Al-Zr-B refiner, preparation method and refining process of Al-Zr-B refiner on zirconium-containing A356 aluminum alloy

Abstract

The invention relates to an Al-Zr-B refiner, a preparation method and a refining process of the Al-Zr-B refiner on zirconium-containing A356 aluminum alloy, and belongs to the technical field of aluminum alloy casting, the Al-Zr-B refiner comprises, by mass, 4.5-5.5% of Zr, 0.5-1.3% of B and the balance Al, and the atomic ratio of Zr to B is 1: 2; the refining process comprises the steps that A356 aluminum alloy is taken to be completely melted, the temperature is increased to 740-760 DEG C, and aluminum alloy melt is obtained after treatment; the Al-Zr-B refiner preheated to 250-300 DEG C is pressed into the aluminum alloy melt according to the adding amount of 0.2-0.6 wt%, and then heat preservation is conducted for 20-90 min at the temperature of 720 DEG C; and a deslagging and degassing agent is added before heat preservation is finished, after heat preservation is finished, slagging-off treatment is carried out, casting is carried out in a preheated mold, and the aluminum alloy casting is obtained. By adopting an innovative Al-Zr-B refiner system, the problem of failure of a traditional refiner can be solved, so that a grain refinement scheme which is low in cost, efficient and stable in process is realized.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy casting technology, specifically involving Al-Zr-B refining agent, preparation method and its refining process for zirconium-containing A356 aluminum alloy. Technical Background In the field of aluminum alloy casting, especially in the forming process of aluminum-silicon hypoeutectic alloys (such as A356 and ZL101), chemical grain refinement is currently the most widely used and cost-effective technical method in industry. This method involves adding a small amount of grain refiner (such as a traditional Al-Ti-B master alloy) to the molten aluminum, causing it to disperse and form numerous heterogeneous nucleation sites within the melt. This transforms the coarse columnar or dendritic crystals after solidification into uniform, fine equiaxed crystals. This optimization of the microstructure significantly improves the mechanical properties of the alloy, particularly its plasticity, toughness, and fatigue strength, while also improving casting processability.

[0002] The development of grain refiners for aluminum alloys has a long history. As early as the 1930s, Rosenhain et al. first revealed the grain-refining effect of titanium (Ti) on aluminum. Subsequently, Cibula et al. systematically studied the effects of elements such as titanium (Ti) and boron (B) on the as-cast microstructure of aluminum and its alloys, and improved the refining effect by optimizing the Ti / B ratio. However, with the continuous improvement of material performance requirements, new technical challenges have emerged. In order to meet the stringent requirements of high-temperature strength and thermal stability for high-performance components (such as automotive engine blocks and cylinder heads), the industry often adds 0.15% to 0.20% zirconium (Zr) to A356 alloys to form modified zirconium-containing A356 alloys; however, when the Zr content in the aluminum alloy exceeds 0.1%, traditional Al-Ti-B grain refiners will suffer severe "poisoning" and fail. The mechanism is that Zr elements preferentially combine with Ti elements in the refiner to form stable intermetallic compounds (such as (Ti,Zr)Al3), which consume a large number of free titanium atoms in the melt. As a result, the TiB2 particles cannot form a titanium-rich activation layer on the surface, which is necessary for α-Al heterogeneous nucleation, thus losing their nucleation ability and causing the refinement effect to decline sharply or even fail completely.

[0003] To address the Zr poisoning problem, the industry has explored various alternative technologies, but all have significant drawbacks: 1. Al-Ti-C refining agents: These utilize TiC particles as nucleation sites, exhibiting some resistance to Zr poisoning due to their low affinity for Zr; however, carbon (C) has extremely low solubility in molten aluminum, and traditional melting methods easily produce coarse Al4C3 or blocky TiC, rather than the desired nanoscale dispersed particles. Existing synthesis processes (such as self-propagating high-temperature synthesis) suffer from easy particle agglomeration, poor dispersibility, and process instability. Problems such as poor quality and high production costs make large-scale promotion difficult; second, Al-Nb-B refining agents: utilizing the different interaction mechanisms between niobium (Nb) and elements such as Zr, Cr, and V, the poisoning problem is avoided in principle; however, the price of Nb is extremely expensive, making the cost unbearable and the industrial preparation extremely difficult. Moreover, the thermodynamic stability, interface matching and optimal composition window of related nucleation phases (such as NbB2) still lack systematic research, the process is extremely immature, and it is currently only in the laboratory exploration stage and cannot be commercialized.

[0004] Therefore, developing a new technology for refining aluminum alloy grains that can effectively resist Zr poisoning, has a stable preparation process, is cost-controllable, and is suitable for industrial production has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an Al-Zr-B grain refiner, its preparation method, and its grain refinement process for zirconium-containing A356 aluminum alloys. The aim is to solve the problem of traditional grain refiner failure by adopting an innovative Al-Zr-B grain refiner system and utilizing the "fight fire with fire" mechanism, thereby achieving a low-cost, efficient, and stable grain refinement scheme.

[0006] On the one hand, the present invention provides an Al-Zr-B refining agent, which adopts the following technical solution: Al-Zr-B refining agent comprises the following components by mass percentage: Zr 4.5-5.5%, B 0.5-1.3%, and the balance being Al; The ratio of Zr to B atoms is 1:1 or 1:2.

[0007] Preferably, the Al-Zr-B refining agent comprises the following components by mass percentage: 5% Zr, 0.56% or 1.19% B, and the balance being Al; The ratio of Zr to B atoms is 1:2.

[0008] On the one hand, the present invention provides a method for preparing the Al-Zr-B refining agent as described above, using the following technical solution: The preparation method of Al-Zr-B refining agent includes the following preparation steps: 1) Take high-purity aluminum and melt it, add Al-10Zr alloy and stir thoroughly until completely melted, continue to add Al-3B alloy and stir thoroughly until there are no lumps at the bottom of the furnace to obtain a mixed melt; 2) The mixed melt prepared in step 1) is kept at 850℃ for 20-60 minutes, and the mixed melt is stirred thoroughly every 10 minutes during the process; 3) Add the slag remover and degasser 5 minutes before the end of the heat preservation time. After the heat preservation time is over, remove the slag and cast it into an ingot. This is the Al-Zr-B refining agent.

[0009] Preferably, the heat preservation time in step 2) is 60 minutes.

[0010] Furthermore, the present invention also provides a refining process for zirconium-containing A356 aluminum alloy as described above, employing the following technical solution: The refining process of zirconium-containing A356 aluminum alloy using Al-Zr-B refining agent includes the following steps: 1) Take A356 aluminum alloy and melt it completely. Heat it to 740-760℃. After refining, degassing and slag removal, the aluminum alloy melt is obtained. 2) Add 0.2-0.6 wt% of Al-Zr-B refining agent preheated to 250-300℃ into the aluminum alloy melt obtained in step 1), and then hold at 720℃ for 20-90 min. During the holding period, stir the aluminum alloy melt thoroughly every 10 min. 3) Add a slag remover and degasser 5 minutes before the end of the heat preservation period. After the heat preservation time is over, remove the slag and pour the casting into a preheated mold to obtain an aluminum alloy casting.

[0011] Preferably, the amount of Al-Zr-B refining agent added in step 2) is 0.4 wt%.

[0012] Preferably, the heat preservation time in step 2) is 30 minutes.

[0013] Preferably, the average size of the α-Al primary grains in the casting obtained in step 3) is 109-145 μm.

[0014] In summary, the present invention has the following beneficial technical effects: 1. This invention effectively solves the problem of "poisoning" failure of traditional Al-Ti-B refining agents in A356 aluminum alloys containing 0.10~0.20wt% zirconium. Through the "fighting poison with poison" mechanism of Al-Zr-B refining agents, a stable anti-Zr poisoning effect is achieved.

[0015] 2. In this invention, by optimizing the process parameters, namely, under the conditions of Al-5Zr-1.19B refining agent, preparation heat preservation for 60 min, addition amount of 0.4wt%, and refining heat preservation for 30 min, the alloy grain size can be refined to 109μm, and a good refining effect can be maintained during the heat preservation period of 20-90 min, that is, the grain size is 109-145μm, and there is no rapid failure phenomenon.

[0016] 3. The refined alloy of this invention can maintain a fine and uniform grain structure, while also maintaining the excellent high-temperature performance and thermal stability of the original zirconium-containing A356 aluminum alloy, thus meeting the usage requirements of key components such as cylinder blocks and cylinder heads of high-performance automotive engines. Attached Figure Description

[0017] Figure 1 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 1 of the present invention; Figure 2 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 2 of the present invention; Figure 3 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 3 of the present invention; Figure 4 This is a bar chart showing the refined grain size of the zirconium-containing A356 aluminum alloy castings obtained through the refinement processes of Examples 1, 2, and 3 of this invention. Figure 5 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 4 of the present invention; Figure 6 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 5 of the present invention; Figure 7 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 6 of the present invention; Figure 8 The above are bar charts showing the refined grain size of the zirconium-containing A356 aluminum alloy castings obtained by the refinement processes in Examples 4, 5, and 6 of this invention. Figure 9 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 7 of the present invention; Figure 10 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 8 of the present invention; Figure 11 The above are bar charts showing the refined grain size of the zirconium-containing A356 aluminum alloy castings obtained by the refinement processes in Examples 6, 7, and 8 of this invention. Figure 12 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 9 of the present invention; Figure 13 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 10 of the present invention; Figure 14 This is a microstructure diagram of the zirconium-containing A356 aluminum alloy casting obtained by the refinement process in Example 11 of the present invention; Figure 15 This is a bar chart showing the refined grain size of the zirconium-containing A356 aluminum alloy castings obtained by the refinement processes in Examples 9, 10, and 11 of this invention. Detailed Implementation

[0018] The following is a combination of preparation examples 1-6, examples 1-11, test examples, and appendices. Figure 1-15 The present invention will be described in further detail below.

[0019] Preparation Example Preparation Example 1 Preparation method of Al-Zr-B refining agent: S1. Take aluminum with a purity ≥ 99.7% and melt it. Add Al-10Zr alloy and stir thoroughly until completely melted. Continue to add Al-3B alloy and stir thoroughly until there are no lumps at the bottom of the furnace to obtain a mixed melt. S2. The mixed melt prepared in step 1) is kept at 850°C for 20 minutes, and the mixed melt is stirred thoroughly every 10 minutes during this period. S3. Add the slag remover and degasser 5 minutes before the end of the heat preservation time. After the heat preservation time is over, remove the slag and cast it into an ingot to obtain the Al-Zr-B refining agent. The content of each component in the Al-Zr-B refining agent is: Zr 5%, B 0.56%, with the balance being Al and unavoidable impurities; the atomic ratio of Zr to B is approximately 1:1.

[0020] Preparation Example 2 The preparation method of Al-Zr-B refining agent differs from that of Preparation Example 1 in that the heat preservation time in step S2 is 40 min; the remaining steps are the same as those in Preparation Example 1.

[0021] Preparation Example 3 The preparation method of Al-Zr-B refining agent differs from that of Preparation Example 1 in that the heat preservation time in step S2 is 60 min; the remaining steps are the same as those in Preparation Example 1.

[0022] Preparation Example 4 The preparation method of Al-Zr-B refining agent differs from that of Preparation Example 1 in that the content of each component of Al-Zr-B refining agent is: Zr 5%, B 1.19%, with the balance being Al and unavoidable impurities; the atomic ratio of Zr to B is approximately 1:2; and the remaining steps are the same as those in Preparation Example 1.

[0023] Preparation Example 5 The preparation method of Al-Zr-B refining agent differs from that of Preparation Example 1 in that the content of each component of Al-Zr-B refining agent is: Zr 5%, B 1.19%, with the balance being Al and unavoidable impurities; the atomic ratio of Zr to B is approximately 1:2; the holding time in step S2 is 40 min; and the remaining steps are the same as those in Preparation Example 1.

[0024] Preparation Example 6 The preparation method of Al-Zr-B refining agent differs from that of Preparation Example 1 in that the content of each component of Al-Zr-B refining agent is: Zr 5%, B 1.19%, with the balance being Al and unavoidable impurities; the atomic ratio of Zr to B is approximately 1:2; the holding time in step S2 is 60 min; and the remaining steps are the same as those in Preparation Example 1.

[0025] Example Example 1 The refining process of zirconium-containing A356 aluminum alloy using Al-Zr-B refining agent includes the following steps: S1. Take A356 aluminum alloy with a Zr content of 0.2wt% and melt it completely. Heat it to 740-760℃ and ensure the macroscopic uniformity of the melt composition and temperature by thorough mechanical stirring. Then, thoroughly refine and degas the melt by rotating and blowing inert gas twice to reduce the hydrogen content and suspended oxide inclusions in the melt. Finally, let it stand for a while to allow the slag to float and collect, and perform a thorough slag removal operation to obtain a clean aluminum alloy melt with stable composition and low hydrogen content. S2. The Al-Zr-B refining agent prepared in Preparation Example 1, preheated to 250-300℃, is added at a rate of 0.2wt% below the surface of the aluminum alloy melt prepared in step S1. Then, the melt is held at 720℃ for 20 minutes to allow the Al-Zr-B refining agent to fully wet the aluminum alloy melt and undergo interfacial reaction (Zr atoms adsorb on the surface of ZrB2 particles). During the holding period, the aluminum alloy melt is thoroughly stirred every 10 minutes to ensure that the nucleated particles in the Al-Zr-B refining agent are evenly distributed. S3. Add slag and degassing agent 5 minutes before the end of heat preservation. After the heat preservation time is over, remove the slag. Finally, cast the aluminum alloy casting into an ingot in a graphite columnar mold preheated to 250°C.

[0026] Example 2 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 1 in that step S2 uses the Al-Zr-B refining agent obtained from Preparation Example 2, while the remaining steps are the same as in Example 1.

[0027] Example 3 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 1 in that step S2 uses the Al-Zr-B refining agent obtained from Preparation Example 3, while the remaining steps are the same as in Example 1.

[0028] Example 4 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 1 in that step S2 uses the Al-Zr-B refining agent obtained from Preparation Example 4, while the remaining steps are the same as in Example 1.

[0029] Example 5 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 1 in that step S2 uses the Al-Zr-B refining agent obtained from Preparation Example 5, while the remaining steps are the same as in Example 1.

[0030] Example 6 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 1 in that step S2 uses the Al-Zr-B refining agent obtained from Preparation Example 6, while the remaining steps are the same as in Example 1.

[0031] Example 7 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 6 in that the amount of Al-Zr-B refining agent added in step S2 is 0.4 wt%, while the remaining steps are the same as in Example 6.

[0032] Example 8 The refining process of zirconium-containing A356 aluminum alloy with Al-Zr-B refining agent differs from that in Example 6 in that the amount of Al-Zr-B refining agent added in step S2 is 0.6 wt%, while the remaining steps are the same as in Example 6.

[0033] Example 9 The refining process of zirconium-containing A356 aluminum alloy by Al-Zr-B refining agent differs from that in Example 7 in that the holding time in step S2 is 30 minutes, while the other steps are the same as in Example 7.

[0034] Example 10 The refining process of zirconium-containing A356 aluminum alloy by Al-Zr-B refining agent differs from that in Example 7 in that the holding time in step S2 is 60 min, while the other steps are the same as in Example 7.

[0035] Example 11 The refining process of zirconium-containing A356 aluminum alloy by Al-Zr-B refining agent differs from that in Example 7 in that the holding time in step S2 is 90 min, while the remaining steps are the same as in Example 7.

[0036] Test case Microstructural analysis: The aluminum alloy samples for grain size measurement were taken from 25 mm below the bottom of the casting. After rough and fine polishing on sandpaper, the samples were etched with an etchant; the etchant formula was 5% HF + 20% HNO3 + 65% HCl + 10% H2O. The etched samples were observed using a metallographic microscope, and macroscopic photographs were taken with a DSLR camera.

[0037] The grain size is measured using the section method. Parallel lines are drawn at equal intervals along areas of uniform grain size on the photograph. The number of grains cut by each line is counted, and then the average grain size is calculated using Equation 1. Formula 1: ; d a The average grain size is (μm). N The total number of parallel lines drawn L Line length (mm); M This represents the total number of grains cut by the parallel lines; To ensure the accuracy of the calculated grain size, multiple measurements were taken and the average value was calculated.

[0038] Reference Figures 1 to 4 , Figures 1 to 3 The images shown are microstructure diagrams of the zirconium-containing A356 aluminum alloy castings obtained by the refinement process in Examples 1-3 of this invention. Figure 4 The figures show the grain size of the zirconium-containing A356 aluminum alloy castings obtained by the refining processes in Examples 1, 2, and 3 of this invention. As can be seen from the figures, when the added Al-Zr-B refining agent is an Al-5Zr-0.56B alloy with a Zr / B ratio of 1:1, the grain size of the refined A356 aluminum alloy castings gradually decreases with the extension of the Al-Zr-B refining agent preparation time, with a minimum value of 192 μm.

[0039] Reference Figures 5 to 8 , Figures 5 to 7 The images shown are microstructure diagrams of the zirconium-containing A356 aluminum alloy castings obtained by the refinement process in Examples 4-6 of this invention. Figure 8The figures show the grain size of the zirconium-containing A356 aluminum alloy castings obtained by the refining processes in Examples 4, 5, and 6 of this invention. As can be seen from the figures, the refining effect exhibited by using an Al-Zr-B refining agent of Al-5Zr-1.19B alloy with a Zr / B ratio of 1:2 is significantly better than that of an Al-5Zr-0.56B alloy with a Zr / B ratio of 1:1. The best refining process is the Al-5Zr-1.19B alloy with a Zr / B ratio of 1:2 and a preparation time of 60 min, which can effectively reduce the grain size of the A356 aluminum alloy castings to 143 μm.

[0040] Reference Figure 7 as well as Figures 9 to 11 , Figures 9 to 10 The images shown are microstructure diagrams of the zirconium-containing A356 aluminum alloy castings obtained by the refinement process in Examples 7-8 of this invention. Figure 11 The figures show the grain size of the zirconium-containing A356 aluminum alloy castings obtained by the refining processes in Examples 6, 7, and 8 of this invention. As can be seen from the figures, adjusting the amount of Al-Zr-B refining agent did not result in a better effect with increased Al-Zr-B refining agent content. The optimal refining effect of 113 μm was achieved when the Al-Zr-B refining agent content was 0.4 wt%. When the content was further increased, the grain size actually increased to 141 μm. However, when the Al-Zr-B refining agent content was excessive, the increased number of nucleating particles increased the probability of collisions during their movement in the melt, leading to particle aggregation and the formation of large particle clusters. This primarily affected the nucleation ability. Furthermore, according to Stokes' law, these large particle clusters were more likely to sink to the bottom of the furnace, resulting in a reduction in the number of effective nucleating particles.

[0041] Reference Figures 12 to 15 , Figures 12 to 14 The images shown are microstructure diagrams of the zirconium-containing A356 aluminum alloy castings obtained by the refinement process in Examples 9-11 of this invention. Figure 15This is a bar chart showing the grain size of the zirconium-containing A356 aluminum alloy castings obtained through the refining process in Examples 9-11 of this invention. As can be seen from the chart, when the Al-Zr-B refining agent dosage is determined to be 0.4 wt%, the grain size of the A356 aluminum alloy castings gradually increases with the extension of the holding time. The optimal holding time is 30 min, which can effectively refine the grain size of the A356 aluminum alloy castings to 109 μm. However, even when the holding time is extended to 90 min, the grain size of the A356 aluminum alloy remains relatively small, on the order of 145 μm. The degradation of the refining effect in this process may be due to the fact that, under prolonged heat treatment, small ZrB2 particles may undergo Ostwald ripening (small particles dissolve, large particles grow) and agglomerate to form larger aggregates. These aggregates become deactivated due to their increased size and reduced effective nucleation surface area. Furthermore, due to the density difference between the ZrB2 in the refining agent and the aluminum alloy melt, they gradually settle to the bottom of the crucible, thus reducing the number of effective nucleation sites in the melt. Unlike the rapid "chemical poisoning" that occurs when using traditional Al-Ti-B, where the effective time may be shortened to less than 30 minutes, the refining effect of this process is maintained for a longer period.

[0042] In summary, Al-5Zr-1.19B alloy, as a grain refiner against Zr poisoning, effectively refines A356 aluminum alloy containing 0.2wt% Zr. When the addition amount of Al-Zr-B grain refiner is 0.4%, it can maintain excellent grain refinement effect for 20-90 minutes, and the refined grain size is 109-145μm.

[0043] The embodiments shown in this specification are only used to illustrate the technical solutions of the present invention and are intended to help those skilled in the art understand the principles and advantages of the present invention. They do not constitute a limitation on the scope of protection of the present invention. Although the present invention has been specifically described, those skilled in the art can still make any modifications, equivalent substitutions or other reasonable variations to the implementation methods without departing from the spirit and scope of the present invention. All equivalent technical solutions resulting therefrom should be considered within the scope of protection of this patent.

Claims

1. An Al-Zr-B refining agent, characterized in that, The composition includes the following components by mass percentage: Zr 4.5-5.5%, B 0.5-1.3%, and the balance Al; The ratio of Zr to B atoms is 1:1 or 1:

2.

2. The Al-Zr-B refining agent according to claim 1, characterized in that, The Al-Zr-B refining agent comprises the following components by mass percentage: 5% Zr, 0.56% or 1.19% B, and the balance being Al; The ratio of Zr to B atoms is 1:

2.

3. A method for preparing an Al-Zr-B refining agent as described in any one of claims 1-2, characterized in that, The preparation steps include the following: 1) Take high-purity aluminum and melt it, add Al-10Zr alloy and stir thoroughly until completely melted, continue to add Al-3B alloy and stir thoroughly until there are no lumps at the bottom of the furnace to obtain a mixed melt; 2) The mixed melt prepared in step 1) is kept at 850℃ for 20-60 minutes, and the mixed melt is stirred thoroughly every 10 minutes during the process; 3) Add the slag remover and degasser 5 minutes before the end of the heat preservation time. After the heat preservation time is over, remove the slag and cast it into an ingot. This is the Al-Zr-B refining agent.

4. The method for preparing the Al-Zr-B refining agent according to claim 3, characterized in that, The heat preservation time in step 2) is 60 minutes.

5. A refining process for zirconium-containing A356 aluminum alloy using the Al-Zr-B refining agent as described in any one of claims 1-2, characterized in that, Includes the following steps: 1) Take A356 aluminum alloy and melt it completely. Heat it to 740-760℃. After refining, degassing and slag removal, the aluminum alloy melt is obtained. 2) Add 0.2-0.6 wt% of Al-Zr-B refining agent preheated to 250-300℃ into the aluminum alloy melt obtained in step 1), and then hold at 720℃ for 20-90 min. During the holding period, stir the aluminum alloy melt thoroughly every 10 min. 3) Add a slag remover and degasser 5 minutes before the end of the heat preservation period. After the heat preservation time is over, remove the slag and pour the casting into a preheated mold to obtain an aluminum alloy casting.

6. The zirconium-containing A356 aluminum alloy refining process resistant to Zr poisoning according to claim 5, characterized in that, The amount of Al-Zr-B refining agent added in step 2) is 0.4 wt%.

7. The zirconium-containing A356 aluminum alloy refining process resistant to Zr poisoning according to claim 5, characterized in that, The heat preservation time in step 2) is 30 minutes.

8. The zirconium-containing A356 aluminum alloy refining process resistant to Zr poisoning according to claim 5, characterized in that, The average size of the α-Al primary grains in the casting obtained in step 3) is 109-145 μm.

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