JP2009041045A - Aluminum alloy sheet having superior paint-baking hardenability and manufacturing method therefor - Google Patents

Aluminum alloy sheet having superior paint-baking hardenability and manufacturing method therefor Download PDF

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JP2009041045A
JP2009041045A JP2007204536A JP2007204536A JP2009041045A JP 2009041045 A JP2009041045 A JP 2009041045A JP 2007204536 A JP2007204536 A JP 2007204536A JP 2007204536 A JP2007204536 A JP 2007204536A JP 2009041045 A JP2009041045 A JP 2009041045A
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aluminum alloy
temperature
aging treatment
strength
density
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Akira Hibino
Takeshi Takada
旭 日比野
健 高田
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Furukawa Sky Kk
Nippon Steel Corp
古河スカイ株式会社
新日本製鐵株式会社
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy having superior paint-baking hardenability and to provide a manufacturing method therefor. <P>SOLUTION: The aluminum alloy sheet includes: by mass%, 0.3 to 2.0% Mg and 0.5 to 2.0% Si, while satisfying Mg/Si≤1.2; and acicular precipitates of 100 to 1,000/μm<SP>2</SP>by number density when the sheet is observed after having been subjected to the ageing treatment of holding the sheet at 170°C for six hours. The acicular precipitates preferably have a length of 0.10 μm or longer. The manufacturing method includes the steps of: solution-heat-treating a cold-rolled sheet by holding it at 500 to 600°C for five minutes or shorter; cooling it to 180°C or lower at a cooling rate of 50°C/s or more; and preliminarily heat-treating the sheet by holding it at a heating temperature T[°C] in such a range as to satisfy -7t+160≤T≤-3t+186 in between 90 and 180°C, for a holding period of time t [hour] in a range between 1 and 15 hours. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aluminum alloy having a high strength after paint baking, which is particularly suitable as an aluminum alloy plate for automobiles.
  As a means for reducing the weight of automobile bodies, aluminum alloys are being used instead of steel. In particular, an aluminum alloy containing Mg and Si (also referred to as a 6000-based alloy or an Al—Mg—Si-based alloy) is called a strength (BH strength) after paint baking among properties required for a material for an automobile panel. ). For this reason, research and development have been advanced on 6000 series alloys in order to improve the BH strength.
  For example, Patent Document 1 proposes an aluminum alloy that has been subjected to a heat treatment that is maintained at a temperature of 50 to 130 ° C. for 1 to 48 hours after the solution treatment. Further, Patent Document 2 proposes an aluminum alloy whose strength and ductility are improved by limiting the cooling rate after solution treatment.
  These methods generate precipitates that contribute to the improvement of the BH strength depending on the holding temperature after the solution treatment. However, it is difficult to directly observe a precipitate effective for improving the BH intensity even if a transmission electron microscope (referred to as TEM) is used, and the type and distribution state cannot be specified.
  For this reason, an aluminum alloy has been proposed in which a precipitation state effective for improving the BH strength is specified by detecting a change in electrical conductivity during heat treatment or detecting a reaction heat at the time of temperature rise by differential scanning calorimetry (for example, Patent Documents 3 and 4). In addition, an aluminum alloy has been proposed in which the precipitation state after a heat treatment for growing precipitates, so-called overaging treatment, is specified (for example, Patent Document 5).
  However, in the methods of Patent Documents 3 and 4, since the precipitation state is not a direct observation method, the number density of the precipitates is unknown. In the method of Patent Document 5, the precipitate formed when held at 180 ° C. for 9 hours is observed, but the number density is very large because the temperature is high and the time is long.
JP-A-4-210456 Japanese Patent Laid-Open No. 11-172390 Japanese Patent Laid-Open No. 9-41062 JP 2001-329328 A Japanese Patent Laid-Open No. 2006-9140 A. K. Gupta, D.C. J. et al. Lloyd, S. A. Coat (AKGupta, DJLloyd, SACourt), "Precipitation hardening processes in an Al-0.4% Mg-1.3% Si alloy. -0.25% Fe) ", Materials Science and Engineering A, England, Elsevier, 2001, A301, p. 140-146
  The present invention provides an aluminum alloy plate having high paint bake strength and a method for producing the same, and more specifically, an aluminum alloy plate having a precipitation form optimum for improving the paint bake strength and a method for producing the same.
  In order to clarify the precipitation state of the high-temperature clusters that improve the BH strength, the present inventors have studied a method of observing the high-temperature clusters grown in beta double prime (β ″) at 170 ° C. It was found that the aging treatment for holding time was optimal. Furthermore, the precipitation state of the high temperature cluster optimum for improving the BH strength, that is, the precipitation state of β ″ after the aging treatment was identified, and the paint bake hardenability was excellent. Appropriate manufacturing conditions for obtaining an aluminum alloy sheet were found. This invention is made | formed based on such knowledge, The summary is as follows. In the following description,% of element content means mass%.
(1) Mg: 0.3 to 2.0%, Si: 0.5 to 2.0%, Mn: 0.03 to 0.60%, Cr: 0.01 to 0.40 %, Zr: 0.01 to 0.40%, V: 0.01 to 0.40%, Fe: 0.03 to 1.00%, Zn: 0.03 to 2.50%, Cu: 0.0. Contains 0.5 or 1.50%, Ti: 0.005 to 0.200%, B: 0.0500% or less, containing one or more, the balance consisting of Al and inevitable impurities,
Mg / Si ≦ 1.2
An aluminum alloy plate excellent in paint bake hardenability, characterized in that the number density of needle-like precipitates observed after aging treatment at 170 ° C. for 6 hours is 100 to 1000 / μm 2 .
(2) The aluminum alloy plate excellent in paint bake hardenability as described in (1) above, wherein the length of the acicular precipitate is 0.10 μm or more.
(3) A method for producing an aluminum alloy plate as described in (1) or (2) above, wherein the solution is held at 500 to 600 ° C. for 5 minutes or less on the aluminum alloy plate comprising the component as described in (1) above. Then, it is cooled to 180 ° C. or lower at a cooling rate of 50 ° C./s or higher, and the heating temperature T [° C.] within the range of 90 to 180 ° C. satisfying the following (formula 1) is 1 to 30 hours. The manufacturing method of the aluminum alloy plate excellent in the paint bake hardenability characterized by performing the pre-aging treatment which hold | maintains the holding time t [hour] in the range.
−7t + 160 ≦ T ≦ −3t + 186 (Formula 1)
(4) The method for producing an aluminum alloy plate excellent in paint bake hardenability as described in (3) above, wherein a solution treatment is performed and a pre-aging treatment is performed within 1 minute after cooling.
  Compared with the case where a conventional aluminum alloy plate is used, the vehicle body rigidity is increased and the running performance is improved by the aluminum alloy plate of the present invention that can obtain high strength after painting and baking. In addition, when steel is used, the industrial contribution is remarkable, such as the alternative application of the material to the aluminum alloy, which contributes to the weight reduction of the vehicle body.
  In the case of an Al—Mg—Si alloy, the strength is determined by β ″ generated in the crystal grains, and limiting the size and number density is necessary for the invention of an alloy having high paint bake strength. This β ″ is an intermetallic compound of Mg and Si having an orientation relationship with the parent phase, and depending on the size, it can be observed with a transmission electron microscope (referred to as TEM) using a thin film sample. When the (100) plane of the parent phase is observed by TEM, a strain field of β ″ is seen as a needle-like contrast. In the present invention, a needle-like contrast which is a strain field of β ″ is defined as a needle-like precipitate. To do.
  When β ″ is formed in the manufacturing process of the aluminum alloy, the strength is increased and the formability, particularly the press formability of the aluminum alloy plate is deteriorated, making it difficult to form the part. By utilizing a fine atomic group called high-temperature cluster, deterioration of formability is suppressed, and after forming, it is grown to β ″ by heat treatment during paint baking, and BH strength is improved. Therefore, in order to achieve both BH strength and formability, it is necessary to set the precipitation form of the high-temperature cluster to an optimum condition.
  However, the high-temperature cluster is extremely fine and cannot be observed as it is with TEM. Therefore, conventionally, the precipitation behavior of the Al—Mg—Si based alloy was, for example, heated to 180 ° C. and held for 9 hours, and β ″ was observed by TEM. When kept at 180 ° C. for a long time, β ″ is newly nucleated by Mg and Si in a solid solution state. On the other hand, at 170 ° C. or lower, β ″ is not newly nucleated even if kept for a long time (for example, Non-Patent Document 1).
  From the above conventional knowledge, it is necessary to perform aging treatment under appropriate conditions in order to measure the number density of high-temperature clusters. Therefore, the inventors of the present invention, when held at 170 ° C., the high-temperature cluster grows into β ″ as it is, and new β ″ does not nucleate. We considered that it was possible to measure the number density (hereinafter, also simply referred to as density) of the generated high-temperature clusters, and examined appropriate aging treatment conditions.
  As a result, it was found that the optimum aging condition for observing β ″ in which only high-temperature clusters grew without nucleation of new β ″ was maintained at 170 ° C. for 6 hours. Furthermore, the length of the acicular precipitate observed by TEM reflects the size of the high-temperature cluster before the aging treatment, and the longer the length, the smaller the solid solution Mg and Si before the aging treatment. It has also been found that an increase in strength is suppressed.
  This is because Mg and Si that did not form high-temperature clusters form low-temperature clusters at room temperature and the strength increases. That is, when there are many solid solution Mg and Si, a low temperature cluster will increase with time and the change with time of strength will become large. On the other hand, since high temperature clusters are stable even at room temperature, if the high temperature clusters are grown greatly, changes with time can be suppressed. The size of the high temperature cluster is reflected in the length of β ″ after aging treatment is performed at 170 ° C. for 6 hours.
The inventors of the present invention formed a sufficient amount of high-temperature clusters, and when the length of β ″ after aging treatment at 170 ° C. for 6 hours was 0.1 μm or more, 60 ° C. at 30 ° C. after production. It was found that the increase in tensile strength of the aluminum alloy sheet during holding for a day was 50 MPa or less, and the number density of acicular precipitates after holding at 170 ° C. for 6 hours was 100 pieces / μm 2 or more. Then, it was found that the initial tensile strength was 190 to 270 MPa.
  In order to optimize the size and number density of the high-temperature cluster in order to achieve both BH strength and formability, it is necessary to perform a pre-aging treatment under appropriate conditions after the solution treatment. In order to obtain such a high-temperature cluster form, the contents of Mg and Si, the temperature of the pre-aging treatment and the holding time are important factors. In the case of an aluminum alloy containing Mg and Si, the formation temperature range of the high temperature cluster is 70 to 180 ° C., but when it is kept at a high temperature for a long time, it grows into β ″. Since β ″ may nucleate when held for a long time, the upper limit of the temperature of the pre-aging treatment is preferably 170 ° C. or less.
  First, Mg and Si need to be added in amounts of 0.3% and 0.5% or more, respectively. If the added amounts of Mg and Si are less than 0.3% and less than 0.5%, respectively, the amount of β ″ phase that contributes to precipitation hardening during baking is reduced, and the BH strength is reduced. When the addition amount of Mg and Si exceeds 2.0%, a coarse Mg-Si based intermetallic compound is generated, and the formability is lowered. % Or less.
  In addition, β ″ grown by aging treatment of high temperature clusters has a structure centered on Si atoms. That is, Si is considered to promote the formation of high temperature clusters serving as precipitation nuclei of β ″. . Therefore, in order to obtain a sufficient number density of high-temperature clusters, it is necessary to satisfy Mg / Si ≦ 1.2. Moreover, the lower limit of Mg / Si is 0.15 or more from the lower limit of Mg amount and the upper limit of Si amount. In order to obtain the effect, it is preferable to set Mg / Si to 0.4 or more.
  Furthermore, one or more of Mn, Cr, Zr, V, Fe, Zn, Cu, Ti, and B are selectively selected to refine crystal grains, improve strength, and bake hardenability. It is necessary to contain.
  Mn, Cr, Zr, V, and Fe are effective for improving the strength and refining the crystal grains. To obtain the effect, Mn and Fe are 0.03% or more, Cr, Zr, and V are respectively It is preferable to add 0.01% or more. On the other hand, the effect is saturated even if Mn exceeds 0.60%, Cr, Zr, V exceeds 0.40% and Fe exceeds 1.00%, respectively. In particular, hem bendability may be impaired.
  Zn is an element effective for improving the bake hardenability and the surface treatment, and 0.03% or more is preferable for obtaining the effect. On the other hand, if the Zn content exceeds 2.50%, moldability and corrosion resistance may be impaired.
  Cu is an element effective for improving strength and formability, and 0.05% or more is preferably added to obtain the effect. On the other hand, if the amount of Cu exceeds 1.50%, the corrosion resistance, particularly the yarn rust resistance, may deteriorate due to the formation of precipitates. When excellent corrosion resistance is required, the Cu content is preferably 1.00% or less.
  Ti is an element effective for refining the ingot structure, and in order to obtain the effect, the content is preferably 0.005% or more. On the other hand, even if adding more than 0.20% Ti, the effect is saturated, coarse crystals are formed, and moldability may be impaired.
  B is an element effective for refining the ingot structure and is preferably added simultaneously with Ti. A suitable upper limit of the amount of B at which the effect of refining and stabilizing the ingot structure is remarkable is 0.0500% or less.
  Furthermore, since addition of Sc is also effective in making the ingot structure finer, Sc may be added. In addition, the range of Sc amount suitable for obtaining the effect is 0.01 to 0.20%.
  The inventors of the present invention contain Mg and Si in an amount of 0.3 to 2.0% and 0.5 to 2.0%, respectively, satisfying Mg / Si ≦ 1.2, and Mn = 0. 03 to 0.60%, Cr: 0.01 to 0.40%, Zr: 0.01 to 0.40%, V: 0.01 to 0.40%, Fe: 0.03 to 1.00% Zn: 0.03 to 2.50%, Cu: 0.05 to 1.50%, Ti: 0.005 to 0.200%, B: 0.0500% or less, one or more In order to form a high-temperature cluster by cold rolling using a cold-rolled sheet of an aluminum alloy containing Al and the balance consisting of Al and inevitable impurities, a solution treatment at 500 to 600 ° C. is carried out at 50 ° C. / After cooling at s or higher, preliminary aging treatment was performed at 90 to 180 ° C.
  JIS Z 2201 No. 5 test piece was sampled, and tensile properties were measured according to JIS Z 2241 using some of the test pieces. The 0.2% yield strength and tensile strength measured after the pre-aging treatment are referred to as initial 0.2% yield strength (YS) and initial tensile strength (TS), respectively. Formability was evaluated using the difference (TS-YS) between the initial tensile strength (TS) and the initial 0.2% yield strength (YS) as an index.
  Furthermore, after introducing a tensile strain of 2% into some test pieces, the test piece was immersed in an oil bath whose temperature was adjusted to 175 ° C. and subjected to a coating baking heat treatment (referred to as BH treatment) for 20 minutes, A tensile test was performed to measure 0.2% yield strength, that is, BH strength. The paint bake hardenability was evaluated by obtaining the difference ΔBH [MPa] between the initial 0.2% proof stress and the BH strength.
  Moreover, some test pieces after the preliminary aging treatment were held in a drying furnace having a furnace temperature of 30 ° C. for 60 days. Thereafter, tensile properties were evaluated according to JIS Z 2241. As an index of change over time, a difference ΔTS [MPa] obtained by subtracting the initial tensile strength from the tensile strength after holding at 30 ° C. for 60 days was obtained.
  After the preliminary aging treatment, an aging treatment was performed at 170 ° C. for 6 hours to grow a high temperature cluster, and a thin film sample for TEM observation was prepared. Using this sample, needle-like precipitates deposited on the (100) plane were observed by TEM, and the number density and length were measured. Specifically, a sample of the thin film prepared was photographed at a magnification of about 150,000 times in a crystal grain of <001> with respect to the electron incident direction, and the number density and length of the needle-like precipitates were determined from the photograph. It was measured.
FIG. 1 shows the relationship between ΔBH at room temperature and the number density of acicular precipitates. As shown in the figure, ΔBH increases with the number density of the needle-like precipitates, and it can be seen that an increase in the number density is effective for obtaining a high BH intensity. It can also be seen that ΔBH is 80 MPa or more when the density is 100 pieces / μm 2 or more.
FIG. 2 shows the relationship between TS-YS and the density of acicular precipitates. TS-YS is an index of moldability, and if this value is large, it is determined that the moldability is good. Although the BH strength increases due to the increase in the density of the needle-like precipitates, TS-YS decreases and the moldability deteriorates. Therefore, in order to ensure moldability, it is necessary to limit the upper limit of the density of acicular precipitates. As shown in FIG. 2, when the experimental data is externally inserted, it is found that the density of acicular precipitates needs to be 1000 pieces / μm 2 or less in order to make TS-YS 100 or more. From the viewpoint of moldability, it is preferable to limit the density of acicular precipitates to 500 pieces / μm 2 or less.
  Furthermore, in order to suppress the change with time, it is effective to control the length of the needle-like precipitates observed by TEM after the aging treatment at 170 ° C. for 6 hours. This is because, as described above, the longer the acicular precipitate, the larger the high-temperature cluster after the pre-aging treatment, and the smaller the solid solution Mg and Si.
  FIG. 3 shows the relationship between ΔTS and the length of the needle-like precipitate when the density of the needle-like precipitate is approximately the same level. When the length of the acicular precipitate is short, Mg and Si in a solid solution state easily form a low-temperature cluster, and thus ΔTS is large. On the other hand, when the length of the needle-like precipitate is 0.10 μm or more, since a large amount of solid solution Mg and Si are used for forming the high temperature cluster, the formation of the low temperature cluster is suppressed and ΔTS becomes small. The upper limit of the length of the acicular precipitate is not particularly specified, but is about 0.25 μm from the contents of Mg and Si of the present invention.
  In order to obtain the material having the precipitate form as described above, it is necessary to limit the temperature and time of the pre-aging treatment conditions after the solution treatment.
FIG. 4 shows the change in the number density of the needle-like precipitates depending on the temperature and time of the pre-aging treatment, and FIG. 5 shows the change in the length of the needle-like precipitates. The numbers in FIG. 4 are the number density of needle-like precipitates [pieces / μm 2 ], and the numbers in FIG. 5 are the lengths of the needle-like precipitates [μm]. The range between the broken lines in FIGS. 4 and 5 is a range that satisfies the condition −7t + 160 ≦ T ≦ −3t + 186. As shown in FIGS. 4 and 5, the temperature T [° C.] and the holding time t [hour] of the pre-aging treatment are
−7t + 160 ≦ T ≦ −3t + 186 (Formula 1)
In a range satisfying the above, the density is 100 to 1000 / μm 2 and the length is 0.10 μm or more.
  Next, the manufacturing method of the aluminum alloy plate of this invention is demonstrated. Production of cold-rolled sheets, that is, casting, homogenization treatment, hot rolling, and cold rolling may be performed by ordinary methods.
  The solution treatment of the cold-rolled sheet needs to be performed under appropriate conditions in order to secure solid solution Mg and solid solution Si, thereby forming a high-temperature cluster with sufficient number density after the preliminary aging treatment. be able to.
  The temperature of the solution treatment needs to be 500 ° C. or higher in order to secure solid solution Mg and solid solution Si. On the other hand, when the temperature of the solution treatment exceeds 600 ° C., crystal grain boundaries may partially dissolve. Further, when the temperature of the solution treatment is high, the plateability in the production line is deteriorated, and therefore, the temperature is preferably set to 590 ° C. or less at which the strength of the aluminum alloy plate can be sufficiently obtained.
  After the solution treatment time has reached the target temperature, cooling may be started immediately in order to increase productivity. In order to increase the solid solution amount of Mg and Si, it is preferable to hold for 1 minute or more. On the other hand, if the holding time exceeds 5 minutes, productivity is impaired, so the upper limit needs to be 5 minutes or less.
Moreover, after solution treatment, in order to suppress precipitation of Mg 2 Si and secure Mg and solid solution Si, it is necessary to cool at a temperature of 50 ° C./s or more to the temperature of the pre-aging treatment. The upper limit of the cooling rate is not particularly defined, but if the cooling rate is too high, strain may be imparted to the aluminum alloy plate, and therefore it is preferably set to 200 ° C./s or less. Cooling can be performed by water cooling or mist cooling.
  After the solution treatment, the solution is cooled to 180 ° C. or lower, and a preliminary aging treatment is performed. The cooling stop temperature is preferably such that β ″ does not nucleate and low temperature clusters do not form. If the cooling stop temperature exceeds 180 ° C., the possibility of β ″ nucleation increases. It shall be below ℃. Further, in order to suppress the nucleation of β ″ and improve the moldability, the cooling stop temperature is preferably set to 170 ° C. or lower. On the other hand, when the cooling stop temperature is lower than 70 ° C., the low temperature cluster In order to produce | generate, it is preferable to set it as 70 degreeC or more.
  The shorter the time from the solution treatment to the cooling and the preliminary aging treatment is, the shorter the better, and the less than 1 minute is preferred. Further, when the stop temperature is in the range of 90 to 180 ° C, preferably in the range of 90 to 170 ° C, the preliminary aging treatment may be performed as it is. In particular, when the stop temperature is less than 90 ° C., it is preferable to perform preliminary aging treatment within 1 minute to suppress the formation of low temperature clusters.
  The number density of high temperature clusters is determined by the conditions of the pre-aging treatment. If the temperature of the pre-aging treatment exceeds 180 ° C., the possibility of β ″ nucleation increases, and 170 ° C. or less is preferable in order to prevent β ″ nucleation. On the other hand, if the temperature of the preliminary aging treatment is less than 90 ° C., a sufficient amount of high-temperature clusters for BH is not formed, and the BH strength may be impaired. Therefore, the preliminary aging treatment needs to be performed at 90 to 180 ° C. at which high-temperature clusters are generated, and is preferably 90 to 170 ° C.
When the preliminary aging treatment is performed at 180 ° C. for a long time, β ″ is nucleated, but if the holding time is shortened, a high temperature cluster can be formed without nucleating β ″. Further, in order to obtain β "effective for improving the BH strength, the high-temperature clusters need to be finely and densely dispersed. For this purpose, the temperature T [° C.] and the holding time of the pre-aging treatment It is necessary to set t [time] at a higher temperature and a longer time than conventional, specifically,
−7t + 160 ≦ T ≦ −3t + 186 (Formula 1)
Must be satisfied. In order to sufficiently form a high-temperature cluster, it is necessary to hold for 1 hour or more, and in order to suppress deterioration of formability, the holding time needs to be 30 hours or less.
  Table 1 shows the composition of the aluminum alloy and the conditions for the pre-aging treatment after solution treatment. All components are expressed in mass%. The production of the aluminum alloy sheet up to cold rolling was carried out by a conventional method. That is, casting, soaking, hot rolling, and cold rolling were performed to obtain an aluminum alloy plate having a thickness of 1 mm. From the cold rolled sheet, a No. 5 tensile test piece of JIS Z 2201 was collected with the rolling direction as the longitudinal direction. The tensile test piece was immersed in a salt bath at 550 ° C. for 2 minutes, subjected to a solution treatment, then immersed in water kept at 90 ° C., cooled, and stored in liquid nitrogen within 1 minute. The cooling rate is 150 ° C./s. Then, it immersed in the oil bath or salt bath which controlled temperature, and performed the preliminary aging treatment of the holding temperature and holding time which were shown in Table 1.
After the preliminary aging treatment, one part of the test piece was immediately heat-treated at 170 ° C. for 6 hours in a salt bath, observed with an electron microscope, and the length of β ″ [μm] and its density [piece] / Μm 2 ] The measured value is an average value obtained from photographs of 20 fields of view.
  A part of the tensile test piece was subjected to a tensile test according to JIS Z 2241 after preliminary aging treatment, and the measured 0.2% proof stress and tensile strength were respectively set to the initial 0.2% proof stress YS [MPa]. And the initial tensile strength TS [MPa]. Furthermore, after preliminary aging treatment, BH strength was measured using some test pieces. The BH strength is 0.2% proof stress measured by introducing a 2% tensile strain into the test piece after the pre-aging treatment and then subjecting it to a 175 ° C. salt bath for 20 minutes and conducting a tensile test. It is.
  ΔBH [MPa] was determined by subtracting the initial 0.2% yield strength from the BH strength, and is shown in Table 2. Since ΔBH of a conventional aluminum alloy is about 60 MPa, it was evaluated that if ΔBH was 80 MPa or more, a strength higher than the conventional baking was obtained.
  A part of the tensile test piece was kept in a drying furnace having a furnace temperature of 30 ° C. for 60 days, and a tensile test was performed in accordance with JIS Z 2241. ΔTS [MPa] was calculated by subtracting the initial tensile strength TS from the tensile strength after holding for 60 days, and is shown in Table 2.
  No. in Table 2 1-4 is an example of this invention, initial tensile strength TS is high, and (DELTA) BH has the intensity | strength after the coating baking process of all 80 MPa or more. On the other hand, no. 5 to 10 are comparative examples, and in each case, ΔBH is less than 80 MPa. No. 6, 8, and 11 have also decreased TS-YS.
  No. In No. 5, since the addition amount of Mg and Si contributing to the improvement of the BH strength is small, ΔBH is lowered. No. In No. 6, since Si is excessive, a coarse intermetallic compound is produced, and the formability is lowered. No. In No. 7, since Mg / Si is 1 or more, there are few precipitation nuclei of high-temperature clusters, and the number density of acicular precipitates is reduced.
  No. In No. 8, the temperature of the pre-aging treatment is high, β ″ is nucleated, the number density of needle-like precipitates is increased, and the moldability is deteriorated. No. 9 is a low temperature in the pre-aging treatment. No. 10 has a short holding time and the number density of needle-like precipitates is reduced, and No. 11 has a holding time that is too long, so that the number density of needle-like precipitates is increased and moldability is reduced.
It is a figure which shows the relationship between the number density of acicular precipitate, and BH property. It is a figure which shows the relationship between the number density of an acicular precipitate, and a moldability. It is a figure which shows the relationship between the length of a needle-like precipitate, and a time-dependent change. It is a figure which shows the relationship between preliminary aging treatment conditions and the number density of a needle-like precipitate. It is a figure which shows the relationship between preliminary aging treatment conditions and the length of acicular precipitate.

Claims (4)

  1. % By mass
    Mg: 0.3-2.0%,
    Si: 0.5 to 2.0%
    Further,
    Mn: 0.03 to 0.60%,
    Cr: 0.01-0.40%,
    Zr: 0.01-0.40%,
    V: 0.01-0.40%,
    Fe: 0.03-1.00%,
    Zn: 0.03 to 2.50%,
    Cu: 0.05 to 1.50%,
    Ti: 0.005 to 0.200%,
    B: It contains 1 type or 2 types or more out of 0.0500% or less, and the balance consists of Al and inevitable impurities,
    Mg / Si ≦ 1.2
    An aluminum alloy plate excellent in paint bake hardenability, characterized in that the number density of needle-like precipitates observed after aging treatment at 170 ° C. for 6 hours is 100 to 1000 / μm 2 .
  2.   The length of the said acicular precipitate is 0.10 micrometer or more, The aluminum alloy plate excellent in the paint bake hardenability of Claim 1 characterized by the above-mentioned.
  3. It is a manufacturing method of the aluminum alloy plate of Claim 1 or 2, Comprising: The aluminum alloy plate which consists of a component of Claim 1 is given the solution treatment hold | maintained at 500-600 degreeC for 5 minutes or less, and 50 The temperature is cooled to 180 ° C. or less at a cooling rate of at least ° C./s. [Time] A method for producing an aluminum alloy sheet excellent in paint bake hardenability, characterized by performing a pre-aging treatment for holding.
    −7t + 160 ≦ T ≦ −3t + 186 (Formula 1)
  4.   The method for producing an aluminum alloy plate excellent in paint bake hardenability according to claim 3, wherein the solution treatment is performed and the preliminary aging treatment is performed within 1 minute after cooling.
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JP2013185218A (en) * 2012-03-08 2013-09-19 Kobe Steel Ltd Aluminum alloy sheet excellent in baking finish hardenability
KR101476284B1 (en) * 2014-09-30 2014-12-24 유선상 Al-Si-Mg Aluminum alloy and manufacturing method thereof
CN104775061A (en) * 2015-04-10 2015-07-15 天津那诺机械制造有限公司 Aluminum alloy material for liquid die forging of automobile hub
WO2015112450A1 (en) * 2014-01-21 2015-07-30 Alcoa Inc. 6xxx aluminum alloys
WO2015156319A1 (en) * 2014-04-10 2015-10-15 株式会社Uacj Bus bar aluminum alloy plate and method for producing same
JP2016027194A (en) * 2014-06-27 2016-02-18 株式会社神戸製鋼所 Rolled aluminum alloy material
JP2016522320A (en) * 2013-04-19 2016-07-28 北京有色金属研究総院General Research Institute for Nonferrous Metals Aluminum alloy material suitable for manufacturing automobile body panel and method for producing the same
JP2017110245A (en) * 2015-12-14 2017-06-22 株式会社神戸製鋼所 Aluminum alloy forged material for automobile
CN104625643B (en) * 2015-01-12 2018-03-27 江苏珀然股份有限公司 A kind of aluminium alloy wheel hub forging method
JP2020509171A (en) * 2016-12-16 2020-03-26 ノベリス・インコーポレイテッドNovelis Inc. High strength and high formability aluminum alloy resistant to natural age hardening and method for producing the same
WO2020117748A1 (en) * 2018-12-05 2020-06-11 Arconic Inc. 6xxx aluminum alloys
US10995397B2 (en) 2016-12-16 2021-05-04 Novelis Inc. Aluminum alloys and methods of making the same

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05125505A (en) * 1991-10-31 1993-05-21 Furukawa Alum Co Ltd Manufacture of baking hardenability aluminum alloy plate for forming
JPH05302154A (en) * 1992-04-27 1993-11-16 Furukawa Electric Co Ltd:The Method for heat-treating al-mg-si aluminum alloy sheet
JPH0874014A (en) * 1994-09-07 1996-03-19 Nippon Steel Corp Production of aluminum alloy sheet having high formability and good baking hardenability
JP2007039773A (en) * 2005-08-05 2007-02-15 Furukawa Sky Kk Aluminum alloy plate to be formed and manufacturing method therefor
JP2008542526A (en) * 2005-05-25 2008-11-27 ノヴェリス インコーポレイテッドNovelis Inc. Aluminum alloy plate and manufacturing method thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05125505A (en) * 1991-10-31 1993-05-21 Furukawa Alum Co Ltd Manufacture of baking hardenability aluminum alloy plate for forming
JPH05302154A (en) * 1992-04-27 1993-11-16 Furukawa Electric Co Ltd:The Method for heat-treating al-mg-si aluminum alloy sheet
JPH0874014A (en) * 1994-09-07 1996-03-19 Nippon Steel Corp Production of aluminum alloy sheet having high formability and good baking hardenability
JP2008542526A (en) * 2005-05-25 2008-11-27 ノヴェリス インコーポレイテッドNovelis Inc. Aluminum alloy plate and manufacturing method thereof
JP2007039773A (en) * 2005-08-05 2007-02-15 Furukawa Sky Kk Aluminum alloy plate to be formed and manufacturing method therefor

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013185218A (en) * 2012-03-08 2013-09-19 Kobe Steel Ltd Aluminum alloy sheet excellent in baking finish hardenability
JP2016522320A (en) * 2013-04-19 2016-07-28 北京有色金属研究総院General Research Institute for Nonferrous Metals Aluminum alloy material suitable for manufacturing automobile body panel and method for producing the same
WO2015112450A1 (en) * 2014-01-21 2015-07-30 Alcoa Inc. 6xxx aluminum alloys
US10190196B2 (en) 2014-01-21 2019-01-29 Arconic Inc. 6XXX aluminum alloys
KR101843343B1 (en) * 2014-04-10 2018-03-29 가부시키가이샤 유에이씨제이 Bus bar aluminum alloy plate and method for producing same
WO2015156319A1 (en) * 2014-04-10 2015-10-15 株式会社Uacj Bus bar aluminum alloy plate and method for producing same
JP2015203117A (en) * 2014-04-10 2015-11-16 株式会社Uacj Aluminum alloy sheet for bus bar and method for producing the same
CN105917013A (en) * 2014-04-10 2016-08-31 株式会社Uacj Bus bar aluminum alloy plate and method for producing same
US10475547B2 (en) 2014-04-10 2019-11-12 Uacj Corporation Aluminum-alloy sheet for bus bar and manufacturing method thereof
EP3130684B1 (en) 2014-04-10 2019-01-30 UACJ Corporation Bus bar aluminum alloy plate and method for producing same
JP2016027194A (en) * 2014-06-27 2016-02-18 株式会社神戸製鋼所 Rolled aluminum alloy material
KR101476284B1 (en) * 2014-09-30 2014-12-24 유선상 Al-Si-Mg Aluminum alloy and manufacturing method thereof
CN104625643B (en) * 2015-01-12 2018-03-27 江苏珀然股份有限公司 A kind of aluminium alloy wheel hub forging method
CN104775061A (en) * 2015-04-10 2015-07-15 天津那诺机械制造有限公司 Aluminum alloy material for liquid die forging of automobile hub
JP2017110245A (en) * 2015-12-14 2017-06-22 株式会社神戸製鋼所 Aluminum alloy forged material for automobile
JP2020509171A (en) * 2016-12-16 2020-03-26 ノベリス・インコーポレイテッドNovelis Inc. High strength and high formability aluminum alloy resistant to natural age hardening and method for producing the same
US10995397B2 (en) 2016-12-16 2021-05-04 Novelis Inc. Aluminum alloys and methods of making the same
WO2020117748A1 (en) * 2018-12-05 2020-06-11 Arconic Inc. 6xxx aluminum alloys

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