JP2006200018A - Aluminum alloy sheet for forming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-Mg Al-Mg aluminum alloy sheet obtained by continuous casting and having higher press moldability. <P>SOLUTION: The Al-Mg aluminum alloy sheet with a sheet thickness of 0.5 to 3 mm subjected to casting by a twin roll type continuous casting process and cold rolling has a composition containing, by mass, >8 to 14% Mg, ≤1.0% Fe and ≤0.5% Si, and the balance Al with inevitable impurities. Among the texture of the sheet, the total of the average area ratios in the orientation components of each texture in the Cube orientation, rotary Cube orientation, Goss orientation, Brass orientation, S orientation, Cu orientation and PP orientation is controlled to ≤35%, thus its press moldability is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a high Mg-containing Al—Mg-based aluminum alloy plate obtained by continuous casting and having high press formability.

  In recent years, in the vehicle body field of transportation equipment such as automobiles, improvement in fuel efficiency has been pursued by reducing the weight in response to global environmental problems caused by exhaust gas and the like. For this reason, the application of lighter Al alloy materials such as rolled plates and extruded shapes instead of steel materials conventionally used for automobile bodies is increasing.

  Of these, panels such as outer panels (outer panels) and inner panels (inner panels) of automobile body panels (panel structures) such as automobile hoods, fenders, doors, roofs, and trunk lids are made of Al-Mg series. The use of AA to JIS 5000 series (hereinafter simply referred to as 5000 series or Al-Mg series) aluminum alloy sheets and Al-Mg-Si series AA to JIS 6000 series aluminum alloy sheets has been studied.

  The aluminum alloy plate for automobile body panels (hereinafter, aluminum is also referred to as Al) is required to have high press formability. From the viewpoint of formability, among the Al alloys, an Al—Mg-based Al alloy having an excellent balance between strength and ductility is advantageous.

  For this reason, with regard to Al-Mg-based Al alloy sheets, examination of component systems and optimization of manufacturing conditions have been conventionally performed. As this Al-Mg based Al alloy, for example, JIS A 5052, 5182 and the like are typical alloy component systems. However, even this Al—Mg-based Al alloy is inferior in ductility and inferior in formability as compared with a cold-rolled steel sheet.

  On the other hand, when the Al-Mg series Al alloy is made to have a high Mg content exceeding 8% by increasing the Mg content, the balance of strength ductility is improved. However, it is difficult to industrially manufacture such a high Mg Al—Mg alloy by an ordinary manufacturing method in which an ingot cast by DC casting or the like is subjected to hot rolling after soaking. The reason for this is that Mg is segregated in the ingot during casting, and the normal hot rolling significantly reduces the ductility of the Al—Mg alloy, so that cracking is likely to occur.

  On the other hand, it is also difficult to hot-roll high-Mg Al—Mg alloys at low temperatures while avoiding the above-described temperature range where cracks occur. This is because, in such low-temperature rolling, the deformation resistance of the high-Mg Al—Mg-based alloy material is remarkably increased, and the product size that can be produced is extremely limited by the current rolling mill capability.

  In addition, a method of adding a third element such as Fe or Si has been proposed in order to increase the allowable Mg content of a high Mg Al—Mg alloy. However, when the content of these third elements is increased, a coarse intermetallic compound is easily formed, and the ductility of the aluminum alloy plate is lowered. For this reason, there is a limit to the increase in the Mg content allowable amount, and it was difficult to contain an amount of Mg exceeding 8%.

  For this reason, various proposals have heretofore been made for producing high-Mg Al—Mg-based alloy plates by a continuous casting method such as a twin roll type. In the twin roll type continuous casting method, molten aluminum alloy is poured from a refractory hot water supply nozzle between a pair of rotating water-cooled copper molds (twin rolls) and solidified. Immediately after that, it is reduced and rapidly cooled to form an aluminum alloy thin plate. As this twin roll type continuous casting method, the Hunter method, the 3C method and the like are known.

  The cooling rate of the twin roll type continuous casting method is 1 to 3 orders of magnitude higher than that of the conventional DC casting method or belt type continuous casting method. For this reason, the obtained aluminum alloy sheet has a very fine structure and is excellent in workability such as press formability. Moreover, the aluminum alloy plate having a relatively thin plate thickness of 1 to 13 mm is obtained by casting. For this reason, steps such as hot rough rolling and hot finish rolling can be omitted as in the case of a conventional DC ingot (thickness 200 to 600 mm). Furthermore, ingot homogenization may be omitted.

An example in which the structure of a high Mg Al—Mg alloy plate manufactured using such a twin-roll type continuous casting method is defined for the purpose of improving formability has been proposed. For example, an aluminum alloy sheet for automobiles with excellent mechanical properties is proposed in which the average size of Al-Mg based intermetallic compounds of Al-Mg based alloy sheets with a high Mg content of 6-10% is 10 μm or less. (See Patent Document 1). Also proposed is an aluminum alloy plate for automobile body sheets in which the number of Al-Mg intermetallic compounds of 10 μm or more is 300 pieces / mm ² or less and the average crystal grain size is 10 to 70 μm (Patent Document 2). See).
Japanese Patent Laid-Open No. 7-252571 (claims, pages 1 to 2) JP-A-8-165538 (Claims, pages 1 to 2)

  As described in Patent Documents 1 and 2, the Al—Mg intermetallic compound that crystallizes during casting is likely to be a starting point of fracture during press molding. Therefore, in order to improve the press formability of high-Mg Al-Mg alloy plates produced using the twin-roll continuous casting method, these Al-Mg-based intermetallic compounds (also referred to as Al-Mg-based compounds) As described in Patent Documents 1 and 2, it is effective to reduce the size or the size of coarse particles. It is also effective to improve the press formability to make the crystal grains of the plate finer.

  However, application of these Al-Mg intermetallic compounds to automobile panels is difficult even if crystal grains are miniaturized only by miniaturizing or reducing the number of coarse ones. Among automotive panels, it is particularly difficult to apply the above-described automotive body panel to an outer panel, an inner panel, or the like. This is because these outer panels and inner panels tend to be larger in size and more complicated in terms of automobile design, and are more difficult to mold.

  Therefore, in order to improve the press formability of the high Mg Al-Mg alloy plate manufactured by using the twin roll type continuous casting method to the actual outer panel or inner panel, as described in Patent Documents 1 and 2 above. Further, it is not sufficient to make crystal grains finer, further to make Al-Mg intermetallic compounds finer, or to reduce coarse ones. For this reason, there is a demand for a high Mg Al-Mg alloy plate having higher press formability.

  The present invention has been made to solve such problems, and the object thereof is a high Mg-containing Al-Mg-based aluminum alloy plate obtained by continuous casting, and has a higher press formability. An aluminum alloy plate is provided.

In order to achieve this object, the gist of the forming aluminum alloy sheet of the present invention is an Al-Mg-based aluminum alloy sheet having a thickness of 0.5 to 3 mm cast and cold-rolled by a twin roll continuous casting method, In mass%, Mg: more than 8% and 14% or less, Fe: 1.0% or less, Si: 0.5% or less, and the balance consisting of Al and unavoidable impurities. Of the texture of this plate, the Cube orientation, rotating Cube Sum of average area ratios of orientation components of textures of orientation, Goss orientation, Brass orientation, S orientation, Cu orientation, and PP orientation, [Cube] + [rotated Cube] + [Goss] + [Brass] + [S] It is assumed that + [Cu] + [PP] is 35% or less.
However, the area ratio of each texture is the area ratio of the azimuth region whose deviation from each ideal azimuth is within ± 15 °.

  Further, as a material characteristic of the aluminum alloy plate, in order to surely achieve higher press formability, the aluminum alloy plate is formed by mass% in the twin roll type continuous casting, Mg: 8-14%, Fe: 1.0% or less, Si: 0.5% or less, and 97% or more of the balance of aluminum alloy molten metal is poured into a pair of rotating twin rolls. It is preferable that it is manufactured by continuously casting at a plate thickness of 1 to 13 mm at not less than ° C / s.

  Furthermore, in order to reliably achieve higher press formability, it is preferable that the twin roll surface is not lubricated during continuous casting.

  In the present invention, in the high Mg Al-Mg based alloy plate exceeding 8%, the texture is controlled, the anisotropy of the plate is reduced, and the press formability is improved.

  The anisotropy of high-Mg Al-Mg alloy sheets cast and cold-rolled by the twin roll continuous casting method is the same as the Al-Mg system produced by ordinary DC casting-soaking-hot rolling-cold rolling. Smaller than aluminum alloy plate. However, it has been found that it is necessary to further reduce the anisotropy of the plate in order to improve the press formability.

  In the field of Al—Mg-based aluminum alloy sheets produced by the above-described normal DC casting process, there has been a technical idea for improving the press formability by controlling the texture. However, in the field of high-Mg Al-Mg alloy thin plates by the twin roll type continuous casting method, there is almost no idea to improve the press formability by controlling the texture as in the present invention.

  In the present invention, in the high-Mg Al-Mg alloy plate exceeding 8%, the texture is controlled, and the anisotropy of the plate is reduced. An excellent press formability can be obtained by a combination of processing.

(Group organization)
FIG. 1 shows the average areas of the orientation components of the textures of Cube orientation, rotational Cube orientation, Goss orientation, Brass orientation, S orientation, Cu orientation, and PP orientation, which are major in the texture of the aluminum alloy sheet. The rate measurement result is shown.

  The black circles in FIG. 1 are 10.5% Mg Al—Mg alloy plates of the present invention (Invention example 2 in the examples described later), and the black triangles are 12.0% Mg Al—Mg alloy sheets of the present invention (examples described later). Invention Example 3) in FIG. The white square is a comparative example of 10.5% Mg Al-Mg alloy plate (Comparative Example 15 in Examples described later), and the white triangle is a comparative example of 12.0% Mg Al-Mg alloy plate ( This is a comparative example 16) in Examples described later. In the comparison between the inventive examples of the same composition and the comparative example, the degree of anisotropy is different between the inventive example and the comparative example, and the inventive example has a smaller anisotropy than the comparative example.

  Each invention example of FIG. 1 is the sum of the average area ratios of the orientation components of each texture of the Cube orientation, the rotational Cube orientation, the Goss orientation, the Brass orientation, the S orientation, the Cu orientation, and the PP orientation in the texture of the plate. [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is 35% or less. On the other hand, in each comparative example of FIG. 1, the sum of the average area ratios of the orientation components of each texture exceeds 35%. And as the Example mentioned later, each invention example of FIG. 1 has good press moldability, and each comparative example of FIG. 1 is inferior to press moldability compared with these each invention example.

  That is, in order to improve the press formability, among the texture of the plate after the final annealing, the orientation of each texture of the Cube orientation, the rotational Cube orientation, the Goss orientation, the Brass orientation, the S orientation, the Cu orientation, and the PP orientation. The sum of the average area ratio of the components, [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is set to 35% or less to reduce the anisotropy of the plate. There is a need.

  On the other hand, if the sum of the average area ratios of the orientation components of each texture exceeds 35%, the anisotropy of the plate is increased only by reducing the press formability. Control of the texture in the present invention is performed by controlling the cold rolling rate in cold rolling described later.

It should be noted that the definition and measurement method of the main orientation component itself of each texture defined in the present invention is almost the same as that of the normal Al-Mg alloy plate by DC casting. That is,
Cube orientation: {001} <100>
Rotating Cube orientation: {001} <110> (Cube orientation is the orientation in which the plate surface is rotated: RW orientation)
Goss orientation: {011} <100>
Brass orientation: {011} <211>
S orientation: {123} <634>
Cu orientation: {112} <111>
(Or D orientation: {4411} <11118>
PP orientation: {011} <122> etc.

  In the present invention, the texture distribution measurement point is preferably a right-angle cross section in the plate width direction, and is preferably measured at ¼ part in the plate thickness direction of the alloy plate. That is, SEM-EBSP is applied to a plane that passes through the center of the plate surface after final annealing (intersection of 1/2 in the plate length direction and 1/2 in the plate width direction) and is orthogonal to the plate surface and parallel to the rolling direction. Measure using (ElectronBackScatteringPattern). However, the area ratio of each texture is the area ratio of the azimuth region whose deviation from each ideal azimuth is within ± 15 °.

  More specifically, mechanical polishing and buffing are performed on the surface of the sample of the cross-section of the plate sampled a plurality from the above site, and then electrolytic polishing is performed. Next, by using SEM-EBSP, a plurality of texture compositions occupying a rectangle having a thickness direction of 500 μm and a rolling direction of 1000 μm are measured, and an average area ratio in each direction is calculated. The measurement is performed from the surface of the plate to the center of the plate thickness, for example, with a step interval of 3 μm or less. As the SEM apparatus, for example, SEM (JEOLJSM5410) manufactured by JEOL Ltd. or FE-SEM (Electrolytic Emission Scanning Electron Microscope, FieldEmission Scanning Electron Microscopy) (XL30S-FEG) manufactured by Philips is used. The EBSP measurement / analysis system uses, for example, EBSP (OIM) manufactured by TSL.

(Average crystal grain size)
It is preferable as a precondition for improving the formability that the average crystal grain size on the surface of the Al alloy plate is refined to 100 μm or less. By making the crystal grain size fine or small within this range, press formability is ensured or improved. When the crystal grain size becomes larger than 100 μm, the press formability is remarkably deteriorated, and defects such as cracks and rough skin during forming tend to occur. On the other hand, even if the average crystal grain size is too small, SS (stretcher strain) marks, which are peculiar to 5000 series Al alloy plates, are generated during press molding. From this point of view, the average crystal grain size is 20 μm or more. It is preferable to do.

  The crystal grain size referred to in the present invention is the maximum diameter of crystal grains in the longitudinal (L) direction of the plate. The crystal grain size is measured by a line intercept method in the L direction by observing the surface of the Al alloy plate that has been mechanically polished by 0.05 to 0.1 mm and then electrolytically etched using a 100 × optical microscope. 1 The measurement line length is 0.95mm, and the total measurement line length is 0.95 x 15mm by observing a total of 5 fields with 3 lines per field.

(Chemical composition)
The significance of each alloy element and the reason for its limitation in the chemical composition of the Al alloy sheet of the present invention will be described below. The Al alloy sheet of the present invention basically includes, in mass%, Mg: more than 8% and 14% or less, Fe: 1.0% or less, Si: 0.5% or less, and the balance is made of Al and inevitable impurities. The chemical composition.

(Mg: Over 8% and 14% or less)
Mg is an important alloy element that increases the strength and ductility of the Al alloy sheet. If the Mg content is 8% or less, the strength and ductility are insufficient, and the characteristics of high-Mg Al-Mg-based Al alloys do not appear. In particular, the press formability to automotive panels intended by the present invention is insufficient. . On the other hand, if Mg is contained in excess of 14%, the crystal quality of the Al-Mg compound can be controlled even if the manufacturing method and conditions such as increasing the cooling rate during continuous casting and increasing the cooling rate after annealing are controlled. Precipitation increases. As a result, press formability is significantly reduced. In addition, the work hardening amount is increased and the cold rollability is also lowered. Therefore, Mg is in the range of more than 8% and not more than 14%.

(Fe: 1.0% or less, Si: 0.5% or less)
Fe and Si are impurities that should be regulated to the smallest possible amount. Fe and Si are produced in a large amount in the amount of Al-Mg compounds composed of Al-Mg- (Fe, Si) and the like, and the amount of compounds other than Al-Mg compounds such as Al-Fe and Al-Si. When the Fe content exceeds 1.0% and the Si content exceeds 0.5%, the amount of these compounds becomes excessive, which significantly impairs fracture toughness and formability. As a result, press formability is significantly reduced. Therefore, Fe is regulated to 1.0% or less, preferably 0.5% or less, and Si is regulated to 0.5% or less, preferably 0.3% or less.

  In addition, Mn, Cu, Cr, Zr, Zn, V 2, Ti, B, etc. are also impurity elements, and it is better that the content is small. However, for example, Mn, Cr, Zr, and V have the effect of refining the rolled plate structure, and Ti and B have the effect of refining the cast plate (ingot) structure. Cu and Zn also have the effect of improving strength. For this reason, it may be included with the aim of these effects, and it is allowed to contain one or more of these elements within a range that does not impair the formability that is a characteristic of the plate of the present invention. These allowable amounts are, respectively,% by mass, Mn: 0.3% or less, Cr: 0.3% or less, Zr: 0.3% or less, V: 0.3% or less, Ti: 0.1% or less, B: 0.05% or less, Cu: 1.0% or less, Zn: 1.0% or less.

(Production method)
Below, the manufacturing method of the Al-Mg type | system | group Al alloy plate in this invention is demonstrated.
As described above, the high-Mg Al-Mg Al alloy plate of the present invention is subjected to hot rolling after soaking of an ingot cast by DC casting or the like. Have difficulty. Therefore, the high-Mg Al—Mg-based Al alloy sheet of the present invention is manufactured by a combination of continuous casting such as a twin roll type, cold rolling and annealing without hot rolling.

(Double roll type continuous casting)
As a continuous casting method for Al alloy thin plates, there are a belt caster type, a Properchi type, a block caster type, etc. in addition to the twin roll type, but in order to increase the cooling rate during casting described later, a twin roll type And

  This twin roll type continuous casting, as described above, between the twin rolls such as a pair of rotating water-cooled copper molds, from the hot water supply nozzle made of refractory material, Al alloy molten metal having the above composition is poured and solidified, and Then, between the twin rolls, the Al alloy thin plate is obtained by reducing and quenching immediately after the solidification.

(Roll lubrication)
At this time, as the twin roll, it is desirable to use a roll whose surface is not lubricated by a lubricant. Conventionally, oxide powder (alumina powder, zinc oxide powder, etc.), SiC powder, graphite powder, In general, a lubricant (release agent) such as oil or molten glass is applied to the twin roll surface or is allowed to flow down. However, when these lubricants are used, the cooling rate becomes slow and the required cooling rate cannot be obtained. For this reason, the crystal grains become coarse, and the formability of a high Mg Al—Mg alloy plate exceeding 8% is lowered.

  In addition, when these lubricants are used, cooling unevenness is likely to occur due to the uneven concentration and thickness of the lubricant on the twin roll surface, and the solidification rate tends to be insufficient depending on the part of the plate. For this reason, the higher the Mg content, the larger the macro segregation and micro segregation, and the higher the possibility that it becomes difficult to make the formability of the Al-Mg alloy plate uniform.

  Incidentally, even in Japanese Patent Laid-Open No. 1-202345, in the twin roll type continuous casting of Al-Mg based alloy plate containing 3.5% or more of Mg, using a roll whose surface is not lubricated by a lubricant, due to uneven cooling, It is disclosed to improve surface quality by preventing spot defects (surface segregation). However, what is disclosed in the examples is the amount of Mg up to 5%, and there is no disclosure of an Al—Mg-based alloy plate with a high amount of Mg exceeding 8% as in the present invention. In other words, in the twin roll type continuous casting in the region of the Al-Mg based alloy plate having a high Mg content exceeding 8% as in the present invention, whether the lubricant should be used or not is effective. In general, it was unclear, and as described above, it was more common to use a lubricant.

(Cooling rate)
For example, in order to reduce the average grain size of high-Mg Al-Mg alloy plates even if the thickness of the cast plate is in the range of relatively thin plates of 1 to 13 mm, the cooling of the casting by this twin roll is used. The speed should be as fast as possible, over 100 ° C / s. When the above-mentioned lubricant is used, even if the cooling rate is high in theoretical calculation, the actual or actual cooling rate tends to be substantially less than 100 ° C./s. For this reason, the average crystal grain size of the high Mg Al—Mg alloy plate exceeding 8% cannot be made fine, and the press formability is significantly lowered.

Since this cooling rate is difficult to measure directly, a method known from the dendrite arm spacing (Dendrite secondary branch interval, DAS) of the cast plate (ingot) (for example, Light Metal Society, 8.20 1988) Published in “Methods of measuring aluminum dendrite arm spacing and cooling rate”). That is, the average distance d between adjacent dendrite secondary arms (secondary branches) in the cast structure of the cast plate was measured using the intersection method (number of fields of view of 3 or more, number of intersections of 10 or more). Using d, the following formula is obtained: d = 62 × C ^−0.337 (where d: dendrite secondary arm interval mm, C: cooling rate ° ^C./s ).

(Cast plate thickness)
The thickness of the thin plate continuously cast by twin rolls is in the range of 1 to 13 mm. And, preferably, a thin plate thickness of 1 mm or more and less than 5 mm. Continuous casting with a thickness of less than 1mm is difficult due to casting limitations such as pouring between twin rolls and controlling the roll gap between twin rolls. On the other hand, when the plate thickness is 13 mm, or more strictly, the plate thickness exceeds 5 mm, the cooling rate of the casting becomes extremely slow, and the overall intermetallic compounds such as Al-Mg system become coarse or a large amount of crystallization occurs. Tend to. As a result, there is a high possibility that the press formability is significantly lowered.

(Pouring temperature)
The pouring temperature when pouring Al alloy molten metal into the twin rolls is preferably set to the liquidus temperature + 30 ° C. or lower. When the pouring temperature exceeds the liquidus temperature + 30 ° C, the casting cooling rate described later becomes small, and all intermetallic compounds such as the Al-Mg system may become coarse or crystallize in large quantities. As a result, the strength-elongation balance is lowered, and the press formability may be significantly lowered. In addition, the rolling effect of the twin rolls is reduced, the number of center defects increases, and the basic mechanical properties of the Al alloy plate itself may be deteriorated.

(Twin roll speed)
The peripheral speed of the pair of rotating twin rolls is preferably 1 m / min or more. If the peripheral speed of the twin roll is less than 1 m 2 / min, the contact time between the molten metal and the mold (twist roll) becomes long, and the surface quality of the cast thin plate may be deteriorated. In this respect, the higher the peripheral speed of the twin rolls, the better, and the preferable peripheral speed is 30 m / min or more.

(Cold rolling)
The Al alloy sheet thus cast is not hot-rolled on-line or off-line, but is cold-rolled to a thickness of 0.5 to 3 mm of a product plate for an automobile panel, and the cast structure is processed. Control of the texture in the present invention is performed by controlling the cold rolling rate (working rate) in this cold rolling. The sum of the average area ratios of the orientation components of each texture of the plate, [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is 35% or less. Therefore, it is preferable that the cold rolling rate in the final cold rolling is 60% or less. When the cold rolling ratio in the final cold rolling exceeds 60%, the sum of the average area ratios of the orientation components of the textures of the plate exceeds 35%, and the anisotropy may increase. high.

  In this regard, when the thickness of the thin plate continuously cast by twin rolls is thick on the upper side of 13 mm, intermediate annealing is performed in the middle of cold rolling, and the cold rolling rate in the final cold rolling should be 60% or less. Is preferred. The degree of work organization in cold rolling depends on the cold rolling rate of cold rolling, and the cast structure may remain due to the above texture control, but the press formability and mechanical properties are It is allowed as long as it does not inhibit.

(Final annealing)
The Al alloy cold-rolled sheet is preferably finally annealed at 400 ° C. to the liquidus temperature. If the annealing temperature is less than 400 ° C, there is a high possibility that no solution effect will be obtained. Further, after this final annealing, it is necessary to cool at a temperature range of 500 to 300 ° C. at an average cooling rate as fast as possible at 5 ° C./s or more. If the average cooling rate after the final annealing is slow and less than 5 ° C / s, a large amount of all intermetallic compounds such as Al-Mg will precipitate during the cooling process. As a result, there is a high possibility that the strength-elongation balance is lowered and the press formability is significantly lowered.

  Examples of the present invention will be described below. Various thicknesses of Al-Mg-based Al alloy melts (Invention Examples A to M, Comparative Examples N to X) having various chemical composition shown in Table 1 under the conditions shown in Table 2 by the twin roll continuous casting method described above. (3 to 10 mm). Each of these Al alloy cast thin plates was cold-rolled up to a thickness of 1.5 mm, with various final cold rolling rates, including the presence or absence of intermediate annealing, as shown in Table 2. When intermediate annealing was used, the annealing conditions were commonly 400 ° C x 5 hours.

  Each of these cold-rolled plates was subjected to final annealing and cooling in a continuous annealing furnace under the conditions shown in Table 2. In both of the inventive examples and the comparative examples, except for Comparative Example 14, the average crystal grain size on the surface of the obtained Al alloy plate was in the range of 30 to 60 μm.

  Here, the peripheral speed of twin rolls during continuous casting of twin rolls is 70 m / min, and the pouring temperature when pouring Al alloy molten metal into twin rolls is the liquidus temperature + 20 ° C, which is constant in each example. It was. Lubricating the twin roll surface with a lubricant in which SiC and alumina powders are suspended in water is performed only in Comparative Example 14 in Table 2, and all other examples are continuously lubricated without lubrication of the twin roll surface (no lubrication). did.

  From the high-Mg Al-Mg-based Al alloy sheet obtained in this way after the final annealing, any measurement location that is 100 mm or more apart from each other in the longitudinal direction of the part to be press-molded, The textures at the five locations (Cube orientation, rotational Cube orientation, Goss orientation, Brass orientation, S orientation, Cu orientation, and the sum of the average area ratio of each orientation component of the PP orientation) in the manner described above. Measured and calculated. Table 3 shows the measurement results.

  Furthermore, specimens were collected from the texture measurement points, and the average value of the mechanical properties of each specimen and the strength ductility balance [tensile strength (TS: MPa) × total elongation (EL:%)] (MPa%) In addition, from the plate part to be press-molded, five arbitrary specimens with a distance of 100 mm or more in the longitudinal direction are collected for each test, and the properties such as formability are also obtained. Measurement and evaluation. These results are shown in Table 3.

  The tensile test was performed according to JIS Z 2201, and the shape of the test piece was a JIS No. 5 test piece, and the test piece was manufactured so that the longitudinal direction of the test piece coincided with the rolling direction. The crosshead speed was 5 mm / min, and the test piece was run at a constant speed until the test piece broke.

  As a material test evaluation of formability, an Erichsen test (mm) was performed in accordance with JIS Z 2247.

  Then, in order to evaluate the formability as an actual automobile outer panel, each of the obtained high Mg Al—Mg-based Al alloy plates was press-formed and bent. These results are also shown in Table 3.

  In the press molding test, five of the sampling specimens (square blanks with a side of 200 mm) were placed in a rectangular tube-shaped projecting part with a side of 60 mm and a height of 30 mm at the center part. A hat-type panel having a flat flange portion around it was stretched by a mechanical press. The wrinkle holding force was 49 kN, the lubricating oil was general rust preventive oil, and the molding speed was 20 mm / min under the same conditions.

  And in 5 times (5 sheets) of press molding, there were no cracks in the four perimeters of the overhang or flat flange part, and in 5 times of press molding there was no crack, but SS mark or rough surface The case where the crack occurred was evaluated as Δ, and the case where the crack occurred even once was evaluated as X.

  Bending workability is evaluated by performing 10% stretch on the test piece at room temperature, simulating flat hem processing after press molding, using the collected test piece as an automobile outer panel, and performing a bending test. did. As the test specimen conditions, the sample specimen was prepared using a No. 3 test specimen (width 30 mm × length 200 mm) defined in JIS Z 2204 so that the longitudinal direction of the specimen coincided with the rolling direction. The bending test was performed by simulating flat hem processing using the V-block method specified in JIS Z 2248, bending it to 60 degrees with a clamp with a tip radius of 0.3 mm and a bending angle of 60 degrees, and then bending to 180 degrees. . At this time, for example, in the hem processing of the outer panel, the inner panel is sandwiched in the bent portion, but in order to make the conditions strict, it was bent at 180 degrees without sandwiching such an Al alloy plate.

  Then, observe the occurrence of cracks in the bent part (curved part) after the bending test, and in the five tests (five sheets), if the bent part surface has no more cracks or rough skin, In both tests, the case where there was no crack but the skin was rough was evaluated as Δ, and the case where there was a crack even once was evaluated as ×.

  As shown in Tables 1 and 2, it is an example of a high Mg Al-Mg-based Al alloy plate having a composition within the scope of the present invention of A to M in Table 1, and is a twin roll continuous casting under the conditions within the scope of the present invention. Inventive Examples 1 to 13 that were cold-rolled and finally annealed included the orientation components of the textures of the Cube orientation, rotational Cube orientation, Goss orientation, Brass orientation, S orientation, Cu orientation, and PP orientation in the texture of the plate. The total of the average area ratio, [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is 35% or less. As a result, the strength ductility balance is high, and the press formability and bending workability are excellent.

  On the other hand, Comparative Example 14 is an example of a high Mg Al-Mg Al alloy having a composition within the scope of the present invention of A in Table 1, but it performs twin roll lubrication and has a cooling rate of 100 ° C / It is manufactured outside the range of preferable manufacturing conditions that are less than s. Therefore, in Comparative Example 14, although [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is within 35%, the surface of the obtained Al alloy plate The average crystal grain size exceeds 100 μm, the strength ductility balance is low, and the bending workability and press formability are poor.

  Comparative Examples 15 and 16 are examples of high Mg Al—Mg-based Al alloys having a composition within the range of the present invention of B 1 in Table 1, but the final cold rolling rate is too high. Therefore, in Comparative Examples 15 and 16, [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] exceeds 35%, and the strength ductility balance is low. It is inferior in bending workability and press formability.

  Comparative Examples 17 to 27 using alloys having compositions outside the N to X range of Table 1 in Table 1 are within the preferable condition range, even though twin roll continuous casting, final cold rolling, and final annealing are performed. Moreover, although [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is within 35%, the press formability is higher than that of the invention example. Remarkably inferior.

Comparative Example 17 uses an alloy of N 2 whose Mg content is too low below the lower limit.
Comparative Example 18 uses an alloy of O 2 whose Mg content exceeds the upper limit and is too high.
Comparative Example 19 uses an alloy of P 2 in which the Fe content exceeds the upper limit and is too high.
Comparative Example 20 uses an alloy of Q whose Si content is more than the upper limit.
Comparative Example 21 uses an R 2 alloy whose Mn content exceeds the upper limit and is too much.
Comparative Example 22 uses an alloy of S 2 in which the Cr content exceeds the upper limit and is too high.
Comparative Example 23 uses an alloy of T 2 whose Zr content exceeds the upper limit and is too high.
Comparative Example 24 uses an alloy of U 2 whose V content exceeds the upper limit and is too high.
Comparative Example 25 uses an alloy of V where the Ti content is too much above the upper limit.
Comparative Example 26 uses an alloy of W 2 whose Cu content exceeds the upper limit and is too high.
Comparative Example 27 uses an alloy of X 2 whose Zn content exceeds the upper limit and is too high.
Therefore, from these, the critical significance of the strength, ductility, strength-ductility balance, and moldability of each element can be understood.

  As described above, according to the present invention, a high Mg content Al-Mg aluminum alloy plate obtained by continuous casting, which can be applied to an outer panel and an inner panel of an automobile, has a higher press formability. An aluminum alloy sheet having the following can be provided. As a result, the application of Al-Mg-based aluminum alloy continuous cast plates for press forming such as automobile panels can be expanded.

It is explanatory drawing which shows the average area ratio measurement result of each orientation component of each texture of this invention aluminum alloy plate.

Claims (4)

Al-Mg-based aluminum alloy sheet with a thickness of 0.5 to 3 mm cast and cold-rolled by a twin-roll continuous casting method, and in mass%, Mg: more than 8% but not more than 14%, Fe: not more than 1.0% Si: 0.5% or less, comprising the balance Al and unavoidable impurities. Among the texture of this plate, each set of Cube orientation, rotational Cube orientation, Goss orientation, Brass orientation, S orientation, Cu orientation, PP orientation Total sum of average area ratio of orientation component of tissue, [Cube] + [Rotating Cube] + [Goss] + [Brass] + [S] + [Cu] + [PP] is 35% or less Aluminum alloy sheet for forming.
However, the area ratio of each texture is the area ratio of the azimuth region whose deviation from each ideal azimuth is within ± 15 °.   The aluminum alloy plate is further mass%, Mn: 0.3% or less, Cr: 0.3% or less, Zr: 0.3% or less, V: 0.3% or less, Ti: 0.1% or less, Cu: 1.0% or less, Zn: The aluminum alloy sheet for forming according to claim 1, comprising 1.0% or less of one or more of them.   In the twin roll continuous casting, the aluminum alloy plate contains Mg: 8 to 14%, Fe: 1.0% or less, Si: 0.5% or less, and the balance is made of Al and unavoidable impurities. It is manufactured by pouring molten metal into a pair of rotating twin rolls and continuously casting the twin rolls at a cooling rate of 100 ° C / s or more in a thickness range of 1 to 13 mm. The aluminum alloy plate for molding according to claim 1 or 2. The forming aluminum alloy plate according to any one of claims 1 to 3, wherein the aluminum alloy plate is cast on the twin roll surface without using a lubricant.

Images