Heat treatment method for improving plasticity of rare earth Y modified ADC12 regenerated aluminum alloy

Abstract

The invention belongs to the technical field of non-ferrous metal processing, and particularly relates to a heat treatment method for improving plasticity of a rare earth Y modified ADC12 regenerated aluminum alloy, which comprises the following steps: heating the rare earth Y modified ADC12 regenerated aluminum alloy to a first temperature at a certain heating rate, keeping the temperature for a first time, and quenching in boiling water for 10-20 seconds. By adopting boiling water quenching, the eutectic Si phase and the alpha-Fe phase in the alloy can have a better spheroidizing effect, especially the spheroidizing effect of the eutectic Si phase is more remarkable, the matrix splitting effect of the eutectic Si phase and the alpha-Fe phase is weakened, and the plasticity of the alloy is better improved. Experiments show that the tensile strength and the ductility of the material are obviously improved by adopting boiling water quenching in the technical scheme, particularly, the ductility is improved by 4.52% and 48.5% compared with the traditional quenching by using water at 60 DEG C, and the improvement effect on the plasticity of the material is obvious.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal processing, and in particular relates to a heat treatment method for improving the plasticity of rare earth Y-modified ADC12 recycled aluminum alloy. Background Art

[0002] The commercial die-casting aluminum alloy JIS (Japanese Industrial Standard) ADC12 modified with rare earth Y is an Al-Si-Cu series secondary aluminum alloy, which belongs to a type of casting aluminum alloy. This alloy has the advantages of excellent casting performance, light weight and easy recycling and reuse, and is widely recognized in industrial production. However, for recycled secondary aluminum alloys, their mechanical properties are often affected by the morphology of the inclusion phase in the matrix. The coarse α-Fe phase and flaky eutectic Si phase in the alloy will seriously split the matrix, thereby affecting its mechanical properties, especially poor plasticity, easy brittle fracture, and inability to undergo large deformation, which greatly limits its scope of application.

[0003] Therefore, in order to improve the mechanical properties of cast recycled aluminum alloy, effective methods must be adopted to optimize the alloy structure. T6 heat treatment is the most commonly used heat treatment process for aluminum-silicon alloys. It can make Al2Cu phase and eutectic Si phase solid dissolve in α-Al phase, effectively strengthen the matrix α-Al phase, and refine α-Fe phase and blocky primary Si phase, thereby improving the mechanical properties of rare earth Y modified ADC12 recycled aluminum alloy. However, although T6 heat treatment can improve the plasticity of rare earth Y modified ADC12 recycled aluminum alloy to a certain extent, the process has limited improvement on the plasticity of the alloy. The metallographic spheroidization degree of the treated rare earth Y modified ADC12 recycled aluminum alloy is low, resulting in unsatisfactory plasticity. Summary of the invention

[0004] Based on this, the present application provides a heat treatment method for improving the plasticity of rare earth Y modified ADC12 recycled aluminum alloy, so as to solve the technical problem that the T6 heat treatment in the prior art has limited effect on improving the plasticity of the alloy, and the metallographic spheroidization degree of the rare earth Y modified ADC12 recycled aluminum alloy after treatment is low, resulting in unsatisfactory plasticity.

[0005] The technical solution of this application to solve the above technical problems is as follows:

[0006] A heat treatment method for improving the plasticity of rare earth Y-modified ADC12 recycled aluminum alloy comprises the following steps:

[0007] Solution treatment: the rare earth Y-modified ADC12 recycled aluminum alloy is heated to a first temperature at a certain heating rate and kept at a first time, and then quenched in boiling water for 10 to 20 seconds.

[0008] Preferably, in the above method, the boiling water temperature is 90°C to 100°C.

[0009] Preferably, in the above method, the heating rate is 8 to 15° C. / min, the first temperature is 400 to 600° C., and the first time length is 5 to 10 h.

[0010] Preferably, in the above method, after the solution treatment, the method further comprises:

[0011] Aging treatment: put the quenched rare earth Y modified ADC12 recycled aluminum alloy into a high temperature drying oven within 5 minutes and keep it at the second temperature for the second time.

[0012] Preferably, in the above method, the second temperature is 150 to 200° C., and the second time period is 7 to 12 hours.

[0013] Preferably, in the above method, the rare earth Y-modified ADC12 recycled aluminum alloy is prepared by the following method: adding 0.05 to 0.15 wt % of rare earth Y to the ADC12 recycled aluminum alloy, and obtaining the rare earth Y-modified ADC12 recycled aluminum alloy after centrifugal casting.

[0014] The present invention adopts the above technical solution, and its beneficial effects are:

[0015] The heat treatment method for the plasticity of rare earth Y-modified ADC12 recycled aluminum alloy provided by the present invention is to heat the rare earth Y-modified ADC12 recycled aluminum alloy to a first temperature at a certain heating rate and keep it warm for a first time, and then put it into boiling water for quenching for 10 to 20 seconds. The use of boiling water quenching can make the eutectic Si phase and α-Fe phase in the alloy have a better spheroidization effect, especially the spheroidization effect of the eutectic Si phase is more significant, and the eutectic Si phase and α-Fe phase The effect of splitting the matrix is ​​weakened, and the plasticity of the alloy is better improved. Experiments show that the boiling water quenching using this technical solution has significantly improved the tensile strength and elongation of the material, especially the elongation, which is 6.33% higher than the original material without quenching treatment, and the improvement rate is 84.4%; compared with the traditional quenching using 60°C water, the elongation is increased by 4.52%, and the improvement rate is 48.5%, which has a significant effect on improving the plasticity of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Metallographic microstructure of ADC12 recycled aluminum alloy samples modified by rare earth Y with different heat treatment processes.

[0017] Figure 2 Microstructure of ADC12 recycled aluminum alloy samples modified by rare earth Y with different heat treatment processes.

[0018] Figure 3 Mechanical properties of rare earth Y modified ADC12 recycled aluminum alloy samples with different heat treatment processes. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The technical solution of the present invention will be further described below in conjunction with the drawings of the embodiments of the present invention, and the present invention is not limited to the following specific implementation methods.

[0020] In a specific embodiment of the present invention, a heat treatment method for improving the plasticity of rare earth Y-modified ADC12 recycled aluminum alloy comprises the following steps:

[0021] Solution treatment: the rare earth Y-modified ADC12 recycled aluminum alloy is heated to a first temperature at a certain heating rate and kept at a first time, and then quenched in boiling water for 10 to 20 seconds.

[0022] T6 heat treatment is divided into solution treatment and aging treatment. In the solution treatment, the alloy material is first heated to a high temperature and kept warm for a certain period of time, so that the soluble elements in the impurity phase, such as magnesium and silicon, are dissolved in the matrix; then the solute elements in the solid solution are quenched so that they do not have time to precipitate, forming a supersaturated solid solution with higher hardness and strength. This supersaturated solid solution also has good ductility and toughness. T6 heat treatment improves the strength and hardness of the alloy by solid solution strengthening of Si in rare earth Y-modified ADC12 recycled aluminum alloy and precipitation of Si particles to increase the content of hard phase in the alloy. The precipitation of Si particles can effectively hinder the movement of grain boundaries, increase the alloy's deformation resistance and fatigue resistance, and the distribution of hard phase particles can effectively hinder the movement of dislocations, thereby improving the tensile strength and hardness of the alloy.

[0023] Quenching is an important step in the T6 heat treatment process. Its function is to increase the hardness and strength of the material by rapid cooling. In addition, quenching can also refine the grains of the material, improve the strengthening effect of the grain interface, and increase the plasticity and toughness of the material. Quenching plays a key role in T6 heat treatment. Different quenching temperatures are used in T6 heat treatment, and the effect of solid solution strengthening is different. Selecting a suitable quenching temperature can make the eutectic Si phase and α-Fe phase in the alloy have a better spheroidization effect, especially the spheroidization effect of the eutectic Si phase is more significant, and the effect of the eutectic Si phase and α-Fe phase splitting the matrix is ​​weakened, which better improves the plasticity of the alloy.

[0024] In the present application, the quenching medium is boiling water. It is worth noting that, since the boiling point of water decreases with the decrease of air pressure, the higher the altitude, the thinner the air, the lower the atmospheric pressure, and the lower the temperature at which water boils. Therefore, further, the boiling water temperature is 90°C to 100°C. Experiments show that with the use of waste water, the number of eutectic Si phase precipitations of rare earth Y-modified ADC12 recycled aluminum alloy increases significantly, most of which are spherical in different sizes and are relatively evenly distributed, and the α-Fe phase is mostly small spherical and evenly distributed. The tensile strength and elongation of the material are significantly improved, especially the elongation, which is 6.33% higher than the original material without quenching treatment, and the improvement rate is 84.4%; compared with the traditional quenching using 60°C water, the elongation is increased by 4.52%, and the improvement rate is 48.5%, which has a significant effect on improving the plasticity of the material.

[0025] In a specific embodiment of the present application, the heating rate is 8 to 15° C. / min, the first temperature is 400 to 600° C., and the first time length is 5 to 10 h.

[0026] In another specific embodiment of the present application, the solution treatment further includes: aging treatment: placing the quenched rare earth Y-modified ADC12 recycled aluminum alloy in a high-temperature drying oven within 5 minutes, and keeping it at a second temperature for a second time. Wherein, the second temperature is 150 to 200°C, and the second time is 7 to 12 hours. The aging treatment in this application is artificial aging, which can rearrange the atoms inside the rare earth Y-modified ADC12 recycled aluminum alloy and further improve the mechanical properties of the material.

[0027] In another specific embodiment of the present application, the rare earth Y modified ADC12 recycled aluminum alloy is prepared by the following method: adding 0.05 to 0.15wt% of rare earth Y to the ADC12 recycled aluminum alloy, and obtaining the rare earth Y modified ADC12 recycled aluminum alloy after centrifugal casting. The addition of rare earth Y can help improve the thermal stability and corrosion resistance of the ADC12 recycled aluminum alloy, so that the material performs better in high temperature and corrosive environments.

[0028] It is worth noting that the process temperature and process time involved in the above-mentioned embodiments are all temperatures or times used in the experimental process. Those skilled in the art can make reasonable adjustments within the error range based on the process temperature and process time provided by the present invention, which should be included in the protection scope of the present invention.

[0029] The technical solution and technical effects of the present invention are further illustrated below through specific experimental examples.

[0030] 1. Experimental Materials

[0031] The rare earth Y-modified ADC12 recycled aluminum alloy is obtained by centrifugal casting of 0.1wt% rare earth Y-modified ADC12 recycled aluminum alloy, wherein the ADC12 recycled aluminum alloy is a new die-casting Al-Si alloy, which is made by recycling and regenerating waste aluminum alloy, and its chemical composition is shown in Table 1.

[0032] Table 1 Main chemical composition of ADC12 recycled aluminum alloy

[0033]

[0034] 2. Comparative Example

[0035] Unheat-treated rare earth Y-modified ADC12 recycled aluminum alloy sample.

[0036] 3. Experimental examples

[0037] The rare earth Y modified ADC12 recycled aluminum alloy sample was heated to 500°C at a heating rate of 10°C / min and kept warm for 7 hours, then quenched in water for 15 seconds, where the water temperatures were 0°C, 10°C, 30°C, 60°C, 80°C and boiling (the experimental location was Yinchuan, with an altitude of 1010m, and the measured boiling point of water was 97°C); after quenching, it was placed in a high-temperature drying oven at 170°C for artificial aging within 5 minutes and kept warm for 10 hours.

[0038] 4. Experimental results analysis

[0039] According to the "GB / T228.1-2010 Metal Material Tensile Test Standard", the tensile test was carried out to test the tensile strength and other mechanical properties of the samples. Figures 1 to 3 .

[0040] Figure 1 The metallographic microstructures of rare earth Y modified ADC12 recycled aluminum alloy samples with different heat treatment processes are shown in Figure 2. Figure 1 (a) It can be seen that the α-Al phase in the ADC12 recycled aluminum alloy that has not been heat treated with T6 is a large area of ​​irregular white phase, and its phase outline is unclear and irregularly distributed. The dark black structure with irregular blocks and large area is the primary Si phase. After heat treatment, the primary Si phase almost disappears, and the precipitated dark black structure is the eutectic Si phase; the dark black structure with strips or fibers and irregular arrangement is the eutectic Si phase; the light black structure is the α-Fe phase, which is irregular blocks or sheets. Figure 2 (a) It can be seen that the irregular block and Chinese character-shaped white phase is the α-Fe phase. It can be seen that the phase is large in size and has obvious agglomeration. The morphology of the eutectic Si phase and the α-Fe phase in the alloy will significantly affect the mechanical properties of the material. The morphology of the Si phase and the α-Fe phase will significantly affect the mechanical properties of the material.

[0041] Depend on Figure 1(b) It can be seen that when the quenching temperature is 0℃, the eutectic Si phase has the best refinement and spheroidization effect, the size is significantly reduced, and the spheroidization is more obvious; the α-Fe phase has the best refinement effect, mostly presenting small irregular polygonal shapes. Figure 1 (c)(d) It can be seen that when the quenching temperature rises from 10℃ to 30℃, the short rod-shaped eutectic Si phase begins to change into a larger block-shaped eutectic Si phase, and the rod-shaped eutectic Si phase increases; at this time, the α-Fe phase is mostly small fishbone or Chinese character-shaped.

[0042] Depend on Figure 1 (e) It can be seen that when the quenching temperature is 60°C, which is the quenching temperature of the traditional process, the edge of the eutectic Si phase becomes more rounded than the edge that has not been heat treated, and most of it turns into short rods with a significantly reduced size. Figure 2 (b) It can be seen that the α-Fe phase has the best refinement effect, and it is mostly small, mostly in the shape of fish bones or Chinese characters, mixed with a small amount of irregular polygonal shapes.

[0043] Depend on Figure 1 (f) It can be seen that when the quenching temperature is 80℃, the precipitation of eutectic Si phase increases, but the spheroidization effect of the eutectic Si phase is improved, and the large block of eutectic Si phase further increases; at this time, the α-Fe phase is mostly irregular polygonal, mixed with a small amount of small fishbone or Chinese character shapes.

[0044] Depend on Figure 1 (g) It can be seen that when the quenching temperature is boiling, the number of eutectic Si phase precipitation increases significantly, most of which are spherical in shape with different sizes and are distributed more evenly. Figure 2 (c) It can be seen that the α-Fe phase is mostly in the form of small spheres and is evenly distributed.

[0045] See also Figure 3 , tensile strength and elongation of rare earth Y modified ADC12 recycled aluminum alloy samples at different quenching temperatures. It can be seen from the figure that with the increase of quenching temperature, the tensile strength of the alloy continues to decrease, which corresponds to the change trend of the solid solution degree and refinement degree of the eutectic Si phase in the metallographic structure; the elongation of the alloy first decreases and then increases, which corresponds to the change of the spheroidization degree of the eutectic Si phase.

[0046] When the quenching temperature is 60°C (traditional process), the alloy strength is mainly improved, corresponding to the microstructure refinement effect; when the quenching temperature is boiling (the process of this application), the alloy plasticity is mainly improved, corresponding to the spheroidization effect of the hard phase in the alloy. The better the spheroidization effect, the better the elongation of the material. Compared with the traditional quenching using 60°C water, the elongation is increased by 4.52% when the quenching temperature is boiling, and the improvement rate is 48.5%, which has a significant effect on improving the plasticity of the material. At the same time, the strength-plasticity product of the rare earth Y-modified ADC12 recycled aluminum alloy in this application scheme reaches more than 3.9, and the strength and toughness level is excellent.

[0047] In summary, the present application scheme quenches the rare earth Y-modified ADC12 recycled aluminum alloy in boiling water, and the metallographic spheroidization degree is high, which significantly improves the tensile strength and elongation of the material, especially the elongation, which means that the plasticity of the material is significantly improved. At the same time, the strength-plasticity product can reach more than 3.9GPa%, and it has excellent comprehensive strength and toughness levels. It can be widely used in transportation, daily packaging, aerospace and other fields, especially in automobile manufacturing, and is used to manufacture gearbox parts, wheel covers, body structural parts, engine blocks, etc.

[0048] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A heat treatment method for improving the plasticity of rare earth Y-modified ADC12 recycled aluminum alloy, characterized in that: The following steps are involved: Solution treatment: the rare earth Y-modified ADC12 recycled aluminum alloy is heated to a first temperature at a certain heating rate and kept at a first time, and then quenched in boiling water for 10 to 20 seconds.

2. The method according to claim 1, characterized in that The boiling water temperature is 90°C to 100°C.

3. The method according to claim 1, characterized in that The heating rate is 8 to 15° C. / min, the first temperature is 400 to 600° C., and the first time is 5 to 10 h.

4. The method according to claim 1, characterized in that: The solution treatment further comprises: Aging treatment: put the quenched rare earth Y modified ADC12 recycled aluminum alloy into a high temperature drying oven within 5 minutes and keep it at the second temperature for the second time.

5. The method according to claim 4, characterized in that The second temperature is 150 to 200° C., and the second time period is 7 to 12 hours.

6. The method according to claim 1, characterized in that The rare earth Y-modified ADC12 recycled aluminum alloy is prepared by the following method: adding 0.05 to 0.15 wt % of rare earth Y into the ADC12 recycled aluminum alloy, and obtaining the rare earth Y-modified ADC12 recycled aluminum alloy through centrifugal casting.

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