CA2563789A1 - Al-mg alloy sheet with excellent formability at high temperatures and high speeds and method of production of same - Google Patents
Al-mg alloy sheet with excellent formability at high temperatures and high speeds and method of production of same Download PDFInfo
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- CA2563789A1 CA2563789A1 CA002563789A CA2563789A CA2563789A1 CA 2563789 A1 CA2563789 A1 CA 2563789A1 CA 002563789 A CA002563789 A CA 002563789A CA 2563789 A CA2563789 A CA 2563789A CA 2563789 A1 CA2563789 A1 CA 2563789A1
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- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 13
- 229910000861 Mg alloy Inorganic materials 0.000 title 1
- 229910000765 intermetallic Inorganic materials 0.000 claims abstract description 39
- 238000005266 casting Methods 0.000 claims abstract description 38
- 238000005097 cold rolling Methods 0.000 claims abstract description 29
- 229910000838 Al alloy Inorganic materials 0.000 claims abstract description 23
- 238000000137 annealing Methods 0.000 claims abstract description 23
- 239000013078 crystal Substances 0.000 claims abstract description 21
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 19
- 239000000956 alloy Substances 0.000 claims abstract description 19
- 238000001816 cooling Methods 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 230000000694 effects Effects 0.000 description 10
- 238000001953 recrystallisation Methods 0.000 description 10
- 229910018134 Al-Mg Inorganic materials 0.000 description 5
- 229910018467 Al—Mg Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 4
- 238000009864 tensile test Methods 0.000 description 4
- 229910019752 Mg2Si Inorganic materials 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910018191 Al—Fe—Si Inorganic materials 0.000 description 2
- -1 TiAl3 is generated Chemical class 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 229910017082 Fe-Si Inorganic materials 0.000 description 1
- 229910017133 Fe—Si Inorganic materials 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- 229910010039 TiAl3 Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
- B22D11/003—Aluminium alloys
-
- 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
- C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
- C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
- B22D11/0605—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two belts, e.g. Hazelett-process
-
- 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
- C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Continuous Casting (AREA)
- Metal Rolling (AREA)
Abstract
To provide an aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming and a method of production of the same. An aluminum alloy sheet consisting of 2.0-8.0 wt% of Mg, 0.06-0.2 wt% of Si, 0.1-0.5 wt% of Fe, 0.1-0.5 wt% of Mn, and the balance of Al and unavoidable impurities, wherein a density of inter-metallic compounds having an equivalent circle diameter of 1 to 5 (m is 5000/mm2 or more and an average crystal grain size is 20 (m or less. A method of production of an aluminum alloy sheet comprising the steps of casting an alloy melt having the above described composition by a twin belt casting machine at a cooling rate of 20 to 150~C/sec at the location of 1/4 of the slab thickness during the casting to form a slab having a thickness of 5 to 15 mm, subsequently rewinding up the slab as a coil, cold rolling the slab taken out from the coil at a cold rolling reduction of 70 to 96%, and performing annealing heating the obtained cold rolled sheet at a heating rate of 50~C/sec or more to 420 to 500~C.
Description
DESCRIPTION
Al-Mg ALLOY SHEET WITH EXCELLENT FORMABILITY
AT HIGH TEMPERATURES AND HIGH SPEEDS
AND METHOD OF PRODUCTION OF SAME
TECHNICAL FIELD
The present invention relates to an Al-Mg alloy sheet with excellent formability at high temperatures and high speeds and a method of production of the same.
BACKGROUND ART
An Al-Mg alloy is light and excellent in strength and corrosion resistance, so is being proposed as an automobile sheet material or other worked or formed material. However, its elongation at room temperature is low, therefore there is the problem that an Al-Mg alloy cannot be formed into a complex shape by cold working.
For this reason, an A1-Mg-based superplastic alloy suppressing the recrystallization at the time of hot working to reduce the size of the crystal grains and obtaining an elongation of several 100% in a high temperature region of for example 500 to 550°C as been developed and is being used for various applications.
A conventional Al-Mg-based superplastic alloy manifests its superplasticity at a slow forming speed (strain rate)~of 10-4 to 10-3/sec and requires a long time, therefore is low in productivity when applied to ordinary press forming and is not practical.
Therefore, an aluminum alloy sheet able to give a sufficient elongation even with high forming speed of a strain rate of for example 0.1/sec or more in the high temperature region for hot working, that is, 100 times or more than that of the prior art, and able to suppress occurrence of cavities at the time of forming has been developed.
For example, Japanese Unexamined Patent Publication (Kokai) No. 10-259441 proposes an aluminum alloy sheet - 2 _ with excellent superplastic formability at high speeds and having a reduced amount of cavities after forming characterized in that it contains 3.0-8.Oo (wt%, same below) of Mg, 0.21-0.500 of Cu, and 0.001-0.10 of Ti, contains as impurities Fe to 0.060 or less and Si to 0.060 or less, and the balance of Al and impurities and has an average crystal grain size of 20 to 200 Vim.
In the prior art, however, in order to achieve a good high temperature high speed formability in the finally obtained sheet product, there is the problem that it is necessary to go through many processes such as large slab casting by semi-continuous casting, surface scalping, soaking, hot rolling, cold rolling, intermediate annealing, final rolling, and final annealing and so the cost increases.
Further, a large slab has a slow cooling speed at the time of casting of for example about 1 to 10 or so °C/sec, therefore the intermetallic compounds of A1-Fe-Si, Al6Mn, etc. become coarse of several tens of ~m or more.
Even in the final sheet product after the soaking, hot rolling, cold rolling, annealing, etc., coarse intermetallic compounds of 10 ~tm or more still remain.
Cavities easily occur due to peeling at the interface between the intermetallic compounds and matrix at the time of high temperature forming. As a countermeasure for this, the method of suppressing the contents of Fe and Si to 0.10 or less is employed, but it is necessary to use expensive high purity metal for this, so there was the problem that the cost rose in the end.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an aluminum alloy sheet solving the above problems of the prior art, not requiring the use of high purity metal accompanied with higher cost, improving the formability at high temperatures and high speeds, and reducing the cavities after forming and a method of production of the same.
To attain the above object, according to the present invention, there is provided an aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming characterized in that it consists of:
Mg: 2.0-8.Owto, Si: 0.06-0.2wto, Fe: 0.1-0.5wto, Mn: 0.1-0.5wto, and the balance of Al and unavoidable impurities, wherein a density of an inter-metallic compound having an equivalent circle diameter of 1 to 5 ~,m is 5000/mm2 or more and an average crystal grain size is 20 ~,m or less.
In order to achieve the above object, according to the present invention, there is further provided a method of production of an aluminum alloy sheet of the present invention with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming characterized in that it comprises the steps of:
preparing an alloy melt having a composition of the aluminum alloy sheet of the present invention, casting the alloy melt by a twin belt casting machine at a cooling rate of 20 to 150°C/sec at the location of 1/4 of the slab thickness during casting to form a slab having a thickness of 5 to 15 mm, subsequently rewinding up the slab as a coil, cold rolling the slab taken out from the coil with a cold rolling reduction of 70 to 960, and performing annealing for heating the obtained cold rolled sheet at a rate of temperature rise of 5°C/sec or more to 420 to 500°C.
The aluminum alloy sheet of the present invention defines ranges of the chemical composition and microstructure and disperses the inter-metallic compounds uniformly and finely so as to improve the formability at high temperatures and high speeds by the increased fineness of the crystal grains without requiring any high purity metal and reduce the cavities after forming.
Further, the method of production of the present invention secures a high cooling rate at the time of casting by twin belt casting, restricts the cold rolling reduction, and limits the annealing conditions after the cold rolling so as to realize a uniform fine dispersion of the inter-metallic compounds and increased fineness of the crystal grains.
By using the aluminum alloy sheet of the present invention, a high grade formed product is obtained, the forming time is shortened, and the productivity is l5 enhanced.
BEST MODE FOR WORKING THE INVENTION
The reasons for the limitation of the chemical composition of the alloy in the present invention will be explained next. The "%" representing the chemical composition in the present description means "wt%" unless particularly indicated otherwise.
[Mg: 2.0-8.Oo]
Mg is an element improving the strength. In order to manifest this effect, it is necessary to set the Mg content to 2.0o or more. However, if the Mg content exceeds 8.0o, the castability of a thin slab is lowered.
Accordingly, the Mg content is limited to 2.0 to 8.0a. If stressing the castability, preferably the upper limit of the Mg content is further limited to 6.0o or less.
[Si: 0. 06-0.2 0]
Si is precipitated as fine particles of Al-Fe-Si-based, Mg2Si, and other inter-metallic compounds at the time of casting and functions as a nucleus generating site of recrystallization at the time of annealing after cold rolling. Accordingly, the larger the number of particles of these inter-metallic compounds, the larger the number of generated recrystallized nucleii and as a result the larger number of fine recrystallized grains formed. Further, the fine particles of the inter-metallic compounds pin the grain boundaries of the generated recrystallized grains and suppress growth due to merging of crystal grains to stably maintain the fine recrystallized grains.
In order to manifest these effects, it is necessary to make the Si content 0.060 or more. However, if the Si content exceeds 0.20, the tendency of the precipitated inter-metallic compounds to become coarser becomes stronger, so the formation of cavities is promoted at the time of high temperature deformation. Accordingly, the Si content is limited to 0.06 to 0.20. The preferred range is 0.07 to 0.150.
In general, Si is regarded as an impurity element to be eliminated in the same way as the following Fe, but in the present invention, conversely a suitable amount of Si is made present in order to increase the fineness of the recrystallized grains as described above. Accordingly, high purity metal is not needed and there is no accompanying rise in cost.
[Fe: 0.1-0.50]
Fe is precipitated as fine grains of Al-Fe-Si-based or other inter-metallic compounds at the time of casting and functions as a nuclei generating site of recrystallization at the time of annealing after cold rolling. Accordingly, the larger the number of particles of these inter-metallic compounds, the larger the number of the generated recrystallized nucleii and as a result the larger the number of fine recrystallized grains formed. Further, the fine particles of the inter-metallic compounds pin the grain boundaries of the generated recrystallized grains and suppress the growth due to merger of crystal grains to stably maintain the fine recrystallized grains. In order to manifest this effect, it is necessary to make the Fe content 0.10 or more.
However, if the Fe content exceeds 0.50, the tendency of the precipitated inter-metallic compounds to become coarser becomes stronger, so the occurrence of cavities is promoted at the time of high. temperature deformation.
Accordingly, the Fe content is limited to 0.1 to 0.50. A
preferred range is 0.1 to 0.30.
In general, Fe is regarded as an impurity element to be eliminated in the same way as the above Si, but in the present invention, conversely a suitable amount of Fe is made present in order to increase the fineness of the recrystallized grains as described above. Accordingly, high purity metal is not needed and there is no accompanying rise in cost.
[Mn: 0.1-0.5%]
Mn is an element increasing the fineness of the recrystallized grains. In order to manifest this effect, it is necessary to make the Mn content 0.10 or more.
However, if the Mn content exceeds 0.50, a coarse Al-(Fe~Mn)-Si-based inter-metal compound is formed, and the occurrence of cavities is promoted at the time of high temperature deformation. Accordingly, the Mn content is limited to 0.1 to 0.5%. Particularly, when stressing the prevention of occurrence of cavities; preferably the upper limit of the Mn content is further restricted to 0.3a.
[Optional ingredient Cu: 0.1-0.50]
In the present invention, Cu can be added within a range of 0.1-0.5o in order to improve the strength of the aluminum alloy sheet. In order to obtain precipitation hardening effect sufficiently, it is necessary to make the amount of addition of Cu 0.10 or more. However if the amount of addition of Cu exceeds 0.5o, the castability is lowered. When stressing the castability, preferably the upper limit of the amount of addition of Cu is further restricted to 0.30 or less.
[Optional ingredients Zr and Cr: 0.1-0.40]
In the present invention, in order to assist the increased fineness of the recrystallized grains, at least one type of Zr and Cr can be incorporated within a range of 0.1-0.40. Zr and Cr are elements for increasing the fineness of the recrystallized grains. In order to manifest this effect, it is necessary to make the amounts of addition of both the Zr and Cr 0.10 or more. However, if the amounts of addition exceed 0.40, coarse inter-metallic compounds are formed at the time of the casting, and the occurrence of cavities is promoted at the time of high temperature deformation. Particularly, when stressing the prevention of the occurrence of cavities, preferably the upper limits of the amounts of addition are further restricted to 0.20 or less.
[Other elements]
In the present invention, in order to increase the fineness of the casting structure, Ti can be added within a range of 0.001-0.150. In order to manifest this effect, it is necessary to make the amount of addition of Ti 0.0010 or more. However, if the amount of addition of Ti exceeds 0.150, a coarse compound such as TiAl3 is generated, the formability at a high temperature is deteriorated, and the occurrence of cavities is promoted.
A preferred range is 0.006-0.100.
Next, the reasons for the limitation of the microstructure of the alloy sheet in the present invention will be explained.
[Density of inter-metallic compounds having equivalent circle diameters of 1 to 5 ~m of 5000/mm2 or more]
The present invention utilizes the fine inter-metallic compound particles as (1) the recrystallized grain nuclei generating sites and (2) means for pinning the grain boundaries of the recrystallized grains and generates finer recrystallized grains by the annealing after the cold rolling. The fine grain structure obtained by this gives a high elongation at the time of deformation at high temperatures and high speeds, whereby the formability at high temperatures and high speeds is - g -enhanced.
In order to obtain the above effect, the inter-metallic compound having the equivalent circle diameter of 1 to 5 ~,m,must be present in a density of 5000/mm2 or more. As the inter-metallic compound, as already mentioned, inter-metallic compounds such as Al-(Fe~Mn)-Si-based compounds, Mg2Si, and Al6Mn are precipitated during casting. In order to manifest the effects of the above (1) and (2) by these inter-metallic compounds, the equivalent circle diameter must be 1 to 5 ~,m. If the equivalent circle diameter is less than 1 Vim., the particles are too small to manifest the effects of (1) and (2) described above. Conversely, if it exceeds 5 Vim, cavities are easily generated at the time of deformation at high temperatures and high speeds, and the strength and elongation after the shaping are lowered.
The inter-metallic compounds having the size within the above described range must be present at a density of 5000/mm2 or more.
If the density is less than 5000/mm2, the recrystallized grain diameter at the time of the annealing exceeds 20 Vim, and the elongation at the time of high temperature deformation.is lowered.
[Average crystal grain diameter of 20 ~tm or less]
In the alloy sheet of the present invention, the average crystal grain diameter is made 20 ~m or less. If the average crystal grain diameter exceeds 20 ~,m, the elongation at the time of the high temperature deformation is lowered.
The reasons for the limitation of conditions of the method of production of the present invention will be explained next.
[Slab having thickness of 5 to 15 mm cast by twin ~ belt casting and taken up in the form of a coil]
The twin belt casting method is a continuous casting method injecting a melt into a mould of a pair of water cooled rotating belts facing each other from one end in the vertical direction, solidifying the melt by the cooling from the belt surfaces to form the slab, pulling out the formed slab from the other end of the mould, and taking it up in the form of a coil.
In the present invention, the thickness of the slab cast by this twin belt casting method is made 5 to 15 mm.
When the thickness is within this range, a high solidification speed can be secured even at the center portion of the sheet thickness, therefore a uniform casting structure can be easily formed. Simultaneously, with the composition of the present invention, it is possible to easily suppress the generation of coarse inter-metallic compounds and it becomes easy to control the average grain size of the recrystallized grains in the final sheet product to 20 ~,m or less. The above described slab thickness range is also suitable from the viewpoint of the twin belt casting.
Namely, if the slab thickness is less than 5 mm, the amount of the aluminum alloy melt passing through the casting machine per unit time becomes too small, so the twin belt casting becomes difficult. If the slab thickness exceeds 15 mm, it becomes difficult to rewind it up as a coil.
[Cooling rate at time of casting of 20 to 150°C/sec]
In the method of production of the present invention, a slab having a thickness of 5 to 15 mm is cast by twin belt casting. At that time, in order to cause the precipitation of inter-metallic compounds having the equivalent circle diameter of 1 to 5 ~m prescribed for the alloy of the present invention with a density of 5000/mm2 or more, the cooling rate at the location of 1/4 of the slab thickness during the casting is made 20 to 150°C/sec. In the aluminum alloy of the present invention, the inter-metallic compounds such as the Al-(Fe~Mn)-Si-based compounds and Mg2Si are precipitated at the time of the casting. If the cooling rate is less than 20°C/sec, these inter-metallic compounds become coarse and the compounds exceeding 5 ~tm increase.
Conversely, if the cooling rate exceeds 150°C/sec, the inter-metallic compounds become finer and the compounds less than 1 ~m increase. In the end, in either case, the density of the inter-metallic compounds having the equivalent circle diameter of 1 to 5 ~m becomes less than 5000/mm2 and the nuclei of the recrystallized grains become fewer at the time of the final annealing (CAL), so the recrystallized grains become coarse.
[Cold rolling with cold rolling reduction of 70 to 960]
Accumulation of dislocation occurring due to the plastic working by the cold rolling around the intermetallic compounds is indispensable for forming the fine recrystallization structure at the time of the final annealing. If the cold rolling reduction is less than 700, the accumulation of the dislocations becomes insufficient and a fine recrystallization structure cannot be obtained. If the cold rolling reduction exceeds 96%, edge cracks occur during the cold rolling, so cold rolling becomes difficult.
[Annealing for heating to 420 to 500°C at a rate of temperature rise of 5°C/sec or more]
In the present invention, the above annealing is conducted as the final annealing after the cold rolling.
This is generally conducted by the continuous annealing, but it is not particularly necessary to limit the annealing to this.
The annealing temperature of the final annealing is made a range of 420 to 500°C. If the temperature is less than 420°C, the energy required for recrystallization is insufficient, therefore the recrystallization becomes insufficient and a fine recrystallization structure cannot be obtained. However, if it exceeds~500°C, the recrystallized grain diameter exceeds 20 ~tm, and the fine recrystallization structure cannot be obtained.
The heating rate to the annealing temperature is made 5°C/sec or more. If the temperature is slowly elevated by a rate less than 5°C/sec, the recrystallized grains become coarse, so the fine recrystallization structure cannot be obtained.
Finally, the forming of the aluminum alloy sheet of the present invention is preferably conducted at a temperature of 400-500°C. If the forming temperature is less than 400°C, a sufficient elongation cannot be obtained. If the forming temperature exceeds 550°C, the coarsening of the crystal grains occurs. Further, burning occurs in an alloy having a high Mg content within the range of the present invention, and the elongation is lowered. The strain rate at the time of the shaping is preferably 0.1/sec or more. If the strain rate is less than 0.1/sec, the coarsening of the crystal grains occurs during the forming, so a drop of the elongation is induced.
Examples Aluminum alloy melts having the compositions shown in Table 1 were cast by the twin belt casting method to form slabs having thicknesses of 7 to 9 mm. Each slab was cold rolled down to a thickness of 1 mm and annealed at 450°C, then test pieces prescribed in JIS H7501 were cut out and measured for elongation after a tensile test.
Further, cross-sections of broken samples were polished, then the area ratios of the cavities (cavity ratios) were measured by an image analyzer. The production process and characteristics are shown in Table 2.
Table 1: Alloy Composition (wto) Alloy Mg Mn Fe Si Cu Zr A 3.1 0.3 0.12 0.07 - -B 5.2 0.3 0.15 0.10 - -C 7.1 0.4 0.10 0.09 - -D 3.2 0.2 0.12 0.07 0.3 -E 3.2 0.2 0.12 0.07 - 0.2 U
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o z m z Sheets obtained by cold rolling thin slabs cast by a twin belt casting machine (products of the present invention, Sample Nos. 1 to 7), as apparent also from the alloy compositions of Table 1, irrespective of the fact that the Fe contents were 0.10 or more and the Si contents were 0.060 or more in all samples, had densities of the inter-metallic compounds having equivalent circle diameters of 1 to 5 ~,m of 5000/mm~ or more and crystal grain sizes of 20 ~.m or less. For this reason, the elongations at the tensile temperature of 500°C were good ones of 2000 or more and also the cavity ratios after the high temperature tension were good ones of the range of 0.15-0.270 or less than 1%.
A sheet obtained by cold rolling a thin slab cast by a twin roll casting machine (comparative example, Sample No. 8) had a large number of very fine intermetallic compounds having equivalent circle diameters less than 1 ~.m since the cooling rate at the time of the casting was a relatively high 300°C/sec, therefore the density of~the inter-metallic compounds having an equivalent circle diameter of 1 to 5 ~.m in the final sheet became less than 5000/mm2 or coarse exceeding the crystal grain size of 20 ~.m or more. For this reason, the cavity ratio after the high temperature tension was a relatively low good one of 0.120, but the elongation at the tensile temperature of 500°C was a poor 80o.
A sheet obtained by soaking an ordinary slab cast by a DC casting machine, then hot rolling the slab down to a thickness of 7 mm, then cold rolling (comparative example, Sample No. 9) had a cooling rate at the time of the casting of a relatively slow 5°C/sec, therefore intermetallic compounds having an equivalent circle diameter exceeding 5 ~,m were generated, therefore the density of intermetallic compounds having an equivalent circle diameter of 1 to 5 ~m in the final sheet became - 15 ~-less than 5000/mm2, and the crystal grains became slightly coarse exceeding 20 Vim. For this reason, the cavity ratio after the high temperature tensile test was a poor high 1.50, while the elongation at the tensile temperature of 500°C was a poor 1600.
A sheet obtained by cold rolling a thin slab cast by a twin belt casting machine down to the sheet thickness of 2 mm, then intermediate annealing the slab at 350°C, then cold rolling down to 1 mm (comparative example, Sample No. 10) had a density of inter-metallic compounds of an equivalent circle diameter of 1 to 5 ~tm in the final sheet of 5000/mm2 or more, but the cold rolling reduction before the final annealing was a low one of less than 700, therefore the crystal grains became slightly coarse exceeding the crystal grain size of 20 ~,m. The elongation at the tensile temperature of 500°C was a poor one of less than 2000.
A sheet obtained by cold rolling a thin slab cast by a twin belt casting machine (comparative example, Sample No. 11) had a density of inter-metallic compounds having an equivalent circle diameter of 1 to 5 ~m in the final sheet of 5000/mm2 or more and a crystal grain size of 20 ~m or less. However, the tensile temperature in the tensile test was a relatively low 350°C, therefore the elongation was a poor one of less than 2000.
A sheet obtained by cold rolling a thin slab cast by a twin belt casting machine (comparative example, Sample No. 12) had a density of inter-metallic compounds having an equivalent circle diameter of 1 to 5 ~tm in the final sheet of 5000/mm2 or more and a crystal grain size of 20 ~.m or less. However, the tensile speed in the tensile test was a relatively slow 0.01/sec, therefore the cavity ratio after the high temperature tension was also a poor 1.8o and the elongation at the tensile temperature of 500°C was a poor one of less than 2000.
INDUSTRIAL APPLICABILITY
According to the present invention, aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after the forming and the method of production of the same are provided.,
Al-Mg ALLOY SHEET WITH EXCELLENT FORMABILITY
AT HIGH TEMPERATURES AND HIGH SPEEDS
AND METHOD OF PRODUCTION OF SAME
TECHNICAL FIELD
The present invention relates to an Al-Mg alloy sheet with excellent formability at high temperatures and high speeds and a method of production of the same.
BACKGROUND ART
An Al-Mg alloy is light and excellent in strength and corrosion resistance, so is being proposed as an automobile sheet material or other worked or formed material. However, its elongation at room temperature is low, therefore there is the problem that an Al-Mg alloy cannot be formed into a complex shape by cold working.
For this reason, an A1-Mg-based superplastic alloy suppressing the recrystallization at the time of hot working to reduce the size of the crystal grains and obtaining an elongation of several 100% in a high temperature region of for example 500 to 550°C as been developed and is being used for various applications.
A conventional Al-Mg-based superplastic alloy manifests its superplasticity at a slow forming speed (strain rate)~of 10-4 to 10-3/sec and requires a long time, therefore is low in productivity when applied to ordinary press forming and is not practical.
Therefore, an aluminum alloy sheet able to give a sufficient elongation even with high forming speed of a strain rate of for example 0.1/sec or more in the high temperature region for hot working, that is, 100 times or more than that of the prior art, and able to suppress occurrence of cavities at the time of forming has been developed.
For example, Japanese Unexamined Patent Publication (Kokai) No. 10-259441 proposes an aluminum alloy sheet - 2 _ with excellent superplastic formability at high speeds and having a reduced amount of cavities after forming characterized in that it contains 3.0-8.Oo (wt%, same below) of Mg, 0.21-0.500 of Cu, and 0.001-0.10 of Ti, contains as impurities Fe to 0.060 or less and Si to 0.060 or less, and the balance of Al and impurities and has an average crystal grain size of 20 to 200 Vim.
In the prior art, however, in order to achieve a good high temperature high speed formability in the finally obtained sheet product, there is the problem that it is necessary to go through many processes such as large slab casting by semi-continuous casting, surface scalping, soaking, hot rolling, cold rolling, intermediate annealing, final rolling, and final annealing and so the cost increases.
Further, a large slab has a slow cooling speed at the time of casting of for example about 1 to 10 or so °C/sec, therefore the intermetallic compounds of A1-Fe-Si, Al6Mn, etc. become coarse of several tens of ~m or more.
Even in the final sheet product after the soaking, hot rolling, cold rolling, annealing, etc., coarse intermetallic compounds of 10 ~tm or more still remain.
Cavities easily occur due to peeling at the interface between the intermetallic compounds and matrix at the time of high temperature forming. As a countermeasure for this, the method of suppressing the contents of Fe and Si to 0.10 or less is employed, but it is necessary to use expensive high purity metal for this, so there was the problem that the cost rose in the end.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide an aluminum alloy sheet solving the above problems of the prior art, not requiring the use of high purity metal accompanied with higher cost, improving the formability at high temperatures and high speeds, and reducing the cavities after forming and a method of production of the same.
To attain the above object, according to the present invention, there is provided an aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming characterized in that it consists of:
Mg: 2.0-8.Owto, Si: 0.06-0.2wto, Fe: 0.1-0.5wto, Mn: 0.1-0.5wto, and the balance of Al and unavoidable impurities, wherein a density of an inter-metallic compound having an equivalent circle diameter of 1 to 5 ~,m is 5000/mm2 or more and an average crystal grain size is 20 ~,m or less.
In order to achieve the above object, according to the present invention, there is further provided a method of production of an aluminum alloy sheet of the present invention with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming characterized in that it comprises the steps of:
preparing an alloy melt having a composition of the aluminum alloy sheet of the present invention, casting the alloy melt by a twin belt casting machine at a cooling rate of 20 to 150°C/sec at the location of 1/4 of the slab thickness during casting to form a slab having a thickness of 5 to 15 mm, subsequently rewinding up the slab as a coil, cold rolling the slab taken out from the coil with a cold rolling reduction of 70 to 960, and performing annealing for heating the obtained cold rolled sheet at a rate of temperature rise of 5°C/sec or more to 420 to 500°C.
The aluminum alloy sheet of the present invention defines ranges of the chemical composition and microstructure and disperses the inter-metallic compounds uniformly and finely so as to improve the formability at high temperatures and high speeds by the increased fineness of the crystal grains without requiring any high purity metal and reduce the cavities after forming.
Further, the method of production of the present invention secures a high cooling rate at the time of casting by twin belt casting, restricts the cold rolling reduction, and limits the annealing conditions after the cold rolling so as to realize a uniform fine dispersion of the inter-metallic compounds and increased fineness of the crystal grains.
By using the aluminum alloy sheet of the present invention, a high grade formed product is obtained, the forming time is shortened, and the productivity is l5 enhanced.
BEST MODE FOR WORKING THE INVENTION
The reasons for the limitation of the chemical composition of the alloy in the present invention will be explained next. The "%" representing the chemical composition in the present description means "wt%" unless particularly indicated otherwise.
[Mg: 2.0-8.Oo]
Mg is an element improving the strength. In order to manifest this effect, it is necessary to set the Mg content to 2.0o or more. However, if the Mg content exceeds 8.0o, the castability of a thin slab is lowered.
Accordingly, the Mg content is limited to 2.0 to 8.0a. If stressing the castability, preferably the upper limit of the Mg content is further limited to 6.0o or less.
[Si: 0. 06-0.2 0]
Si is precipitated as fine particles of Al-Fe-Si-based, Mg2Si, and other inter-metallic compounds at the time of casting and functions as a nucleus generating site of recrystallization at the time of annealing after cold rolling. Accordingly, the larger the number of particles of these inter-metallic compounds, the larger the number of generated recrystallized nucleii and as a result the larger number of fine recrystallized grains formed. Further, the fine particles of the inter-metallic compounds pin the grain boundaries of the generated recrystallized grains and suppress growth due to merging of crystal grains to stably maintain the fine recrystallized grains.
In order to manifest these effects, it is necessary to make the Si content 0.060 or more. However, if the Si content exceeds 0.20, the tendency of the precipitated inter-metallic compounds to become coarser becomes stronger, so the formation of cavities is promoted at the time of high temperature deformation. Accordingly, the Si content is limited to 0.06 to 0.20. The preferred range is 0.07 to 0.150.
In general, Si is regarded as an impurity element to be eliminated in the same way as the following Fe, but in the present invention, conversely a suitable amount of Si is made present in order to increase the fineness of the recrystallized grains as described above. Accordingly, high purity metal is not needed and there is no accompanying rise in cost.
[Fe: 0.1-0.50]
Fe is precipitated as fine grains of Al-Fe-Si-based or other inter-metallic compounds at the time of casting and functions as a nuclei generating site of recrystallization at the time of annealing after cold rolling. Accordingly, the larger the number of particles of these inter-metallic compounds, the larger the number of the generated recrystallized nucleii and as a result the larger the number of fine recrystallized grains formed. Further, the fine particles of the inter-metallic compounds pin the grain boundaries of the generated recrystallized grains and suppress the growth due to merger of crystal grains to stably maintain the fine recrystallized grains. In order to manifest this effect, it is necessary to make the Fe content 0.10 or more.
However, if the Fe content exceeds 0.50, the tendency of the precipitated inter-metallic compounds to become coarser becomes stronger, so the occurrence of cavities is promoted at the time of high. temperature deformation.
Accordingly, the Fe content is limited to 0.1 to 0.50. A
preferred range is 0.1 to 0.30.
In general, Fe is regarded as an impurity element to be eliminated in the same way as the above Si, but in the present invention, conversely a suitable amount of Fe is made present in order to increase the fineness of the recrystallized grains as described above. Accordingly, high purity metal is not needed and there is no accompanying rise in cost.
[Mn: 0.1-0.5%]
Mn is an element increasing the fineness of the recrystallized grains. In order to manifest this effect, it is necessary to make the Mn content 0.10 or more.
However, if the Mn content exceeds 0.50, a coarse Al-(Fe~Mn)-Si-based inter-metal compound is formed, and the occurrence of cavities is promoted at the time of high temperature deformation. Accordingly, the Mn content is limited to 0.1 to 0.5%. Particularly, when stressing the prevention of occurrence of cavities; preferably the upper limit of the Mn content is further restricted to 0.3a.
[Optional ingredient Cu: 0.1-0.50]
In the present invention, Cu can be added within a range of 0.1-0.5o in order to improve the strength of the aluminum alloy sheet. In order to obtain precipitation hardening effect sufficiently, it is necessary to make the amount of addition of Cu 0.10 or more. However if the amount of addition of Cu exceeds 0.5o, the castability is lowered. When stressing the castability, preferably the upper limit of the amount of addition of Cu is further restricted to 0.30 or less.
[Optional ingredients Zr and Cr: 0.1-0.40]
In the present invention, in order to assist the increased fineness of the recrystallized grains, at least one type of Zr and Cr can be incorporated within a range of 0.1-0.40. Zr and Cr are elements for increasing the fineness of the recrystallized grains. In order to manifest this effect, it is necessary to make the amounts of addition of both the Zr and Cr 0.10 or more. However, if the amounts of addition exceed 0.40, coarse inter-metallic compounds are formed at the time of the casting, and the occurrence of cavities is promoted at the time of high temperature deformation. Particularly, when stressing the prevention of the occurrence of cavities, preferably the upper limits of the amounts of addition are further restricted to 0.20 or less.
[Other elements]
In the present invention, in order to increase the fineness of the casting structure, Ti can be added within a range of 0.001-0.150. In order to manifest this effect, it is necessary to make the amount of addition of Ti 0.0010 or more. However, if the amount of addition of Ti exceeds 0.150, a coarse compound such as TiAl3 is generated, the formability at a high temperature is deteriorated, and the occurrence of cavities is promoted.
A preferred range is 0.006-0.100.
Next, the reasons for the limitation of the microstructure of the alloy sheet in the present invention will be explained.
[Density of inter-metallic compounds having equivalent circle diameters of 1 to 5 ~m of 5000/mm2 or more]
The present invention utilizes the fine inter-metallic compound particles as (1) the recrystallized grain nuclei generating sites and (2) means for pinning the grain boundaries of the recrystallized grains and generates finer recrystallized grains by the annealing after the cold rolling. The fine grain structure obtained by this gives a high elongation at the time of deformation at high temperatures and high speeds, whereby the formability at high temperatures and high speeds is - g -enhanced.
In order to obtain the above effect, the inter-metallic compound having the equivalent circle diameter of 1 to 5 ~,m,must be present in a density of 5000/mm2 or more. As the inter-metallic compound, as already mentioned, inter-metallic compounds such as Al-(Fe~Mn)-Si-based compounds, Mg2Si, and Al6Mn are precipitated during casting. In order to manifest the effects of the above (1) and (2) by these inter-metallic compounds, the equivalent circle diameter must be 1 to 5 ~,m. If the equivalent circle diameter is less than 1 Vim., the particles are too small to manifest the effects of (1) and (2) described above. Conversely, if it exceeds 5 Vim, cavities are easily generated at the time of deformation at high temperatures and high speeds, and the strength and elongation after the shaping are lowered.
The inter-metallic compounds having the size within the above described range must be present at a density of 5000/mm2 or more.
If the density is less than 5000/mm2, the recrystallized grain diameter at the time of the annealing exceeds 20 Vim, and the elongation at the time of high temperature deformation.is lowered.
[Average crystal grain diameter of 20 ~tm or less]
In the alloy sheet of the present invention, the average crystal grain diameter is made 20 ~m or less. If the average crystal grain diameter exceeds 20 ~,m, the elongation at the time of the high temperature deformation is lowered.
The reasons for the limitation of conditions of the method of production of the present invention will be explained next.
[Slab having thickness of 5 to 15 mm cast by twin ~ belt casting and taken up in the form of a coil]
The twin belt casting method is a continuous casting method injecting a melt into a mould of a pair of water cooled rotating belts facing each other from one end in the vertical direction, solidifying the melt by the cooling from the belt surfaces to form the slab, pulling out the formed slab from the other end of the mould, and taking it up in the form of a coil.
In the present invention, the thickness of the slab cast by this twin belt casting method is made 5 to 15 mm.
When the thickness is within this range, a high solidification speed can be secured even at the center portion of the sheet thickness, therefore a uniform casting structure can be easily formed. Simultaneously, with the composition of the present invention, it is possible to easily suppress the generation of coarse inter-metallic compounds and it becomes easy to control the average grain size of the recrystallized grains in the final sheet product to 20 ~,m or less. The above described slab thickness range is also suitable from the viewpoint of the twin belt casting.
Namely, if the slab thickness is less than 5 mm, the amount of the aluminum alloy melt passing through the casting machine per unit time becomes too small, so the twin belt casting becomes difficult. If the slab thickness exceeds 15 mm, it becomes difficult to rewind it up as a coil.
[Cooling rate at time of casting of 20 to 150°C/sec]
In the method of production of the present invention, a slab having a thickness of 5 to 15 mm is cast by twin belt casting. At that time, in order to cause the precipitation of inter-metallic compounds having the equivalent circle diameter of 1 to 5 ~m prescribed for the alloy of the present invention with a density of 5000/mm2 or more, the cooling rate at the location of 1/4 of the slab thickness during the casting is made 20 to 150°C/sec. In the aluminum alloy of the present invention, the inter-metallic compounds such as the Al-(Fe~Mn)-Si-based compounds and Mg2Si are precipitated at the time of the casting. If the cooling rate is less than 20°C/sec, these inter-metallic compounds become coarse and the compounds exceeding 5 ~tm increase.
Conversely, if the cooling rate exceeds 150°C/sec, the inter-metallic compounds become finer and the compounds less than 1 ~m increase. In the end, in either case, the density of the inter-metallic compounds having the equivalent circle diameter of 1 to 5 ~m becomes less than 5000/mm2 and the nuclei of the recrystallized grains become fewer at the time of the final annealing (CAL), so the recrystallized grains become coarse.
[Cold rolling with cold rolling reduction of 70 to 960]
Accumulation of dislocation occurring due to the plastic working by the cold rolling around the intermetallic compounds is indispensable for forming the fine recrystallization structure at the time of the final annealing. If the cold rolling reduction is less than 700, the accumulation of the dislocations becomes insufficient and a fine recrystallization structure cannot be obtained. If the cold rolling reduction exceeds 96%, edge cracks occur during the cold rolling, so cold rolling becomes difficult.
[Annealing for heating to 420 to 500°C at a rate of temperature rise of 5°C/sec or more]
In the present invention, the above annealing is conducted as the final annealing after the cold rolling.
This is generally conducted by the continuous annealing, but it is not particularly necessary to limit the annealing to this.
The annealing temperature of the final annealing is made a range of 420 to 500°C. If the temperature is less than 420°C, the energy required for recrystallization is insufficient, therefore the recrystallization becomes insufficient and a fine recrystallization structure cannot be obtained. However, if it exceeds~500°C, the recrystallized grain diameter exceeds 20 ~tm, and the fine recrystallization structure cannot be obtained.
The heating rate to the annealing temperature is made 5°C/sec or more. If the temperature is slowly elevated by a rate less than 5°C/sec, the recrystallized grains become coarse, so the fine recrystallization structure cannot be obtained.
Finally, the forming of the aluminum alloy sheet of the present invention is preferably conducted at a temperature of 400-500°C. If the forming temperature is less than 400°C, a sufficient elongation cannot be obtained. If the forming temperature exceeds 550°C, the coarsening of the crystal grains occurs. Further, burning occurs in an alloy having a high Mg content within the range of the present invention, and the elongation is lowered. The strain rate at the time of the shaping is preferably 0.1/sec or more. If the strain rate is less than 0.1/sec, the coarsening of the crystal grains occurs during the forming, so a drop of the elongation is induced.
Examples Aluminum alloy melts having the compositions shown in Table 1 were cast by the twin belt casting method to form slabs having thicknesses of 7 to 9 mm. Each slab was cold rolled down to a thickness of 1 mm and annealed at 450°C, then test pieces prescribed in JIS H7501 were cut out and measured for elongation after a tensile test.
Further, cross-sections of broken samples were polished, then the area ratios of the cavities (cavity ratios) were measured by an image analyzer. The production process and characteristics are shown in Table 2.
Table 1: Alloy Composition (wto) Alloy Mg Mn Fe Si Cu Zr A 3.1 0.3 0.12 0.07 - -B 5.2 0.3 0.15 0.10 - -C 7.1 0.4 0.10 0.09 - -D 3.2 0.2 0.12 0.07 0.3 -E 3.2 0.2 0.12 0.07 - 0.2 U
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o z m z Sheets obtained by cold rolling thin slabs cast by a twin belt casting machine (products of the present invention, Sample Nos. 1 to 7), as apparent also from the alloy compositions of Table 1, irrespective of the fact that the Fe contents were 0.10 or more and the Si contents were 0.060 or more in all samples, had densities of the inter-metallic compounds having equivalent circle diameters of 1 to 5 ~,m of 5000/mm~ or more and crystal grain sizes of 20 ~.m or less. For this reason, the elongations at the tensile temperature of 500°C were good ones of 2000 or more and also the cavity ratios after the high temperature tension were good ones of the range of 0.15-0.270 or less than 1%.
A sheet obtained by cold rolling a thin slab cast by a twin roll casting machine (comparative example, Sample No. 8) had a large number of very fine intermetallic compounds having equivalent circle diameters less than 1 ~.m since the cooling rate at the time of the casting was a relatively high 300°C/sec, therefore the density of~the inter-metallic compounds having an equivalent circle diameter of 1 to 5 ~.m in the final sheet became less than 5000/mm2 or coarse exceeding the crystal grain size of 20 ~.m or more. For this reason, the cavity ratio after the high temperature tension was a relatively low good one of 0.120, but the elongation at the tensile temperature of 500°C was a poor 80o.
A sheet obtained by soaking an ordinary slab cast by a DC casting machine, then hot rolling the slab down to a thickness of 7 mm, then cold rolling (comparative example, Sample No. 9) had a cooling rate at the time of the casting of a relatively slow 5°C/sec, therefore intermetallic compounds having an equivalent circle diameter exceeding 5 ~,m were generated, therefore the density of intermetallic compounds having an equivalent circle diameter of 1 to 5 ~m in the final sheet became - 15 ~-less than 5000/mm2, and the crystal grains became slightly coarse exceeding 20 Vim. For this reason, the cavity ratio after the high temperature tensile test was a poor high 1.50, while the elongation at the tensile temperature of 500°C was a poor 1600.
A sheet obtained by cold rolling a thin slab cast by a twin belt casting machine down to the sheet thickness of 2 mm, then intermediate annealing the slab at 350°C, then cold rolling down to 1 mm (comparative example, Sample No. 10) had a density of inter-metallic compounds of an equivalent circle diameter of 1 to 5 ~tm in the final sheet of 5000/mm2 or more, but the cold rolling reduction before the final annealing was a low one of less than 700, therefore the crystal grains became slightly coarse exceeding the crystal grain size of 20 ~,m. The elongation at the tensile temperature of 500°C was a poor one of less than 2000.
A sheet obtained by cold rolling a thin slab cast by a twin belt casting machine (comparative example, Sample No. 11) had a density of inter-metallic compounds having an equivalent circle diameter of 1 to 5 ~m in the final sheet of 5000/mm2 or more and a crystal grain size of 20 ~m or less. However, the tensile temperature in the tensile test was a relatively low 350°C, therefore the elongation was a poor one of less than 2000.
A sheet obtained by cold rolling a thin slab cast by a twin belt casting machine (comparative example, Sample No. 12) had a density of inter-metallic compounds having an equivalent circle diameter of 1 to 5 ~tm in the final sheet of 5000/mm2 or more and a crystal grain size of 20 ~.m or less. However, the tensile speed in the tensile test was a relatively slow 0.01/sec, therefore the cavity ratio after the high temperature tension was also a poor 1.8o and the elongation at the tensile temperature of 500°C was a poor one of less than 2000.
INDUSTRIAL APPLICABILITY
According to the present invention, aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after the forming and the method of production of the same are provided.,
Claims (6)
1. An aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming characterized in that it consists of:
Mg: 2.0-8.0wt %, Si : 0.06-0.2wt %, Fe: 0.1-0.5wt%, Mn: 0.1-0.5wt%, and the balance of Al and unavoidable impurities, wherein a density of an inter-metallic compound having an equivalent circle diameter of 1 to 5 µm is 5000/mm2 or more and an average crystal grain size is 20 µm or less.
Mg: 2.0-8.0wt %, Si : 0.06-0.2wt %, Fe: 0.1-0.5wt%, Mn: 0.1-0.5wt%, and the balance of Al and unavoidable impurities, wherein a density of an inter-metallic compound having an equivalent circle diameter of 1 to 5 µm is 5000/mm2 or more and an average crystal grain size is 20 µm or less.
2. An aluminum alloy sheet as set forth in claim 1, characterized by further containing Cu: 0.1 to 0.5 wt%.
3. An aluminum alloy sheet as set forth in claim 1 or 2, characterized by further containing at least one of Zr: 0.1 to 0.4 wt% and Cr: 0.1 to 0.4 wt%.
4. An aluminum alloy sheet as set forth in any one of claims 1 to 3, characterized in that an elongation during tensile deformation at a strain rate of 0.1 to 1.0/sec in a temperature region of 400 to 550°C is at least 200%.
5. An aluminum alloy sheet as set forth in claim 4, characterized in that a cavity ratio in a cross-section after breakage due to the tensile deformation is not more than 10.
6. A method of production of an aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming as set forth in any one of claims 1 to 5, characterized in that said method comprises the steps of:
preparing an alloy melt having a composition as set forth in any one of claims 1 to 3, casting the alloy melt by a twin belt casting machine at a cooling rate of 20 to 150°C/sec at the location of 1/4 of the slab thickness during casting to form a slab having a thickness of 5 to 15 mm, subsequently rewinding up the slab as a coil, cold rolling the slab taken out from the coil with a cold rolling reduction of 70 to 96%, and performing annealing for heating the obtained cold rolled sheet at a heating rate of 5°C/sec or more to 420 to 500°C.
preparing an alloy melt having a composition as set forth in any one of claims 1 to 3, casting the alloy melt by a twin belt casting machine at a cooling rate of 20 to 150°C/sec at the location of 1/4 of the slab thickness during casting to form a slab having a thickness of 5 to 15 mm, subsequently rewinding up the slab as a coil, cold rolling the slab taken out from the coil with a cold rolling reduction of 70 to 96%, and performing annealing for heating the obtained cold rolled sheet at a heating rate of 5°C/sec or more to 420 to 500°C.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004128040A JP4534573B2 (en) | 2004-04-23 | 2004-04-23 | Al-Mg alloy plate excellent in high-temperature high-speed formability and manufacturing method thereof |
| JP2004-128040 | 2004-04-23 | ||
| PCT/JP2005/007657 WO2005103313A1 (en) | 2004-04-23 | 2005-04-15 | Al-mg alloy sheet with excellent formability at high temperatures and high speeds and method of production of same |
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| CA2563789A1 true CA2563789A1 (en) | 2005-11-03 |
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| CA002563789A Abandoned CA2563789A1 (en) | 2004-04-23 | 2005-04-15 | Al-mg alloy sheet with excellent formability at high temperatures and high speeds and method of production of same |
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| Country | Link |
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| US (1) | US20070217943A1 (en) |
| EP (1) | EP1737995A1 (en) |
| JP (1) | JP4534573B2 (en) |
| KR (1) | KR20060135849A (en) |
| CN (1) | CN100519797C (en) |
| CA (1) | CA2563789A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| JPS5822363A (en) * | 1981-07-30 | 1983-02-09 | Mitsubishi Keikinzoku Kogyo Kk | Preparation of ultra-plastic aluminum alloy plate |
| JP2671121B2 (en) * | 1986-03-10 | 1997-10-29 | スカイアルミニウム 株式会社 | Rolled aluminum alloy sheet for forming, which has excellent elongation, bendability, and overhanging property, and method for producing the same |
| AT394580B (en) * | 1989-11-30 | 1992-05-11 | Austria Metall Aktienges | METHOD FOR PRODUCING A SHEET FROM AN ALUMINUM ALLOY FOR COMPONENTS |
| JPH04325659A (en) * | 1991-04-26 | 1992-11-16 | Sky Alum Co Ltd | Manufacture of aluminum alloy hard sheet for forming excellent in tearing property |
| JP2865499B2 (en) * | 1991-09-26 | 1999-03-08 | 健 増本 | Superplastic aluminum-based alloy material and method for producing superplastic alloy material |
| US5332456A (en) * | 1991-09-26 | 1994-07-26 | Tsuyoshi Masumoto | Superplastic aluminum-based alloy material and production process thereof |
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| JPH08199272A (en) * | 1995-01-19 | 1996-08-06 | Nippon Steel Corp | Aluminum alloy sheet and forming method |
| JP3145904B2 (en) * | 1995-08-23 | 2001-03-12 | 住友軽金属工業株式会社 | Aluminum alloy sheet excellent in high speed superplastic forming and its forming method |
| FR2752244B1 (en) * | 1996-08-06 | 1998-09-18 | Pechiney Rhenalu | PRODUCT FOR WELDED CONSTRUCTION IN ALMGMN ALLOY WITH IMPROVED CORROSION RESISTANCE |
| JPH10259441A (en) * | 1997-03-19 | 1998-09-29 | Sumitomo Light Metal Ind Ltd | Aluminum alloy sheet excellent in high speed superplastic formability and small number of cavity after forming and its production |
| JP3685973B2 (en) * | 2000-03-23 | 2005-08-24 | 株式会社神戸製鋼所 | Al-Mg-based Al alloy plate with excellent formability |
| JP4001059B2 (en) * | 2002-06-21 | 2007-10-31 | 日本軽金属株式会社 | Method for producing aluminum alloy sheet with excellent bake resistance |
| US6811625B2 (en) * | 2002-10-17 | 2004-11-02 | General Motors Corporation | Method for processing of continuously cast aluminum sheet |
-
2004
- 2004-04-23 JP JP2004128040A patent/JP4534573B2/en not_active Expired - Fee Related
-
2005
- 2005-04-15 EP EP05734276A patent/EP1737995A1/en not_active Withdrawn
- 2005-04-15 WO PCT/JP2005/007657 patent/WO2005103313A1/en not_active Application Discontinuation
- 2005-04-15 CA CA002563789A patent/CA2563789A1/en not_active Abandoned
- 2005-04-15 CN CNB2005800124198A patent/CN100519797C/en not_active Expired - Fee Related
- 2005-04-15 US US11/578,908 patent/US20070217943A1/en not_active Abandoned
- 2005-04-15 KR KR1020067020240A patent/KR20060135849A/en not_active Application Discontinuation
- 2005-04-22 TW TW094112865A patent/TWI310789B/en not_active IP Right Cessation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8016958B2 (en) | 2006-07-18 | 2011-09-13 | Nippon Light Metal Company, Ltd. | High strength aluminum alloy sheet and method of production of same |
| CN110216166A (en) * | 2019-06-21 | 2019-09-10 | 天津忠旺铝业有限公司 | A kind of production method of television stand aluminium alloy strips |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2005307300A (en) | 2005-11-04 |
| CN100519797C (en) | 2009-07-29 |
| JP4534573B2 (en) | 2010-09-01 |
| WO2005103313A1 (en) | 2005-11-03 |
| TWI310789B (en) | 2009-06-11 |
| CN1946861A (en) | 2007-04-11 |
| US20070217943A1 (en) | 2007-09-20 |
| EP1737995A1 (en) | 2007-01-03 |
| KR20060135849A (en) | 2006-12-29 |
| TW200540280A (en) | 2005-12-16 |
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