A special dehydrogenating agent for aluminum alloy melt and an aluminum alloy casting process

Abstract

The application relates to the alloy smelting technical field and provides a special hydrogen removal agent for an aluminum alloy melt and an aluminum alloy melting and casting process, solves the defects that the hydrogen removal effect of an existing aluminum alloy preparation process is poor, and the hydrogen removal agent added into the aluminum alloy smelting process can cause pollution and harm to human health; the special hydrogen removal agent comprises the following raw materials in parts by weight: 80-90 parts by weight of industrial pure aluminum, 38-46 parts by weight of MgCl2, 18-26 parts by weight of NaCl, 20-28 parts by weight of KCl, 27-29 parts by weight of CaCl2, 5-8 parts by weight of BaCl2, 5-10 parts by weight of Ce and 5-10 parts by weight of Y; the melting and casting process of the aluminum alloy comprises the following steps: 1) pretreatment; 2) melting; 3) refining; 4) ultrasonic treatment; and 5) ingot casting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy smelting, in particular to a special hydrogen removal agent for aluminum alloy melt and an aluminum alloy melting and casting process. BACKGROUND

[0002] Aluminum alloy has been widely concerned due to its low density, high specific strength, good electrical and thermal conductivity, low cost and good corrosion resistance, and has become the best material in non-ferrous metals. The preparation of aluminum alloy material must go through the process of melting and casting. When the alloy is melted, the aluminum melt will absorb a large amount of air (mainly hydrogen). If the hydrogen is not removed in time before casting and solidification, pores will be formed in the ingot, which will affect the tensile strength, yield strength, elongation and corrosion resistance of the alloy. Therefore, hydrogen removal of aluminum alloy melt is a problem that must be solved.

[0003] Chinese patent application No. 201810127386.0 discloses an aluminum-lithium alloy and a preparation method thereof. Pure aluminum ingot, pure Cu plate, 15% Al-Mn intermediate alloy, pure Mg ingot, pure Zn ingot, 4% Al-Ti intermediate alloy, 4% Al-Zr intermediate alloy, pure Li ingot and pure Ag ingot are prepared and loaded into the furnace. The aluminum ingot is loaded first, then the other pure metals are loaded, and finally the intermediate alloy is loaded. After the loading is completed, smelting is carried out at a temperature of 730℃. Argon refining is carried out at 740℃, and the refining time is 30 minutes to obtain an alloy liquid. The alloy liquid is subjected to vacuum refining at 740℃ and a vacuum degree of less than 300MPa for 1-3 hours to obtain a melt. During the smelting process, the hydrogen content is reduced by using static furnace bottom gas permeation and online treatment to remove hydrogen. The aluminum-lithium alloy prepared by the present application has high hardness, but the hydrogen removal effect is relatively poor.

[0004] Chinese patent application No. 201910684339.0 discloses a high-performance A356 aluminum alloy refining and toughening heat treatment process method. An aluminum alloy melt composite refining covering deslagging agent is configured by selecting C2Cl6, K2TiF6, CaF2, Na2SiF6 and Na3AlF6 components. Among them, components C2Cl6, K2TiF6 and CaF2 are mainly used to remove free H, and components Na2SiF6 and Na3AlF6 are mainly used to remove Al2O3 inclusions. The technical problems of high hydrogen content, excessive slagging and uneven composition in traditional A356 aluminum alloy smelting can be overcome. In addition, due to the high silicon content in the ingot, the brittleness is significant, and the balance between formability and aging strength is difficult to balance. However, using C2Cl6 as a raw material will cause greater environmental pollution and harm to human health. SUMMARY

[0005] Therefore, aiming at the above problems, the application provides a special dehydrogenation agent for aluminum alloy melt and an aluminum alloy melting and casting process, which solves the poor dehydrogenation effect of the existing aluminum alloy preparation process, and the defects that the dehydrogenation agent added into the aluminum alloy melting process will cause pollution and harm to human health.

[0006] To achieve the above object, the application adopts the following technical scheme:

[0007] A special dehydrogenation agent for aluminum alloy melt, characterized in that it comprises the following raw materials by weight: 80-90 parts of industrial pure aluminum, 38-46 parts of MgCl2, 18-26 parts of NaCl, 20-28 parts of KCl, 27-29 parts of CaCl2, 5-8 parts of BaCl2, 5-10 parts of Ce and 5-10 parts of Y.

[0008] Further, the preparation method of the special dehydrogenation agent for aluminum alloy melt comprises the following steps:

[0009] Comprising the following preparation steps:

[0010] a. The raw materials MgCl2, NaCl, KCl, CaCl2, BaCl2, Ce and Y are respectively ball milled, sieved in a vacuum environment, and the sieved raw materials are weighed according to the weight parts and mixed uniformly, and then dried to obtain the mixed raw materials;

[0011] b. The dried industrial pure aluminum is weighed and added to a preheated graphite crucible, put into a resistance furnace, heated to 800-900℃ for melting, stirred for 10-30 min, and then the temperature is increased to 1200-1300℃, the dried mixed raw materials are added, stirred for 10-30 min, poured into a preheated copper mold, naturally cooled, crushed, sieved through a 50-70 mesh sieve, and the dehydrogenation agent is obtained.

[0012] Further, the ball milling is carried out in a vacuum ball mill at a speed of 200-400 r / min for 3-4 h; the sieving is sieved through a 300-400 mesh sieve; the drying is carried out in a drying box at a temperature of 150-200℃ for 3-4 h; and the stirring is electromagnetic stirring at a speed of 100-120 r / min.

[0013] An aluminum alloy melting and casting process, comprising the following steps:

[0014] S1, pretreatment: the aluminum alloy raw materials are weighed according to the proportions of 80-90 parts of Al, 5-10 parts of Si, 1-8 parts of Cu and 1-5 parts of Mg, the surface is polished bright, and then dried;

[0015] S2, melting: evenly brush the inside of the iron crucible with paint, preheat, put the dried raw materials after step S1 into the iron crucible, melt in the melting furnace with gas protection, the temperature is 630-700℃, the time is 10-30min;

[0016] S3, refining: add 0.5-2 parts by weight of the hydrogen removal agent prepared by claim 2 to the melt, stir uniformly, raise the temperature to 700-900℃, the time is 10-20min, remove the slag on the surface of the melt and the slag attached to the crucible wall with a preheated skimmer, put it back into the furnace after skimming, repeat the above operation 2-3 times;

[0017] S4, ultrasonic: quickly insert the preheated ultrasonic probe from above the crucible, the insertion depth is 20-30mm, turn on the ultrasonic generator, the output power is 100-200w, the frequency is 20-30kHz, ultrasonic treatment for 90-120s, then keep warm for 20-40s;

[0018] S5, ingot casting: turn off the argon protection, pour the melt into a copper mold, and naturally cool at room temperature to obtain the aluminum alloy.

[0019] Further, in step S2, the paint is composed of the following raw materials by weight: 60-80 parts by weight of talcum powder, 5-15 parts by weight of Na2SiO3, and 5-10 parts by weight of water.

[0020] Further, the gas is argon, the purity is 99.990-99.999%, the argon pressure is adjusted to 0.2-0.3MPa, and the gas flow is 0.3-0.5L / min.

[0021] Further, the preheating is carried out in an oven, the temperature is 300-400℃, and the time is 30-60min.

[0022] By adopting the foregoing technical scheme, the present application has the following advantages:

[0023] The application discloses a special hydrogen removal agent for aluminum alloy melt and an aluminum alloy melting and casting process, and solves the defects of poor performance improvement effect of the existing flux on the aluminum alloy and environmental pollution in the use process, and the principle is that rare earth elements are introduced into the cast aluminum alloy, the atomic particle size of the rare earth elements is large, the solid solution degree of the rare earth elements in the Al matrix is low, the insoluble rare earth atoms are gathered at the front of the solidification interface of the columnar dendritic structure alpha-Al, the grain nucleation rate is promoted, and the growth of the dendritic structure alpha-Al is inhibited, and the effect of composition undercooling is achieved; on the other hand, the rare earth elements are added into the cast aluminum alloy, and eutectic reaction occurs at 640 DEG C, and intermetallic compounds are generated with the aluminum matrix, the intermetallic compounds can be used as heterogeneous nucleation cores to promote the generation of alpha-Al grains and play the role of refining the grains. The reserves of the rare earth element Ce are the largest among the 17 kinds of rare earth elements, and the comprehensive performance of the cast aluminum alloy can be improved by introducing the Ce element into the cast aluminum alloy. Compared with other rare earth elements, the Y element has better effect on improving the morphology of the Si phase and other intermetallic compounds in the hypoeutectic Al-Si cast aluminum alloy, the size of the refined grains in the alloy is smaller, and therefore the mechanical properties of the alloy can be significantly improved. DETAILED DESCRIPTION

[0024] Embodiment 1

[0025] A special hydrogen removal agent for aluminum alloy melt comprises the following raw materials in parts by weight:

[0026] 80 parts by weight of industrial pure aluminum, 38 parts by weight of MgCl2, 18 parts by weight of NaCl, 20 parts by weight of KCl, 27 parts by weight of CaCl2, 5 parts by weight of BaCl2, 5 parts by weight of Ce and 5 parts by weight of Y;

[0027] The preparation method of the special hydrogen removal agent for aluminum alloy melt comprises the following steps:

[0028] (1) the raw materials MgCl2, NaCl, KCl, CaCl2, BaCl2, Ce and Y are respectively subjected to ball milling treatment in a vacuum environment, the rotating speed is 200 r / min, the time is 3 h, then the materials are sieved through a 300-mesh sieve, the sieved raw materials are weighed according to the weight parts and uniformly mixed, and then drying treatment is carried out in a drying box, the temperature is 150 DEG C, and the time is 3 h, so that the mixed raw materials are obtained;

[0029] (2) the industrial pure aluminum after drying is weighed and added to a graphite crucible preheated in an oven at 300℃ for 30 min, placed in a resistance furnace, heated to 800℃ for melting, electromagnetic stirring for 20 min at a speed of 100 r / min, the temperature is increased to 1200℃, the dried mixed raw materials are added, stirred uniformly, electromagnetic stirring for 20 min at a speed of 120 r / min, poured into a copper mold preheated in an oven at 300℃ for 30 min, naturally cooled, crushed, and sieved through a 50-mesh sieve to obtain the hydrogen removal agent.

[0030] Example 2

[0031] A hydrogen removal agent for aluminum alloy melt, comprising the following raw materials by weight:

[0032] 85 parts by weight of industrial pure aluminum, 40 parts by weight of MgCl2, 20 parts by weight of NaCl, 25 parts by weight of KCl, 28 parts by weight of CaCl2, 6 parts by weight of BaCl2, 8 parts by weight of Ce, and 8 parts by weight of Y;

[0033] The preparation method of the hydrogen removal agent for aluminum alloy melt, comprising the following steps:

[0034] (1) the raw materials MgCl2, NaCl, KCl, CaCl2, BaCl2, Ce and Y are respectively ball milled in a vacuum environment at a speed of 300 r / min for 3.5 h, sieved through a 300-mesh sieve, and the sieved raw materials are weighed according to the weight parts, mixed uniformly, and dried in a drying box at a temperature of 180℃ for 3 h to obtain the mixed raw materials;

[0035] (2) the industrial pure aluminum after drying is weighed and added to a graphite crucible preheated in an oven at 300℃ for 30 min, placed in a resistance furnace, heated to 800℃ for melting, electromagnetic stirring for 20 min at a speed of 100 r / min, the temperature is increased to 1200℃, the dried mixed raw materials are added, stirred uniformly, electromagnetic stirring for 20 min at a speed of 120 r / min, poured into a copper mold preheated in an oven at 300℃ for 30 min, naturally cooled, crushed, and sieved through a 50-mesh sieve to obtain the hydrogen removal agent.

[0036] Example 3

[0037] A hydrogen removal agent for aluminum alloy melt, comprising the following raw materials by weight:

[0038] 90 parts by weight of industrial pure aluminum, 45 parts by weight of MgCl2, 25 parts by weight of NaCl, 25 parts by weight of KCl, 29 parts by weight of CaCl2, 8 parts by weight of BaCl2, 10 parts by weight of Ce, and 10 parts by weight of Y;

[0039] The preparation method of the hydrogen removal agent for the aluminum alloy melt comprises the following steps:

[0040] (1) The raw materials MgCl2, NaCl, KCl, CaCl2, BaCl2, Ce and Y are respectively ball milled in a vacuum environment at a speed of 400 r / min for 3 h, and then sieved through a 400-mesh sieve. The sieved raw materials are weighed according to the weight parts and uniformly mixed, and then dried in a drying box at a temperature of 200 ℃ for 3 h to obtain the mixed raw materials;

[0041] (2) The dried industrial pure aluminum is weighed and added to a graphite crucible preheated in an oven at 300 ℃ for 30 min, and then placed in an electric resistance furnace. The temperature is raised to 900 ℃ for melting, and the electromagnetic stirring is performed at a speed of 120 r / min for 20 min. Then the temperature is raised to 1300 ℃, and the dried mixed raw materials are added and uniformly mixed. The electromagnetic stirring is performed at a speed of 120 r / min for 20 min. Then the mixture is poured into a copper mold preheated in an oven at 300 ℃ for 30 min, and naturally cooled. After crushing and sieving through a 70-mesh sieve, the hydrogen removal agent is obtained.

[0042] Example 4

[0043] An aluminum alloy melting and casting process comprises the following steps:

[0044] S1, pretreatment: the aluminum alloy raw materials are weighed according to the proportions of 80 parts by weight of Al, 5 parts by weight of Si, 4 parts by weight of Cu and 2 parts by weight of Mg. After the surface is polished bright, the materials are dried in a drying box at a temperature of 150 ℃ for 3 h;

[0045] S2, melting: 75 parts by weight of talcum powder, 15 parts by weight of Na2SiO3 and 10 parts by weight of water are uniformly mixed to obtain the coating. The inside of the iron crucible is uniformly brushed with the coating, and preheated in an oven at 300 ℃ for 30 min. The dried raw materials obtained in step S1 are placed in the iron crucible, and melted in a melting furnace under the protection of argon gas with a purity of 99.999%. The argon gas pressure is adjusted to 0.2 MPa, the gas flow is 0.3 L / min, the temperature is 630 ℃, and the time is 20 min;

[0046] S3, refining: 0.8 parts by weight of the hydrogen removal agent prepared in Example 1 is added to the melt, and stirred uniformly. The temperature is raised to 700 ℃ for 20 min. The preheated skimming ladle is used to remove the slag on the surface of the molten pool and the slag adhered to the wall of the crucible. After skimming, the ladle is re-placed in the furnace, and the above operation is repeated for 3 times.

[0047] S4, ultrasonic: the ultrasonic probe preheated in the oven at 300°C for 30 min is quickly inserted from above the crucible with an insertion depth of 20 mm, the ultrasonic generator is turned on, the output power is 100 w, the frequency is 20 kHz, and after ultrasonic treatment for 90 s, the melt is kept still for 20 s;

[0048] S5, ingot casting: the argon protection is turned off, the melt is poured into a copper mold, and the aluminum alloy is obtained by natural cooling at room temperature.

[0049] Example 5

[0050] A melting and casting process of an aluminum alloy, comprising the following steps:

[0051] S1, pretreatment: the aluminum alloy raw materials are weighed according to the proportions of 85 parts by weight of Al, 8 parts by weight of Si, 6 parts by weight of Cu, and 3 parts by weight of Mg, the surface is polished and then dried in a drying box at a temperature of 150°C for 3h;

[0052] S2, melting: 80 parts by weight of talc powder, 10 parts by weight of Na2SiO3, and 10 parts by weight of water are uniformly mixed to obtain the coating, the inside of the iron crucible is uniformly brushed with the coating, the iron crucible is preheated in an oven at 350°C for 30 min, the raw materials dried in step S1 are placed in the iron crucible, and the raw materials are melted in a melting furnace under the protection of argon gas with a purity of 99.999%, the argon gas pressure is adjusted to 0.25 MPa, the gas flow is 0.4 L / min, the temperature is 650°C, and the time is 20 min;

[0053] S3, refining: 1.2 parts by weight of the hydrogen removal agent prepared in Example 2 is added to the melt, stirred uniformly, the temperature is raised to 800°C, the time is 20 min, the preheated skimmer is used to remove the slag on the surface of the melt pool and the slag adhered to the wall of the crucible, the skimmer is reinserted into the furnace after skimming, and the above operation is repeated for 3 times;

[0054] S4, ultrasonic: the ultrasonic probe preheated in the oven at 350°C for 30 min is quickly inserted from above the crucible with an insertion depth of 25 mm, the ultrasonic generator is turned on, the output power is 150 w, the frequency is 25 kHz, and after ultrasonic treatment for 90 s, the melt is kept still for 30 s;

[0055] S5, ingot casting: the argon protection is turned off, the melt is poured into a copper mold, and the aluminum alloy is obtained by natural cooling at room temperature.

[0056] Example 6

[0057] A melting and casting process of an aluminum alloy, comprising the following steps:

[0058] S1, pretreatment: each aluminum alloy raw material was weighed according to the ratio of 90 parts by weight of Al, 10 parts by weight of Si, 8 parts by weight of Cu, and 5 parts by weight of Mg, and after the surface was polished bright, drying treatment was performed in a drying oven at a temperature of 150°C for 3h;

[0059] S2, melting: 90 parts by weight of talc powder, 5 parts by weight of Na2SiO3, and 5 parts by weight of water were uniformly mixed to obtain the coating, the inside of the iron crucible was uniformly brushed with the coating, and preheating was performed in an oven at 400°C for 30min; each raw material after drying in step S1 was placed in the iron crucible, and was melted in a melting furnace under the protection of argon gas with a purity of 99.999%; the argon gas pressure was adjusted to 0.3MPa, the gas flow was 0.5L / min, the temperature was 700°C, and the time was 20min;

[0060] S3, refining: 1.6 parts by weight of the hydrogen removal agent prepared in Example 3 was added to the melt, and was uniformly stirred, the temperature was increased to 900°C, and the time was 20min; the molten slag on the surface of the molten pool and the molten slag adhered to the wall of the crucible were removed with a preheated skimmer, and after skimming, the furnace was reloaded, and the above operation was repeated 3 times;

[0061] S4, ultrasonic: the ultrasonic generating probe preheated in the oven at 400°C for 30min was quickly inserted from above the crucible with an insertion depth of 30mm, the ultrasonic generator was turned on, the output power was 200w, the frequency was 30kHz, and after ultrasonic treatment for 90s, the temperature was kept for 40s;

[0062] S5, ingot casting: the argon protection was turned off, the melt was poured into a copper mold, and was naturally cooled at room temperature to obtain the aluminum alloy.

[0063] Comparative Example 1

[0064] The difference from Example 3 is that the rare earth elements Ce and Y are not used as the raw material of the hydrogen removal agent, and a commercially available known aluminum alloy refining agent is used, the raw material composition of which includes: 50-60 parts by weight of KCl, 20-25 parts by weight of K2CO3, 10-15 parts by weight of MgCl2, 30-35 parts by weight of AlF3, 10-12 parts by weight of potassium fluoroaluminate, 5-10 parts by weight of CaF2, 5-10 parts by weight of graphite powder, 15-25 parts by weight of light calcium carbonate, and 1-10 parts by weight of C2Cl6; the melting and casting process of pretreatment, melting, refining, ultrasonic, and ingot casting is not used, and the melting and casting process of mixing, melting, refining, and ingot casting is used. Other technical solutions are the same as those of Example 1.

[0065] The performance detection results of the products of the above-mentioned Example 4, Example 5, Example 6, and Comparative Example 1 are as follows.

[0066] Table 1

[0067]

[0068] Hydrogen content, slag content, average grain size performance test: refer to the standard "High purity fine grain aluminum and aluminum alloy round ingot" (GB / T40123-2021).

[0069] As can be seen from the above table, the hydrogen content of the aluminum alloy ingot prepared by the hydrogen removal agent raw material and the melting and casting process of the present application is ≤0.080 mL / 100g, the slag content is ≤0.01 mm 2 / kg, the average grain size is ≤90 μm, the hardness is ≥90 HB, the tensile strength is ≥288 MPa, the yield strength is ≥216 MPa, the elongation is ≥13.7%, the pinhole degree reaches the first level, indicating that the aluminum alloy flux product has good performance.

[0070] Although the present application is specifically shown and described in connection with preferred embodiments, those skilled in the art will understand that various modifications in form and detail can be made therein without departing from the spirit and scope of the application as defined in the appended claims.

Claims

1. A hydrogen scavenger for aluminum alloy melts, characterized by, The raw materials include the following weight parts: 80-90 parts by weight of industrial pure aluminum, 38-46 parts by weight of MgCl2, 18-26 parts by weight of NaCl, 20-28 parts by weight of KCl, 27-29 parts by weight of CaCl2, 5-8 parts by weight of BaCl2, 5-10 parts by weight of Ce, and 5-10 parts by weight of Y; The hydrogen removal agent comprises the following preparation steps: a. Ball milling, sieving, and drying the raw materials MgCl2, NaCl, KCl, CaCl2, BaCl2, Ce, and Y in a vacuum environment, respectively, to obtain a mixture of the raw materials; b. The dried industrial pure aluminum is weighed and added to a preheated graphite crucible, which is placed in a resistance furnace, and the temperature is raised to 800-900°C for melting, and stirred for 10-30 min. Then the temperature is raised to 1200-1300°C, and the dried mixture of the raw materials is added and stirred for 10-30 min. Then the mixture is poured into a preheated copper mold, and naturally cooled. After crushing and sieving through a 50-70 mesh sieve, the hydrogen removal agent is obtained.

2. The hydrogen scavenger for aluminum alloy melt according to claim 1, characterized in that: The ball milling is performed in a vacuum ball mill at a speed of 200-400 r / min for 3-4 h. The sieving is performed through a 300-400 mesh sieve. The drying is performed in a drying box at a temperature of 150-200°C for 3-4 h. The stirring is electromagnetic stirring at a speed of 100-120 r / min.

3. A process for the casting of an aluminum alloy, characterized in that, The method comprises the following steps: S1. Pretreatment: The aluminum alloy raw materials are weighed according to the ratio of 80-90 parts by weight of Al, 5-10 parts by weight of Si, 1-8 parts by weight of Cu, and 1-5 parts by weight of Mg. The surface is polished and then dried; S2. Melting: The inside of the iron crucible is uniformly coated with paint, and preheating is performed. The dried raw materials from step S1 are placed in the iron crucible and melted in a gas-protected melting furnace at a temperature of 630-700°C for 10-30 min; S3. Refining: 0.5-2 parts by weight of the hydrogen removal agent prepared by the method of claim 2 is added to the melt and stirred uniformly. The temperature is raised to 700-900°C for 10-20 min. The surface of the molten pool and the molten slag adhered to the crucible wall are removed with a preheated skimming ladle. After skimming, the molten slag is re-placed in the furnace, and the operation of removing and skimming the molten slag is repeated 2-3 times; S4. Ultrasonic: The preheated ultrasonic probe is quickly inserted from above the crucible with an insertion depth of 20-30 mm. The ultrasonic generator is turned on with an output power of 100-200 W and a frequency of 20-30 kHz. After ultrasonic treatment for 90-120 s, the temperature is maintained for 20-40 s; S5. Ingot casting: The argon protection is turned off, and the melt is poured into a copper mold and naturally cooled at room temperature to obtain the aluminum alloy.

4. A process for the casting of an aluminum alloy as defined in claim 3, characterized in that In step S2, the paint is composed of the following weight parts of raw materials: 60-80 parts by weight of talcum powder, 5-15 parts by weight of Na2SiO3, and 5-10 parts by weight of water.

5. A process for the casting of an aluminum alloy as defined in claim 3, characterized in that: The gas is argon, the purity is 99.990-99.999%, the argon pressure is adjusted to 0.2-0.3 MPa, and the gas flow is 0.3-0.5 L / min.

6. A process for the casting of an aluminum alloy as defined in claim 3 wherein: The preheating is carried out in an oven, the temperature is 300-400 DEG C, and the time is 30-60 min.

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