Method for solving bottom shrinkage cavity of high-aluminum-zinc-aluminum-magnesium alloy ingot

Abstract

The invention provides a method for solving shrinkage cavities in the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot. The method comprises the following steps: adding Si, Zr, Sr and Ca into an alloy to obtain the high-aluminum-zinc-aluminum-magnesium alloy which comprises the following components in percentage by mass: 47.0%-53.0% of Al, 1.0%-3.0% of Mg, 0.01%-0.125% of Si, 0.01%-0.08% of Zr, 0.01%-0.08% of Sr, 0.05%-0.15% of Ca and the balance of Zn and inevitable impurities, during pouring of the high-aluminum zinc aluminum magnesium alloy, alloy liquid in the smelting furnace is sequentially poured back and forth for multiple times through a chute according to the sequence of the molds until all the molds are fully poured; and sequentially and forcibly cooling the molds from bottom to top after the first time of pouring is completed during pouring according to the sequence of the molds, and cooling and solidifying the alloy liquid in the molds to complete pouring. According to the method for solving the shrinkage cavity at the bottom of the high-aluminum zinc aluminum magnesium alloy ingot, the shrinkage cavity generated at the bottom of the alloy ingot due to gravity segregation and solidification shrinkage can be effectively controlled.

Description

Technical Field

[0001] The invention relates to the technical field of alloy material production and application, and in particular to a method for solving the shrinkage cavity at the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot. Background Art

[0002] Zinc-aluminum-magnesium alloy has excellent flat corrosion resistance, strong incision self-healing, low process cost and other characteristics. Once developed, it has been widely promoted and used in the field of steel corrosion protection and has become the fourth generation of anti-corrosion metal materials. Among them, high-aluminum zinc-aluminum-magnesium alloy is an aluminum alloy developed on the basis of aluminum-zinc-silicon coating alloy. The aluminum alloy is composed of Al: 47% to 57%, Mg: 1% to 3%, and the rest is Zn. Its flat corrosion resistance is stronger than that of zinc-aluminum-magnesium alloy with low and medium aluminum content, and it is widely used in the fields of construction and home appliances.

[0003] from Figure 1 The Zn-Al-Mg ternary alloy phase diagram shows that the high aluminum zinc aluminum magnesium alloy structure mainly contains Al-rich phase (FCC), Zn-rich phase (HCP), MgZn2 phase and Mg2Zn 11 Phase. Its phase structure belongs to the binary zinc-aluminum percrystalline phase of the zinc-aluminum-magnesium alloy coating. The following reactions will occur during cooling and solidification:

[0004] L→Mg2Zn 11 +Al+Zn

[0005] L→(Al)+Al6Mg 11 Zn 11

[0006] L→MgZn2+Al+Zn

[0007] L→(Al)+Al3Mg2+Al6Mg 11 Zn 11

[0008] L→Al 12 Mg 17 +Al6Mg 11 Zn 11

[0009] L+Al 12 Mg 17 →Al3Mg2+Al6Mg 11 Zn 11

[0010] During the phase structure change of this zinc-aluminum-magnesium alloy, an aluminum-rich phase will first precipitate and grow, and then a binary eutectic reaction will occur while a zinc-rich phase and a magnesium compound Zn+Mg2Zn11 phase will precipitate. Finally, the remaining liquid coating will undergo a ternary eutectic reaction while precipitating a ternary eutectic Zn+Al+Mg2Zn 11Phase. During the solidification process, the density of the hypoeutectic zinc-aluminum-magnesium alloy coating at the liquidus temperature and the eutectic temperature will change with the change of Zn, Al, and Mg content.

[0011] The reaction of zinc-aluminum-magnesium alloy from liquid phase to solid phase is determined by the alloy composition and solution temperature. The solid phase density of zinc-aluminum-magnesium alloy decreases with the increase of Al content. When the temperature drops below the liquidus line of the composition, the aluminum-rich dendrites contact each other to form a phase solid phase skeleton. The transformation between the liquid and solid phases is accompanied by thermal expansion and contraction in the liquid state and solidification and contraction during liquid-solid transformation to form shrinkage cavities. The remaining liquid phase flows between the dendrite skeletons. As the temperature gradually decreases, zinc-rich phases, MgZn2 and Mg2Si are continuously precipitated between the dendrites to fill the shrinkage cavities, and the alloy continues to shrink. Figure 2 , after the formation of Al dendrites, the Zn-Al-Mg ternary eutectic phase solidifies and shrinks between the Zn dendrite skeletons.

[0012] Since the density of zinc is 7.14 g / cm 3 , while the density of aluminum is 2.69g / cm 3 The two are very different. When placed in liquid state, gravity segregation will occur due to gravity, that is, the upper liquid contains more aluminum and the lower liquid contains less aluminum. The alloy at the bottom of the mold has a slow heat transfer efficiency due to the accumulation of heat. The alloy liquid on the upper surface of the mold has a large surface area in contact with the air and has a better heat transfer efficiency than the bottom. In addition, due to gravity segregation, the proportion of high melting point structures on the upper surface is better than that on the bottom, and it cools and shrinks first. Due to the negative pressure caused by the solidification shrinkage of the upper part and the capillary action between the dendrites, the alloy liquid shrinks from bottom to top. Finally, the solidified bottom cannot be supplemented and shrinkage occurs, resulting in bottom shrinkage. See Figure 3 , the defect morphology produced when the bottom of the high aluminum zinc aluminum magnesium product solidifies and shrinks.

[0013] When the above defects occur, on the one hand, it will affect the surface physical specifications of the alloy ingot. If it is exposed to rain or moisture, moisture is likely to exist in the shrinkage cavity. During the zinc pot feeding process, the moisture in the ingot will cause uneven heating of the zinc liquid locally, which is likely to cause "zinc explosion" injuries caused by metal liquid splashing, posing a major safety hazard. On the other hand, alloy element segregation is likely to occur, and the coating composition is likely to be uneven during the downstream hot-dip plating process, resulting in defects such as zinc flow lines, local bright spots, and white floccules.

[0014] Therefore, there is an urgent need for a method to solve the shrinkage cavity at the bottom of high-aluminum-zinc-aluminum-magnesium alloy ingots, which can effectively control gravity segregation and solidification shrinkage and cause shrinkage cavity at the bottom of the alloy ingot. Summary of the invention

[0015] The technical problem to be solved by the present invention is to provide a method for solving the shrinkage cavity at the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot, which can effectively control the gravity segregation and solidification shrinkage and cause the shrinkage cavity at the bottom of the alloy ingot.

[0016] In order to solve the above technical problems, the present invention provides a method for solving the shrinkage cavity at the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot, comprising the following method:

[0017] Si, Zr, Sr and Ca are added to the alloy to obtain a high aluminum zinc aluminum magnesium alloy including, by mass percentage, Al: 47.0% to 53.0%, Mg: 1.0% to 3.0%, Si: 0.01% to 0.125%, Zr: 0.01% to 0.08%, Sr: 0.01% to 0.08%, Ca: 0.05% to 0.15%, and the remainder being Zn and unavoidable impurities;

[0018] When pouring high aluminum-zinc-aluminum-magnesium alloy, the alloy liquid in the smelting furnace is poured back and forth multiple times in the mold sequence through the chute until each mold is filled;

[0019] When pouring in sequence in each mold, after the first pouring is completed, each mold is forced to be cooled from bottom to top in turn, and the alloy liquid in each mold is cooled and solidified to complete the casting.

[0020] Furthermore, the mass ratio of Zr, Sr and Ca in the high-aluminum-zinc-aluminum-magnesium alloy is controlled to be 1:1:2.

[0021] Furthermore, the pouring height of each mold is calculated by the following formula according to the law of conservation of heat Q1=Q2=Q3:

[0022] Q1=C1×ρ1×(a1b1h)×(t1-450)

[0023] Q2=50×(a1b1+2a1h+2b1h)×(t2-300)

[0024] Q3=C3×(abh-a1b1h1)×(t3-t4)

[0025] Among them: Q1 is the heat required for the solidification of the alloy liquid, Q2 is the heat conducted by the mold wall, and Q3 is the heat transferred by the liquid water in the mold; a is the outer width of the mold, b is the outer length of the mold, and h is the outer height of the mold; a1 is the inner width of the mold, b1 is the inner length of the mold, and h1 is the inner height of the mold; C1 is the heat transfer coefficient of the alloy liquid, C2 is the heat transfer coefficient of the mold, and C3 is the heat transfer coefficient of the water at ambient temperature; ρ1 is the density of the alloy liquid, and ρ2 is the density of water; t1 is the temperature of the alloy liquid in the furnace, t2 is the mold temperature, t3 is the water temperature at the outlet, and t4 is the ambient temperature.

[0026] Furthermore, when pouring the high-aluminum-zinc-aluminum-magnesium alloy, the alloy liquid is first poured from the first mold to the last mold through the chute to one-third of each mold and the last mold to one-quarter of the mold to complete the first pouring of each mold, and then poured from the last mold to the first mold to one-third of each mold to complete the second pouring, and then poured from the first mold to the last mold to one-third of each mold to complete the third pouring.

[0027] Furthermore, after the first and second pouring of each mold is completed, part of the surface sticky slag formed by the casting impact in each mold needs to be fished out respectively, and then the next pouring of each mold is carried out.

[0028] Furthermore, the forced cooling of each mold from bottom to top in sequence is that after each mold completes the first pouring, the mold circulating cooling water system is turned on to forcedly cool each mold from bottom to top in sequence.

[0029] Furthermore, during the forced bottom-up cooling, the cooling heat transfer amount is controlled by controlling the inlet and outlet water flow rates, and the direction of the water flow through each mold is consistent with the direction of the order of pouring each mold during the first pouring.

[0030] Furthermore, the water temperature in each mold is lower than the solidification point of the alloy liquid.

[0031] The present invention provides a method for solving the shrinkage cavity at the bottom of a high-aluminum zinc-aluminum-magnesium alloy ingot. By adding 0.01% to 0.125% of Si, 0.01% to 0.08% of Zr, 0.01% to 0.08% of Sr and 0.05% to 0.15% of Ca trace elements into the high-aluminum zinc-aluminum-magnesium alloy, and in the pouring process, by adopting a step pouring method in which the alloy liquid in the smelting furnace is poured back and forth for multiple times in sequence through a chute in the mold sequence until each mold is filled, and by adopting a bottom-up forced cooling method, the growth and distribution of the solidification structure phase of the high-aluminum zinc-aluminum-magnesium alloy ingot on the longitudinal surface of the mold can be controlled, the segregation of elements in the high-aluminum zinc-aluminum-magnesium alloy can be controlled, and shrinkage cavities at the bottom of the zinc-aluminum-magnesium alloy ingot due to solidification shrinkage can be avoided, thereby solving the defect of shrinkage pits at the bottom of the zinc-aluminum-magnesium alloy ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A phase diagram of the high aluminum zinc aluminum magnesium alloy provided by the present invention;

[0033] Figure 2 The solidification structure diagram of the high aluminum zinc aluminum magnesium alloy provided by the present invention;

[0034] Figure 3 The bottom shrinkage diagram of the high aluminum zinc aluminum magnesium alloy ingot obtained by the prior art provided by the present invention;

[0035] Figure 4A solidification structure diagram of a high aluminum zinc aluminum magnesium alloy after adding Si element to the high aluminum zinc aluminum magnesium alloy provided in an embodiment of the present invention;

[0036] Figure 5 A solidification microstructure diagram of a high aluminum zinc aluminum magnesium alloy after adding Zr element to the high aluminum zinc aluminum magnesium alloy provided in an embodiment of the present invention;

[0037] Figure 6 A solidification microstructure diagram of a high aluminum-zinc-aluminum-magnesium alloy after adding Sr element to the high aluminum-zinc-aluminum-magnesium alloy provided in an embodiment of the present invention;

[0038] Figure 7 A solidification structure diagram of a high aluminum zinc aluminum magnesium alloy after adding Ca element to the high aluminum zinc aluminum magnesium alloy provided in an embodiment of the present invention;

[0039] Figure 8 A surface morphology of the bottom of a zinc-aluminum-magnesium alloy ingot produced by a method for solving the shrinkage cavity at the bottom of a high-aluminum zinc-aluminum-magnesium alloy ingot provided in Example 1 of the present invention;

[0040] Fig. 9 This is a surface morphology of the bottom of a zinc-aluminum-magnesium alloy ingot produced by a method for solving the shrinkage cavity at the bottom of a high-aluminum zinc-aluminum-magnesium alloy ingot provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0041] An embodiment of the present invention provides a method for solving the problem of shrinkage cavities at the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot. In order to avoid shrinkage cavities at the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot, the following two methods are adopted.

[0042] First, a certain amount of Si, Zr, Sr, Ca and other elements are added to the high aluminum zinc aluminum magnesium alloy. That is, after adding Si, Zr, Sr and Ca to the high aluminum zinc aluminum magnesium alloy, the obtained high aluminum zinc aluminum magnesium alloy includes Al: 47.0% to 53.0%, Mg: 1.0% to 3.0%, Si: 0.01% to 0.125%, Zr: 0.01% to 0.08%, Sr: 0.01% to 0.08%, Ca: 0.05% to 0.15%, and the rest is Zn and unavoidable impurities.

[0043] The present invention adds 0.01% to 0.125% Si element to the high aluminum zinc aluminum magnesium alloy, which can increase the number of aluminum-rich phase nuclei in the alloy and make the microstructure phase distribution more uniform. Figure 4 The present invention adds 0.01% to 0.08% Zr element to the high aluminum zinc aluminum magnesium alloy, which can make the primary Al phase in the alloy change from dendrite to flower shape, and the size decreases with the increase of Zr content, as shown in FIG. Figure 5The present invention adds 0.01% to 0.08% of Sr element to the high aluminum zinc aluminum magnesium alloy, which can gradually reduce the dendritic primary Al phase in the alloy, and the secondary Al / MgZn2 binary symbiotic structure reaches a "complete symbiotic state", and the structure is more uniform, such as Figure 6 The present invention adds 0.05% to 0.15% of Ca element to the high aluminum zinc aluminum magnesium alloy, which can increase the amount of aluminum-rich phase in the alloy and refine the dendrites. Figure 7 By adding the above-mentioned elements to the high-aluminum zinc-aluminum-magnesium alloy, the formation of shrinkage cavities at the bottom of the zinc-aluminum-magnesium alloy ingot due to solidification shrinkage can be effectively avoided.

[0044] In order to achieve the best effect mentioned above, as a specific implementation of the present invention, the mass ratio of Zr, Sr and Ca in the high aluminum zinc aluminum magnesium alloy is controlled to be 1:1:2.

[0045] Secondly, when pouring high-aluminum-zinc-aluminum-magnesium alloy, the molten alloy in the smelting furnace is poured back and forth multiple times in sequence through the chute in the mold until each mold is filled by a step-pouring method and a bottom-up forced cooling method is adopted to avoid shrinkage holes at the bottom of the high-aluminum-zinc-aluminum-magnesium alloy ingot.

[0046] Among them, the specific method for the stepped casting of high aluminum zinc aluminum magnesium alloy is as follows.

[0047] 1) In terms of mass percentage, Al: 47.0% to 53.0%, Mg: 1.0% to 3.0%, Si: 0.01% to 0.125%, Zr: 0.01% to 0.08%, Sr: 0.01% to 0.08%, Ca: 0.05% to 0.15%, and the rest is Zn and unavoidable impurities.

[0048] Among them, the zinc raw material is 0# zinc ingot (i.e. zinc ingot with zinc content higher than 99.995%), the aluminum raw material is aluminum ingot, and other raw materials can be alloys or pure substances.

[0049] 2) Add zinc ingots, aluminum ingots, and aluminum-silicon master alloys into a smelting furnace, raise the temperature of the smelting furnace to 600° C., and after the zinc ingots, aluminum ingots, and aluminum-silicon master alloys are completely melted, add magnesium ingots, Zr, Sr, and Ca master alloys, continue to stir and melt, and after confirming that all materials are completely melted, add 0.12% of the total mass of ammonium chloride slag-making mixture of the raw materials for slag-making, retreat, keep warm, and stand for 20 to 40 minutes, rake the slag, and obtain a high-aluminum zinc-aluminum-magnesium alloy liquid.

[0050] 3) The high aluminum zinc aluminum magnesium alloy liquid in the smelting furnace is poured back and forth multiple times in the mold sequence through the chute until all the molds are filled.

[0051] Among them, the pouring height of each mold each time is calculated according to the law of conservation of heat Q1 = Q2 = Q3 by the following formula:

[0052] Q1=C1×ρ1×(a1b1h)×(t1-450)

[0053] Q2=50×(a1b1+2a1h+2b1h)×(t2-300)

[0054] Q3=C3×(abh-a1b1h1)×(t3-t4)

[0055] Among them: Q1 is the heat required for the solidification of the alloy liquid, Q2 is the heat conducted by the mold wall, and Q3 is the heat transferred by the liquid water in the mold; a is the outer width of the mold, b is the outer length of the mold, and h is the outer height of the mold; a1 is the inner width of the mold, b1 is the inner length of the mold, and h1 is the inner height of the mold; C1 is the heat transfer coefficient of the alloy liquid, C2 is the heat transfer coefficient of the mold, and C3 is the heat transfer coefficient of the water at ambient temperature; ρ1 is the density of the alloy liquid, and ρ2 is the density of water; t1 is the temperature of the alloy liquid in the furnace, t2 is the mold temperature, t3 is the water temperature at the outlet, and t4 is the ambient temperature.

[0056] As a specific implementation of the present invention, the height of each pouring from the first mold to the penultimate mold is one third of the capacity height of each mold, and the last mold is poured with one quarter of its capacity each time.

[0057] Specifically, during pouring, first pour from the first mold to the last mold to one-third of each mold, and pour from the last mold to one-quarter of the mold to complete the first pouring of each mold, then pour from the last mold to the first mold to one-third of each mold to complete the second pouring, and then pour from the first mold to the last mold to one-third of each mold to complete the third pouring.

[0058] The first mold can be the first mold from left to right or the first mold from right to left. That is, the first pouring of each mold can be completed by pouring from left to right or from right to left to one-third of each mold, and the last mold can be poured to one-quarter of the mold, and then poured in reverse order, so that the second pouring can be performed when the alloy liquid is almost solidified, reducing the pouring texture and the degree of gravity segregation. The third pouring is performed in the order of the first pouring to fill all the molds.

[0059] Among them, after each mold completes the first and second pouring, it is necessary to remove part of the surface sticky slag formed by the casting impact in each mold, so that there is no surface sticky slag formed by the casting impact on the surface of the alloy liquid in each mold, and then the next pouring of each mold can be carried out.

[0060] 4) After the first pouring is completed according to the pouring sequence of each mold, each mold is forced to be cooled from bottom to top in turn, and the casting is completed after the alloy liquid in each mold is cooled and solidified.

[0061] That is, after each mold completes the first pouring, the mold circulating cooling water system is turned on to force each mold to be cooled from bottom to top in turn.

[0062] When each mold is forced to be cooled from bottom to top, the cooling heat transfer amount is controlled by controlling the water flow rate at the inlet and outlet. In addition, the direction of water flow through each mold is consistent with the direction of the order of pouring each mold during the first pouring, which can accelerate the cooling of the alloy liquid and reduce the generation of gravity segregation, and avoid the formation of shrinkage holes at the bottom of the zinc-aluminum-magnesium alloy ingot due to solidification shrinkage.

[0063] At the same time, in order to ensure that the water in each mold can play a good cooling role, the water temperature in each mold must be lower than the solidification point of the alloy liquid.

[0064] The present invention provides a method for solving the shrinkage cavity at the bottom of a high-aluminum zinc-aluminum-magnesium alloy ingot. By adding a certain amount of Si, Zr, Sr, Ca and other elements into the high-aluminum zinc-aluminum-magnesium alloy, and during the pouring process, by adopting a step pouring method in which the alloy liquid in the smelting furnace is poured back and forth multiple times in sequence through a chute in the mold sequence until each mold is filled, and by adopting a bottom-up forced cooling method, the growth and distribution of the solidification structure phase of the high-aluminum zinc-aluminum-magnesium alloy ingot on the longitudinal surface of the mold can be controlled, the segregation of elements in the high-aluminum zinc-aluminum-magnesium alloy can be controlled, and shrinkage cavities at the bottom of the zinc-aluminum-magnesium alloy ingot due to solidification shrinkage can be avoided, thereby solving the defect of shrinkage pits at the bottom of the zinc-aluminum-magnesium alloy ingot.

[0065] The following is a specific description of a method for solving the shrinkage cavity at the bottom of a high-aluminum-zinc-aluminum-magnesium alloy ingot provided by the present invention through an embodiment.

[0066] Example 1

[0067] The zinc raw material is 0# zinc ingot (zinc ingot with zinc content higher than 99.995%), the aluminum raw material is aluminum ingot, and the others can be alloys or pure substances, and the alloy liquid composition is configured as follows: Al: 47 weight%, Mg 2.5 weight%, Si 0.1 weight%, Zr 0.08 weight%, Sr 0.08 weight%, Ca 0.08 weight%. The reverberatory furnace temperature rises to 600°C, and after the zinc ingot, aluminum ingot, and aluminum silicon master alloy (wherein the silicon content is 48%) are completely melted, magnesium ingot, Zr, Sr, Ca master alloy are added, and stirring and melting are continued. After confirming that all materials are completely melted, an ammonium chloride slag mixture with a total metal content of 0.12% is poured in for slag making, and the mixture is withdrawn, kept warm, and left to stand for 30 minutes, and the slag is raked to obtain a high-aluminum zinc-aluminum-magnesium alloy liquid.

[0068] The alloy liquid in the reverberatory furnace is poured sequentially through the chute, poured to the three-point line of the mold, and the last piece is poured to the four-point line of the mold, and the surface sticky slag formed by the casting impact is removed, so that there is no surface sticky slag formed by the casting impact on the surface of the alloy liquid in the casting mold. After the first pouring of each mold is completed in sequence, the mold circulating cooling water system is turned on, and the cooling heat transfer is controlled by controlling the inlet and outlet water flow speed. The water flow direction is consistent with the first casting direction, and each mold is forced to be cooled from bottom to top in turn to accelerate the cooling of the alloy liquid and reduce the generation of gravity segregation.

[0069] Then reverse the casting order, so that the second pouring can be done when the alloy liquid is about to solidify, reducing the pouring texture and the degree of gravity segregation. Then pour the third time in sequence to fill all the molds. When the alloy liquid cools and solidifies with the mold, the casting is completed. The bottom surface morphology of the high aluminum zinc aluminum magnesium alloy ingot is as follows: Figure 8 As shown. Figure 8 It can be seen that the method for solving the shrinkage cavity at the bottom of a high-aluminum zinc-aluminum-magnesium alloy ingot provided in an embodiment of the present invention can produce a zinc-aluminum-magnesium alloy ingot with a relatively smooth bottom surface and no shrinkage cavity at the bottom.

[0070] Example 2

[0071] The zinc raw material is 0# zinc ingot (zinc ingot with zinc content higher than 99.995%), the aluminum raw material is aluminum ingot, and the others can be alloys or pure substances, and the alloy liquid composition is configured as follows: Al: 52 weight%, Mg 2.5 weight%, Si 0.1 weight%, Zr 0.08 weight%, Sr 0.08 weight%, Ca 0.08 weight%. The reverberatory furnace temperature rises to 600°C, and after the zinc ingot, aluminum ingot, and aluminum silicon master alloy (wherein the silicon content is 45%) are completely melted, magnesium ingot, Zr, Sr, Ca master alloy are added, and stirring and melting are continued. After confirming that all materials are completely melted, 2 bags of granular refining agent and shovel ammonium chloride slag mixture are injected for slag making, the mixture is withdrawn and kept warm for 35 minutes, and the slag is raked to obtain high aluminum zinc aluminum magnesium alloy liquid.

[0072] The alloy liquid in the reverberatory furnace is poured sequentially through the chute, poured to the three-point line of the mold, and the last piece is poured to the four-point line of the mold, and the surface sticky slag formed by the casting impact is removed, so that there is no surface sticky slag formed by the casting impact on the surface of the alloy liquid in the casting mold. After the first pouring of each mold is completed in sequence, the mold circulating cooling water system is turned on, and the cooling heat transfer is controlled by controlling the inlet and outlet water flow speed. The water flow direction is consistent with the first casting direction, and each mold is forced to be cooled from bottom to top in turn to accelerate the cooling of the alloy liquid and reduce the generation of gravity segregation.

[0073] Then reverse the casting order, so that the second pouring can be done when the alloy liquid is about to solidify, reducing the pouring texture and the degree of gravity segregation. Then pour the third time in sequence to fill all the molds. When the alloy liquid cools and solidifies with the mold, the casting is completed. The bottom surface morphology of the high aluminum zinc aluminum magnesium alloy ingot is as follows: Fig. 9 As shown. Fig. 9 It can be seen that the method for solving the shrinkage cavity at the bottom of a high-aluminum zinc-aluminum-magnesium alloy ingot provided in an embodiment of the present invention can produce a zinc-aluminum-magnesium alloy ingot with a relatively smooth bottom surface and no shrinkage cavity at the bottom.

[0074] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for solving the shrinkage cavity at the bottom of a high aluminum-zinc-aluminum-magnesium alloy ingot, characterized in that: The following methods are included: Si, Zr, Sr and Ca are added to the alloy to obtain a high aluminum zinc aluminum magnesium alloy including, by mass percentage, Al: 47.0% to 53.0%, Mg: 1.0% to 3.0%, Si: 0.01% to 0.125%, Zr: 0.01% to 0.08%, Sr: 0.01% to 0.08%, Ca: 0.05% to 0.15%, and the remainder being Zn and unavoidable impurities; When pouring high aluminum-zinc-aluminum-magnesium alloy, the alloy liquid in the smelting furnace is poured back and forth multiple times in the mold sequence through the chute until each mold is filled; When pouring in sequence in each mold, after the first pouring is completed, each mold is forced to be cooled from bottom to top in turn, and the alloy liquid in each mold is cooled and solidified to complete the casting.

2. The method for solving the shrinkage cavity at the bottom of high aluminum-zinc-aluminum-magnesium alloy ingot according to claim 1 is characterized in that: The mass ratio of Zr, Sr and Ca in the high-aluminum zinc-aluminum-magnesium alloy is controlled to be 1:1:

2.

3. The method for solving the bottom shrinkage cavity of high aluminum zinc aluminum magnesium alloy ingot according to claim 1 is characterized in that: The pouring height of each mold is calculated by the following formula according to the law of conservation of heat: Q1=Q2=Q3: Q1=C1×ρ1×(a1b1h)×(t1-450) Q2=50×(a1b1+2a1h+2b1h)×(t2-300) Q3=C3×(abh-a1b1h1)×(t3-t4) Among them: Q1 is the heat required for the solidification of the alloy liquid, Q2 is the heat conducted by the mold wall, and Q3 is the heat transferred by the liquid water in the mold; a is the outer width of the mold, b is the outer length of the mold, and h is the outer height of the mold; a1 is the inner width of the mold, b1 is the inner length of the mold, and h1 is the inner height of the mold; C1 is the heat transfer coefficient of the alloy liquid, C2 is the heat transfer coefficient of the mold, and C3 is the heat transfer coefficient of the water at ambient temperature; ρ1 is the density of the alloy liquid, and ρ2 is the density of water; t1 is the temperature of the alloy liquid in the furnace, t2 is the mold temperature, t3 is the water temperature at the outlet, and t4 is the ambient temperature.

4. The method for solving the shrinkage cavity at the bottom of high aluminum-zinc-aluminum-magnesium alloy ingot according to claim 3 is characterized in that: When pouring the high-aluminum-zinc-aluminum-magnesium alloy, the alloy liquid is first poured from the first mold to the last mold through a chute to one-third of each mold, and the last mold is poured to one-quarter of the mold to complete the first pouring of each mold, and then one-third of each mold is poured from the last mold to the first mold to complete the second pouring, and then one-third of each mold is poured from the first mold to the last mold to complete the third pouring.

5. The method for solving the shrinkage cavity at the bottom of high aluminum-zinc-aluminum-magnesium alloy ingot according to claim 1 is characterized in that: After the first and second pouring of each mold is completed, part of the surface sticky slag formed by the casting impact in each mold needs to be fished out respectively, and then the next pouring of each mold is carried out.

6. The method for solving the shrinkage cavity at the bottom of high aluminum-zinc-aluminum-magnesium alloy ingot according to claim 5 is characterized in that: The forced cooling of each mold from bottom to top in sequence is that after each mold completes the first pouring, the mold circulating cooling water system is turned on to force the cooling of each mold from bottom to top in sequence.

7. The method for solving the shrinkage cavity at the bottom of high aluminum-zinc-aluminum-magnesium alloy ingot according to claim 6 is characterized in that: During the forced bottom-up cooling, the cooling heat transfer amount is controlled by controlling the inlet and outlet water flow speeds, and the direction of the water flow through each mold is consistent with the direction of the order of pouring each mold during the first pouring.

8. The method for solving the shrinkage cavity at the bottom of high aluminum-zinc-aluminum-magnesium alloy ingot according to claim 7 is characterized in that: The water temperature in each mold is lower than the solidification point of the alloy liquid.

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