KR20150111373A - Aluminum alloy sheet for battery case having good moldability and weldability - Google Patents

Abstract

Al-Fe-based aluminum alloy plate which has a high strength applicable to a large-sized lithium ion battery container, excellent in moldability, and also excellent in laser weldability. Wherein the steel sheet contains 0.3 to 1.5% by mass of Fe, 0.3 to 1.0% by mass of Mn, and 0.002 to 0.20% by mass of Ti, the mass ratio of Mn / Fe is 0.2 to 1.0 and the balance Al and inevitable impurities, Si, Cu and Mg as the impurities are respectively composed of less than 0.30 mass% of Si, less than 0.20 mass% of Cu and less than 0.20 mass% of Mg, and less than 0.5 mass / An aluminum alloy plate having a metal structure, a cold rolled steel sheet having a drawn value of 5% or more and a tensile strength of 90 MPa or more. Or a cold rolled annealing material having a simply stretched value of 20% or more. 0.05 to 0.20 mass% of Zr may be further added to prevent ingot cracking during casting or bead cracking during laser welding.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an aluminum alloy plate for a battery case,

The present invention relates to an aluminum alloy plate excellent in formability and laser weldability, which is used in a container for a secondary battery such as a lithium ion battery.

Al-Mn based 3000 series alloys are relatively excellent in strength, formability, and laser weldability, and therefore, they are used as materials for manufacturing secondary battery containers such as lithium ion batteries. Molded into a desired shape, sealed by sealing with laser welding, and used as a container for a secondary battery. There has been developed an aluminum alloy plate for a secondary battery container in which the 3000 alloy and the 3000 alloy are used as a base and the strength and moldability are improved.

For example, in Japanese Patent No. 4001007, the aluminum alloy sheet has a composition of 0.10 to 0.60 mass% of Si, 0.20 to 0.60 mass% of Fe, 0.10 to 0.70 mass% of Cu, 0.60 to 1.50 mass% of Mn, : 0.20 to 1.20 mass%, Zr: more than 0.12 to less than 0.20 mass%, Ti: 0.05 to 0.25 mass%, and B: 0.0010 to 0.02 mass%, the balance Al and inevitable impurities, And an aluminum alloy sheet for a rectangular cross-sectional battery container characterized in that a 45 ° earring with respect to the rolling direction is 4 to 7% by a drawing forming method.

On the other hand, recently, an aluminum alloy plate for a rectangular type lithium ion battery case having sufficient strength, drawing-ironing workability and creep characteristics as a battery case and excellent in laser weldability and capable of suppressing an increase in case thickness during a charge- . Japanese Patent Application Laid-Open No. 2010-126804 discloses a steel sheet comprising at least 0.8% by mass of Mn, at most 1.8% by mass, at most 0.6% by mass and at most 1.2% by mass of Mg, and at most 1.5% by mass of Cu, , A Fe content as an impurity of 0.5% by mass or less and Si content of 0.3% by mass or less, a balance Al and inevitable impurities, a bearing density C of {001} (C / S) of the orientation density S of the orientation is 0.65 or more and 1.5 or less, and the tensile strength after final cold rolling is 250 MPa or more and 330 MPa or less and the elongation is 1% or more.

However, it has been known that an aluminum alloy plate whose composition is improved by using a 3000-based alloy as a base has a problem of insufficient weld penetration depth, and in some cases, an abnormal bead is generated, thereby causing a problem in laser weldability.

Therefore, an aluminum alloy plate for a secondary battery container excellent in laser weldability based on a 1000-system has also been developed. Japanese Patent Application Laid-Open No. 2009-127075 discloses a pulsed laser welding method in which an aluminum alloy material for pulsed laser welding capable of forming an excellent welded portion by preventing occurrence of an abnormal portion by pulsed laser welding, . According to this, in order to prevent the formation of an abnormal portion when the A1000 system aluminum is welded by the pulse laser welding, Ti added to suppress coarsening of crystal grains during the casting process adversely affects the welded portion , And that the content of Ti contained in pure aluminum is limited to less than 0.01% by mass.

Japanese Unexamined Patent Application Publication No. 2003-7260 discloses an aluminum alloy having improved strength, formability and weldability based on a 3000-based alloy. The aluminum alloy contains 0.3 to 1.5 mass% of Mn, more than 1.0 and 1.8 mass% of Fe, An aluminum alloy plate for a secondary battery case comprising a remaining amount Al and inevitable impurities has been proposed. And may further contain 0.1 to 0.8% by mass of Cu and / or more than 0.10 to 1.0% by mass of Cu and 0.05 to 0.2% by mass and / or Zr: 0.05 to 0.2% by mass of Cr. However, the weldability has not been examined in detail.

Surely, the 1000 system has a problem that the weldability is stable (the number of beads is more than that), the formability is excellent but the strength is low. Therefore, while the lithium ion battery is being made larger, high-strength characteristics are also expected to be required, and there is a problem in applying 1000-series aluminum material as it is.

As described above, although the 3000 series alloy plate has strength and a deep penetration depth, it has a lower moldability than the 1000 series alloy plate and tends to have a larger number of abnormal beads. Further, in the case of the alloy sheet of 1000 series, the moldability is excellent and the number of abnormal beads is decreased, but there is a fear of insufficient strength.

An object of the present invention is to provide an Al-Fe-based aluminum alloy plate that has high strength that can be applied to a large-sized lithium ion battery container, is excellent in moldability, and is also excellent in laser weldability .

The aluminum alloy sheet for a battery case having excellent moldability and weldability of the present invention contains 0.3 to 1.5% by mass of Fe, 0.3 to 1.0% by mass of Mn and 0.002 to 0.20% by mass of Ti, Cu, and Mg as inevitable impurities are contained in an amount of less than 0.30 mass% of Si, less than 0.20 mass% of Cu, less than 0.20 mass% of Si, 0.20 mass% of Mg, and a balance of Al and inevitable impurities. % And a number of second phase particles having a circle-equivalent diameter of 5 m or more and less than 500 pieces / mm < 2 >.

In the case of a cold-rolled ash, a stretching value of 5% or more and a tensile strength of 90 MPa or more are to be exhibited. Further, in the case of a cold-rolled annealing material, it is assumed that an elongation value of 20% or more is exhibited.

In order to prevent ingot cracking during casting and bead cracking during laser welding, Zr: 0.05 to 0.20 mass% may also be contained.

Since the aluminum alloy plate of the present invention has high strength and excellent moldability and also has excellent laser weldability, it is possible to manufacture a container for a secondary battery which is excellent in sealing performance and can suppress inflating have.

In particular, when the material is a cold-rolled material, it has a tensile strength of 90 MPa or more. When the material is a cold-rolled annealing material, the drawn value is 20% or more.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram for explaining a method for measuring / evaluating abnormal bead counts, and is a graph showing a change in bead width along (A) a top view of a weld bead and (B) a bead length direction.
Fig. 2 is a conceptual diagram for explaining a method of measuring / evaluating the penetration depth. Fig. 2 (A) is a top view and (B) sectional view of a weld bead.

The secondary battery is manufactured by inserting an electrode body into a container, sealing it with a lid by welding or the like. When such a secondary battery is used in a cellular phone or the like, the temperature inside the container rises during charging, and the pressure inside the container may increase. Therefore, when the strength of the material constituting the container is low, there is a problem that large swelling is generated in the container produced. Therefore, it is required to have high strength as a material to be used.

Further, since the press method is generally used as a method for constructing the container, it is required that the material itself used has excellent press formability.

In addition, since the welding method is used as a method of covering and sealing the lid, it is also required to have excellent weldability. In many cases, a laser welding method is used as a welding method at the time of manufacturing a secondary battery container or the like.

However, regarding the laser weldability, it is a problem to obtain a deeper penetration depth with respect to (1) stability of weld bead width, stability of penetration depth, and (2) weld bead width.

Generally, if the width of the weld bead is widened, the penetration depth tends to be deepened. Therefore, the width of the weld bead is locally widened at the ideal bead portion, the penetration depth is deepened, and if it is too large, penetration of the molten portion occurs, resulting in degradation of the performance and reliability of the battery.

On the other hand, in order to investigate the penetration depth, it is necessary to observe a large number of cross sections and labor is required. However, since the weld bead width and the weld depth are correlated in the same alloy as described above, the weld bead width is measured and the abnormal (coarse) bead is detected, so that the ratio of the bead having an abnormal penetration depth, which is a problem, .

The inventors of the present invention have conducted intensive investigations to obtain an aluminum alloy plate excellent in laser weldability through investigation of the number of abnormal beads occurring in the welded portion and the depth of penetration in the welded portion while achieving excellent press formability at high strength, did.

The contents will be described below.

First, the function, proper content, and the like of each element contained in the aluminum alloy sheet for a secondary battery container of the present invention will be described.

Fe : 0.3 to 1.5 mass%

Fe is an indispensable element for increasing the strength of the aluminum alloy plate and ensuring the depth of penetration in laser welding. If the Fe content is less than 0.3% by mass, the strength of the aluminum alloy sheet is lowered, and the penetration depth at the time of laser welding is reduced, which is not preferable. When the content of Fe exceeds 1.5 mass%, this action intermetallic compounds such as Al- (Fe · Mn) -Si-based, Al ₆ Fe is crystallized at the time of ingot casting, at the same time that the moldability of the final degradation , These intermetallic compounds tend to evaporate more easily than the Al matrix during laser welding, and the number of abnormal beads increases, which deteriorates the weldability.

Therefore, the Fe content is in the range of 0.3 to 1.5% by mass. A more preferable Fe content is in the range of 0.5 to 1.5% by mass. A more preferable content of Fe is 0.7 to 1.5% by mass.

Mn : 0.3 to 1.0 mass%

Mn is an indispensable element in order to increase the strength of the aluminum alloy sheet and ensure the depth of penetration in laser welding. If the Mn content is less than 0.3% by mass, the strength of the aluminum alloy sheet is lowered, and the depth of penetration at the time of laser welding is reduced, which is not preferable. When the content of Mn exceeds 1.0%, this action of intermetallic compounds such as Al- (Fe · Mn) -Si-based, Al ₆ Mn during casting ingot is extruded at the same time that the moldability of the final degradation , These intermetallic compounds tend to evaporate more easily than the Al matrix during laser welding, and the number of abnormal beads increases, which deteriorates the weldability.

Therefore, the Mn content is set in the range of 0.3 to 1.0 mass%. A more preferable Mn content is in the range of 0.3 to 0.8% by mass. More preferably, the Mn content is in the range of 0.4 to 0.7 mass%.

Ti : 0.002 to 0.20 mass%

Ti acts as a grain refining agent at the time of ingot casting, and can prevent casting cracks.

Of course, Ti may be added singly, but because it can coexist with B, a finer effect of crystal grains can be anticipated. Therefore, it may be added in a rod hardener such as Al-5% Ti-1% B.

If the Ti content is less than 0.002 mass%, the effect of making the ingot in casting insufficient is insufficient, which may cause casting cracks, which is not preferable. When the Ti content is more than 0.20 mass%, a coarse intermetallic compound such as TiAl ₃ is crystallized at the time of ingot casting to lower the formability in the final plate, which is not preferable.

Therefore, the Ti content is set in the range of 0.002 to 0.20 mass%. The more preferable Ti content is in the range of 0.002 to 0.15 mass%. The Ti content is more preferably in the range of 0.005 to 0.10 mass%.

Zr : 0.05 to 0.20 mass%

Like Zr, Zr acts as a grain refining agent at the time of ingot casting, and casting cracks can be prevented. Coexistence of Ti and Zr also prevents the generation of cracks at the time of solidification of the weld bead portion accompanied by quenching and solidification, thereby enabling high speed pulsed laser welding. When Ti, Zr and B are coexisted, the effect of preventing cracking during solidification of the weld bead portion accompanied by quenching and solidification becomes more significant. For this reason, it is contained if necessary.

When the Zr content exceeds 0.20 mass%, ZrAl ₃ Or the like is crystallized to lower the moldability in the final plate, which is not preferable. If the Zr content is less than 0.05 mass%, sufficient effect can not be obtained. Therefore, the preferable Zr content is 0.05 to 0.20 mass%. A more preferable Zr content is in the range of 0.07 to 0.20 mass%. More preferably, the Zr content is in the range of 0.07 to 0.18 mass%.

B: 0.0005 to 0.10 mass%

B, like Ti and Zr, acts as a crystal grain refining agent at the time of ingot casting and can prevent casting cracks, so that B may be added as needed.

If the B content exceeds 0.10% by mass, TiB ₂ becomes a stabilized intermetallic compound, attenuating the grain refinement effect and, at the same time, raising the roughness of the outer surface after DI molding, which is not preferable. If the B content is less than 0.0005 mass%, sufficient grain refinement effect can not be obtained. Therefore, the preferred B content is 0.0005 to 0.10 mass%. The B content is more preferably in the range of 0.001 to 0.05 mass%. The B content is more preferably in the range of 0.001 to 0.01 mass%.

Inevitable  Impurity Si  Content: less than 0.30 mass%

The content of Si as an inevitable impurity is preferably limited to less than 0.30 mass%. When the Si content is 0.30 mass% or more, a coarse intermetallic compound such as Al- (Fe.Mn) -Si is crystallized at the time of ingot casting and the formability is lowered. The more preferable Si content is less than 0.25 mass%. More preferably, the Si content is less than 0.20 mass%.

In the present invention, when the Si content is less than 0.20 mass%, the properties such as moldability and weldability do not deteriorate.

Inevitable  Impurity Cu : Less than 0.2% by mass

Cu as an unavoidable impurity may be contained in an amount of less than 0.2 mass%. In the present invention, when the Cu content is less than 0.2% by mass, the properties such as moldability and weldability do not deteriorate.

Inevitable  Impurity Mg : Less than 0.2% by mass

Mg as an unavoidable impurity may be contained in an amount of less than 0.2 mass%. In the present invention, when the Mg content is less than 0.2 mass%, the properties such as moldability and weldability do not deteriorate.

Other Inevitable  impurities

Inevitable impurities are inevitably incorporated from raw materials, rebar, etc., and their allowable content is, for example, less than 0.25% by mass of Zn, less than 0.20% by mass of Ni, And less than 0.05% by mass, respectively, for Pb, Bi, Sn, Na, Ca, and Sr in the range of less than 0.05% It is not.

Mn / Fe Mass ratio: 0.2 to 1.0

If the Mn / Fe ratio is less than 0.2 within the range of the contents of Fe and Mn within the range of the present invention, the depth of penetration during laser welding decreases, which is not preferable. If the Mn / Fe ratio is in excess of 1.0 within the range of Fe and Mn within the range of the present invention, the number of abnormal beads increases, which is not preferable.

However, the mass ratio of Mn / Fe affects the kind and amount of the intermetallic compound to be crystallized at the time of ingot casting. For example, when the Mn / Fe mass ratio is increased, it is also known that the number of intermetallic compounds of the Al ₆ Mn system increases.

On the other hand, intermetallic compounds such as Al ₆ Mn thereof is unstable readily evaporated as compared to the intermetallic compound such as _{Al-Fe-Si, Al 6} Fe, Al 3 Fe at the time of laser welding. Therefore, when the Mn / Fe ratio exceeds 1.0, it is considered that the number of abnormal beads at the time of laser welding increases and weldability decreases.

Further, Mn is an element more important than Fe in securing the depth of penetration in laser welding because it increases the thermal resistance of the material by solid-melting in the Al matrix.

Therefore, if the Mn / Fe ratio is less than 0.2, it is considered that the penetration depth at the time of laser welding is insufficient.

Tensile strength and Elongation value

Cold rolled ash: Stretched  Value of 5% or more, and a tensile strength of 90 MPa  More than

Cold rolling Annealing material : Stretched  More than 20% value

However, when an Al-Fe-based aluminum alloy plate is applied to a large lithium ion battery container or the like, it is necessary to not only have high strength, excellent laser weldability, but also excellent moldability. The strength of the material is the tensile strength at the time of performing the tensile test, and the formability can be known by the stretched value at the time of the tensile test.

The Al-Fe-based aluminum alloy sheet of the present invention, which is applied to a large-sized lithium ion battery container or the like, has a stretched value of not less than 5% and a tensile strength of not less than 90 MPa It is preferable that the cold-rolled annealing material has a characteristic that the drawn value is 20% or more.

The number of the second phase particles having a circle-equivalent diameter of at least 5 mu m in the metal structure is less than 500 pieces /

Such characteristics are expressed by finely adjusting the metal structure of the Al-Fe-based aluminum alloy sheet having the specified chemical composition.

Concretely, the number of the second phase particles having a circle-equivalent diameter of 5 탆 or more in the metal structure may be less than 500 pieces / mm 2.

There is no difference in the metal structure between the cold rolled annealed sheet and the cold rolled annealed sheet. In the cold-rolled ash, if the metal structure as described above is present, it shows a stretched value of 5% or more, a tensile strength of 90 MPa or more, and a cold rolled annealing material of 20% or more.

Next, a method of manufacturing the aluminum alloy plate for a secondary battery container as described above will be briefly described.

Solvent · Solvent

After the raw material is introduced into the melting furnace and reaches a predetermined melting temperature, the flux is appropriately charged and agitated. After degassing in a furnace using a lance or the like as required, Remove the residue.

In this dissolving / solvent, it is important to take a sufficient amount of time until the flux and debris float from the molten aluminum alloy to the hot water surface, though the raw material such as the parent alloy is also important in order to obtain a predetermined alloy component. Do. The soaking time is preferably 30 minutes or longer.

In some cases, the molten aluminum alloy dissolved in the melting furnace may be once cast into the holding furnace after the molten iron is once cast, but may be cast directly from the melting furnace. A more preferred sedative time is 45 minutes or more.

If necessary, it may be passed through an inline degassing filter.

In-line degassing is a type in which an inert gas or the like is blown into the molten aluminum from a rotating rotor, and hydrogen gas in the molten metal is diffused into the foam of the inert gas and removed.

When nitrogen gas is used as the inert gas, it is important to control the dew point to, for example, -60 占 폚 or less. The amount of hydrogen gas of the ingot is preferably reduced to 0.20 cc / 100 g or less.

When the amount of hydrogen gas in the ingot is large, porosity is generated in the final solidified portion of the ingot. Therefore, the rolling reduction per pass in the hot rolling step should be restricted to 7% or more, for example, .

The hydrogen gas dissolved in supersaturated gas in the ingot is also subjected to the conditions of the homogenization treatment before the hot rolling step, but the hydrogen gas may precipitate at the time of laser welding after forming the final plate to generate a large number of blow holes in the bead. Therefore, the amount of the hydrogen gas of the ingot is more preferably 0.15 cc / 100 g or less.

casting

The ingot is manufactured by semi-continuous casting (DC casting). In the case of ordinary semi-continuous casting, since the thickness of the ingot is generally about 400 to 600 mm, the solidification cooling rate at the center of the ingot is about 1 캜 / sec. Therefore, in the case of semi-continuous casting of an aluminum alloy melt having a high content of Fe and Mn, a relatively rough intermetallic compound such as Al- (Fe.Mn) -Si is formed in the center of the ingot from the molten aluminum alloy ).

The casting speed in semi-continuous casting depends on the width and thickness of the ingot, but is usually 50 to 70 mm / min in consideration of productivity. However, considering the retention time of the molten metal in the degassing treatment tank, the flow rate of the molten aluminum (the molten metal supply amount per unit time) is small even if the degassing conditions such as the flow rate of the inert gas are performed The efficiency of degassing in the containing tank is improved, and the amount of hydrogen gas in the ingot can be reduced. It is preferable to regulate the casting speed to 30 to 50 mm / min in order to reduce the amount of hydrogen gas of the ingot. A more preferable casting speed is 30 to 40 mm / min. Of course, if the casting speed is less than 30 mm / min, the productivity is lowered, which is not preferable. In addition, it is a matter of course that the slower the casting speed, the lower the inclination of the sump (solid / liquid interface) in the ingot becomes, and the casting crack can be prevented.

Homogenization  Treatment: 420 to 600 占 폚 占 1 hour or more

The ingot obtained by casting by the semi-continuous casting method is homogenized.

The homogenization treatment is a process for maintaining the ingot at a high temperature to facilitate the rolling, thereby eliminating the residual stress in the casting segregation and the ingot. In the present invention, it is necessary to maintain at a holding temperature of 420 to 600 占 폚 for 1 hour or more. In this case, it is also a process for solving transition elements or the like constituting the intermetallic compound crystallized during casting to a degree as large as the matrix. If the holding temperature is excessively low or the holding temperature is short, the employment of the transition elements and the like does not proceed and the recrystallized grains are roughened, so that the outer surface of the DI molded body may not be finished cleanly. If the holding temperature is too high, CuMgAl ₂ So-called " burning " occurs. The more preferable homogenization treatment temperature is 420 to 590 캜.

Hot rolling process

The ingot held at a high temperature for a predetermined time is suspended from a crane as it is after the homogenizing treatment and is carried into a hot rolling mill. Depending on the model of the hot rolling mill, the ingot is usually hot rolled by several rolling passes, To about 8 mm.

Cold rolling process

The roll on which the hot-rolled sheet is wound is passed through a cold-rolling machine, and usually subjected to cold rolling in several passes. At this time, since work hardening is caused by plastic deformation introduced by cold rolling, an intermediate annealing process is performed if necessary. Since the intermediate annealing is usually a softening treatment, the cold rolling roll may be inserted into the batch furnace depending on the material, and the annealing may be performed at a temperature of 300 to 450 캜 for 1 hour or more. If the holding temperature is lower than 300 ° C, softening is not promoted, and if the holding temperature exceeds 450 ° C, the treatment cost is increased. Further, the intermediate annealing may be performed by a continuous annealing furnace, for example, at a temperature of 450 to 550 캜 for 15 seconds, and then rapidly cooled to double the solution treatment. If the holding temperature is lower than 450 占 폚, softening is not promoted, and if the holding temperature exceeds 550 占 폚, burning may occur.

final Annealing

In the present invention, the final annealing performed after the final cold rolling may be a batch treatment which is carried out by, for example, an annealing furnace at a temperature of 400 to 500 DEG C for 1 hour or more, but may be carried out by a continuous annealing furnace, Lt; 0 > C for 15 seconds or less, and then rapidly cooled, the solution treatment may also be performed.

Regardless, in the present invention, the final annealing is not necessarily indispensable, but it is preferable to soften the final plate as much as possible in consideration of the moldability in DI molding. In consideration of the moldability in the mold forming process, it is preferable to use an annealing material or a solution treatment material.

When the mechanical strength is higher than the formability, it is provided as a cold rolled ash.

final Cold rolling rate

The final cold rolling ratio in the case of performing the final annealing is preferably in the range of 50 to 90%. When the final cold rolling ratio is within this range, the average recrystallized grains in the final plate after annealing can be 20 to 100 占 퐉 and the stretched value can be 20% or more, and the outer appearance surface after molding can be finely finished. A more preferable final cold rolling ratio is in the range of 60 to 90%.

On the other hand, it is preferable that the final cold rolling ratio in the case of making a cold rolled material without final annealing is in the range of 5 to 40%. When the ironing process is increased during DI molding, it is necessary to provide a final plate slightly harder than the annealing material. If the final cold rolling rate is less than 5%, it becomes difficult to make the tensile strength of the final plate at 90 MPa or more depending on the composition, and if the final cold rolling rate exceeds 40%, the elongation at the final plate It is difficult to make the ratio to 5% or more.

When the final cold rolling ratio is within this range, the stretched value in the final plate in the cold state can be set to 5% or more, and the tensile strength can be set to 90 MPa or more. A more preferable final cold rolling ratio is in the range of 10 to 30%.

Through the above-described ordinary steps, an aluminum alloy plate for a secondary battery container can be obtained.

[Example]

Creation of final edition

A predetermined variety of ingots were weighed and compounded, and an ingot of 6 kg (total of 8 pieces) was loaded into a # 20 crucible coated with a release material. These crucibles were inserted into the electric furnace, and dissolved at 780 DEG C to remove the residues. Thereafter, the temperature of the molten metal was maintained at 760 DEG C, and then 6 g of the flux for the debris was enclosed by an aluminum foil, .

Subsequently, a lance was inserted into the molten metal, and N ₂ gas was blown in at a flow rate of 1.0 L / min for 10 minutes to carry out a degassing treatment. Thereafter, sedimentation for 30 minutes was carried out, and the residue floating on the surface of the molten metal was removed with a stirring bar, and a disc sample was taken from a mold for component analysis with a spoon.

Subsequently, a sequential crucible was taken out of the electric furnace by using a jig, and aluminum melt was cast into a preheated metal mold (250 mm x 200 mm x 30 mm). The disc samples of the respective specimens were subjected to compositional analysis by emission spectroscopic analysis. The results are shown in Table 1.

[Table 1]

               Composition of ingredients

The ingot was cut in a thickness of 2 mm on both sides after cutting the iron block, and the thickness was 26 mm.

The ingot was inserted into an electric heating furnace, heated at 430 ° C at a heating rate of 100 ° C / hr, homogenized at 430 ° C for 1 hour, hot rolled to a thickness of 6 mm in a hot rolling mill .

This hot-rolled sheet was subjected to cold-rolling to obtain a cold-rolled sheet having a thickness of 1.25 mm. The cold-rolled sheet was inserted into an annular furnace, and after the intermediate annealing process at 390 占 폚 for one hour, the annealed sheet was taken out from the annealer and air-cooled. Next, this annealing plate was cold-rolled to obtain a cold-rolled sheet having a thickness of 1.0 mm. The final cold rolling rate in this case was 20%.

The cold-rolled annealed sheet was subjected to cold rolling without performing intermediate annealing on the hot rolled sheet to obtain a cold rolled sheet having a thickness of 1 mm. The final cold rolling rate in this case was 83.3%. In the final annealing, the cold-rolled sheet was inserted into an annealer, annealed at 390 ° C for one hour, taken out of the annealer, and air-cooled.

Next, evaluation of moldability and laser weldability was carried out on the final plate thus obtained (each of the blank materials).

Evaluation of formability

The formability of the resulting final plate was evaluated by stretching (%) of the tensile test.

Specifically, a JIS No. 5 test piece was taken so that the tensile direction became parallel to the rolling direction, and a tensile strength test (UTS), a 0.2% proof stress (YS) and an elongation (fracture elongation) were obtained in accordance with JIS Z2241.

In the final plate in the cold rolled state, the sealant having a stretched value of 5% or more was regarded as good formability () and the sealant having less than 5% was regarded as poor moldability (). The evaluation results are shown in Table 2.

In the final plate subjected to the annealing after cold rolling, the specimen having a stretched value of 20% or more was regarded as good formability (), and the specimen having less than 20% was regarded as poor formability (). The evaluation results are shown in Table 3.

The disclosure item No. in Table 3 is indicated by the number with 10 in each disclosure item number shown in Table 1.

Laser welding conditions

The resulting final plate was subjected to pulse laser irradiation to evaluate the laser weldability. (2) plates (2) of the same plate material under the conditions of a frequency of 37.5 Hz, a welding speed of 450 mm / min, an energy of 6.0 J per pulse and a shield gas (nitrogen) flow rate of 1.5 (L / min) using a YAG laser welder JK701 manufactured by LUMONICS Was subjected to pulsed laser welding with a total length of 120 mm along the portion opposite to each other with no gap between the ends.

Above evaluation of laser weldability Bead  Measurement / Evaluation of Numbers

Next, as the evaluation of the laser weldability, the number of abnormal beads occurred in the welded portion was measured. First, among the weld lines of 120 mm in length, a weld line having a length of 60 mm at the center was defined as a measurement region. Next, as shown in Fig. 1, the widths of the round molten beads formed by the respective pulses formed along the welding line of 60 mm length were successively measured at intervals of 0.05 mm in the welding direction, and the average welding was carried out every 10 mm Bead width " was calculated, and the number of points indicating the bead widths which were 1.1 or more apart as a ratio from the " average weld bead width " in each section was counted. This count was totaled by 60 mm (6 intervals), and the number of abnormal beads of the disclosed material was determined.

In the present specification, the disclosure material having an abnormal bead number of less than 10 was defined as the ideal bead number evaluation good (O), and the disclosure material having the abnormal bead number of 10 or more was defined as the abnormal bead number evaluation failure (X). The results of the evaluation are shown in Table 2 for cold rolled ash, and in Table 3 for cold annealed annealed sheet.

Penetration  Measurement / evaluation of depth

Next, as the evaluation of the laser weldability, the penetration depth in the welded portion was measured. As shown in Fig. 2, the plate cross section in the direction perpendicular to the welding direction was cut out, and embedded in the thermoplastic resin, mirror polished to observe the metal structure of the vertical cross section of the welded portion.

The intermetallic compound crystallized at the time of casting is heated to a high temperature by heating by pulsed laser irradiation and dissolved in aluminum, and immediately thereafter, the molten beads are quenched to form Fe, Mn, Si or the like The element becomes a structure that is solubilized in supersaturated Al matrix.

Therefore, by observing the metal structure of the vertical cross-section of the welded portion, the region of only the Al matrix in which the intermetallic compound is not observed in the cross section is the molten portion, and by measuring the maximum depth from the surface of the final plate of the region, Can be measured.

The penetration depth of five sections was measured with respect to one specimen, and the average value of the penetration depths was determined as the penetration depth (mu m) in the specimen. In this case, the cross section of the abnormal bead described above is out of the measurement target.

In the present specification, a specimen having a penetration depth of 220 占 퐉 or more was defined as a penetration depth evaluation good (?), And a specimen having a penetration depth of less than 220 占 퐉 was evaluated as a penetration depth evaluation failure (占). The results of the evaluation are shown in Table 2 for cold rolled ash, and in Table 3 for cold annealed annealed sheet.

[Table 2]

       Evaluation result of the disclosure material (ash in cold rolled state)

[Table 3]

       Evaluation result of the disclosure material (cold annealing material)

Evaluation of each disclosure material

Examples 1 to 4 in Table 2 showing the evaluation results of the cold rolled ash are cold-rolled materials within the composition range of the present invention, and the laser weldability (abnormal bead number evaluation, penetration depth evaluation) All the saints were good (○).

In Comparative Example 1, the Mn content was as high as 1.27 mass% and the Mn / Fe ratio was 2.59, which was out of the scope of the present invention and the penetration depth evaluation was good (O) ×).

In the second comparative example, the Fe content was as high as 1.6 mass% and was out of the range of the present invention, and the penetration depth evaluation was good (O), but the formability defects (X) and abnormal bead number evaluation defects (X).

In Comparative Examples 3 to 5, both of Fe and Mn were low and out of the scope of the present invention, and the formability was good (good) and the abnormal bead number was good (good), but the penetration depth evaluation was bad (poor).

In Comparative Example 6, the Si content was as high as 0.5 mass% and was out of the range of the present invention, and the penetration depth evaluation good (O) and the abnormal bead number evaluation good (O), but the poor formability (X).

The eleventh to fourteenth examples in Table 3 showing the evaluation results on the cold-rolled annealing material are annealing materials within the composition range of the present invention, and the laser weldability (abnormal bead number evaluation, penetration depth evaluation) All were completely good (O).

In Comparative Example 11, the Mn content was as high as 1.27 mass% and the Mn / Fe ratio was 2.59, which was out of the scope of the present invention, and the penetration depth evaluation was good (O) and the formability was good (O) ×).

In Comparative Example 12, the Fe content was as high as 1.6% by mass, was out of the scope of the present invention, and the penetration depth evaluation was good (O), but the formability defects (X) and the abnormal bead number evaluation defects (X).

In Comparative Examples 13 to 15, both of Fe and Mn were low and out of the scope of the present invention, and the formability was good (good) and the abnormal bead number was good (good), but the penetration depth evaluation was poor (bad).

In Comparative Example 16, the Si content was as high as 0.5% by mass and was out of the scope of the present invention, and the penetration depth evaluation good (O) and the abnormal bead number evaluation good (O), but the moldability was bad (X).

Measurement of the number of second phase particles in a metal structure

A longitudinal section (a section perpendicular to the LT direction) parallel to the rolling direction of the obtained final plate was cut out, embedded in a thermoplastic resin, mirror-polished, and observed for metal structure. The micro-metal structure was photographed with an optical microscope (area per 1 field of view: 0.0334 mm 2, 10 fields of view in each sample), and the image analysis of the photograph was conducted to measure the number of second phase particles having a circle- . The results of the image analysis are shown in Table 4 for the cold rolled material and in Table 5 for the cold annealed plate.

[Table 4]

Number of second phase particles (unit: number / mm2) (cold rolled material)

[Table 5]

Number of second phase particles (unit: number / mm2) (cold annealing material)

From Table 4 showing the evaluation results of the cold rolled ash, when the number of the second phase particles having a circle equivalent diameter of 5 mu m or more in the metal structure is 500 pieces / mm2 or more (Comparative Examples 2 and 6) , Peeling easily occurs at the interface between the relatively coarse grains of the second phase and the matrix, so that the stretched value is lowered to less than 5%. Therefore, in the present invention, it is understood that the number of the second-phase particles having a circle-equivalent diameter of at least 5 mu m in the metal structure needs to be less than 500 pieces / mm < 2 >

From Table 5 showing the evaluation results of the cold-rolled annealing material, when the number of the second phase particles having a circle equivalent diameter of 5 占 퐉 or more in the metal structure was 500 pieces / mm2 or more (Comparative Examples 12 and 16) , It can be seen that the stretched value is lowered to less than 20% because peeling easily occurs at the interface between the relatively coarse grains of the second phase and the matrix.

Therefore, it is understood that the number of the second phase particles having a circle equivalent diameter of 5 탆 or more in the metal structure needs to be less than 500 pieces / mm 2 in order to make the stretched value 20% or more.

According to the present invention, there is provided an Al-Fe-based aluminum alloy plate which has a high strength applicable to a large-sized lithium ion battery container and which is also excellent in moldability and also excellent in laser weldability.

Claims (2)

0.3 to 1.5 mass% of Fe, 0.3 to 1.0 mass% of Mn, 0.002 to 0.20 mass% of Ti, 0.001 to 0.05 mass% of Zr and 0.0005 to 0.10 mass% of B, wherein the mass ratio of Mn / Fe is 0.2 And a second component having a particle size of 5 탆 or more and a circle-equivalent diameter of 5 탆 or more, wherein the first component has a composition of Si of less than 0.30 mass%, Cu of less than 0.20 mass%, and Mg of less than 0.20 mass% Wherein the cold-rolled steel sheet is a cold-rolled steel sheet having a metal structure of less than 500 / mm < 2 >, a stretched value of 5% or more, and a tensile strength of 140 MPa or more. 0.3 to 1.5 mass% of Fe, 0.3 to 1.0 mass% of Mn, 0.002 to 0.20 mass% of Ti, 0.001 to 0.05 mass% of Zr and 0.0005 to 0.10 mass% of B, wherein the mass ratio of Mn / Fe is 0.2 And a second component having a particle size of 5 탆 or more and a circle-equivalent diameter of 5 탆 or more, wherein the first component has a composition of Si of less than 0.30 mass%, Cu of less than 0.20 mass%, and Mg of less than 0.20 mass% An aluminum alloy plate for a battery case having excellent formability and weldability, characterized by being a cold-rolled annealing material having a metal texture of less than 500 / mm < 2 > and exhibiting an elongation of 20% or more.

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