0033] In addition, it also includes removing impurities from the surface of the beryllium aluminum pre-alloy.

[0034] S2, adding cerium to the beryllium aluminum pre-alloy for remelting;

[0035] The pre-alloy and cerium are sequentially placed in a clean crucible for remelting. The melting crucible is an alumina crucible. The amount of cerium added is 0.1-10% of the total mass.

[0036] During remelting, the vacuum induction melting furnace was evacuated to 1×10 -2 When the temperature is below Pa, start heating until the beryllium aluminum begins to melt, then continue to raise the temperature to 1400-1550°C, and slowly tilt the melting crucible until the raw materials are completely melted and fully mixed.

[0037] During the remelting process, since the melting point of Be is 1287°C and the melting point of Al is 660°C, the raw materials are completely melted at the above remelting temperature, so they have good fluidity, and by slowly tilting the melting crucible, some heavier impurities sink to the bottom of the crucible, while other impurities are vaporized, thereby further reducing the impurity content in the beryllium aluminum alloy.

[0038] When the melting crucible is slowly tilted, the maximum deflection angle of the crucible is 60°.

[0039] S3, cooling the remelted alloy melt to a pouring temperature and injecting it into a preheated mold shell;

[0040] In the present invention, the pouring temperature of the beryllium aluminum alloy is 1220-1250° C. Before pouring, the mold shell is preheated at a temperature of 740-780° C. Since the above pouring temperature is close to the melting point of beryllium, at this temperature, the fluidity of the beryllium aluminum alloy melt deteriorates and presents a porridge-like state, which can avoid the loose defects caused by pyrolysis of the melt during the solidification process.

[0041] During the pouring process, the mold shell rotates alternately forward and reverse, and the rotation of the mold shell compensates for the poor fluidity caused by the low pouring temperature, avoiding casting defects such as insufficient pouring, shrinkage and shrinkage. For example, the mold shell rotates alternately forward and reverse at a speed of 100 to 150 r / min and a period of 0.2 s.

[0042] After the pouring is completed, the vacuum is turned off, and the protective gas is filled in and left to stand for 3 to 5 minutes. For example, the protective gas is argon or other inert gas with a purity of more than 99.9%.

[0043] S4. Take out the casting and place it in an air cooling tower to cool it to room temperature to obtain a beryllium aluminum alloy casting.

[0044] By means of the above method, a non-dendritic alloy with fine and uniform structure can be prepared. The alloy has fine and dense grains, high mechanical properties, low degree of component segregation, and good plasticity and processing formability.

[0045] Embodiment 1:

[0046] (1) 65 wt.% beryllium and 34 wt.% aluminum are selected. The beryllium raw material adopts purified beryllium ingots with a purity higher than 98.5 wt.% and an aluminum purity higher than 99 wt.%.

[0047] (2) Add the above raw materials in weight percentage into the melting crucible of vacuum induction melting furnace equipment, and add 1wt.% of cerium with a purity higher than 99wt.%. The crucible is an alumina crucible, and the furnace door is closed. Turn on the vacuum system and keep the vacuum degree lower than 1×10 -2Pa, turn on the medium-frequency induction heating device for the melting crucible and the mold shell preheating power supply in the melting system, and slowly adjust the power of the device to raise the melting temperature of the crucible to 1450°C, while the mold shell preheating temperature is set to 740°C.

[0048] (3) Maintain the melt temperature at 1450°C for 30 minutes, and slowly rotate the melting crucible during this process, with a rotation range of 30° to 45°. Slowly adjust the power of the device to raise the melting temperature of the crucible to 1220°C; turn on the mold shell and adjust the speed to 120r / min, rotate it alternately in forward and reverse directions at a cycle of 0.2s, and pour the molten alloy liquid into the mold shell.

[0049] (4) After all the materials have been poured, argon is filled again to normal pressure, the furnace door is opened, and the mold shell is taken out and cooled to room temperature in an air cooling tower.

[0050] The beryllium aluminum alloy casting of this embodiment has a dense internal structure. The addition of cerium reduces the surface tension on the beryllium aluminum two-phase interface, thereby increasing the growth rate of the crystal nucleus. At the same time, a surface active film can be formed between the crystal grains and the molten liquid to prevent the generated crystal grains from growing and refine the alloy structure.

[0051] Embodiment 2:

[0052] (1) 64wt.% beryllium and 30wt.% aluminum are selected. The beryllium raw material adopts purified beryllium ingots with a purity higher than 98.5wt.% and an aluminum purity higher than 99wt.%.

[0053] (2) Add the above raw materials in weight percentage into the melting crucible of vacuum induction melting furnace equipment, and add cerium 6wt.%, the purity of which is higher than 99wt.%, and the crucible is made of alumina crucible, close the furnace door; turn on the vacuum system, and when the vacuum degree is lower than 1×10 -2 Pa, turn on the medium-frequency induction heating device for the melting crucible and the mold shell preheating power supply in the melting system, and slowly adjust the power of the device to raise the melting temperature of the crucible to 1550°C, while the mold shell preheating temperature is set to 760°C.

[0054] (3) Maintain the melt temperature at 1550°C for 30 min. During this process, slowly rotate the melting crucible with a rotation range of 30° to 45°. Slowly adjust the power of the device to raise the melting temperature of the crucible to 1250°C. Turn on the mold shell and adjust the speed to 140 r / min. Alternately rotate forward and reverse at a period of 0.2 s, and pour the molten alloy liquid into the mold shell.

[0055] (4) After all the materials have been poured, argon is filled again to normal pressure, the furnace door is opened, and the mold shell is taken out and cooled to room temperature in an air cooling tower.

[0056] When the cerium content in the internal structure of the beryllium aluminum alloy casting of this embodiment is 6.0%, there is no obvious casting defects such as shrinkage and cracks. Cerium and aluminum form a large number of spherical or short rod-shaped intermetallic compounds Al4Ce, which are distributed in the grains or grain boundaries, and a large number of dislocations and fine grain spheroidized structures and dispersed Al4Ce compounds appear, producing micro-alloying effects such as second phase strengthening.

[0057] According to another embodiment, the present invention also provides a complex thin-walled beryllium aluminum alloy casting, consisting of the following components (in mass percentage):

[0058] Beryllium, 45-80wt.%;

[0059] Aluminum, 10-45wt.%;

[0060] Cerium, 0.1~10wt.%.

[0061] According to another embodiment, the present invention also provides a beryllium aluminum alloy consisting of the following components (in mass percentage):

[0062] Beryllium, 45-80wt.%;

[0063] Aluminum, 10-45wt.%;

[0064] Cerium, 0.1~10wt.%.

[0065] The present invention solves the problems of poor internal quality, easy shrinkage / cracks and other defects and uneven performance of beryllium aluminum alloys prepared by existing casting technology, and can obtain beryllium aluminum alloy castings with good performance, which can meet the performance requirements of aviation and aerospace fields for beryllium aluminum alloy parts, especially complex thin-walled beryllium aluminum alloy parts.

[0066] Although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the inventive concept of the present invention, the technical solutions of the embodiments of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for casting complex thin-walled beryllium aluminum alloy parts, characterized in that: The method includes: S1, preparing beryllium aluminum pre-alloy; S2, adding cerium to the beryllium aluminum pre-alloy for remelting; S3, cooling the remelted alloy melt to a pouring temperature, and injecting the melt into a mold shell in a rotating state; Among them, the temperature rises to 1400-1550°C during remelting; the pouring temperature is 1220-1250°C.

2. The method according to claim 1, characterized in that The amount of cerium added is 0.1 to 10% of the total mass.

3. The method according to claim 2, characterized in that The composition of the beryllium aluminum pre-alloy is: 45-80wt.% metal beryllium and 10-45wt.% aluminum.

4. The method according to claim 2, characterized in that: The amount of cerium added is 6% of the total mass.

5. The method according to claim 1, characterized in that The mold shell rotates alternately forward and reverse at a predetermined period.

6. The method according to claim 5, characterized in that The mold shell rotates alternately forward and reverse at a speed of 100 to 150 r / min and a period of 0.2 s.

7. A complex thin-walled beryllium aluminum alloy casting, characterized in that: It is composed of the following ingredients: Beryllium, 45-80wt.%; Aluminum, 10-45wt.%; Cerium, 0.1~10wt.%.

8. A beryllium aluminum alloy, characterized in that: It is composed of the following ingredients: Beryllium, 45-80wt.%; Aluminum, 10-45wt.%; Cerium, 0.1~10wt.%.