RU2749073C1 - Heat-resistant cast deformable aluminum alloys based on al-cu-y and al-cu-er systems (options) - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, mainly to heat-resistant cast deformable aluminum alloys of Al-Cu-Y and Al-Cu-Er systems hardened by heat and deformation treatment. The options of heat-resistant cast deformable aluminum alloys are claimed. The alloy contains, wt.%: cuprum 4-6.5; yttrium 1.6-2.3; manganese 0.6-0.9; zirconium 0.2-0.3; titanium 0.1-0.15; boron 0.02-0.03; magnesium 0.8-1.1; aluminum is the rest. The alloy contains, wt.%: cuprum 4-6.5; erbium 2.7-4.05; manganese 0.6-0.9; zirconium 0.2-0.3; titanium 0.1-0.15; boron 0.02-0.03; magnesium 0.8-1.1; aluminum is the rest. In both options, the alloy composition consists of complex-alloyed solid solution and intermetallic particles with the size up to 3 mcm.

EFFECT: alloys are characterized in high level of cast properties, high strength values at room and elevated temperatures, and especially high fluidity limit under tension and compression at temperatures of 200-300°C.

4 cl, 8 dwg, 20 tbl, 8 ex

Description

The invention relates to the field of metallurgy, mainly to the melting and casting of non-ferrous metal alloys, and is intended for the manufacture of heat-resistant casting and wrought aluminum alloys, hardened by heat and deformation treatment.

Known industrial aluminum alloys of the Al-Cu and Al-Cu-Mg systems, which are characterized by a sufficiently high strength. For example, the cast alloy AM5 (GOST 1583-93) has a tensile strength of 314-333 MPa, a relative elongation of 2-8%, a hardness of 70-90 HB and a hot brittleness index for a pencil test of more than 16 mm. Wrought alloy D16 in the cold-worked and annealed state in the form of sheets (GOST 21631-76) has a yield strength of 230-360 MPa, a tensile strength of 365-475 MPa, an elongation of 8-13%, and in the form of bars (GOST R-51834-2001 ) - yield strength 325-345 MPa, ultimate strength 450-470 MPa, relative elongation 8-10%. Recrystallized rods (GOST R-51834-2001) have a yield strength of 265 MPa, a tensile strength of 410 MPa with a relative elongation of 12%. Wrought alloy AK4-1 with increased heat resistance (GOST R-51834-2001) in the form of rods has a yield strength of 335 MPa, a tensile strength of 390 MPa with a relative elongation of 6%.

The disadvantages of the alloys described above are the worst processability among all aluminum alloys during casting and insufficiently high strength at elevated temperatures.

Known casting alloy based on aluminum (WO 2011023059 A1, publ. 03.03.2011), containing in wt. %: Cu 1.0-10.0; Mn 0.05-1.5; Cd 0.01-0.5; Ti 0.01-0.5; B 0.01-0.2 or C 0.0001-0.15; Zr 0.01-1.0; R 0.001-3 or (R1 + R2) 0.001-3; RE 0.05-5 and the rest is aluminum, where R, R1 and R2 are Be, Co, Cr, Li, Mo, Nb, Ni, W.

The disadvantages of this invention are the presence in the composition of the alloy of harmful cadmium and a high content of additives of transition and rare earth metals, which greatly affects the level of mechanical properties.

Known wrought aluminum-based alloy (CA 2493401 C, publ. 03/04/2004) containing in wt. %: Cu 3.6-4.9; Mg: 1.0-1.8; Mn 0.50 (preferably less than 0.30); Si 0.10-0.40; Zr 0.15; Cr≤0.15; Fe≤0.10, featuring improved fatigue properties.

The disadvantage of the alloy is not a high yield point of 310-325 MPa.

Known aluminum wrought alloy (CN 101597710 A, publ. 09.12.2009) containing in wt. %: Mg 1.3-1.5; Cu 3.5-4.05; Si≤0.1; Fe≤0.1; Mn 0.5-0.7; Cr≤0.1; Ti≤0.15; Zr 0.1-0.15.

The disadvantages of the invention are the low content of iron and silicon impurities, which complicates the use of secondary raw materials and a low yield point of 320-350 MPa.

Closest to the proposed invention is an alloy (RU 2558807, publ. 08/10/2015), containing in wt. %: Cu 2.0-5.5; Mn 0.1-2.5; Cd 0.01-1.5; Si 0.01-1.0; Mg 0.01-0.9; Fe 0.01-1.0; at least one element from the group: Ti 0.01-0.5; Zr 0.01-0.5; Y 0.001-0.5; In 0.001-0.5; Al is the rest.

The disadvantage of this alloy is a high content of harmful cadmium, a low level of casting properties and a wide range of titanium, zirconium, yttrium, and indium contents.

The objective of this invention is to obtain cast and wrought aluminum alloys with increased heat resistance, manufacturability in casting and good strength.

The technical result of the proposed invention is new casting and wrought aluminum alloys based on the Al-Cu-Y and Al-Cu-Er systems with a good level of casting properties, a high level of strength at room and elevated temperatures, especially the yield strength in tension and compression at temperatures of 200 -300 ° C.

The specified technical result is achieved in the first embodiment of the invention due to the fact that the heat-resistant casting and wrought aluminum alloy contains the following alloying elements: copper, yttrium, manganese, zirconium, titanium, boron, magnesium with the following composition, wt. %:

Copper 4-6.5 Yttrium 1.6-2.3 Manganese 0.6-0.9 Zirconium 0.2-0.3 Titanium 0.1-0.15 Boron 0.02-0.03 Magnesium 0.8-1.1 Aluminum rest,

in this case, the ratio of the content (wt%) of copper to yttrium in the alloy is 2.8, the structure of the alloy consists of a complex alloyed solid solution and intermetallic particles up to 3 μm in size.

The specified technical result is achieved in the second embodiment of the invention due to the fact that the heat-resistant casting and wrought aluminum alloy contains the following alloying elements: copper, erbium, manganese, zirconium, titanium, boron, magnesium with the following composition, wt. %:

Copper 4-6.5 Erbium 2.7-4.05 Manganese 0.6-0.9 Zirconium 0.2-0.3 Titanium 0.1-0.15 Boron 0.02-0.03 Magnesium 0.8-1.1 Aluminum rest,

the ratio of the content (wt%) of copper to erbium in the alloy is 1.5, the structure of the alloy consists of a complex alloyed solid solution and intermetallic particles up to 3 μm in size.

In this case, with a copper content of 4-6.5%, erbium 2.7-4.05% "or yttrium 1.6-2.3% and their indicated ratio, the alloys have a narrow crystallization range and a high solidus temperature, and the resulting intermetallic compounds of crystallization origin such as Al ₈ Cu ₄ Y and Al ₈ Cu ₄ Er have a small size and high thermal stability. The alloy can be smelted on A7 grade aluminum, that is, the concentration of iron and silicon impurities does not exceed 0.15 wt. % of each and in the amount of less than 0.3 mass. %. The alloy is additionally alloyed with manganese, zirconium, titanium, boron, magnesium. Manganese and zirconium in amounts of 0.6-0.9% and 0.2-0.3%, respectively, are introduced for strengthening due to the formation of dispersoids of the Al ₂₀ Cu ₂ Mn ₃ and A ₃ (Zr, Er) phases during homogenization annealing before hardening. Small additions of titanium 0.1-0.15% and boron 0.02-0.03% are introduced to modify the grain structure of the ingots. Magnesium in an amount of 0.8-1.1% is introduced to increase the aging effect after quenching due to metastable precipitates of the S phase (Al ₂ CuMg).

The invention is illustrated by a drawing, where:

in fig. 1 shows the grain structure of the first alloy containing yttrium Y (light microscope), FIG. 2 shows various microstructures of the first alloy (scanning electron microscope), FIG. 3 shows the dependence of the hardness on the aging time of the first alloy at different temperatures, FIG. 4 shows the dependence of the hardness on the time of annealing of the deformed first alloy at different temperatures and the grain structure after annealing of the deformed sheet; FIG. 5 shows the grain structure of the second erbium-containing alloy Er (light microscope); FIG. 6 shows various microstructures of the second alloy (scanning electron microscope), FIG. 7 shows the dependence of the hardness on the aging time of the second alloy at different temperatures, FIG. 8 shows the dependence of the hardness on the time of annealing of the deformed second alloy at different temperatures and the grain structure after annealing of the deformed sheet.

FIG. 1 shows the grain structure 1 of the first alloy; in fig. 2 shows cast microstructure 2 and microstructure 3 after homogenization before quenching at 575 ° C for 3 hours of the first alloy; in fig. 3 shows the dependences 4, 5, 6 of hardness on the aging time of the first alloy at 150, 180 and 210 ° C, respectively; in fig. 4 shows the dependences 7, 8, 9 of hardness on the time of annealing of the deformed first alloy at 150, 180 and 210 ° C, respectively, and grain structure 10 after annealing the deformed sheet at 575 ° C for 15 minutes; in fig. 5 shows the grain structure 11 of the second alloy; in fig. 6 shows the cast microstructure 12 and microstructure 13 after homogenization before quenching at 575 ° C for 3 hours of the second alloy; in fig. 7 shows the dependences 14, 15 16 of the hardness on the aging time of the second alloy at 150, 180 and 210 ° C, respectively; in fig. 8 shows the dependences 17, 18, 19 of hardness on the time of annealing of the deformed second alloy at 150, 180 and 210 ° C, respectively, and grain structure 20 after annealing the deformed sheet at 575 ° C for 15 minutes.

The implementation of the invention is as follows.

The proposed alloy is obtained by the following technology: alloying elements in the form of ligatures Al-Cu, Al-Mn, Al-Er, Al-Y, Al-Zr, Al are introduced into the melt of aluminum grade A7 (or more pure) at a temperature of 850 ° C -Ti-B and pure magnesium. After the introduction of alloying elements, the melt is mixed and poured from a temperature of 850 C into a water-cooled copper mold, graphite mold or steel chill mold to obtain blanks for tensile tests at room and elevated temperatures.

Homogenization annealing is carried out at a temperature of 575 ° C for 1-3 hours, followed by quenching in water. Further, for the casting alloy, an aging operation is carried out at a temperature of 210 ° C for 6 hours. For the wrought alloy, pressure treatment and subsequent annealing are carried out. Pressure processing includes hot rolling at temperatures of 540-560 ° C (reduction rate up to 80%) and subsequent cold rolling (total reduction rate up to 95%). Annealing after rolling is carried out in two modes: cold-worked state - annealing 150-210 ° C for 1-3 hours; soft state - annealing at 575 ° C for 5-15 minutes with quenching in water and aging at a temperature of 210 ° C for 3 hours.

The study of the structure of the alloys is carried out using scanning electron microscopy, X-ray structural analysis. The evaluation of mechanical properties was carried out according to the results of measuring the hardness by the Vickers method (HV) and tests for uniaxial tension at room and elevated temperatures, long-term strength, compression at elevated temperatures. The average linear coefficient of thermal expansion (CTE) was determined using a dilatometer in a temperature range of 20-200 ° C. The hot brittleness index was determined by a pencil test, by three pouring into a steel split chill mold.

Example 1.

Alloy composition Al-5.6% Cu-2.0% Y-0.8% Mn-0.3% Zr-0.15% Ti-0.15% Fe-0.15% Si-1% Mg ( first alloy) was obtained as follows. For smelting, pure metals were used: aluminum and magnesium and alloys Al-53.5% Cu, Al-10% Mn, Al-10% Y, Al-5% Zr, Al-5% Ti-1% B. The melting was carried out in graphite-fireclay crucibles in a resistance furnace of the "Nabertherm" company. The casting was carried out at a temperature of 850 ° C.

FIG. 1 shows the grain structure 1 of the first alloy. The grain size of the ingot is in the range of 20-50 microns. The microstructure of the first alloy is shown in FIG. 2. The cast microstructure 2 of the first alloy contains an aluminum solid solution and a dispersed eutectic with an intermetallic phase thickness of 200-1000 nm. In microstructure 3, after homogenization before quenching at a temperature of 575 ° C for 3 hours, a nonequilibrium excess of phases of crystallization origin dissolves, and the intermetallic phases are fragmented and increase in size up to 1-3 μm. Formations of phases less than 100 nm in size were noted inside the aluminum matrix. After quenching, the alloy is aged at 150-210 ° C. The hardness increases sharply after 0.5 hour aging, and then smoothly reaches a maximum, the maximum hardness of 132 HV is obtained after 6 hours of aging at 210 ° C, which is illustrated by the dependences of 4, 5, 6 on the aging time at 150, 180 and 210 ° C respectively.

Compression test results at elevated temperatures are shown in Table 1.

The results of uniaxial tensile tests at room and elevated temperatures and long-term strength are presented in Table 2.

The average coefficient of thermal expansion of the alloy in the temperature range in the quenched and aged at 210 ° C for 6 hours is presented in Table 3.

The hot brittleness index for a pencil sample is 12-14 mm.

Example 2.

The first alloy shown in Example 1, after homogenization at 575 ° C for 3 hours, was rolled at 550 ° C from a thickness of 20 mm to a thickness of 6 mm, and then to a thickness of 1 mm at room temperature.

After rolling, the alloy was annealed at temperatures of 150-210 ° C. In the process of annealing at 150-180 ° C, an increase in hardness occurs due to aging, which overlaps the softening associated with polygonization. As a result, the hardness of the alloy is 130-145HV, which is illustrated by the dependences 7, 8, 9 of hardness on the time of annealing. Annealing the alloy at 575 ° C for 15 min leads to recrystallization and the grain size is 8-10 μm, which corresponds to grain structure 10.

The uniaxial tensile test results of the annealed alloy sheets at room temperature are shown in Table 4.

The results of uniaxial tensile tests for specimens annealed at 150 ° C for 6 hours before and after general corrosion tests are presented in Table 5.

Example 3.

Alloy composition Al-5.4% Cu-3.0% Er-0.9% Mn-0.3% Zr-0.15% Ti-0.15% Fe-0.15% Si-1.1% Mg (second alloy) was obtained as follows. For smelting, pure metals were used: aluminum and magnesium and alloys A1-53.5% Cu, A1-10% Mn, A1-10% Er, Al-5% Zr, Al-5% Ti-1% B. The melting was carried out in graphite-fireclay crucibles in a resistance furnace of the "Nabertherm" company. The casting was carried out at a temperature of 850 ° C.

FIG. 5 shows the grain structure 11 of the second alloy. The grain size of the ingot is in the range of 10-30 microns. The microstructure of the alloy is shown in FIG. 6. The cast microstructure 12 contains an aluminum solid solution and a dispersed eutectic with an intermetallic phase thickness of 200-1000 nm. In microstructure 13, after homogenization before quenching at a temperature of 575 ° C for 3 hours, a nonequilibrium excess of phases of crystallization origin dissolves, and the intermetallic phases are fragmented and increase in size up to 1-3 μm. Formations of phases less than 100 nm in size were noted inside the aluminum matrix. After quenching, the alloy is aged at 150-210 ° C. The hardness increases sharply after 0.5 hour aging, and then gradually reaches a maximum, the maximum hardness of 130 HV is obtained after 6 hours of aging at 210 ° C, which is illustrated by the dependences of 14, 15, 16 on the aging time at 150, 180 and 210 ° C respectively.

Compression test results at elevated temperatures are shown in Table 6.

The results of uniaxial tensile tests at room and elevated temperatures and long-term strength are presented in table 7.

The average coefficient of thermal expansion of the alloy in the temperature range in the quenched and aged at 210 ° C for 6 hours is presented in Table 8.

The hot brittleness index for a pencil sample is 12-14 mm.

Example 4.

The second alloy shown in example 3, after homogenization at 575 ° C for 3 hours, was rolled at 550 ° C from a thickness of 20 mm to a thickness of 6 mm, and then to a thickness of 1 mm at room temperature.

After rolling, the alloy was annealed at temperatures of 150-210 ° C. In the process of annealing at 150-180 ° C, an increase in hardness occurs due to aging, which overlaps the softening associated with polygonization. As a result, the hardness of the alloy is 134-150HV, which is illustrated by the dependences 17, 18, 19 of the hardness on the annealing time. Annealing the alloy at 575 ° C for 15 min leads to recrystallization and the grain size is 8-10 μm, which corresponds to grain structure 20.

The uniaxial tensile test results of the annealed alloy sheets at room temperature are shown in Table 9.

The results of uniaxial tensile tests on samples annealed at 150 ° C for 6 hours before and after general corrosion tests are presented in Table 10.

Example 5.

Alloy composition Al-4.5% Cu-1.6% Y-0.6% Mn-0.2% Zr-0.10% Ti-0.15% Fe-0.15% Si-0.9% Mg was obtained as follows. For smelting, pure metals were used: aluminum and magnesium and alloys Al-53.5% Cu, Al-10% Mn, Al-10% Y, Al-5% Zr, Al-5% Ti-1% B. The melting was carried out in graphite-fireclay crucibles in a resistance furnace of the "Nabertherm" company. The casting was carried out at a temperature of 850 ° C.

The grain size of the ingot is in the range of 20-50 microns. The cast structure contains an aluminum solid solution and a dispersed eutectic with an intermetallic phase thickness of 200-1000 nm. After homogenization before quenching at a temperature of 575 ° C for 1 hour, a nonequilibrium excess of phases of crystallization origin dissolves, and the intermetallic phases are fragmented and increase in size up to 1-3 microns. Formations of phases less than 100 nm in size were noted inside the aluminum matrix. After quenching, the alloy is aged at 150-210 ° C. The maximum hardness of 120 HV is obtained after 6 hours aging at 210 ° C.

Compression test results at elevated temperatures are shown in Table 11.

The results of uniaxial tensile tests at room and elevated temperatures and long-term strength are presented in table 12.

The average coefficient of thermal expansion of the alloy in the temperature range in the quenched and aged at 210 ° C for 6 hours is presented in Table 13.

The hot brittleness index for a pencil sample is 12-14 mm.

Example 6.

The alloy of the composition shown in example 1, after homogenization at 575 ° C for 1 hour, was rolled at 550 ° C from a thickness of 20 mm to a thickness of 6 mm, and then to a thickness of 1 mm at room temperature.

After rolling, the alloy was annealed at temperatures of 150-210 ° C. In the process of annealing at 150-180 ° C, an increase in hardness occurs due to aging, which overlaps the softening associated with polygonization. As a result, the hardness of the alloy is 125-138HV. Annealing the alloy at 575 ° C for 15 min leads to recrystallization and the grain size is 8-10 μm.

The uniaxial tensile test results of the annealed alloy sheets at room temperature are shown in Table 14.

The results of uniaxial tensile tests for samples annealed at 150 ° C for 6 hours before and after general corrosion tests are presented in Table 15.

Example 7.

Alloy composition Al-4.0% Cu-2.7% Er-0.8% Mn-0.2% Zr-0.10% Ti-0.15% Fe-0.15% Si-0.8% Mg was obtained as follows. For smelting, pure metals were used: aluminum and magnesium and alloys Al-53.5% Cu, Al-10% Mn, Al-10% Er, Al-5% Zr, Al-5% Ti-1% B. The melting was carried out in graphite-fireclay crucibles in a resistance furnace of the "Nabertherm" company. The casting was carried out at a temperature of 850 ° C.

The grain size of the ingot is in the range of 30-100 microns. The cast structure contains an aluminum solid solution and a dispersed eutectic with an intermetallic phase thickness of 200-1000 nm. After homogenization before quenching at a temperature of 575 ° C for 1 hour, a nonequilibrium excess of phases of crystallization origin dissolves, and the intermetallic phases are fragmented and increase in size up to 1-3 microns. Formations of phases less than 100 nm in size were noted inside the aluminum matrix. After quenching, the alloy is aged at 150-210 ° C. The maximum hardness of 118 HV is obtained after 6 hours aging at 210 ° C.

Compression test results at elevated temperatures are shown in Table 16.

The results of uniaxial tensile tests at room and elevated temperatures and long-term strength are presented in table 17.

The average coefficient of thermal expansion of the alloy in the temperature range in the quenched and aged at 210 ° C for 6 hours is presented in table 18.

The hot brittleness index for a pencil sample is 12-14 mm.

Example 8.

The alloy of the composition shown in example 3, after homogenization at 575 ° C for 1 hour, was rolled at a temperature of 550 ° C from a thickness of 20 mm to a thickness of 6 mm, and then to a thickness of 1 mm at room temperature.

After rolling, the alloy was annealed at temperatures of 150-210 ° C. In the process of annealing at 150-180 ° C, an increase in hardness occurs due to aging, which overlaps the softening associated with polygonization. As a result, the hardness of the alloy is 118-132HV. Annealing the alloy at 575 ° C for 15 min leads to recrystallization and the grain size is 8-10 μm.

The uniaxial tensile test results of the annealed alloy sheets at room temperature are shown in Table 19.

The results of uniaxial tensile tests of samples annealed at 150 ° C for 6 hours before and after general corrosion tests are presented in Table 20.

Claims (8)

1. Heat-resistant aluminum alloy casting or wrought, containing copper, yttrium, manganese, zirconium, titanium, magnesium and aluminum, characterized in that it additionally contains boron, with the following ratio of components, wt. %: Copper 4-6.5 Yttrium 1.6-2.3 Manganese 0.6-0.9 Zirconium 0.2-0.3 Titanium 0.1-0.15 Boron 0.02-0.03 Magnesium 0.8-1.1 Aluminum rest, the structure of the alloy consists of a complex alloyed solid solution and intermetallic particles of Al ₈ Cu ₄ Y up to 3 microns in size. 2. An alloy according to claim 1, characterized in that the ratio of the copper to yttrium content is 2.8. 3. Heat-resistant aluminum alloy casting or wrought, containing copper, manganese, zirconium, titanium, magnesium and aluminum, characterized in that it additionally contains erbium and boron, with the following ratio of components, wt. %: Copper 4-6.5 Erbium 2.7-4.05 Manganese 0.6-0.9 Zirconium 0.2-0.3 Titanium 0.1-0.15 Boron 0.02-0.03 Magnesium 0.8-1.1 Aluminum rest, the structure of the alloy consists of a complex alloyed solid solution and intermetallic particles Al ₈ Cu ₄ Er up to 3 microns in size. 4. The alloy according to claim 3, characterized in that the ratio of the copper to erbium content is 1.5.

Images