Rare earth microalloyed aluminum alloy cast rod and production process thereof

Abstract

The invention relates to the technical field of aluminum alloy materials, in particular to a rare earth microalloyed aluminum alloy cast rod and a production process thereof, and the aluminum alloy cast rod comprises the following chemical components in percentage by mass: 8.0%-9.0% of Zn, 2.2%-2.8% of Cu, 1.8%-2.5% of Mg, 0.005%-0.01% of Ti, 0.005%-0.01% of Si, 0.005%-0.01% of Mn, 0.005%-0.01% of Fe, 0.01%-0.05% of Cr, 0.01%-0.05% of Cl, 0.05%-0.4% of rare earth elements and the balance of Al and inevitable impurities. The rare earth elements are La, Ce and Nd. Rare earth elements in a certain proportion are added into the chemical components, so that the proportion of the alloy components is optimized, and the mechanical property of the aluminum alloy cast rod is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy materials, and in particular to a rare earth micro-alloyed aluminum alloy casting rod and a production process thereof. Background Art

[0002] Aluminum alloy is the most widely used type of nonferrous metal material in the manufacturing industry. It has many advantages such as low density, wide range of mechanical properties, excellent plastic formability, good corrosion resistance, etc. It can be applied to various service conditions and has been widely used in emerging strategic manufacturing industries such as new energy and transportation. Correspondingly, the emerging strategic manufacturing industry has a strong development momentum, and higher requirements are also put forward for the carrying capacity of raw materials such as aluminum alloys. Wheels are important components of new energy vehicles. Aluminum alloy wheels are gradually replacing steel wheels in automobiles with their advantages of beautiful appearance, light weight, good heat dissipation, and excellent acceleration and braking performance. In the production process of aluminum alloy wheels, the requirements for aluminum alloy casting rod materials are very high. The quality and performance of aluminum alloy casting rods will directly affect the production of aluminum alloy wheels.

[0003] There are some problems when aluminum alloy casting rods are produced by conventional casting methods. First, refiners are usually added to the aluminum liquid during casting to improve the performance of the aluminum alloy by controlling the grain size. However, the addition of conventional refiners such as aluminum titanium boron wire can easily produce a small amount of bubbles due to poor dosage control or unstable production conditions, making the internal structure of the aluminum alloy unevenly distributed, and it is easy to produce cracks, affecting the mechanical properties of the aluminum alloy such as hardness and tensile strength; second, forced cooling causes uneven cooling of the cross section of the cast rod, resulting in certain casting stress in the cast rod, which will also affect the mechanical properties of the aluminum alloy, making it difficult to meet the mechanical performance requirements of the wheel hub of new energy vehicles. Summary of the invention

[0004] Aiming at the technical problem that the mechanical properties of aluminum alloy cast rods are easily affected by process conditions such as refiners, the present invention provides a rare earth micro-alloyed aluminum alloy cast rod and a production process thereof. No refiner is needed. A certain ratio of rare earth elements is added to the composition and combined with filtering, refining and electromagnetic treatment to achieve the effect of grain refinement and uniform tissue distribution. Moreover, through three-stage forced annealing, the annealing temperature conditions are strictly controlled, the casting stress is eliminated, and the mechanical properties of the aluminum alloy are improved.

[0005] In a first aspect, the present invention provides a rare earth microalloyed aluminum alloy casting rod, comprising the following chemical components in mass percentage: Zn 8.0%-9.0%, Cu 2.2%-2.8%, Mg 1.8%-2.5%, Ti 0.005%-0.01%, Si 0.005%-0.01%, Mn 0.005%-0.01%, Fe 0.005%-0.01%, Cr 0.01%-0.05%, Cl 0.01%-0.05%, rare earth elements 0.05%-0.4%, the rest are Al and unavoidable impurities; The rare earth elements are La, Ce and Nd.

[0006] Furthermore, the mass percentages of La, Ce and Nd in the aluminum alloy cast rod are 0.02%-0.2%, 0.02%-0.1% and 0.01%-0.3%, respectively.

[0007] In a second aspect, the present invention provides a production process for the above-mentioned rare earth microalloyed aluminum alloy casting rod, comprising the following steps: (1) Melting: All chemical components are melted to obtain aluminum alloy melt; (2) Filtration: The aluminum alloy melt is filtered using a ceramic filter plate; (3) Refining: Add refining agent to the filtered aluminum alloy melt for refining treatment, the dosage is 0.7-1.0kg / t Al, then heat to 750-760℃, degas online in a rotary degassing device, and the argon flow rate is 3-5Nm 3 / h, after refining, the slag is removed to obtain aluminum alloy refined liquid; (4) Electromagnetic treatment: The aluminum alloy refined liquid is subjected to electromagnetic treatment, with a magnetic induction intensity of 130-200 mT and a magnetic induction intensity change rate of 8-15 T / s; (5) Casting: The aluminum alloy refined liquid after electromagnetic treatment is cast by a hot top casting machine. The temperature of the aluminum alloy melt is maintained at 700-720°C to obtain aluminum alloy cast bars; (6) Homogenization annealing: After the cast aluminum alloy rod is cut, it is subjected to homogenization annealing treatment, the temperature is controlled at 580-590°C, and the holding time is 10-12h; (7) Cooling: After homogenization annealing, the aluminum alloy casting rod is placed in a cooling chamber for 10 minutes for three-stage forced cooling; the temperature drops to 400-450°C after the first stage of cooling, the temperature drops to 150-200°C after the second stage of cooling, and the temperature drops to room temperature after the third stage of cooling.

[0008] Furthermore, the refining agent composition is ZnCl2 43% and MgCl2 57%.

[0009] Furthermore, the rotor speed of the rotary degassing device is 200-500 rpm.

[0010] Furthermore, the electromagnetic treatment time is 30 minutes, and the magnetic field excitation current waveform is a triangular wave.

[0011] Furthermore, the casting speed is 75-80 mm / min, and the cooling water pressure is 0.07-0.12 MPa.

[0012] Furthermore, during the three-stage forced cooling, the cooling time of the first two stages is controlled to be within 20 minutes.

[0013] The beneficial effects of the present invention are: The rare earth microalloyed aluminum alloy casting rod provided by the present invention contains a certain amount of rare earth elements La, Ce and Nd, optimizes the alloy component ratio, and the test results show that its tensile strength reaches 334MPa, the yield strength reaches 291MPa, the elongation is above 13.9%, the hardness value reaches 214HB, and the high-temperature deformation is as low as 0.03, which meets the mechanical performance requirements of new energy vehicles for the wheel hub. The rare earth microalloyed aluminum alloy casting rod is filtered, refined and electromagnetically treated during production. The ceramic filter plate filters out coarse inclusions, controls the argon blowing conditions to further purify the aluminum alloy melt, changes the magnetic induction conditions to promote nucleation, and improves the nucleation rate. Through a series of operations, the organization distribution is improved, the organization uniformity is improved, and the casting defects are reduced, so as to achieve the effect of refining and uniforming the organization structure of the aluminum alloy casting rod after omitting the refiner, and improve the mechanical properties of the aluminum alloy casting rod. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0015] Example 1 A rare earth microalloyed aluminum alloy casting rod comprises the following chemical components in mass percentage: Zn 9.0%, Cu 2.5%, Mg 1.8%, Ti 0.008%, Si 0.005%, Mn 0.009%, Fe 0.007%, Cr0.05%, Cl 0.05%, La 0.05%, Ce 0.05%, Nd 0.3%, the rest are Al and inevitable impurities; The production process includes the following steps: (1) Melting: Place all chemical components in a melting furnace and melt them at 700°C to obtain aluminum alloy melt; (2) Filtration: The aluminum alloy melt is filtered through a 60-mesh ceramic filter plate to remove primary coarse inclusions larger than 10 μm in the aluminum alloy melt; (3) Refining: A refining agent was added to the filtered aluminum alloy melt for refining treatment. The refining agent composition was 43% ZnCl2 and 57% MgCl2, and the dosage was 0.8 kg / t Al. Then the temperature was raised to 750 °C and degassed online in a rotary degassing device. The rotor speed was 400 rpm and the argon flow rate was 5 Nm 3 / h, after refining, the slag is removed to obtain aluminum alloy refined liquid; (4) Electromagnetic treatment: The aluminum alloy refined liquid is subjected to electromagnetic treatment for 30 min, the magnetic induction intensity is 180 mT, the magnetic induction intensity change rate is 10 T / s, and the magnetic field excitation current waveform is a triangular wave; (5) Casting: The aluminum alloy refined liquid after electromagnetic treatment is cast by a hot top casting machine. During the casting process, the casting speed is controlled at 75 mm / min, the cooling water pressure is controlled at 0.12 MPa, and the temperature of the aluminum alloy melt is maintained at 700°C to obtain aluminum alloy cast bars; (6) Homogenization annealing: The ends and tails of the cast aluminum alloy rods are cut and then placed in a 700 kW box-type resistance homogenization furnace for homogenization annealing. The temperature of the box-type resistance homogenization furnace is controlled at 590°C and the holding time is 12 hours. (7) Cooling: After homogenization annealing treatment, the aluminum alloy cast rod is placed in a cooling chamber for 10 minutes for three-stage forced cooling; the first stage is to cool the aluminum alloy cast rod to 400°C within 20 minutes, the second stage is to cool the aluminum alloy cast rod to 180°C within 20 minutes, and the third stage is to use water mist cooling method to reduce the temperature of the aluminum alloy cast rod to room temperature, remove it from the cooling chamber, and perform flaw detection to obtain rare earth micro-alloyed aluminum alloy cast rod.

[0016] Example 2 A rare earth microalloyed aluminum alloy casting rod comprises the following chemical components in mass percentage: Zn 8.0%, Cu 2.2%, Mg 2.5%, Ti 0.005%, Si 0.01%, Mn 0.01%, Fe 0.005%, Cr0.01%, Cl 0.01%, La 0.02%, Ce 0.02%, Nd 0.01%, the rest are Al and inevitable impurities; The production process includes the following steps: (1) Melting: Place all chemical components in a melting furnace and melt them at 720°C to obtain aluminum alloy melt; (2) Filtration: The aluminum alloy melt is filtered through a 60-mesh ceramic filter plate to remove primary coarse inclusions larger than 10 μm in the aluminum alloy melt; (3) Refining: A refining agent was added to the filtered aluminum alloy melt for refining treatment. The refining agent composition was 43% ZnCl2 and 57% MgCl2, and the dosage was 0.7 kg / t Al. Then the temperature was raised to 750°C and degassed online in a rotary degassing device. The rotor speed was 500 rpm and the argon flow rate was 4 Nm 3 / h, after refining, the slag is removed to obtain aluminum alloy refined liquid; (4) Electromagnetic treatment: The aluminum alloy refined liquid is subjected to electromagnetic treatment for 30 min, the magnetic induction intensity is 130 mT, the magnetic induction intensity change rate is 8 T / s, and the magnetic field excitation current waveform is a triangular wave; (5) Casting: The aluminum alloy refined liquid after electromagnetic treatment is cast by a hot top casting machine. During the casting process, the casting speed is controlled at 80 mm / min, the cooling water pressure is controlled at 0.11 MPa, and the temperature of the aluminum alloy melt is maintained at 700 °C to obtain aluminum alloy cast bars; (6) Homogenization annealing: The ends and tails of the cast aluminum alloy rods were cut and then placed in a 700 kW box-type resistance homogenization furnace for homogenization annealing. The temperature of the box-type resistance homogenization furnace was controlled at 580 °C and the holding time was 11 h. (7) Cooling: After homogenization annealing treatment, the aluminum alloy cast rod is placed in a cooling chamber for 10 minutes for three-stage forced cooling; the first stage is to cool the aluminum alloy cast rod to 420°C within 20 minutes, the second stage is to cool the aluminum alloy cast rod to 150°C within 20 minutes, and the third stage is to use water mist cooling method to reduce the temperature of the aluminum alloy cast rod to room temperature, remove it from the cooling chamber, and perform flaw detection to obtain rare earth micro-alloyed aluminum alloy cast rod.

[0017] Example 3 A rare earth microalloyed aluminum alloy casting rod comprises the following chemical components in mass percentage: Zn 8.0%, Cu 2.8%, Mg 1.8%, Ti 0.01%, Si 0.006%, Mn 0.005%, Fe 0.01%, Cr0.03%, Cl 0.03%, La 0.2%, Ce 0.1%, Nd 0.1%, the rest are Al and inevitable impurities; The production process includes the following steps: (1) Melting: Place all chemical components in a melting furnace and melt them at 740°C to obtain aluminum alloy melt; (2) Filtration: The aluminum alloy melt is filtered through a 60-mesh ceramic filter plate to remove primary coarse inclusions larger than 10 μm in the aluminum alloy melt; (3) Refining: A refining agent was added to the filtered aluminum alloy melt for refining treatment. The refining agent composition was 43% ZnCl2 and 57% MgCl2. The dosage was 1.0 kg / t Al. The temperature was then raised to 760°C and degassed online in a rotary degassing device. The rotor speed was 200 rpm and the argon flow rate was 3 Nm 3 / h, after refining, the slag is removed to obtain aluminum alloy refined liquid; (4) Electromagnetic treatment: The aluminum alloy refined liquid is subjected to electromagnetic treatment for 30 min, the magnetic induction intensity is 200 mT, the magnetic induction intensity change rate is 15 T / s, and the magnetic field excitation current waveform is a triangular wave; (5) Casting: The aluminum alloy refined liquid after electromagnetic treatment is cast by a hot top casting machine. During the casting process, the casting speed is controlled at 80 mm / min, the cooling water pressure is controlled at 0.10 MPa, and the temperature of the aluminum alloy melt is maintained at 720°C to obtain aluminum alloy cast bars; (6) Homogenization annealing: The ends and tails of the cast aluminum alloy rods are cut and then placed in a 700 kW box-type resistance homogenization furnace for homogenization annealing. The temperature of the box-type resistance homogenization furnace is controlled at 590°C and the holding time is 10 hours. (7) Cooling: After homogenization annealing treatment, the aluminum alloy cast rod is placed in a cooling chamber for 10 minutes for three-stage forced cooling; the first stage is to cool the aluminum alloy cast rod to 450°C within 20 minutes, the second stage is to cool the aluminum alloy cast rod to 200°C within 20 minutes, and the third stage is to use water mist cooling method to reduce the temperature of the aluminum alloy cast rod to room temperature, remove it from the cooling chamber, and perform flaw detection to obtain rare earth micro-alloyed aluminum alloy cast rod.

[0018] Comparative Example 1 A rare earth microalloyed aluminum alloy casting rod comprises the following chemical components in mass percentage: Zn 9.0%, Cu 2.5%, Mg 1.8%, Ti 0.008%, Si 0.005%, Mn 0.009%, Fe 0.007%, Cr0.05%, Cl 0.05%, La 0.3%, Ce 0.3%, the rest are Al and inevitable impurities; The production process is the same as in Example 1.

[0019] Comparative Example 2 A rare earth microalloyed aluminum alloy casting rod comprises the following chemical components in mass percentage: Zn 9.0%, Cu 2.5%, Mg 1.8%, Ti 0.008%, Si 0.005%, Mn 0.009%, Fe 0.007%, Cr0.05%, Cl 0.05%, Nd 0.4%, the rest are Al and inevitable impurities; The production process is the same as in Example 1.

[0020] Comparative Example 3 A rare earth microalloyed aluminum alloy casting rod, the chemical composition and mass percentage thereof are the same as those in Example 1; The production process includes the following steps: (1) Melting: Place all chemical components in a melting furnace and melt them at 720°C to obtain aluminum alloy melt; (2) Refining: A refining agent was added to the aluminum alloy melt for refining treatment. The refining agent composition was 43% ZnCl2 and 57% MgCl2. The dosage was 0.7 kg / t Al. The temperature was then raised to 750°C and degassed online in a rotary degassing device. The rotor speed was 500 rpm and the argon flow rate was 4 Nm 3 / h, after refining, the slag is removed to obtain aluminum alloy refined liquid; (3) Electromagnetic treatment: The aluminum alloy refined liquid is subjected to electromagnetic treatment for 30 min, the magnetic induction intensity is 130 mT, the magnetic induction intensity change rate is 8 T / s, and the magnetic field excitation current waveform is a triangular wave; (4) Casting: The aluminum alloy refined liquid after electromagnetic treatment is cast by a hot top casting machine. During the casting process, the casting speed is controlled at 80 mm / min, the cooling water pressure is controlled at 0.11 MPa, and the temperature of the aluminum alloy melt is maintained at 700°C to obtain aluminum alloy cast bars; (5) Homogenization annealing: The ends and tails of the cast aluminum alloy rods were cut and then placed in a 700 kW box-type resistance homogenization furnace for homogenization annealing. The temperature of the box-type resistance homogenization furnace was controlled at 580°C and the holding time was 11 hours. (6) Cooling: After homogenization annealing treatment, the aluminum alloy cast rod is placed in a cooling chamber for 10 minutes for three-stage forced cooling; the first stage is to cool the aluminum alloy cast rod to 420°C within 20 minutes, the second stage is to cool the aluminum alloy cast rod to 150°C within 20 minutes, and the third stage is to use water mist cooling method to reduce the temperature of the aluminum alloy cast rod to room temperature, remove it from the cooling chamber, and perform flaw detection to obtain rare earth micro-alloyed aluminum alloy cast rod.

[0021] Comparative Example 4 A rare earth microalloyed aluminum alloy casting rod, the chemical composition and mass percentage thereof are the same as those in Example 1; The production process is the same as in Example 1, except that: (3) Refining: During online degassing in the rotary degassing device, the rotor speed is 100 rpm and the argon flow rate is 2 Nm 3 / h.

[0022] Comparative Example 5 A rare earth microalloyed aluminum alloy casting rod, the chemical composition and mass percentage thereof are the same as those in Example 1; The production process is the same as that of Example 1, except that (4) during the electromagnetic treatment, the magnetic induction intensity is 110 mT and the rate of change of the magnetic induction intensity is 18 T / s.

[0023] Comparative Example 6 A rare earth microalloyed aluminum alloy casting rod, the chemical composition and mass percentage thereof are the same as those in Example 1; The production process is the same as that of Example 1, except that (7) during cooling, the aluminum alloy cast rods are subjected to homogenization annealing treatment and then placed in a cooling chamber for 10 minutes for two stages of forced cooling; the first stage is to cool the aluminum alloy cast rods to 180°C within 20 minutes, and the second stage is to use a water mist cooling method to reduce the temperature of the aluminum alloy cast rods to room temperature.

[0024] Experimental example The samples of Examples 1-3 and Comparative Examples 1-6 were subjected to performance tests, wherein the tensile strength, yield strength and elongation were obtained by conventional methods at room temperature; The hardness test was conducted using a small-load Vickers hardness tester (HV-10B) with a loading weight of 5 kg and a holding time of 15 s.

[0025] High temperature deformation test: heat from room temperature to 180℃, heating rate is 10℃ / min, keep warm for 5h, then cool to room temperature, cooling rate is 10℃ / min, keep warm at room temperature for 1h, heating-warming-cooling-warming is one cycle, and a total of 3 cycles are performed. Measure the high temperature deformation of each sample after 3 cycles.

[0026] The performance test results are shown in Table 1.

[0027] Table 1 Test results of tensile strength, yield strength, elongation, hardness and high temperature deformation

[0028] It can be seen from the data in Table 1 that, compared with Comparative Examples 1-6, the aluminum alloy cast rods obtained in Examples 1-3 showed better mechanical properties in the tests of tensile strength, yield strength, elongation, hardness and high-temperature deformation rate.

[0029] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A rare earth microalloyed aluminum alloy casting rod, characterized in that: The chemical composition includes the following mass percentages: Zn 8.0%-9.0%, Cu 2.2%-2.8%, Mg 1.8%-2.5%, Ti 0.005%-0.01%, Si 0.005%-0.01%, Mn0.005%-0.01%, Fe 0.005%-0.01%, Cr 0.01%-0.05%, Cl 0.01%-0.05%, rare earth elements 0.05%-0.4%, the rest are Al and unavoidable impurities; The rare earth elements are La, Ce and Nd.

2. The rare earth microalloyed aluminum alloy cast rod according to claim 1, characterized in that: The mass percentages of La, Ce and Nd in the aluminum alloy cast rod are 0.02%-0.2%, 0.02%-0.1% and 0.01%-0.3%, respectively.

3. A process for producing rare earth microalloyed aluminum alloy casting rods as claimed in claim 1, characterized in that: The steps include: (1) Melting: All chemical components are melted to obtain aluminum alloy melt; (2) Filtration: The aluminum alloy melt is filtered using a ceramic filter plate; (3) Refining: Add refining agent to the filtered aluminum alloy melt for refining treatment, the amount is 0.7-1.0kg / tAl, then heat to 750-760℃, degas online in a rotary degassing device, and the argon flow rate is 3-5Nm 3 / h, after refining, the slag is removed to obtain aluminum alloy refined liquid; (4) Electromagnetic treatment: The aluminum alloy refined liquid is subjected to electromagnetic treatment, with a magnetic induction intensity of 130-200 mT and a magnetic induction intensity change rate of 8-15 T / s; (5) Casting: The aluminum alloy refined liquid after electromagnetic treatment is cast by a hot top casting machine. The temperature of the aluminum alloy melt is maintained at 700-720°C to obtain aluminum alloy cast bars; (6) Homogenization annealing: After the cast aluminum alloy rod is cut, it is subjected to homogenization annealing treatment, the temperature is controlled at 580-590°C, and the holding time is 10-12h; (7) Cooling: After homogenization annealing, the aluminum alloy casting rod is placed in a cooling chamber for 10 minutes for three-stage forced cooling; the temperature drops to 400-450°C after the first stage of cooling, the temperature drops to 150-200°C after the second stage of cooling, and the temperature drops to room temperature after the third stage of cooling.

4. The process for producing rare earth microalloyed aluminum alloy casting rod according to claim 3, characterized in that: The refining agent composition is 43% ZnCl2 and 57% MgCl2 by mass percentage.

5. The process for producing rare earth microalloyed aluminum alloy casting rods according to claim 3, characterized in that: The rotor speed of the rotary degasser was 200-500 rpm.

6. The process for producing rare earth microalloyed aluminum alloy casting rods according to claim 3, characterized in that: The electromagnetic treatment time is 30 minutes, and the magnetic field excitation current waveform is a triangular wave.

7. The process for producing rare earth microalloyed aluminum alloy casting rod according to claim 3, characterized in that: The casting speed is 75-80mm / min, and the cooling water pressure is 0.07-0.12MPa.

8. The process for producing rare earth microalloyed aluminum alloy casting rod according to claim 3, characterized in that: During three-stage forced cooling, the cooling time of the first two stages is controlled within 20 minutes.

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