A method for refining, modifying and alloying ZL114A alloy

Abstract

A method for refining, modifying and alloying a ZL114A alloy, which belongs to the field of non-ferrous metal casting and forming. The purpose of the invention is to increase the mechanical properties of the alloy by adding the alloying element Al‑50Cu to precipitate a strengthening phase and adding Al‑5Ti‑B and Al‑10Y intermediate alloys to refine and modify the alloy. Method: 1. Prepare aluminum alloy ingots; 2. Heat treatment. The advantage of the present invention is that the Cu element is added to generate a strengthening phase, and Al‑5Ti‑B and Al‑10Y are added for refinement and modification to change the morphology of eutectic Si; the composite addition enhances the mechanical properties of the alloy, with a hardness of up to 136.7HV and a tensile strength of up to 274.1MPa.

Description

Technical Field

[0001] The invention belongs to the field of nonferrous metal casting and molding, and in particular relates to a method for refining, modifying and alloying a ZL114A alloy. Background Art

[0002] As the country increases its efforts to save energy and reduce emissions, automobile lightweighting has become one of the hottest topics. This places higher demands on automotive structural materials, requiring not only high strength but also light weight. Aluminum alloys have the advantages of high strength, light weight, and low density, and are widely used in automobiles, aviation, and other fields. Aluminum alloys are mainly divided into two categories: cast aluminum alloys and deformed aluminum alloys. Compared with other alloys, cast aluminum alloys can reduce more weight while meeting performance requirements. Cast Al-Si alloys are the most common and widely used cast aluminum alloys. ZL114A is a hypoeutectic cast Al-Si alloy with the advantages of good casting performance, heat treatment strengthening, and good processing performance. It can be used in engineering through microalloying, refinement, and final heat treatment strengthening.

[0003] For the refinement and modification of eutectic Si, the twin valley principle and the interface step principle are two relatively recognized modification principles. Na, Sr, Sb and RE are the main modifiers of eutectic silicon. Among them, Na modifier is not easy to prepare and will increase the gas absorption of the alloy. It is a short-term modifier, which leads to its reduced application. Sr

[0004] It is a long-term modifier that can greatly change the shape of the silicon phase and significantly improve the tensile strength and hardness of the alloy. However, the operation is complicated and it is easy to increase the air absorption of the alloy, resulting in a large number of pore defects. Rare earth Y is a green long-term modifier with good modification effect, which can effectively increase the mechanical properties of the alloy. Single microalloying will improve the mechanical properties of the alloy by precipitating strengthening phases, but it cannot improve the morphology of eutectic Si. Coarse needle-shaped eutectic Si still exists, and there are many alloy defects, so the combination of microalloying and refinement modification can improve this problem. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for refining, modifying and alloying a ZL114A alloy.

[0006] Microalloying can improve the mechanical properties of the alloy, but the morphology of the coarse needle-shaped eutectic Si remains unchanged, and stress concentration and internal defects occur at the tip of the eutectic Si. Therefore, the purpose of the present invention is to increase the mechanical properties of the alloy by adding the alloy element Al-50Cu to precipitate the strengthening phase and adding Al-5Ti-B and Al-10Y master alloys to refine and modify the alloy, and to provide a method for refining and alloying the ZL114A alloy.

[0007] A method for refining, modifying and alloying a ZL114A alloy is specifically completed by the following steps:

[0008] 1. Preparation of aluminum alloy ingots:

[0009] ①, weigh ZL114A alloy, Al-50Cu master alloy, Al-10Y master alloy and Al-5Ti-B master alloy to obtain raw materials;

[0010] The mass of Cu in the Al-50Cu master alloy described in step 1① is 1.2% of the mass of the ZL114A alloy;

[0011] The mass of Y in the Al-10Y master alloy described in step 1① is 0.15% to 0.45% of the mass of the ZL114A alloy;

[0012] The mass of the Al-5Ti-B master alloy described in step 1① is 0.5% of the mass of the ZL114A alloy;

[0013] ②Put the ZL114A alloy into a preheated crucible at 250℃~300℃, and then put it into a pit crucible furnace for heating, and melt it at 750℃~780℃. After it is fully melted, remove the upper oxide film, put in the Al-50Cu master alloy wrapped in aluminum foil, keep it warm for 20min~30min, and stir it with a stone mill for 30s~60s. Then adjust the temperature of the crucible furnace to 720℃~730℃, put in the Al-5Ti-B master alloy and Al-10Y master alloy wrapped in aluminum foil, and keep it warm for 2 0min~30min, wherein after 10min~15min, stir with a stone mill rod, finish heat preservation, adjust the temperature of the crucible furnace to 750℃~780℃, use a bell jar to press hexachloroethane wrapped in newspaper into the molten metal, the amount of hexachloroethane added is 1wt.% of the mass of the raw material weighed in step 1, stir, stand for 10min~15min after degassing, skim slag, and then pour the molten metal into a metal mold preheated at 250℃~300℃, the pouring temperature is 720℃~730℃, and obtain an aluminum alloy ingot;

[0014] 2. Heat treatment:

[0015] The aluminum alloy ingot is wire cut, then subjected to solution treatment and then aging treatment to obtain the refined, modified and alloyed ZL114A alloy.

[0016] Principle of the present invention:

[0017] The tensile strength of ZL114A alloy mainly depends on the morphology of α-Al, eutectic Si and strengthening phase; the addition of Cu can inhibit the growth of eutectic Si, and the supersaturated solid solution obtained after solution treatment and water quenching is then placed in an aging environment to promote the precipitation of strengthening phases Mg2Si and Al2Cu, which plays a role in heat treatment strengthening; after adding Al-5Ti-B, the nucleation inhibition phase TiAl3 will be generated, which has a good refinement effect on the primary α-Al, and the coarse needle-shaped eutectic Si will have edges and corners. This morphology of silicon will produce stress concentration at the tip and have a splitting effect on the matrix. After adding Al-10Y, it can promote silicon nucleation and adsorb on the silicon surface to hinder its growth. The eutectic Si is transformed from a coarse needle to a short rod, which increases the mechanical properties of the alloy.

[0018] Advantages of the present invention:

[0019] The advantages of the present invention are that the Cu element is added to generate a strengthening phase, and Al-5Ti-B and Al-10Y are added to refine and modify the alloy, thereby changing the morphology of eutectic Si; the composite addition enhances the mechanical properties of the alloy, with a hardness of up to 136.7 HV and a tensile strength of up to 274.1 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 1;

[0021] Figure 2 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 2;

[0022] Figure 3 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 3;

[0023] Figure 4 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 4;

[0024] Figure 5 The metallographic image (T6 state) of the ZL114A alloy prepared in Comparative Example 1;

[0025] Figure 6 This is the metallographic image (T6 state) of the ZL114A alloy after refinement and alloying prepared in Comparative Example 2. DETAILED DESCRIPTION

[0026] Specific implementation method 1: This implementation method is a method for refining, modifying and alloying a ZL114A alloy, which is specifically completed in the following steps:

[0027] 1. Preparation of aluminum alloy ingots:

[0028] ①, weigh ZL114A alloy, Al-50Cu master alloy, Al-10Y master alloy and Al-5Ti-B master alloy to obtain raw materials;

[0029] The mass of Cu in the Al-50Cu master alloy described in step 1① is 1.2% of the mass of the ZL114A alloy;

[0030] The mass of Y in the Al-10Y master alloy described in step 1① is 0.15% to 0.45% of the mass of the ZL114A alloy;

[0031] The mass of the Al-5Ti-B master alloy described in step 1① is 0.5% of the mass of the ZL114A alloy;

[0032] ②Put the ZL114A alloy into a preheated crucible at 250℃~300℃, and then put it into a pit crucible furnace for heating, and melt it at 750℃~780℃. After it is fully melted, remove the upper oxide film, put in the Al-50Cu master alloy wrapped in aluminum foil, keep it warm for 20min~30min, and stir it with a stone mill for 30s~60s. Then adjust the temperature of the crucible furnace to 720℃~730℃, put in the Al-5Ti-B master alloy and Al-10Y master alloy wrapped in aluminum foil, and keep it warm for 2 0min~30min, wherein after 10min~15min, stir with a stone mill rod, finish heat preservation, adjust the temperature of the crucible furnace to 750℃~780℃, use a bell jar to press hexachloroethane wrapped in newspaper into the molten metal, the amount of hexachloroethane added is 1wt.% of the mass of the raw material weighed in step 1, stir, stand for 10min~15min after degassing, skim slag, and then pour the molten metal into a metal mold preheated at 250℃~300℃, the pouring temperature is 720℃~730℃, and obtain an aluminum alloy ingot;

[0033] 2. Heat treatment:

[0034] The aluminum alloy ingot is wire cut, then subjected to solution treatment and then aging treatment to obtain the refined, modified and alloyed ZL114A alloy.

[0035] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the composition of the ZL114A alloy described in step 1① is as follows by mass fraction: Si: 6.25% to 7.5%, Mg: 0.45% to 0.75%, Cu: 0.15 to 0.2%, Zn: ≤0.1% and the balance is Al. The other steps are the same as those in specific embodiment 1.

[0036] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the mass of Y in the Al-10Y master alloy described in step 1① is 0.15% of the mass of the ZL114A alloy. The other steps are the same as those of specific implementation method 1 or 2.

[0037] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the mass of Y in the Al-10Y master alloy described in step 1① is 0.25% of the mass of the ZL114A alloy. The other steps are the same as those of specific embodiments 1 to 3.

[0038] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the mass of Y in the Al-10Y master alloy described in step 1① is 0.35% of the mass of the ZL114A alloy. The other steps are the same as those of specific embodiments 1 to 4.

[0039] Specific implementation method 6: This implementation method is different from specific implementation methods 1 to 5 in that the mass of Y in the Al-10Y master alloy described in step 1① is 0.45% of the mass of the ZL114A alloy. The other steps are the same as specific implementation methods 1 to 5.

[0040] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that in step 2, the aluminum alloy ingot is wire-cut into aluminum alloy ingots with a diameter of 55 mm to 65 mm and a height of 8 mm to 10 mm. The other steps are the same as those of specific embodiments 1 to 6.

[0041] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that: the solution treatment process described in step two is: put the aluminum alloy ingot into a box-type resistance furnace and heat it to 530℃~540℃ in the furnace, keep it at 530℃~540℃ for 8h~9h, then quench it with 40℃~60℃ water, and then transfer it to an aging furnace. The other steps are the same as specific embodiments one to seven.

[0042] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the transfer time to the aging furnace is less than 10 seconds, and the heating rate is 8°C / min to 10°C / min. The other steps are the same as those of specific embodiments 1 to 8.

[0043] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the aging treatment temperature in step 2 is 170°C to 175°C, the aging treatment time is 6h to 7h, and air cooling is performed after the aging treatment to obtain a refined, modified and alloyed ZL114A alloy. The other steps are the same as those of specific embodiments 1 to 9.

[0044] The following examples are used to verify the beneficial effects of the present invention:

[0045] Embodiment 1: A method for refining, modifying and alloying ZL114A alloy is accomplished by the following steps:

[0046] 1. Preparation of aluminum alloy ingots:

[0047] ①, weigh ZL114A alloy, Al-50Cu master alloy, Al-10Y master alloy and Al-5Ti-B master alloy to obtain raw materials;

[0048] The mass of Cu in the Al-50Cu master alloy described in step 1① is 1.2% of the mass of the ZL114A alloy;

[0049] The mass of Y in the Al-10Y master alloy described in step 1① is 0.15% of the mass of the ZL114A alloy;

[0050] The mass of the Al-5Ti-B master alloy described in step 1① is 0.5% of the mass of the ZL114A alloy;

[0051] The composition of the ZL114A alloy described in step 1① is as follows by mass fraction: Si: 6.25%, Mg: 0.7%, Cu: 0.15%, Zn: 0.08% and the balance is Al;

[0052] ②, put the ZL114A alloy into a crucible preheated at 300°C, then put it into a pit crucible furnace for heating, smelt at 750°C, skim off the upper oxide film after it is fully melted, put in Al-50Cu master alloy wrapped in aluminum foil, keep it warm for 20 minutes, stir it with a stone mill for 30 seconds, then adjust the temperature of the crucible furnace to 730°C, put in Al-5Ti-B master alloy and Al-10Y master alloy wrapped in aluminum foil, keep it warm for 30 minutes, stir it with a stone mill after putting it in for 15 minutes, and after the insulation is completed, adjust the temperature of the crucible furnace to 750°C, press hexachloroethane wrapped in newspaper into the molten metal with a bell jar, the amount of hexachloroethane added is 1wt.% of the raw material mass, stir, stand for 15 minutes after degassing, skim off the slag, and then pour the molten metal into a metal mold preheated at 300°C, the pouring temperature is 730°C, and an aluminum alloy ingot is obtained;

[0053] 2. Heat treatment:

[0054] The aluminum alloy ingot is wire cut into an aluminum alloy ingot with a diameter of 65 mm and a height of 10 mm, and then subjected to a solid solution treatment, and then an aging treatment, and air cooling after the aging treatment to obtain a refined, modified and alloyed ZL114A alloy;

[0055] The solution treatment process described in step 2 is: placing the aluminum alloy ingot into a box-type resistance furnace and heating it to 530°C in the furnace, keeping it at 530°C for 8 hours, then quenching it with 50°C water, and then transferring it to an aging furnace, and the transfer time is less than 10 seconds; the heating rate is 10°C / min;

[0056] The temperature of the aging treatment in step 2 is 175° C., and the time of the aging treatment is 6 hours.

[0057] Embodiment 2: The difference between this embodiment and embodiment 1 is that the mass of Y in the Al-10Y master alloy described in step 1① is 0.25% of the mass of the ZL114A alloy. The other steps and parameters are the same as those in embodiment 1.

[0058] Embodiment 3: The difference between this embodiment and embodiment 1 is that the mass of Y in the Al-10Y master alloy described in step 1① is 0.35% of the mass of the ZL114A alloy. The other steps and parameters are the same as those in embodiment 1.

[0059] Embodiment 4: The difference between this embodiment and embodiment 1 is that the mass of Y in the Al-10Y master alloy described in step 1① is 0.45% of the mass of the ZL114A alloy. The other steps and parameters are the same as those in embodiment 1.

[0060] Comparative Example 1: The difference between this embodiment and embodiment 1 is that in step 1①, only ZL114A alloy is weighed to obtain the raw material; this embodiment omits the use of Al-50Cu master alloy, Al-10Y master alloy and Al-5Ti-B master alloy. The other steps and parameters are the same as those in embodiment 1.

[0061] Comparative Example 2: The difference between this embodiment and embodiment 1 is that in step 1①, ZL114A alloy, Al-50Cu master alloy, and Al-5Ti-B master alloy are weighed to obtain raw materials; the Al-10Y master alloy is omitted in this embodiment. The other steps and parameters are the same as those in embodiment 1.

[0062] Mechanical properties:

[0063] In order to test the mechanical properties of aluminum alloy plates, Vickers hardness and room temperature tensile properties tests were carried out on aluminum alloy plates: the Vickers hardness adopted a test force of 0.1kgf, a loading time of 15s, the measured value was the average of three measurements, and the spacing between the three sampling points was 1mm; for the room temperature tensile properties test, samples were taken along the rolling direction of the plates, and processed into tensile specimens in accordance with the provisions of GB / T228.1-2021 "Room Temperature Tensile Test of Metal Materials". The tensile test was carried out on an electronic universal testing machine. The strain rate was 1mm / min, and the value was taken as the average of three measurements.

[0064] The relevant performance test data of the ZL114A alloys after refinement, modification and alloying prepared in Examples 1 to 4 and the ZL114A alloys prepared in Comparative Examples 1 to 2 are shown in Table 1;

[0065] Table 1

[0066] Example Hardness (HV) Tensile strength(MPa) Elongation Example 1 128.4 259.1 6.452％ Example 2 133.5 270.1 6.333％ Example 3 135.5 274.1 6.267％ Example 4 125.9 250.4 6.433％ Comparative Example 1 110.9 226.8 6.710％ Comparative Example 2 115.8 239.4 6.680％

[0067] From the mechanical properties data in Table 1, it can be seen that by adding a small amount of Cu for microalloying, adding refiner Al-5Ti-B and different contents of Al-10Y, and finally strengthening by heat treatment, the mechanical properties of ZL114A alloy can be increased to varying degrees. The hardness is increased by up to 22.18%, and the tensile strength is increased by up to 20.86%. While the hardness and tensile strength are improved, the elongation is only slightly reduced, and the ZL114A alloy with excellent comprehensive strength and plasticity is obtained.

[0068] Figure 1 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 1;

[0069] from Figure 1 It can be seen that the morphology of eutectic Si is equiaxed cellular dendrites, not coarse dendrites, the distance between dendrites becomes smaller, and the alloy refinement effect is obvious.

[0070] Figure 2 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 2;

[0071] from Figure 2 It can be seen that the morphology of eutectic Si is equiaxed cellular dendrites, the dendrite spacing becomes smaller, and the alloy refinement effect is obvious.

[0072] Figure 3 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 3;

[0073] from Figure 3 It can be seen that the morphology of eutectic Si is equiaxed cellular dendrites, the dendrite spacing is the smallest, and the alloy refinement effect is the most obvious, which is consistent with the mechanical properties test results.

[0074] Figure 4 The metallographic image (T6 state) of the ZL114A alloy after refinement, modification and alloying prepared in Example 4;

[0075] from Figure 4 It can be seen that the morphology of eutectic Si is the coexistence of equiaxed cellular dendrites and dendrites. This is because excessive addition of Al-10Y master alloy will cause the dendrites to become larger and the mechanical properties to decrease.

[0076] Figure 5 This is the metallographic phase diagram (T6 state) of the ZL114A alloy prepared in Comparative Example 1.

[0077] from Figure 5 It can be seen that the coarse needle-shaped eutectic Si still exists in the matrix, which proves that the single alloying cannot change the morphology of eutectic Si. The stress is concentrated at the tip of the eutectic Si, and the sample breaks at this point during the tensile test. Therefore, the mechanical properties are relatively low.

[0078] Figure 6 The metallographic image (T6 state) of the ZL114A alloy after refinement and alloying prepared in Comparative Example 2

[0079] from Figure 6 It can be seen that the morphology of eutectic Si is the coexistence of equiaxed cellular dendrites and dendrites, indicating that the addition of refiner Al-5Ti-B can refine the alloy, but the effect is not as good as the composite refinement and modification effect with Al-10Y.

Claims

1. A method for refining, modifying and alloying ZL114A alloy, characterized in that The ZL114A alloy prepared by the method after refinement, modification and alloying has a hardness of 135.5 HV, a tensile strength of 274.1 MPa and an elongation of 6.267%; The method is specifically completed according to the following steps:

1. Preparation of aluminum alloy ingots: ①, weigh ZL114A alloy, Al-50Cu master alloy, Al-10Y master alloy and Al-5Ti-B master alloy to obtain raw materials; The mass of Cu in the Al-50Cu master alloy described in step 1① is 1.2% of the mass of the ZL114A alloy; The mass of Y in the Al-10Y master alloy described in step 1① is 0.35% of the mass of the ZL114A alloy; The mass of the Al-5Ti-B master alloy described in step 1① is 0.5% of the mass of the ZL114A alloy; The composition of the ZL114A alloy described in step 1① is as follows by mass fraction: Si: 6.25%, Mg: 0.7%, Cu: 0.15%, Zn: 0.08% and the balance is Al; ②, put the ZL114A alloy into a crucible preheated at 300°C, then put it into a pit crucible furnace for heating, smelt at 750°C, skim off the upper oxide film after it is fully melted, put in Al-50Cu master alloy wrapped in aluminum foil, keep it warm for 20 minutes, stir it with a stone mill for 30 seconds, then adjust the temperature of the crucible furnace to 730°C, put in Al-5Ti-B master alloy and Al-10Y master alloy wrapped in aluminum foil, keep it warm for 30 minutes, stir it with a stone mill after putting it in for 15 minutes, and after the insulation is completed, adjust the temperature of the crucible furnace to 750°C, press hexachloroethane wrapped in newspaper into the molten metal with a bell jar, the amount of hexachloroethane added is 1wt.% of the raw material mass, stir, stand for 15 minutes after degassing, skim off the slag, and then pour the molten metal into a metal mold preheated at 300°C, the pouring temperature is 730°C, and an aluminum alloy ingot is obtained; 2. Heat treatment: The aluminum alloy ingot is wire cut into an aluminum alloy ingot with a diameter of 65 mm and a height of 10 mm, and then subjected to a solid solution treatment, and then an aging treatment, and air cooling after the aging treatment to obtain a refined, modified and alloyed ZL114A alloy; The solution treatment process described in step 2 is: placing the aluminum alloy ingot into a box-type resistance furnace and heating it to 530°C in the furnace, keeping it at 530°C for 8 hours, then quenching it with 50°C water, and then transferring it to an aging furnace, and the transfer time is less than 10 seconds; the heating rate is 10°C / min; The temperature of the aging treatment in step 2 is 175° C., and the time of the aging treatment is 6 hours.

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