Introduction method for entrainment structure oxidation film in aluminum alloy casting

Abstract

The invention belongs to the technical field of internal defect analysis of aluminum alloy castings, and particularly relates to a method for introducing an oxidation film with an entrainment structure in an aluminum alloy casting, which comprises the following steps: S1, fishing the oxidation film on the surface of aluminum alloy liquid; s2, the fished oxidation film is selected and placed between the two pieces of solid metal, and a solid aluminum alloy / oxidation film / solid aluminum alloy structure is formed; and S3, the structure is subjected to induction melting treatment, the solid aluminum alloy / oxidation film / solid aluminum alloy structure is combined into a whole, and the solid aluminum alloy casting internally containing the oxidation film is obtained. According to the method, the defects of the entrainment structure oxidation film in a real casting can be simulated in a manual introduction mode, the structural form and size of the method are kept consistent with those found in an actual casting, and the entrainment structure oxidation film which is uncontrollable and difficult to accurately position in an original casting is accurately recognized; and a foundation is laid for deep research on defects of the oxidation film with the structure in a subsequent casting.

Description

Technical Field

[0001] The invention belongs to the technical field of internal defect analysis of aluminum alloy castings, and in particular relates to a method for introducing an entrained structure oxide film into an aluminum alloy casting. Background Art

[0002] With the rapid development of the manufacturing industry, the requirements for the quality of aluminum alloy castings are becoming higher and higher. The most critical issue affecting the quality of castings is the defects inside the castings, which directly affect the performance reliability of the castings. Among the many casting defects, the inclusion structure oxide film defects are difficult to be accurately found in actual castings due to their hidden characteristics, which means that such defects become potential hidden dangers for castings during service.

[0003] Therefore, if you want to produce castings that meet performance standards, you must conduct a systematic analysis of these defects. However, the prerequisite for overcoming this problem is to accurately locate the entrained structure oxide film defects in the castings. Only by correctly identifying the entrained structure oxide film defects in the castings can we explain the evolution of the entrained structure oxide film defects in the castings, and then achieve a significant improvement in the reliability and pass rate of casting performance.

[0004] At present, the systematic analysis of the inclusion structure oxide film defects in aluminum alloy castings has always troubled the industry. The fundamental reason is that the distribution of such defects in the castings is disordered, so even if the castings are dissected, it is difficult to accurately locate such defects. As you can imagine, the research on such defects has always stagnated.

[0005] In order to solve this problem, foreign foundry practitioners have proposed the "Oxide / metal / oxide (OMO) sandwich technology", the core idea of ​​which is to increase the oxide film content in the molten metal by blowing bubbles. The collision of bubbles will cause the oxide film to overlap, thus forming an entrained structure oxide film defect. Using this method, entrained structure oxide film defects can be obtained in the contact area of ​​the impact bubble, and then the relevant research on this type of defect can be completed.

[0006] However, the existing "Oxide / metal / oxide (OMO) sandwich technology" has serious limitations. On the one hand, the entrained structure oxide film defects obtained by the collision of bubbles are uneven, the thinnest at the collision contact point, and the thicker the farther away from the contact point, this structure is inconsistent with the real entrained structure oxide film defects. On the other hand, the size of the new oxide film defects (10mm) obtained by bubble collision seriously exceeds the actual situation (<1mm), which means that the evolution law or deformation mode of this bubble collision structure in subsequent links is completely different from the real new oxide film defects. Therefore, under the existing technology, it is difficult to conduct a systematic study of entrained structure oxide film defects in castings. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the main purpose of the present invention is to propose a method for introducing an entrained structure oxide film in an aluminum alloy casting, overcome the randomness of the distribution of such defects in the casting, solve the problem of precise positioning, and provide a path and method for the subsequent study of the evolution of the entrained structure oxide film inside the casting.

[0008] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions: A method for introducing an entrained structure oxide film into an aluminum alloy casting comprises the following steps: S1. Remove the oxide film on the surface of the aluminum alloy liquid; S2, selecting the fished oxide film and placing it between two solid aluminum alloys to form a solid aluminum alloy / oxide film / solid aluminum alloy structure; S3. The above structure is subjected to induction melting treatment, and the solid aluminum alloy / oxide film / solid aluminum alloy structure is combined into one, so as to obtain a solid aluminum alloy casting containing an oxide film with an entrained structure inside.

[0009] As a preferred embodiment of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, in step S1, a scooping net is used to scoop up the oxide film, and the scooping net includes a circular ring, a net is arranged inside the circular ring, and holding rods are connected to the outer edges of both sides of the circular ring.

[0010] As a preferred embodiment of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, the aluminum alloy liquid is one of ZL101A alloy liquid, ZL205A alloy liquid or ZL702A alloy liquid.

[0011] As a preferred embodiment of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, wherein: in step S1, the surface of the aluminum alloy liquid is subjected to slag removal before scooping.

[0012] As a preferred embodiment of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, in which: in step S2, the contact end surface between the solid aluminum alloy and the oxide film is ground and polished.

[0013] As a preferred embodiment of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, in step S3, during induction melting treatment, the oxide film of the solid aluminum alloy / oxide film / solid aluminum alloy structure is placed at the center of the coil of the induction device.

[0014] As a preferred solution of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, the induction device is an induction heater.

[0015] As a preferred embodiment of the method for introducing an entrained structure oxide film into an aluminum alloy casting described in the present invention, wherein: in step S3, during the induction melting treatment, the induction heater is turned on, the current parameter is adjusted to 18-19A, and the heating time is 5-10s.

[0016] The beneficial effects of the present invention are as follows: The present invention proposes a method for introducing entrained structure oxide film in aluminum alloy castings, which can simulate the entrained structure oxide film defects in real castings in an artificial way. The structural form and size of the entrained structure oxide film are consistent with those found in actual castings, and the entrained structure oxide film that is uncontrollable and difficult to accurately locate in the original casting can be accurately identified, laying a foundation for in-depth research on the entrained structure oxide film defects in subsequent castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the process of introducing the method in the present invention.

[0019] Figure 2 It is a structural schematic diagram of the scoop net of the present invention.

[0020] Figure 3 This is a morphological diagram of the oxide film fished out in the present invention.

[0021] Figure 4 This is a morphological diagram of the oxide film defects of the entrained structure after introduction in Example 1 of the present invention.

[0022] Figure 5 This is a schematic diagram of the entrained structure oxide film defects in the actual casting selected by the present invention.

[0023] Figure 6 This is an X-ray flaw detection identification diagram of the entrained structural oxide film defects in the actual casting selected by the present invention.

[0024] Figure 7 for Figure 5 SEM image of the oxide film defects with entrained structure.

[0025] Figure 8 This is a thickness analysis diagram of the oxide film defect of the entrained structure introduced in Example 1 of the present invention.

[0026] In the figure: 1-wire mesh; 2-ring; 3-gripping rod.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] According to one aspect of the present invention, the present invention provides the following technical solution: A method for introducing an entrained structure oxide film into an aluminum alloy casting comprises the following steps: S1. Remove the oxide film on the surface of the aluminum alloy liquid; S2, selecting the fished oxide film and placing it between two solid aluminum alloys to form a solid aluminum alloy / oxide film / solid aluminum alloy structure; S3. The above structure is subjected to induction melting treatment, and the solid aluminum alloy / oxide film / solid aluminum alloy structure is combined into one, so as to obtain a solid aluminum alloy casting containing an oxide film with an entrained structure inside.

[0030] See also Figure 1 The oxide film on the surface of the aluminum alloy liquid can be scooped up in the form of a scooping net to obtain an oxide film of a certain size (the size of the oxide film is mainly determined by the mesh size of the scooping net), and one of the scooped oxide films is selected and placed between two solid aluminum alloys to assemble a solid aluminum alloy / oxide film / solid aluminum alloy structure, which is placed in a container and then subjected to induction melting treatment in the container, the solid aluminum alloy is melted, and the contact surface of the solid aluminum alloy and the oxide film is fused together to form a whole, thereby completing the introduction of the entrained structure oxide film.

[0031] The existing technology "Oxide / metal / oxide (OMO) sandwich" is to prepare the entrained structure oxide film by bubble contact, and its structure has great defects. The present invention firstly fishes out the oxide film close to the real entrained structure oxide film in the alloy liquid. The oxide film is not prepared, but formed on the surface of the alloy liquid, which is in line with the formation process of the actual entrained structure oxide film (the actual entrained structure oxide film is mainly formed by the oxide film generated on the surface of the alloy liquid due to the instability of the liquid surface and rolled into the interior), and then spreads the oxide film between two solid aluminum alloys, and after induction melting treatment, with the movement of the melt, the contact interface of the solid aluminum alloy / oxide film / solid aluminum alloy structure is able to form a whole, completing the directional and precise introduction of the entrained structure oxide film.

[0032] The present invention introduces a real oxide film, which conforms to the situation of oxide film defects in actual castings, and the position of the introduced oxide film is controllable, rather than randomly distributed in the casting, thereby achieving the directional and precise introduction of oxide film defect structure inside the aluminum alloy, and after induction melting treatment, during the fusion process of the contact interface of the solid aluminum alloy / oxide film / solid aluminum alloy structure, the deformation of the oxide film is controllable, and large-scale deformation and breakage will not occur. The introduced entrainment structure domain oxide film is uniform and of appropriate size, which is convenient for subsequent research and analysis.

[0033] Preferably, in step S1, a scooping net is used to scoop up the oxide film, wherein the scooping net comprises a circular ring, a net is arranged inside the circular ring, and holding rods are connected to the outer edges of both sides of the circular ring.

[0034] Specifically, the process of making a scoop net is as follows: Take steel wire to weave a net, cut it into a circle, spot weld a ring 2 (steel ring to prevent the net from deformation) on the outside of the wire mesh 1, and then weld two holding rods 3 (made of steel rods to hold and scoop up the oxide film) on the outer edges of both sides of the ring surface. The net structure is as follows: Figure 2 shown.

[0035] Preferably, the aluminum alloy liquid may be various aluminum alloy liquids such as ZL101A alloy liquid, ZL205A alloy liquid, ZL702A alloy liquid, etc.

[0036] Preferably, in step S1, the surface of the aluminum alloy liquid is subjected to a slag removal treatment before scooping out to remove an old oxide film on the surface of the molten metal.

[0037] Preferably, in step S2, the contact end surface between the solid aluminum alloy and the oxide film is ground and polished.

[0038] Preferably, in step S3, during the induction melting process, the oxide film of the solid aluminum alloy / oxide film / solid aluminum alloy structure is placed at the center of the coil of the induction device.

[0039] Preferably, the induction device is an induction heater.

[0040] Preferably, in step S3, during the induction melting process, the induction heater is turned on, the current parameter is adjusted to 18-19A, and the heating time is 5-10s.

[0041] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0042] Example 1 A method for introducing an entrained structure oxide film into an aluminum alloy casting comprises the following steps: S1. Make a scoop net with a mesh size of 5mm×5mm and a diameter of 30mm. After slagging the surface of the ZL101A alloy liquid, quickly sink the round net of the scoop net into the middle of the ZL101A alloy liquid, let it stand for 5s, and then slagging the surface of the metal liquid for the second time. After 2s of slagging, take the scoop net out of the ZL101A alloy liquid to obtain multiple 5mm×5mm oxide films. S2. Process the aluminum alloy into two rod-shaped solid aluminum alloys with a diameter of 8 mm and a height of 20 mm, grind and polish the end faces of the two rods with sandpaper, and ultrasonically clean them in anhydrous ethanol for 15 minutes, select a piece of oxide film and place it on the end face of the first rod-shaped solid aluminum alloy, and then place another rod-shaped solid aluminum alloy on the end face of the first rod-shaped solid aluminum alloy (the oxide film has been placed on the surface) to form a solid aluminum alloy / oxide film / solid aluminum alloy structure, and place the structure in a glass test tube with a diameter of 8.5 mm; S3. Place the glass test tube into the induction coil of the induction heater with a diameter of 15 mm, and keep the position of the oxide film at the center of the induction coil. After turning on the cooling water circulation for 3 minutes, turn on the induction heater, adjust the current parameter to 18A, and keep it for 5 seconds. Turn off the induction heater and cooling water circulation, and take the test tube out of the induction coil to obtain a solid aluminum alloy casting containing an entrained structure oxide film, thus completing the introduction of the entrained structure oxide film.

[0043] The oxide film morphology obtained in step S1 of this embodiment is as follows Figure 3 As shown, the size of the oxide film is approximately 5mm×5mm; the morphology of the entrained structure oxide film introduced at the end is as follows Figure 4 As shown ( Figure 4 The left side shows the camera shooting mode. Figure 4 The right side shows the morphology taken with a scanning electron microscope). It can be seen that radial, horizontal, and concentrated defects are found in large numbers where the entrained structure oxide film is placed, and the range of the defect area is highly consistent with the size of the introduced entrained structure oxide film (side length 3-5mm).

[0044] A batch of actual castings were selected for delivery and pressure testing. It was found that leakage occurred at the defective position. After dissection, the actual castings were dissected. Figure 5 (The inclusion structure oxide film defect was found). It was not found before because in actual castings, traditional non-destructive testing cannot find this defect (see Figure 6 ), and the oxide film defects after dissection were analyzed by scanning electron microscopy (see Figure 7 ).

[0045] Based on the results of laser confocal microscopy, see Figure 8The thickness of the entrained structure oxide film defect introduced by the present invention is less than 1 mm, which is consistent with that found in actual castings. It can be seen that the evolution of the entrained structure oxide film defect after artificial introduction by this method is similar to the formation of defects in actual castings, and can simulate the entrained structure oxide film defect in real castings.

[0046] Example 2 A method for introducing an entrained structure oxide film into an aluminum alloy casting comprises the following steps: S1. Make a scoop net with a mesh size of 4mm×4mm and a diameter of 30mm. After slagging the surface of the ZL205A alloy liquid, quickly sink the round net of the scoop net into the middle of the ZL205A alloy liquid, let it stand for 5s, and then slagging the surface of the metal liquid for the second time. After 5s of slagging, take the scoop net out of the ZL205A alloy liquid to obtain multiple 4mm×4mm oxide films; S2. Process the aluminum alloy into two rod-shaped solid aluminum alloys with a diameter of 8 mm and a height of 20 mm, grind and polish the end faces of the two rods with sandpaper, and ultrasonically clean them in anhydrous ethanol for 15 minutes, select a piece of oxide film and place it on the end face of the first rod-shaped solid aluminum alloy, and then place another rod-shaped solid aluminum alloy on the end face of the first rod-shaped solid aluminum alloy (the oxide film has been placed on the surface) to form a solid aluminum alloy / oxide film / solid aluminum alloy structure, and place the structure in a glass test tube with a diameter of 8.5 mm; S3. Place the glass test tube into the induction coil of the induction heater with a diameter of 15 mm, and keep the position of the oxide film at the center of the induction coil. After turning on the cooling water circulation for 3 minutes, turn on the induction heater, adjust the current parameter to 18A, and keep it for 6 seconds. Turn off the induction heater and cooling water circulation, and take the test tube out of the induction coil to obtain a solid aluminum alloy casting containing an entrained structure oxide film inside, completing the introduction of the entrained structure oxide film.

[0047] Example 3 A method for introducing an entrained structure oxide film into an aluminum alloy casting comprises the following steps: S1. Make a scoop net with a mesh size of 6mm×6mm and a diameter of 30mm. After slagging the surface of the ZL702A alloy liquid, quickly sink the round net of the scoop net into the middle of the ZL702A alloy liquid, let it stand for 5s, and then slagging the surface of the metal liquid for the second time. After 10s of slagging, take the scoop net out of the ZL702A alloy liquid to obtain multiple 6mm×6mm oxide films. S2. Process the aluminum alloy into two rod-shaped solid aluminum alloys with a diameter of 8 mm and a height of 20 mm, grind and polish the end faces of the two rods with sandpaper, and ultrasonically clean them in anhydrous ethanol for 15 minutes, select a piece of oxide film and place it on the end face of the first rod-shaped solid aluminum alloy, and then place another rod-shaped solid aluminum alloy on the end face of the first rod-shaped solid aluminum alloy (the oxide film has been placed on the surface) to form a solid aluminum alloy / oxide film / solid aluminum alloy structure, and place the structure in a glass test tube with a diameter of 8.5 mm; S3. Place the glass test tube into the induction coil of the induction heater with a diameter of 15 mm, and keep the position of the oxide film at the center of the induction coil. After turning on the cooling water circulation for 3 minutes, turn on the induction heater, adjust the current parameter to 18A, and keep it for 10 seconds. Turn off the induction heater and cooling water circulation, and take the test tube out of the induction coil to obtain a solid aluminum alloy casting containing an entrained structure oxide film inside, completing the introduction of the entrained structure oxide film.

[0048] Example 4 A method for introducing an entrained structure oxide film into an aluminum alloy casting comprises the following steps: S1. Make a scoop net with a mesh size of 5mm×5mm and a diameter of 30mm. After slagging the surface of the ZL101A alloy liquid, quickly sink the round net of the scoop net into the middle of the ZL101A alloy liquid, let it stand for 5s, and then slagging the surface of the metal liquid for the second time. After 2s of slagging, take the scoop net out of the ZL101A alloy liquid to obtain multiple 5mm×5mm oxide films. S2. Process the aluminum alloy into two rod-shaped solid aluminum alloys with a diameter of 8 mm and a height of 20 mm, grind and polish the end faces of the two rods with sandpaper, and ultrasonically clean them in anhydrous ethanol for 15 minutes, select a piece of oxide film and place it on the end face of the first rod-shaped solid aluminum alloy, and then place another rod-shaped solid aluminum alloy on the end face of the first rod-shaped solid aluminum alloy (the oxide film has been placed on the surface) to form a solid aluminum alloy / oxide film / solid aluminum alloy structure, and place the structure in a glass test tube with a diameter of 8.5 mm; S3. Place the glass test tube into the induction coil of the induction heater with a diameter of 15 mm, and keep the position of the oxide film at the center of the induction coil. After turning on the cooling water circulation for 3 minutes, turn on the induction heater, adjust the current parameter to 19A, and keep it for 8 seconds. Turn off the induction heater and cooling water circulation, and take the test tube out of the induction coil to obtain a solid aluminum alloy casting containing an entrained structure oxide film inside, completing the introduction of the entrained structure oxide film.

[0049] The entrained structure oxide film defects introduced in Example 2, Example 3, and Example 4 have slight differences in size, thickness, and distribution breadth due to differences in scoop net size, scooping time, and induction melting treatment process conditions, but are basically similar to the structure introduced in Example 1, and no significant structural changes are observed.

[0050] It can be seen that the method of the present invention can ensure that the form of the artificially introduced entrained structure oxide film is consistent with that found in the actual casting, the overall thickness of the introduced entrained structure oxide film is uniform, and the size of the artificially introduced entrained structure oxide film is consistent with that found in the actual casting, both <1 mm. The present invention can simulate the entrained structure oxide film defects in real castings, and realizes the directional and precise introduction of oxide film defect structures inside aluminum alloys, which can lay the foundation for in-depth research on entrained structure oxide film defects in subsequent castings.

[0051] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for introducing an entrained structure oxide film into an aluminum alloy casting, characterized in that: The steps include: S1. Remove the oxide film on the surface of the aluminum alloy liquid; S2, selecting the oxide film that has been fished out and placing it between two solid aluminum alloys to form a solid aluminum alloy / oxide film / solid aluminum alloy structure; S3. The above structure is subjected to induction melting treatment, and the solid aluminum alloy / oxide film / solid aluminum alloy structure is combined into one, so as to obtain a solid aluminum alloy casting containing an oxide film with an entrained structure inside.

2. The method for introducing an entrained structure oxide film into an aluminum alloy casting according to claim 1, characterized in that: In step S1, the oxide film is scooped up with a scooping net, wherein the scooping net comprises a circular ring, a net is arranged inside the circular ring, and holding rods are connected to the outer edges of both sides of the circular ring.

3. The method for introducing an entrained structure oxide film into an aluminum alloy casting according to claim 2, characterized in that: The aluminum alloy liquid is one of ZL101A alloy liquid, ZL205A alloy liquid or ZL702A alloy liquid.

4. The method for introducing an entrained structure oxide film into an aluminum alloy casting according to claim 2, characterized in that: In step S1, the surface of the aluminum alloy liquid is subjected to slag removal before being scooped out.

5. The method for introducing an oxide film with an entrained structure into an aluminum alloy casting according to claim 1, characterized in that: In step S2, the contact end surface between the solid aluminum alloy and the oxide film is ground and polished.

6. The method for introducing an entrained structure oxide film into an aluminum alloy casting according to claim 1, characterized in that: In step S3, during the induction melting process, the oxide film of the solid aluminum alloy / oxide film / solid aluminum alloy structure is placed at the center of the coil of the induction device.

7. The method for introducing an entrained structure oxide film into an aluminum alloy casting according to claim 6, characterized in that: The induction device is an induction heater.

8. The method for introducing an entrained structure oxide film into an aluminum alloy casting according to claim 7, characterized in that: In step S3, during the induction melting process, the induction heater is turned on, the current parameter is adjusted to 18-19A, and the heating time is 5-10s.

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