CN116590556A - Die-casting forming heat-cracking-resistant heat-treatment-free aluminum alloy and preparation method thereof - Google Patents
Die-casting forming heat-cracking-resistant heat-treatment-free aluminum alloy and preparation method thereof Download PDFInfo
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- 238000004512 die casting Methods 0.000 title claims abstract description 120
- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 23
- 238000005336 cracking Methods 0.000 title claims abstract description 16
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000000956 alloy Substances 0.000 claims abstract description 165
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 158
- 238000005266 casting Methods 0.000 claims abstract description 61
- 238000000034 method Methods 0.000 claims abstract description 51
- 239000000203 mixture Substances 0.000 claims abstract description 19
- 229910052782 aluminium Inorganic materials 0.000 claims description 62
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 62
- 238000003723 Smelting Methods 0.000 claims description 53
- 238000007670 refining Methods 0.000 claims description 40
- 239000007788 liquid Substances 0.000 claims description 32
- 238000002347 injection Methods 0.000 claims description 29
- 239000007924 injection Substances 0.000 claims description 29
- 239000003795 chemical substances by application Substances 0.000 claims description 26
- 239000002994 raw material Substances 0.000 claims description 20
- UQZIWOQVLUASCR-UHFFFAOYSA-N alumane;titanium Chemical compound [AlH3].[Ti] UQZIWOQVLUASCR-UHFFFAOYSA-N 0.000 claims description 18
- HIPVTVNIGFETDW-UHFFFAOYSA-N aluminum cerium Chemical compound [Al].[Ce] HIPVTVNIGFETDW-UHFFFAOYSA-N 0.000 claims description 18
- HIMLGVIQSDVUJQ-UHFFFAOYSA-N aluminum vanadium Chemical compound [Al].[V] HIMLGVIQSDVUJQ-UHFFFAOYSA-N 0.000 claims description 18
- 229910021419 crystalline silicon Inorganic materials 0.000 claims description 18
- UNQHSZOIUSRWHT-UHFFFAOYSA-N aluminum molybdenum Chemical compound [Al].[Mo] UNQHSZOIUSRWHT-UHFFFAOYSA-N 0.000 claims description 17
- 238000007872 degassing Methods 0.000 claims description 17
- YNDGDLJDSBUSEI-UHFFFAOYSA-N aluminum strontium Chemical compound [Al].[Sr] YNDGDLJDSBUSEI-UHFFFAOYSA-N 0.000 claims description 16
- 238000011049 filling Methods 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 14
- 238000000465 moulding Methods 0.000 claims description 12
- 238000004321 preservation Methods 0.000 claims description 12
- 239000010936 titanium Substances 0.000 claims description 11
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 10
- 238000001816 cooling Methods 0.000 claims description 9
- 238000003825 pressing Methods 0.000 claims description 9
- 238000007711 solidification Methods 0.000 claims description 6
- 230000008023 solidification Effects 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000011780 sodium chloride Substances 0.000 claims description 5
- 238000005507 spraying Methods 0.000 claims description 5
- 229910000765 intermetallic Inorganic materials 0.000 abstract description 8
- 238000001228 spectrum Methods 0.000 abstract description 8
- 229910052720 vanadium Inorganic materials 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 4
- 229910052742 iron Inorganic materials 0.000 abstract description 4
- 238000005728 strengthening Methods 0.000 abstract description 4
- 229910052719 titanium Inorganic materials 0.000 abstract description 4
- 239000000047 product Substances 0.000 description 23
- 239000002893 slag Substances 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 13
- 229910000676 Si alloy Inorganic materials 0.000 description 12
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 12
- 238000012360 testing method Methods 0.000 description 12
- 239000010949 copper Substances 0.000 description 10
- 229910052751 metal Inorganic materials 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- 238000002425 crystallisation Methods 0.000 description 7
- 230000008025 crystallization Effects 0.000 description 7
- 238000004227 thermal cracking Methods 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000011777 magnesium Substances 0.000 description 6
- 239000012071 phase Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000003973 paint Substances 0.000 description 5
- 230000035882 stress Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000005485 electric heating Methods 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 4
- 239000007790 solid phase Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- -1 aluminum-molybdenum-iron-silicon Chemical compound 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 238000012797 qualification Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- FWGZLZNGAVBRPW-UHFFFAOYSA-N alumane;strontium Chemical compound [AlH3].[Sr] FWGZLZNGAVBRPW-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000001680 brushing effect Effects 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 229910001338 liquidmetal Inorganic materials 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 229910018125 Al-Si Inorganic materials 0.000 description 1
- 229910018520 Al—Si Inorganic materials 0.000 description 1
- 229910018566 Al—Si—Mg Inorganic materials 0.000 description 1
- 229910018594 Si-Cu Inorganic materials 0.000 description 1
- 229910008465 Si—Cu Inorganic materials 0.000 description 1
- ZXTFQUMXDQLMBY-UHFFFAOYSA-N alumane;molybdenum Chemical compound [AlH3].[Mo] ZXTFQUMXDQLMBY-UHFFFAOYSA-N 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000001938 differential scanning calorimetry curve Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/03—Making non-ferrous alloys by melting using master alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
- B22D1/002—Treatment with gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/026—Alloys based on aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/02—Alloys based on aluminium with silicon as the next major constituent
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention provides a die-casting forming heat-cracking-resistant heat-treatment-free aluminum alloy and a preparation method thereof. The preparation method controls certain alloy composition, wherein, specific amounts of Ti and V elements play a role in grain refinement on one hand, and the alloy material can obtain higher strength and elongation after refinement; on the other hand, ti and V form AlTiV intermetallic compounds in the alloy (energy spectrum shows that atomic percent is about Al 90 Ti 4 V 4 Ce 2 ) The second phase strengthening effect is achieved, the heat resistance of the alloy is improved, and the high toughness of the alloy is maintained; at the same time, mo and Fe form AlMoFe intermetallic compounds in the alloy (the energy spectrum shows that the atomic percentage is about Al 74 Si 12 Mo 12 Fe 2 ) The thermal expansion coefficient is small, the volume stability is excellent, and the small deformation of the size of the part is effectively prevented; the invention also controls certain process steps and parameters, improves the uniformity of the structure, reduces the internal stress of the casting, improves the casting performance of the alloy, and the like.
Description
Technical Field
The invention relates to the field of metal materials, in particular to a die-casting molding anti-hot-cracking heat-treatment-free aluminum alloy and a preparation method thereof.
Background
It is known that in the solution treatment of die-cast structural members, the cast needs to be heated to a temperature close to the solidus temperature, at this time, the strength of the cast is drastically reduced, and in the subsequent cooling process, due to the large difference in cooling rates of the respective parts, large thermal stress is extremely easily formed and thermal deformation is induced, so that the dimensional and positional accuracy of the cast is reduced. To overcome this problem, the production system needs to introduce a plurality of shaping procedures, which results in high manufacturing cost, low efficiency and uncontrolled effect in the whole process. In order to meet the market demand of large-scale integrated die-casting parts of new energy automobiles, enterprises at home and abroad develop various types of heat treatment-free alloy materials successively.
The mature heat treatment-free alloy is mainly an Al-Si series, and the most representative is a Silafont-36, magsimal-59 and Castasil-37 high-strength die-casting aluminum alloy which is developed by the Rhin aluminum industry company in Germany in sequence, and alloy elements such as Cu, mg, mn and the like are mainly added. In recent years, more Al-Si-Cu and Al-Si-Mg series heat treatment-free alloys are developed successively by domestic automobile enterprises, die casting enterprises and aluminum alloy research and development enterprises, including FAW-ZTHJ01 developed by Qinghai university and China-China joint, techCAST (JDA 1 b) developed by Shanghai university-China transportation and communication, LDHM-02 developed by the vertical group and the like. The alloy has good strength and toughness because of no need of heat treatment and is widely applied to integrated parts of new energy automobiles, such as front cabins, rear floors and the like.
One of the main challenges of the existing heat treatment-free material integrated die-casting part products is the deformation and dimension chain guarantee of the product stability, and the deformation of the dimension of the integrated die-casting part products only by one thousandth directly affects the procedures of dimensional accuracy, subsequent assembly and the like of the castings, so that the castings are stably deformed and the deformation is in a predictable range. However, the existing mainstream heat treatment-free alloy die-casting parts can not completely eliminate the problem of product deformation.
At present, main alloy elements such as Cu, mg, mn and the like are generally added into the main stream heat treatment-free die casting aluminum alloy material, and the main stream heat treatment-free die casting aluminum alloy material has the advantages of improving the fluidity, the tensile strength and the hardness of the alloy, the machining performance and the like. As is well known, studies according to the text show that: the hypoeutectic alloy has low solubility of Cu in the aluminum-silicon alloy at room temperature along with the increase of Cu content, and the hot cracking tendency is increased, wherein the Cu content reaches 4 weight percent, and the hot cracking tendency is maximum; the Mg element causes large alloy cooling shrinkage, so that heat cracks and loose formation are easy to generate; mn element can effectively reduce the harmful influence of Fe element, reduce sticking of die and form Al 74 Si 12 Mn 12 Fe 2 However, the compound is liable to be segregated into a precipitate, which affects the shrinkage of the alloy wire.
On one hand, the shrinkage deformation problem caused by uneven casting temperature can occur in the air cooling process of the existing integrated die casting; on the other hand, the outline dimension of the integrated die casting is more than 1m, and the die casting is of a complex thin-wall structure, even a small thermal strain can cause larger warpage, and correction cannot be carried out through subsequent correction or machining, so that the procedures of dimensional accuracy, subsequent assembly and the like of the casting are directly affected, and the qualification rate of the casting product is reduced.
On the basis of ensuring that the integrated die casting product has good toughness and elongation, the stable deformation and dimension chain of the product are ensured, and the heat crack resistance of the alloy is improved, so that the method is also a problem to be solved in the industry.
Disclosure of Invention
In view of the above, the invention provides a die-casting heat-resistant heat-treatment-free aluminum alloy and a preparation method thereof. The aluminum alloy prepared by the invention has excellent hot cracking resistance, high toughness and good casting performance.
The invention provides a preparation method of die-casting forming heat-cracking-resistant heat-treatment-free aluminum alloy, which comprises the following steps:
a) Preheating:
preheating a smelting tool;
b) And (3) batching:
batching the raw materials according to the target alloy composition;
the composition of the target alloy is as follows in percentage by mass:
Si：6％～11％；
V：0.3％～1.2％；
Ti：0.4％～1.2％；
Mo：0.2％～0.8％；
Ce：0.2％～0.6％；
Sr：0.01％～0.07％；
Fe：≤0.2％；
al: the balance;
the raw materials comprise: aluminum ingot, crystalline silicon, aluminum molybdenum master alloy, aluminum titanium master alloy, aluminum vanadium master alloy, aluminum strontium master alloy and aluminum cerium master alloy;
c) Smelting:
adding aluminum ingot, crystalline silicon and aluminum-molybdenum intermediate alloy into a smelting furnace, heating to 800-820 ℃, preserving heat, then cooling to 760-780 ℃, adding aluminum-titanium intermediate alloy, aluminum-vanadium intermediate alloy and aluminum-cerium intermediate alloy into the smelting furnace, and carrying out heat preservation smelting;
d) Refining and degassing:
when the temperature of the aluminum liquid in the smelting furnace is reduced to 720-740 ℃, adding an aluminum-strontium intermediate alloy and an environment-friendly refining agent into the smelting furnace for online degassing refining;
e) And (3) die casting and forming:
pouring molten aluminum into a pressing chamber of a die casting machine, enabling a punch to advance at a set injection speed, enabling the molten aluminum to pass through a pouring system until a cavity is full, starting vacuumizing, and carrying out pressurizing casting after the filling is finished to obtain an aluminum alloy die casting;
the process conditions of the die casting molding are as follows:
die casting die temperature: 180-220 ℃;
casting temperature of aluminum liquid: 680-710 ℃;
and (3) injection: low speed of 0.10-0.18 m/s, high speed of 3.5-6.5 m/s, high speed of the punch head of 420-500 mm, and total injection stroke of 750-800 mm;
and (3) filling time: 110-162 s;
vacuum degree: less than or equal to 150mbar;
casting pressure: 800-1200 MPa.
Preferably, in the step A), the preheating temperature is 150-200 ℃ and the preheating time is more than or equal to 2 hours.
Preferably, in the step B), the aluminum molybdenum master alloy is AlMo5;
the aluminum-titanium intermediate alloy is AlTi10;
the aluminum-vanadium intermediate alloy is AlV4;
the aluminum-strontium intermediate alloy is AlSr10;
the aluminum cerium intermediate alloy is AlCE10.
Preferably, in step C):
heating to 800-820 ℃ for heat preservation for 0.5-1 h;
the heat preservation time is 1.5-2.5 h after the aluminum-titanium intermediate alloy, the aluminum-vanadium intermediate alloy and the aluminum-cerium intermediate alloy are added.
Preferably, in the step D), the refining time is 8-12 min, and the compressed air flow is 0.8-1.2 m 3 And/h, wherein the rotor speed is 850-950 r/min.
Preferably, in the step D), the main components of the environment-friendly refining agent are 35-45 wt% of NaCl and 35-45 wt% of KCl.
Preferably, in the step D), the dosage of the environment-friendly refining agent is 0.5-1% of the total mass of the raw materials.
Preferably, in step E), the die-casting process specifically includes:
e1 Cleaning the mounted die-casting die;
e2 Debugging the mounted die-casting die;
e3 Preheating a die-casting die;
e4 Spraying a die-casting release agent on the die-casting die, and setting condition parameters in the die-casting process through a control cabinet;
e5 Pouring aluminum liquid into the pressure chamber, and starting vacuumizing;
e6 The punch head advances to the full closed pouring gate at the set injection speed;
e7 The aluminum liquid passes through the pouring system until the cavity is filled with the aluminum liquid;
e8 After the filling, carrying out pressurization treatment and solidification;
e9 The movable die and the fixed die are separated, and the die casting is taken out to obtain the alloy die casting.
Preferably, in step E3), the preheating temperature is 180-220 ℃.
The invention also provides the die-casting molding heat-resistant heat-treatment-free aluminum alloy prepared by the preparation method.
At present, the heat treatment-free material for integrated die casting is mostly added with Cu or Mg or Mn elements, so that the hot cracking tendency of alloy parts is increased, the casting is easy to bend and deform, and the qualification rate of the casting is reduced. According to the preparation method, a certain alloy composition is controlled, wherein a specific amount of Ti and V elements play a role in grain refinement, and high strength and elongation can be obtained after the alloy material is refined; on the other hand, ti and V form AlTiV intermetallic compounds in the alloy (energy spectrum shows that atomic percent is about Al 90 Ti 4 V 4 Ce 2 ) The second phase strengthening effect is achieved, the heat resistance of the alloy is improved, and the high toughness of the alloy is maintained; at the same time, mo and Fe form AlMoFe intermetallic compounds in the alloy (the energy spectrum shows that the atomic percentage is about Al 74 Si 12 Mo 12 Fe 2 ) The thermal expansion coefficient is small, the volume stability is excellent, and the small deformation of the size of the part is effectively prevented; in addition, the invention also controls certain process steps, especially controls certain process parameters (including the injection speed, the high-speed switching point of the punch, the total injection stroke, the filling time, the casting pressure, the vacuum degree, the temperature of the die casting mold and the casting temperature of the aluminum liquid) in the casting molding, improves the casting performance, improves the structural uniformity of the alloy, reduces the internal stress of the casting, and the like, thereby improving the hot cracking resistance and the high toughness of the product. Namely, the invention controls the casting simultaneously through the two aspects of alloy components and the preparation processThe deformation and stress of the alloy product have great influence on the casting, and the performance of the alloy product is improved.
The test result shows that the aluminum alloy provided by the invention has the tensile strength of more than 280MPa at normal temperature, the yield strength of more than 134MPa at normal temperature, the liquid-solid phase temperature difference of less than 68, the crystallization latent heat of more than 341KJ/kg, the linear shrinkage rate of less than 0.50%, the thermal cracking resistance value of more than 678N and the linear expansion coefficient of 20.7X10 -6 The volume stability value is below 0.012%, no heat treatment process treatment is needed, and the product also has excellent high-strength toughness, stable deformation and thermal cracking resistance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a test die of a 2000T high vacuum cold chamber die casting machine used in a die casting process and a die casting product; wherein, fig. 1 (a) - (b) are schematic diagrams of test molds, and fig. 1 (c) is a schematic diagram of die-casting products;
FIG. 2 is a graph (500X) of the microstructure of the aluminum-silicon alloy casting obtained in example 1 at different magnifications;
FIG. 3 is a graph (2000X) of the microstructure of the aluminum-silicon alloy casting obtained in example 1 at various magnifications;
FIG. 4 is an EDS layered image (2000X) of the aluminum-silicon alloy casting obtained in example 1;
FIG. 5 is a microstructure (500X) of the aluminum-silicon alloy casting obtained in example 2;
FIG. 6 is a surface scanning texture chart (500X) of the aluminum-silicon alloy casting obtained in example 3;
FIG. 7 is a DSC graph of the aluminum-silicon alloy casting obtained in example 1.
Detailed Description
The invention provides a preparation method of die-casting forming heat-cracking-resistant heat-treatment-free aluminum alloy, which comprises the following steps:
a) Preheating:
preheating a metal furnace burden and a smelting tool;
b) And (3) batching:
batching the raw materials according to the target alloy composition;
the composition of the target alloy is as follows in percentage by mass:
Si：6％～11％；
V：0.3％～1.2％；
Ti：0.4％～1.2％；
Mo：0.2％～0.8％；
Ce：0.2％～0.6％；
Sr：0.01％～0.07％；
Fe：≤0.2％；
al: the balance;
the raw materials comprise: aluminum ingot, crystalline silicon, aluminum molybdenum master alloy, aluminum titanium master alloy, aluminum vanadium master alloy, aluminum strontium master alloy and aluminum cerium master alloy;
c) Smelting:
adding aluminum ingot, crystalline silicon and aluminum-molybdenum intermediate alloy into a smelting furnace, heating to 800-820 ℃, preserving heat, then cooling to 760-780 ℃, adding aluminum-titanium intermediate alloy, aluminum-vanadium intermediate alloy and aluminum-cerium intermediate alloy into the smelting furnace, and carrying out heat preservation smelting;
d) Refining and degassing:
when the temperature of the aluminum liquid in the smelting furnace is reduced to 720-740 ℃, adding an aluminum-strontium intermediate alloy and an environment-friendly refining agent into the smelting furnace for online degassing refining;
e) And (3) die casting and forming:
pouring molten aluminum into a pressing chamber of a die casting machine, advancing a punch at a set injection speed, enabling the molten aluminum to pass through a pouring system until a cavity is full, vacuumizing, and carrying out pressurizing casting after the mold filling is finished to obtain an aluminum alloy die casting;
the process conditions of the die casting molding are as follows:
die casting die temperature: 180-220 ℃;
casting temperature of aluminum liquid: 680-710 ℃;
and (3) injection: low speed of 0.10-0.18 m/s, high speed of 3.5-6.5 m/s, high speed of the punch head of 420-500 mm, and total injection stroke of 750-800 mm;
and (3) filling time: 110-162 s;
vacuum degree: less than or equal to 150mbar;
casting pressure: 800-1200 MPa.
Regarding step A): preheating
According to the invention, the smelting tool is preheated.
In the invention, the smelting tool is preheated prior to smelting. The smelting tool is a conventional smelting tool comprising: bell jar, ladle, slag ladle, stirring ladle, etc. Specifically, the preheating mode may be to place the preheating object on the high-temperature smelting furnace cover for preheating. In the invention, the preheating temperature is preferably 150-200 ℃; the preheating time is preferably more than or equal to 2 hours. In the present invention, it is preferable to brush a paint on the surface of the smelting tool before preheating to prevent the introduction of Fe impurities. Specifically, the paint can be applied for 2 to 3 times. The coating preferably comprises the following components in percentage by mass: 10 percent of red coating powder, 2 percent of water glass and 90 percent of water.
In the present invention, it is preferable to preheat the refining agent and the metal charge to be used later, in addition to preheating the melting tool. The preheating mode can be specifically that a preheating object is placed on a high-temperature smelting furnace cover to be preheated. The preheating temperature is preferably 150-200 ℃; the preheating time is preferably more than or equal to 2 hours. The preheating treatment of the step A) is beneficial to controlling the impurities of the cast aluminum-silicon alloy.
Regarding step B): proportioning materials
According to the invention, the raw materials are dosed according to the target alloy composition.
In the invention, the composition of the target alloy is as follows in percentage by mass:
Si：6％～11％；
V：0.3％～1.2％；
Ti：0.4％～1.2％；
Mo：0.2％～0.8％；
Ce：0.2％～0.6％；
Sr：0.01％～0.07％；
Fe：≤0.2％；
al: the balance.
The Si content may be specifically 6%, 7%, 8%, 9%, 10%, or 11%. The content of V may be specifically 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%. The Ti content may be specifically 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%. The content of Mo may be specifically 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%. The content of Ce may be specifically 0.2%, 0.3%, 0.4%, 0.5%, 0.6%. The Sr content may be specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%.
In the present invention, the raw materials (i.e., premelt material) include: aluminum ingot, crystalline silicon, aluminum molybdenum master alloy, aluminum titanium master alloy, aluminum vanadium master alloy, aluminum strontium master alloy and aluminum cerium master alloy. Wherein, the aluminum ingot is preferably industrial high-purity aluminum, and the Al content is more than or equal to 99.90wt%. The Si content in the crystalline silicon is more than or equal to 98.5wt%. The aluminum molybdenum intermediate alloy is preferably AlMo5. The aluminum-titanium master alloy is preferably AlTi10. The aluminum vanadium master alloy is preferably AlV4. The aluminum strontium master alloy is preferably AlSr10. The aluminum cerium intermediate alloy is preferably AlCE10.
Regarding step C): smelting
According to the invention, aluminum ingot, crystalline silicon and aluminum-molybdenum intermediate alloy are added into a smelting furnace, the temperature is raised to 800-820 ℃ and kept at the same time, then the temperature is lowered to 760-780 ℃, and aluminum-titanium intermediate alloy, aluminum-vanadium intermediate alloy and aluminum-cerium intermediate alloy are added into the smelting furnace for heat preservation smelting.
In the invention, aluminum ingot, crystalline silicon and aluminum-molybdenum intermediate alloy are added into a smelting furnace to heat up and preserve heat. Wherein the heating rate of the heating is preferably 145-150 ℃/h, and specifically 145 ℃/h, 146 ℃/h, 147 ℃/h, 148 ℃/h, 149 ℃/h and 150 ℃/h. The target temperature for heating is 800-820 ℃, specifically 800 ℃, 805 ℃, 810 ℃, 815 ℃ and 820 ℃. The time for heat preservation after the temperature reaches the target temperature is preferably 0.5 to 1h, and more specifically, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, and 1.0h. In the heat preservation, the aluminum ingot, the crystalline silicon and the aluminum-molybdenum intermediate alloy are fully melted and the temperature is kept stable, and then the temperature is reduced. The temperature is reduced to 760-780 ℃, specifically 760 ℃, 765 ℃, 770 ℃, 775 ℃ and 780 ℃. And (3) adding the aluminum-titanium intermediate alloy, the aluminum-vanadium intermediate alloy and the aluminum-cerium intermediate alloy into the smelting furnace after the temperature is reduced to the above temperature for heat preservation smelting. The heat preservation time is preferably 1.5-2.5 h, and can be specifically 1.5h, 2.0h and 2.5h.
According to the method, the aluminum ingot, the crystalline silicon and the aluminum-molybdenum intermediate alloy are added firstly, then the aluminum-titanium intermediate alloy, the aluminum-vanadium intermediate alloy and the aluminum-cerium intermediate alloy are added, and then the aluminum-strontium intermediate alloy is added in the next step (step D) according to the specific charging sequence, so that the method is beneficial to improving the uniformity of alloy components, preventing the segregation of aluminum-molybdenum-iron-silicon phase components and further improving the product performance; if the above-mentioned feeding sequence is broken, for example, an aluminum-titanium intermediate alloy, an aluminum-vanadium intermediate alloy and an aluminum-cerium intermediate alloy are added first, then an aluminum ingot, crystalline silicon and an aluminum-molybdenum intermediate alloy are added, or all the raw materials are added together, etc., the uniformity of the alloy components is lowered, the component segregation occurs, and the product performance is deteriorated.
Regarding step D): refining degassing
According to the invention, when the temperature of the aluminum liquid in the smelting furnace is reduced to 720-740 ℃, adding aluminum-strontium intermediate alloy and environment-friendly refining agent into the smelting furnace for online degassing refining.
In the invention, after smelting in the step C), the temperature is reduced to 720-740 ℃, specifically 720 ℃, 725 ℃, 730 ℃, 735 ℃ and 740 ℃ of aluminum liquid in the smelting furnace. When the temperature is reduced, adding the aluminum-strontium intermediate alloy and the environment-friendly refining agent, and carrying out online degassing refining at the temperature. Specific: when the temperature is reduced, adding the aluminum-strontium intermediate alloy and the environment-friendly refining agent, starting the deaerator, automatically sinking the rotor and the baffle, and automatically entering the refining stage. The refining timePreferably 8-12 min, specifically 8min, 9min, 10min, 11min, 12min. The flow rate of refined argon is preferably 0.8-1.2 m 3 And/h is specifically 0.8m 3 /h、0.9m 3 /h、1.0m 3 /h、1.1m 3 /h、1.2m 3 And/h. The rotor speed is preferably 850-950 r/min, and specifically 850r/min, 860r/min, 870r/min, 880r/min, 890r/min, 900r/min, 910r/min, 920r/min, 930r/min, 940r/min, 950r/min.
After degassing, the rotor rises, and the ventilation holes of the rotor are dredged by a tool immediately to perform slag-removing treatment. Specific: according to the separation condition of aluminum slag after refining and rotating degassing, stirring slag on the liquid surface for at least 2-4 min by using a slag scooping spoon, scooping out scum on the surface of the aluminum liquid, pouring the scooped slag into a slag frying platform or a slag frying barrel, and scattering the slag as much as possible.
In the invention, the environment-friendly refining agent is a commercially available traditional refining agent, and comprises the following main components: 35 to 45 weight percent of NaCl and 35 to 45 weight percent of KCl. In the invention, the dosage of the environment-friendly refining agent is preferably 0.5% -1% of the total mass of the raw materials, and can be specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1.0%.
Regarding step E): die casting molding
According to the invention, aluminum liquid is poured into a pressing chamber of a die casting machine, a punch head advances at a set injection speed, the aluminum liquid passes through a pouring system until a cavity is filled, and the aluminum alloy die casting is obtained by vacuumizing and pressurizing casting after the die filling is finished. Specifically, after the metal melt is refined and qualified, the casting temperature of molten aluminum is kept at 680-710 ℃, and a casting is obtained by using a die-casting molding process. In the die casting process, the liquid metal is filled at a high speed, and meanwhile, the vacuum pumping is performed to reduce slag production of molten metal coil gas, and solidification is performed under high pressure, so that a casting with compact structure and excellent performance is obtained.
In the present invention, the process conditions in the above-mentioned die casting molding are preferably as follows:
die casting die temperature: 180-220 ℃;
casting temperature of aluminum liquid: 680-710 ℃;
and (3) injection: low speed of 0.10-0.18 m/s, high speed of 3.5-6.5 m/s, high speed of the punch head of 420-500 mm, and total injection stroke of 750-800 mm;
and (3) filling time: 110-162 s;
vacuum degree: less than or equal to 150mbar;
casting pressure: 800-1200 MPa.
In the present invention, the die casting machine used for the die casting molding is preferably a cold chamber die casting machine, and may specifically be a 2000T cold chamber die casting machine. The die casting machine generally comprises a combination mechanism, a injection mechanism, a hydraulic system, an electric control system, parts, a stand and the like. The injection mechanism mainly comprises an injection chamber, an injection punch, an injection rod, an injection cylinder, a supercharger and the like. The die casting die is a tool for casting metal parts and is matched with a die casting machine to complete a die casting process. The die casting die mainly comprises a movable die and a fixed die, wherein the fixed die is connected with a pressing mechanism of the die casting machine and is fixed on a fixed die seat of one side of a pressing chamber of the pressing mechanism of the die casting machine, the fixed die comprises a part of die casting die cavity, and a sprue is arranged on the fixed die and is directly connected with the pressing chamber or a spray head of the die casting machine. The movable die is fixed on a movable die mounting plate of the die-casting machine, and when the movable die mounting plate is used for opening and closing the die to move and clamp the die, the movable die is closed to form a cavity and a pouring system, and liquid metal fills the cavity under high pressure; when the die is opened, the movable die is separated from the fixed die, and the casting is pushed out by means of a push-out mechanism arranged on the movable die.
In the present invention, the die casting process preferably specifically includes:
e1 Cleaning the mounted die-casting die;
e2 Debugging the mounted die-casting die;
e3 Preheating a die-casting die;
e4 Spraying a die-casting release agent on the die-casting die, and setting condition parameters in the die-casting process through a control cabinet;
e5 Pouring aluminum liquid into the pressure chamber, and starting vacuumizing;
e6 The punch head advances to the full closed pouring gate at the set injection speed;
e7 The aluminum liquid passes through the pouring system until the cavity is filled with the aluminum liquid;
e8 After the filling, carrying out pressurization treatment and solidification;
e9 The movable die and the fixed die are separated, and the die casting is taken out to obtain the alloy die casting.
In the above-mentioned die casting process, the test die and die casting product of the 2000T high vacuum cold chamber die casting machine are shown in FIG. 1, wherein FIGS. 1 (a) - (b) are test dies, and 1 (c) is die casting product (450 mm long by 300mm wide by 1-3 mm thick).
Regarding step E1): and removing oil stains, rust stains, old paint and the like on the surface of the die casting die through cleaning.
Regarding step E3): in the present invention, the preheating can be performed by using an electric heating device. The electric heating device is preferably a low-voltage high-current electric heating device. In the invention, the preheating temperature is preferably 180-220 ℃, namely the temperature of another die casting die reaches 180-220 ℃, and can be 180 ℃, 190 ℃, 200 ℃, 210 ℃ and 220 ℃.
Regarding step E4): in the present invention, the kind of the die-casting release agent is not particularly limited, and may be a conventional die-casting release agent in the art. Because the casting adopts a sequential solidification mode, when spraying and brushing the die-casting release agent, the coating should be thicker in the area close to the riser and the thin-wall area, and thinner in the area far from the riser and the wide and thick part of the casting. The condition parameters in the control die casting process are mainly control injection process parameters, and specifically: the low speed is 0.10-0.18 m/s, the high speed is 3.5-6.5 m/s, the high speed switching point of the punch is 420-500 mm, and the total injection stroke is 750-800 mm. Wherein the low speed may be specifically 0.10m/s, 0.11m/s, 0.12m/s, 0.13m/s, 0.14m/s, 0.15m/s, 0.16m/s, 0.17m/s, 0.18m/s. The high speed may be 3.5m/s, 4.0m/s, 4.5m/s, 5.0m/s, 5.5m/s, 6.0m/s, 6.5m/s. The punch high speed switching points may be 420mm, 430mm, 440mm, 450mm, 460mm, 470mm, 480mm, 490mm, 500mm in particular. The total injection stroke can be 750mm, 760mm, 770mm, 780mm, 790mm and 800mm.
Regarding step E5): specifically, a ladle may be used to quantitatively scoop up the molten aluminum from the crucible and then pour into the plenum. Meanwhile, a vacuumizing system is started to vacuumize, so that slag production of molten metal coiled gas is reduced. The vacuum is preferably 150mbar or less.
Regarding step E7): the process is maintained under vacuum. Specifically, the vacuum conditions described above are maintained. The casting temperature of the molten aluminum is preferably 680 to 710 ℃, and specifically 680 ℃, 685 ℃, 690 ℃, 695 ℃, 700 ℃, 705 ℃ and 710 ℃.
Regarding step E8): the filling time is preferably 110-162 s, and can be specifically 110s, 120s, 130s, 140s, 150s, 160s and 162s. The pressurizing treatment is preferably to 800-1200 MPa (namely casting pressure), and specifically can be 800MPa, 900MPa, 1000MPa, 1100MPa and 1200MPa. Through the pressurization treatment, the gas is prevented from being mixed into the metal melt, and meanwhile, the compact casting is ensured to be obtained.
The invention also provides the die-casting molding heat-resistant heat-treatment-free aluminum alloy prepared by the preparation method.
At present, the heat treatment-free material for integrated die casting is mostly added with Cu or Mg or Mn elements, so that the hot cracking tendency of alloy parts is increased, the casting is easy to bend and deform, and the qualification rate of the casting is reduced. According to the preparation method, a certain alloy composition is controlled, wherein a specific amount of Ti and V elements play a role in grain refinement, and high strength and elongation can be obtained after the alloy material is refined; on the other hand, ti and V form AlTiV intermetallic compounds in the alloy (energy spectrum shows that atomic percent is about Al 90 Ti 4 V 4 Ce 2 ) The second phase strengthening effect is achieved, the heat resistance of the alloy is improved, and the high toughness of the alloy is maintained; at the same time, mo and Fe form AlMoFe intermetallic compounds in the alloy (the energy spectrum shows that the atomic percentage is about Al 74 Si 12 Mo 12 Fe 2 ) The thermal expansion coefficient is small, the volume stability is excellent, and the small deformation of the size of the part is effectively prevented; in addition, the invention also controls certain process steps, especially controls certain process parameters (including the injection speed, the high-speed switching point of the punch, the total injection stroke, the filling time, the casting pressure, the vacuum degree, the temperature of the die casting mold and the pouring temperature of the molten aluminum) in the casting molding, improves the casting performance, improves the tissue uniformity of the alloy, reduces the internal stress of the casting, and the like, therebyThe hot cracking resistance and the high strength and toughness of the product are improved. The invention simultaneously controls the deformation and stress of the casting to produce great influence on the casting through the two aspects of alloy components and the preparation process, thereby improving the performance of alloy products.
The test result shows that the aluminum alloy provided by the invention has the tensile strength of more than 280MPa at normal temperature, the yield strength of more than 134MPa at normal temperature, the liquid-solid phase temperature difference of less than 68, the crystallization latent heat of more than 341KJ/kg, the linear shrinkage rate of less than 0.50%, the thermal cracking resistance value of more than 678N and the linear expansion coefficient of 20.7X10 -6 The volume stability value is below 0.012%, no heat treatment process treatment is needed, and the product also has excellent high-strength toughness, stable deformation and thermal cracking resistance.
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
Examples 1 to 9
A) Preheating:
the surface of a smelting tool (comprising a bell jar, a pouring ladle, a slag skimming ladle, a stirring ladle and the like) is coated with the paint for 3 times, so that Fe impurities are prevented from being brought in. Preheating smelting tools, refining agents required to be used in subsequent steps and metal furnace charges (placing the metal furnace charges on a high-temperature smelting furnace cover for preheating), and particularly drying the metal furnace charges at 180 ℃ for 2 hours.
B) And (3) batching:
the raw materials are proportioned according to the target alloy composition.
Wherein, see table 1 for raw materials:
table 1: raw materials
| Name of the name | Chemical composition |
| Industrial high purity aluminum | Al≥9990wt％ |
| Crystalline silicon | Si≥98.5wt％ |
| Aluminium molybdenum intermediate alloy | AlMo5 |
| Aluminum-titanium intermediate alloy | AlTi10 |
| Aluminum vanadium intermediate alloy | AlV4 |
| Aluminium strontium intermediate alloy | AlSr10 |
| Aluminum cerium intermediate alloy | AlCe10 |
The alloy compositions of examples 1-9 are shown in Table 2:
table 2: alloy composition
C) Smelting:
adding aluminum ingot, crystalline silicon and aluminum-molybdenum intermediate alloy into a smelting furnace, heating to 810 ℃ at 150 ℃/h, preserving heat for 1h, cooling to 770 ℃ after the melting of the aluminum ingot, the crystalline silicon and the aluminum-molybdenum intermediate alloy is ensured and the temperature is kept stable, adding aluminum-titanium intermediate alloy, aluminum-vanadium intermediate alloy and aluminum-cerium intermediate alloy into the smelting furnace, and preserving heat for 2h.
D) Refining and degassing:
when the temperature of the aluminum liquid in the smelting furnace is reduced to 730 ℃, adding an aluminum-strontium intermediate alloy and an environment-friendly refining agent (the main components are 35% -45% of NaCl and 35% -45% of KCl, and the adding amount of the refining agent is 0.8% of the total mass of the raw materials) into the smelting furnace, starting a degassing machine, automatically sinking a rotor and a baffle, and automatically entering a refining stage. The rotor speed is 900r/min, the refining time is 10min, and the argon flow is 1.0m 3 /h。
And (3) deslagging: after degassing, the rotor rises, and the ventilation holes of the rotor are dredged by a tool immediately to perform slag-removing treatment. Specific: according to the separation condition of aluminum slag after refining and rotating degassing, stirring slag on the liquid surface for at least 3min by using a slag scooping spoon, scooping out scum on the surface of the aluminum liquid, pouring the scooped slag into a slag frying platform or a slag frying barrel, and scattering the slag as much as possible.
E) And (3) die casting and forming:
pouring aluminum liquid into a pressing chamber of a 2000T cold chamber die casting machine, advancing a punch at a set injection speed, enabling the aluminum liquid to pass through a pouring system until the die cavity is full, vacuumizing, and carrying out pressurizing casting after the die filling is finished to obtain an aluminum alloy die casting. Specifically, the die casting process flow is as follows:
e1 Cleaning the mounted die-casting die to remove oil stain, rust, old paint and the like on the surface of the die-casting die.
E2 Debugging the mounted die casting die.
E3 The die casting die is preheated, specifically, an electric heating (low-voltage high-current) device is used for preheating the die, so that the temperature of the die is controlled to be 200 ℃.
E4 Spraying and brushing a die-casting release agent on the die-casting die, and setting condition parameters in the die-casting process through a control cabinet.
E5 The aluminum liquid is quantitatively scooped from the crucible by a ladle and then poured into the pressure chamber. And simultaneously, starting a vacuumizing system to vacuumize.
E6 The punch is advanced to fully close the port at the set shot speed.
E7 The aluminium liquid passes through the casting system until the mould cavity is full, and the process is maintained under vacuum.
E8 After the mold filling is finished, pressurizing treatment is carried out, and solidification is carried out.
E9 The movable die and the fixed die are separated, and the die casting is taken out to obtain the alloy die casting.
Wherein, the condition parameters of examples 1-9 in the above die casting process are shown in Table 3:
table 3: die casting process parameters
Comparative examples 1 to 3
A) Preheating: as in example 1.
B) And (3) batching:
the raw materials are proportioned according to the target alloy composition.
Wherein, see table 4 for raw materials:
table 4: raw materials
| Name of the name | Chemical composition |
| Industrial high purity aluminum | Al≥99.90wt％ |
| Crystalline silicon | Si≥98.5wt％ |
| Pure magnesium ingot | Mg≥99.95wt％ |
| Pure copper plate | Cu≥99.95wt％ |
| Aluminium-manganese intermediate alloy | AlMn20 |
| Aluminium strontium intermediate alloy | AlSr10 |
The alloy compositions of comparative examples 1-3 are shown in Table 5:
table 5: alloy composition
C) Smelting:
adding aluminum ingot, crystalline silicon, pure copper plate and aluminum-manganese intermediate alloy into a smelting furnace, heating to 810 ℃ at 150 ℃/h, preserving heat for 1h, then cooling to 770 ℃, adding aluminum-strontium intermediate alloy into the smelting furnace, and preserving heat for 2h.
D) Refining and degassing:
when the temperature of the aluminum liquid in the smelting furnace is reduced to 730 ℃, adding pure magnesium ingots and an environment-friendly refining agent (the main components are 35% -45% NaCl and 35% -45% KCl, and the adding amount of the refining agent is 0.8% of the total mass of the raw materials) into the smelting furnace, starting a degassing machine, automatically sinking a rotor and a baffle, and automatically entering a refining stage. The rotor speed is 900r/min, the refining time is 10min, and the argon flow is 1.0m 3 /h。
And (3) deslagging: as in example 1.
E) And (3) die casting and forming:
the alloy casting products of comparative examples 1 to 3 were obtained by carrying out the operations of examples 1 to 3, respectively. That is, the condition parameters of comparative examples 1 to 3 in the die casting process are the same as those of examples 1 to 3, respectively (comparative example 1 corresponds to example 1, comparative example 2 corresponds to example 2, and comparative example 3 corresponds to example 3).
Test example:
1. metallographic analysis
FIGS. 2 to 3 are respectively microscopic structure diagrams (500X and 2000X, respectively) of the aluminum-silicon alloy castings obtained in example 1 at different magnifications, and FIG. 4 is an implementationEDS layered image (2000X) of the aluminum-silicon alloy casting obtained in example 1. Analysis of the SEM microstructure graph and the EDS graph shows that Ti and V in the alloy in the embodiment 1 play a role in grain refinement on one hand, and the alloy material can obtain higher strength and elongation after refinement; on the other hand, ti and V form AlTiV intermetallic compounds in the alloy (energy spectrum shows that atomic percent is about Al 90 Ti 4 V 4 Ce 2 ) Plays a second phase strengthening role; at the same time, mo and Fe form AlMoFe intermetallic compounds in the alloy (the energy spectrum shows that the atomic percentage is about Al 74 Si 12 Mo 12 Fe 2 ) The thermal expansion coefficient is small, the volume stability is excellent, and the small deformation of the size of the part is effectively prevented; wherein the light gray block is AlMoFe compound and the light white block is AlTiV compound, which is covered on the dark gray matrix aluminum matrix. The three-phase region is very wide and the phases are easily distinguished.
Fig. 5 is a microstructure (500X) of the aluminum-silicon alloy casting obtained in example 2, and fig. 6 is a surface scanning microstructure (500X) of the aluminum-silicon alloy casting obtained in example 3.
2. Tensile Strength, yield Strength and elongation
The alloy cast products obtained in each of the examples and comparative examples were tested for tensile strength, yield strength and elongation, respectively, and the results are shown in Table 6.
Table 6: tensile Strength, yield Strength and elongation
| Tensile Strength at Normal temperature (MPa) | Yield strength at normal temperature (MPa) | Elongation (%) | |
| Example 1 | 291.51 | 137.26 | 13.3 |
| Example 2 | 286.34 | 141.27 | 11.59 |
| Example 3 | 288.5 | 145.5 | 12.8 |
| Example 4 | 283.94 | 134.73 | 13.09 |
| Example 5 | 289.05 | 140.37 | 13.22 |
| Example 6 | 290.42 | 139.6 | 12.5 |
| Example 7 | 289.17 | 138.96 | 13.05 |
| Example 8 | 281.39 | 135.17 | 11.69 |
| Example 9 | 284.35 | 141.03 | 12.75 |
| Comparative example 1 | 265.58 | 119.25 | 11.65 |
| Comparative example 2 | 269.25 | 127.36 | 12.25 |
| Comparative example 3 | 274.21 | 125.21 | 10.34 |
3. Resistance to hot cracking
The width of the effective crystallization temperature interval of the alloy determines the absolute shrinkage of the alloy in the thermal cracking temperature range. It can be seen that the smaller the effective crystallization window from the onset of line shrinkage to solidus, the smaller the absolute shrinkage of the alloy in this temperature range, and the less stress is generated in the casting. The less the tendency of the alloy to form hot cracks. The smaller the difference between the liquidus temperature and the solidus temperature or the greater the latent heat of crystallization, the greater the heat crack resistance value.
The test results of each example and comparative example are shown in table 7. Among them, the liquid solidus temperature test is referred to GB/T1425-1996 standard. The test of the linear shrinkage is referred to JB/T4022.1-1999 standard. The test of the thermal resistance value is referred to JB/T4022.2-1999 standard. The linear expansion coefficient is referred to the QB/T1321-2012 standard, and the volume stability is referred to the GB/T1148-2010 standard. The DSC curve of the alloy obtained in example 1 is shown in FIG. 7.
Table 7: thermal cracking related performance
As can be seen from the test results in tables 6 to 7, the ordinary temperature tensile strength of examples 1 to 9 of the present invention reached 280MPa or more, the ordinary temperature yield strength reached 134MPa or more, the liquid-solid phase temperature difference was 68 or less, the latent heat of crystallization was 341KJ/kg or more, the linear shrinkage was 0.50% or less, the heat crack resistance value was 678N or more, and the linear expansion coefficient was 20.7X10 -6 The volume stability value is below 0.012%, no heat treatment process treatment is needed, and the product also has excellent high-strength toughness, stable deformation and thermal cracking resistance. Comparative examples 1 to 3 were found to have a room temperature tensile strength of 275MPa or less, a room temperature yield strength of 128MPa or less, a liquid-solid phase temperature difference of 83 or more, a latent heat of crystallization of 335KJ/kg or less, a linear shrinkage of 0.58% or more, a heat crack resistance value of 657N or less, and a linear expansion coefficient of 21.5X10 -6 The volume stability value is more than 0.015%, and the toughness, the stable deformation and the hot cracking resistance are obviously deteriorated.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to aid in understanding the method of the invention and its core concept, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims. The scope of the patent protection is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims (10)
1. The preparation method of the die-casting forming heat-cracking-resistant heat-treatment-free aluminum alloy is characterized by comprising the following steps of:
a) Preheating:
preheating a smelting tool;
b) And (3) batching:
batching the raw materials according to the target alloy composition;
the composition of the target alloy is as follows in percentage by mass:
Si：6％～11％；
V：0.3％～1.2％；
Ti：0.4％～1.2％；
Mo：0.2％～0.8％；
Ce：0.2％～0.6％；
Sr：0.01％～0.07％；
Fe：≤0.2％；
al: the balance;
the raw materials comprise: aluminum ingot, crystalline silicon, aluminum molybdenum master alloy, aluminum titanium master alloy, aluminum vanadium master alloy, aluminum strontium master alloy and aluminum cerium master alloy;
c) Smelting:
adding aluminum ingot, crystalline silicon and aluminum-molybdenum intermediate alloy into a smelting furnace, heating to 800-820 ℃, preserving heat, then cooling to 760-780 ℃, adding aluminum-titanium intermediate alloy, aluminum-vanadium intermediate alloy and aluminum-cerium intermediate alloy into the smelting furnace, and carrying out heat preservation smelting;
d) Refining and degassing:
when the temperature of the aluminum liquid in the smelting furnace is reduced to 720-740 ℃, adding an aluminum-strontium intermediate alloy and an environment-friendly refining agent into the smelting furnace for online degassing refining;
e) And (3) die casting and forming:
pouring molten aluminum into a pressing chamber of a die casting machine, enabling a punch to advance at a set injection speed, enabling the molten aluminum to pass through a pouring system until a cavity is full, starting vacuumizing, and carrying out pressurizing casting after the filling is finished to obtain an aluminum alloy die casting;
the process conditions of the die casting molding are as follows:
die casting die temperature: 180-220 ℃;
casting temperature of aluminum liquid: 680-710 ℃;
and (3) injection: low speed of 0.10-0.18 m/s, high speed of 3.5-6.5 m/s, high speed of the punch head of 420-500 mm, and total injection stroke of 750-800 mm;
and (3) filling time: 110-162 s;
vacuum degree: less than or equal to 150mbar;
casting pressure: 800-1200 MPa.
2. The process according to claim 1, wherein in step A), the preheating is carried out at a temperature of 150 to 200℃for a period of not less than 2 hours.
3. The method according to claim 1, wherein in step B), the aluminum molybdenum master alloy is AlMo5;
the aluminum-titanium intermediate alloy is AlTi10;
the aluminum-vanadium intermediate alloy is AlV4;
the aluminum-strontium intermediate alloy is AlSr10;
the aluminum cerium intermediate alloy is AlCE10.
4. The method according to claim 1, wherein in step C):
heating to 800-820 ℃ for heat preservation for 0.5-1 h;
the heat preservation time is 1.5-2.5 h after the aluminum-titanium intermediate alloy, the aluminum-vanadium intermediate alloy and the aluminum-cerium intermediate alloy are added.
5. The process according to claim 1, wherein in step D), the refining time is 8 to 12min, and the compressed air is usedThe flow is 0.8-1.2 m 3 And/h, wherein the rotor speed is 850-950 r/min.
6. The method according to claim 1, wherein in the step D), the main components of the environment-friendly refining agent are 35wt% to 45wt% of NaCl and 35wt% to 45wt% of KCl.
7. The method according to claim 1 or 6, wherein in the step D), the amount of the environment-friendly refining agent is 0.5% to 1% of the total mass of the raw materials.
8. The method according to claim 1, wherein in step E), the die casting process specifically comprises:
e1 Cleaning the mounted die-casting die;
e2 Debugging the mounted die-casting die;
e3 Preheating a die-casting die;
e4 Spraying a die-casting release agent on the die-casting die, and setting condition parameters in the die-casting process through a control cabinet;
e5 Pouring aluminum liquid into the pressure chamber, and starting vacuumizing;
e6 The punch head advances to the full closed pouring gate at the set injection speed;
e7 The aluminum liquid passes through the pouring system until the cavity is filled with the aluminum liquid;
e8 After the filling, carrying out pressurization treatment and solidification;
e9 The movable die and the fixed die are separated, and the die casting is taken out to obtain the alloy die casting.
9. The process according to claim 8, wherein in step E3), the preheating is carried out at a temperature of 180 to 220 ℃.
10. A die-cast heat-resistant heat-treatment-free aluminum alloy produced by the production method according to any one of claims 1 to 9.
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| CN117655302A (en) * | 2024-01-31 | 2024-03-08 | 烟台市东林精密金属制品有限公司 | Die casting process for intermediate casting of aluminum die casting product |
| CN117655302B (en) * | 2024-01-31 | 2024-04-05 | 烟台市东林精密金属制品有限公司 | Die casting process for intermediate casting of aluminum die casting product |
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