CN102373353B - The aluminium alloy plate having excellent formability - Google Patents

Abstract

The present invention provides the Al-Mg system alloy sheets that generation is less and press molding is excellent of degradation new problem under a kind of bendability not producing and being caused by the age-hardening under room temperature, SS stricture of vagina. By comprising when forming the Al-Mg line aluminium alloy plate manufacture formed of specific Mg, Cu, not only interim rate of cooling when controlling the Quenching Treatment after solid solution, and control additional anneal condition, the cluster making this alloy sheets is carried out the Cu that the endothermic peak height between 180��280 DEG C of the heating curves that differential thermal analysis obtains starts from room temperature represents exists, it is difficult to spread during as Mg, and the plate tissue that zigzag is difficult to occur is to suppress the generation of press molding SS stricture of vagina.

Description

The aluminium alloy plate having excellent formability

Technical field

The present invention relates to the Al-Mg line aluminium alloy plate having excellent formability. Aluminium alloy plate described in the present invention is hot rolling making sheet and cold rolling making sheet, refers to and has carried out the aluminium alloy plate that solution treatment and Quenching Treatment etc. are modified. Also aluminum is called Al it addition, following.

Background technology

In recent years, from the view point of consider earth environment etc., the light-weighted social desirability of the vehicles such as automobile improves day by day. In order to tackle this requirement, as car panel, especially the material of the large-scale body panels (outside plate, inner panel) such as car bonnet, car door, roof, except the ferrous materials such as steel plate, is also studying the application of aluminum alloy materials.

The 5000 line aluminium alloy plates (hereinafter also referred to Al-Mg system alloy sheets) of the JIS5052 alloy of Al-Mg system and JIS5182 alloy etc. are due to ductility and excellent strength, so be used as the press molding raw material of these large-scale body panels all the time.

But, as disclosed in patent documentation 1 grade, if these Al-Mg system alloy sheets are carried out tension test, then have near the yield point on load-deformation curve and produce the situation that surrender stretches, additionally also have under the dependent variable (such as tensile elongation more than 2%) that the comparison having exceeded yield point is high, load-deformation curve produces the situation of zigzag or stair-stepping zigzag (vibration). Phenomenon on these load-deformation curves causes the generation of so-called elongation strain (StretcherStrain) (being also denoted as SS stricture of vagina below) in actual press molding, this is for the large-scale body panels as formed products, especially the outside plate that outward appearance is critically important, becomes the very big problem of loss commodity value.

This SS stricture of vagina is such as known described can be divided into: at the so-called random stricture of vagina of the irregular banding apperance such as flamboyancy that the position that dependent variable is relatively low occurs, and at the higher position of dependent variable about to become the parallel band of the parallel banding apperance occurred in the way of in the of 50 �� relative to draw direction. Known the former random stricture of vagina by yield point stretch cause, additionally the parallel band of the latter by paragraph 0004 record load-deformation curve on zigzag (vibration) cause.

All the time, it is proposed that the method for these SS stricture of vaginas of various eliminations. Such as, as main method, it is known to by the crystal grain adjustment of Al-Mg system alloy sheets thick method to a certain degree. But, even if the method for adjustment of this crystal grain is in SS stricture of vagina, the generation preventing parallel band recorded in paragraph 0004 is not effective. If it addition, crystal grain becomes big excessively mutually, then produce table in press molding on the contrary and on other problem of coarse grade occurs.

Additionally, as other methods eliminating SS stricture of vagina, it is known that following methods: before the press molding to large-scale body panels, the modified material that the O material (soft material) of Al-Mg system alloy sheets or T4 process material etc. in advance applies the processing (preprocessing) such as skin-pass processing or leveling processing, and provides some strains (prestrain) in advance. But, even if such pre-add engineering method, when degree of finish becomes too high, the zigzag (vibration) also easily produced in paragraph 0004 on the load-deformation curve of record, even if when actual press molding, also easily it is related to the generation of the clearly parallel band of wide cut degree. Therefore, the degree of finish of preprocessing is had very big restriction, cannot stable against the generation of random stricture of vagina during reduction degree of finish. Therefore, in this pre-add engineering method, owing to the optimal process degree preventing the generation of parallel band is contrary with the optimal process degree preventing random stricture of vagina from occurring, so both cannot be prevented simultaneously.

On the other hand, in aforesaid patent documentation 1, it is proposed that also inhibits the generation of the parallel band of wide cut degree, the SS stricture of vagina method for making that few Al-Mg system alloy sheets occurs while suppressing the generation of random stricture of vagina. Specifically, the milled sheet of Al-Mg system alloy is implemented with the solid solution under the specified conditions cooled down rapidly, Quenching Treatment, carries out the cold working as the preprocessing under specified conditions afterwards, then implement the final annealing under specified conditions. Then obtain being created substantially absent the most soleplate of the coarse grain that average crystal grain footpath is less than 55 ��m and more than 150 ��m.

Here, it is also known that in Al-Mg system alloy sheets field, although the generation suppressing SS stricture of vagina may not directly be mentioned, but the thermal change utilizing differential thermal analysis (DSC) to measure alloy sheets is obtained, the position of the endothermic peak of heating curves that starts from room temperature and its index highly improved as the press molding of this plate.

Such as, patent documentation 2 proposes, by utilizing the endothermic peak height of the ad-hoc location of heating curves that the differential thermal analysis (DSC) of Al-Mg system alloy sheets obtains, that start from room temperature, as the index that press molding improves. This differential thermal analysis (DSC) is general in the field of aluminium alloy plate, its reason is in that, when not differentiating and identify during the micro-assembly robot such as TEM is observed and can not directly prove existence cluster (intermetallic compound) that characteristic is influential, by the endothermic peak position of the ad-hoc location of aforementioned heating curves with highly carry out indirect proof with or without structural differences such as clusters or as index.

In this patent documentation 2, cast in the Al-Mg system alloy sheets of the manufactured high Mg more than 8 mass % continuously by double-roll type, making the endothermic peak height between 50��100 DEG C of the heating curves started from room temperature is 50.0 more than �� W, thus makes press molding improve. This follows, and this endothermic peak height represents the existing forms stability of precipitation state (solid solution) of the Al-Mg series intermetallic compound being referred to as �� phase in Al-Mg system alloy sheets tissue.

But, nearest large-scale body panels, in the outside plate that especially outward appearance is critically important, the requirement level of surface texture is more strict, even these patent documentations 1 or patent documentation 2, requires that it is also insufficient for suppressing the countermeasure that SS stricture of vagina occurs for such. Such as, in patent documentation 1, make stair-stepping zigzag slight (being documented in the stepped zigzag explanation of evaluation of the embodiment of patent documentation 1) as far as possible, therefore can not suppress the parallel band as one of SS stricture of vagina completely.

To this, in patent documentation 3, the problems referred to above are improved, and propose the generation not only suppressing random stricture of vagina, also suppress the generation of parallel band simultaneously, and inhibit the Al-Mg line aluminium alloy plate that the press molding etc. to car panel of SS stricture of vagina has excellent formability. In the document 3, for Al-Mg line aluminium alloy plate, especially make it contain Zn0.1��4.0%, improve the critical strain (limiting strain amount) that zigzag occurs further. Namely, by the 3rd elements such as Zn containing, add, the amount of being formed making the cluster (ultra tiny intermetallic compound) formed by Al and Mg as the cluster comprising Zn etc. increases, so that the increase effect of the limiting strain amount caused by these clusters improves further. And, thus suppress zigzag, and suppress the parallel band due to this, it is suppressed that the generation of SS stricture of vagina.

This comprises the size that cluster is below Nano grade of Zn etc., can not differentiate and identify in the micro-assembly robot such as the FE-TEM of about 100,000 times are observed, it is impossible to directly prove that it exists. Therefore, even if this patent documentation 3, also same with aforementioned patent literature 2, to the structural difference with or without cluster etc., differential thermal analysis (DSC) will be utilized to measure the endothermic peak position of ad-hoc location of aforementioned heating curves of thermal change and the height index as tissue difference. Specifically, what the Al-Mg cluster comprising Zn etc. can be speculated as aforementioned DSC heating curves endothermic peak between 100��150 DEG C will be because of, and this endothermic peak height is more than 200.0 �� W (microwatt).

But, the opinion according to the present inventor etc., in Al-Mg line aluminium alloy plate, time as shown in this patent documentation 3 in a large number containing Zn, create following new problem: easily produce the age-hardening in room temperature. This can be speculated as due in patent documentation 3 as the excellent stratagem suppressing SS stricture of vagina to occur want generate what the cluster (ultra tiny intermetallic compound) utilizing Zn to be formed easily caused in room temperature generation. That is, Zn content is more many, at room temperature forms aforementioned cluster amount and more increases, and can be speculated as what age-hardening at room temperature excessively carried out causing as a result. Usual Al-Mg line aluminium alloy plate is not be configured to large-scale body panels etc. in automobile factory after aluminium sheet maker manufacture at once, and generally generally has the interval of more than several weeks. It is thus possible, for instance from the manufacture of plate after 1 month, when being configured to large-scale body panels etc., produce age-hardening and remarkable break-throughs, bendability and press molding can be obstructed such new (other) problem on the contrary.

As described in known, compared with easily producing age-hardening, heat treatment type Al-Mg-Si system (6000 are) aluminium alloy plate under room temperature with the cluster that reason Mg, Si are formed, the age-hardening at room temperature of usual Al-Mg line aluminium alloy plate is difficult to produce. But, as described in patent documentation 3, even if such Al-Mg line aluminium alloy plate, when Zn content is more, abnormal is and the 6000 same age-hardenings displayed that under room temperature of line aluminium alloy plate.

Conventional art document

Patent documentation

Patent documentation 1: Japanese Unexamined Patent Publication 7-224364 publication

Patent documentation 2: Japanese Unexamined Patent Publication 2006-249480 publication

Patent documentation 3: Japanese Unexamined Patent Publication 2010-77506 publication

Summary of the invention

In view of the above problems, it is an object of the invention to provide degradation new problem under the bendability not producing to be brought by the age-hardening under room temperature, not only suppress to be stretched the generation of the random stricture of vagina caused by aforementioned surrender, also suppressed the generation of parallel band simultaneously, SS stricture of vagina can be suppressed to occur, make the Al-Mg line aluminium alloy plate that the press molding to car panel improves.

In order to reach this purpose, being intended to of the aluminium alloy plate having excellent formability of the present invention: it is count containing Mg:2.0��6.0%, Cu with quality %: more than 0.3% and for less than 2.0%, surplus be the Al-Mg line aluminium alloy plate of Al and inevitable impurity, utilize that the thermal change that differential thermal analysis measures this this plate obtains from the heating curves that room temperature starts, the maximum endothermic peak height between 180��280 DEG C is more than 5W/g.

The opinion of the present inventor etc. is as follows: as the element with the inhibition that SS stricture of vagina occurs, and selects Cu to replace easily producing the Zn of the age-hardening under room temperature. That is, if being Cu, so that it may do not produce the age-hardening under the such room temperature of Zn, there is the inhibition that SS stricture of vagina occurs.

But, the present inventor waits also has following opinion: even there is also the situation of the generation inhibition not having SS stricture of vagina equally containing Cu, for instance even the Al-Mg line aluminium alloy plate of identical Cu content, the inhibition that SS stricture of vagina is occurred also has bigger difference. From above-mentioned situation it is contemplated that be not singly containing Cu, and the difference of the existence (structural state) of the Cu in Al-Mg line aluminium alloy plate, the generation state of SS stricture of vagina also there is is large effect.

The result studied further for the existence of this Cu is, the present inventor etc. speculate the amount of the fine cluster (the fine cluster based on Cu) of specific (novel) Cu and with or without existence, make the inhibition that SS stricture of vagina occurs be a greater impact.

But, the existence of the cluster of this Cu actually can not directly be assert. Such as, to containing Cu and the cluster that Cu can be generated, the Al-Mg line aluminium alloy plate of modified (aftermentioned) that implement specified conditions, even if the FE-TEM (transmission electron microscope) using 100,000 times carries out structure observation, do not find the existence of the cluster of this Cu yet. In other words, it is possible to speculate that the cluster of this Cu is identical with the Al-Mg series intermetallic compound of aforementioned patent literature 2,3 etc., be the microsize of below Nano grade. Therefore, the analysis method of SEM, TEM of common structure observation method it is adopted as, it is impossible to determine the cluster of this Cu.

Accordingly, the present inventor etc. are to can not the existence of cluster of this novel Cu of indirect proof study. Then find, to containing Cu and also implement the modified Al-Mg line aluminium alloy plate of specified conditions, utilize that the thermal change that differential thermal analysis (DSC) measures this plate obtains, from the heating curves (DSC heating curves) that room temperature starts, there is obvious endothermic peak between 180��280 DEG C. And the height of this maximum endothermic peak is when being more than 5W/g, there is the inhibition that SS stricture of vagina occurs.

It is clear that endothermic peak between 180��280 DEG C of this DSC heating curves, can be that some cluster existed in the tissue by Al-Mg system alloy sheets determines, and the height of this endothermic peak be to be determined by the amount of some cluster. And, as described later, endothermic peak between 180��280 DEG C of this DSC heating curves, only containing Cu and also implement in the modified Al-Mg line aluminium alloy plate of specified conditions and occur, though not containing the Al-Mg line aluminium alloy plate of Cu or containing Cu but be not carried out in the modified Al-Mg line aluminium alloy plate of specified conditions and occur without. Therefore, the endothermic peak between 180��280 DEG C of this DSC heating curves can be specified at least determined by the cluster relevant to Cu.

As a result, the present inventor etc. recognize that the endothermic peak between 180��280 DEG C of this DSC heating curves represents the amount of cluster and this cluster that there is the novel Cu with the inhibition that SS stricture of vagina occurs. And, although the endothermic peak between the cluster of this Cu or even 180��280 DEG C of DSC heating curves describes in detail below, but in current clearly scope, only modified by the plate of the rolling in the manufacturing process of plate, that is, specifically modified (process) that be only combined by the additional anneal under the control of rate of cooling during to Quenching Treatment after solution treatment and the specified conditions more than 100 DEG C afterwards is generated. It is too low or when not implementing additional anneal etc. when the deviation of modified condition that the control of the rate of cooling when this Quenching Treatment not necessarily departs from the temperature of optimum condition or this additional anneal, even if such as containing Cu equally, do not produce the endothermic peak between 180��280 DEG C of DSC heating curves, and not there is the inhibition that SS stricture of vagina occurs yet. Therefore, in this case, it is easy to speculate that the cluster of the specific Cu with the inhibition that SS stricture of vagina occurs does not generate.

By the present invention in that the Cu using the age-hardening under the room temperature not producing Zn as above etc, thus control the tissue of Al-Mg line aluminium alloy plate, and hinder free Mg atom to move to transposition, tissue as Mg diffusion difficulty, it is difficult to produce saw-toothed projections, it is possible to obtain the alloy that SS stricture of vagina is excellent.

Accompanying drawing explanation

Fig. 1 indicates that the explanation figure of the heating curves started from room temperature that differential thermal analysis aluminium alloy plate of the present invention obtains.

Detailed description of the invention

Below in relation to embodiments of the present invention, each important document is specifically described.

(tissue)

By the heating curves (DSC heating curves) started from room temperature carrying out that differential thermal analysis (DSC) obtains containing the Al-Mg line aluminium alloy plate of Cu of the present invention is shown in Figure 1 with heavy line. The DSC heating curves (heavy line) of this Fig. 1 is the example 4 of embodiment table 1,2 described later. It addition, in the Fig. 1 merged, as comparative example, the DSC heating curves of the Al-Mg line aluminium alloy plate without Cu also represents with fine rule. The DSC heating curves (fine rule) of this Fig. 1 is the comparative example 14 of embodiment table 1,2 described later.

The DSC heating curves (heavy line) of this example 4 was stable curve before the temperature 180 DEG C of transverse axis, it does not have in the endothermic peak being recessed below (protruding downwards). But start to decline downwards after being above 180 DEG C, between 180��280 DEG C, as the peak that can substantially differentiate relative to aforementioned stable curved portion, exist in the endothermic peak (summit, top) being recessed below, and this endothermic peak has certain endothermic peak height. When the existence of the endothermic peak between these 180��280 DEG C is compared with the DSC heating curves (fine rule) of aforementioned comparative example 14, then become apparent from. In the DSC heating curves (fine rule) of comparative example 14, between 180��280 DEG C, there is no the aforementioned endothermic peak that can differentiate, through 100��300 DEG C of transverse axis, all only there is stable curve. Additionally once, in the transverse axis position more than 300 DEG C, there is the bigger exothermal peak protruded up and originate from the Al-Mg-Cu system distinctive peak value of alloy of S ' phase, all same common existence in the DSC heating curves of comparative example. But it is contemplated that the existence that reason be aforementioned cluster bigger than the peak of comparative example of the peak of example 4 promotes the formation of aforementioned S ' phase.

This endothermic peak height so-called refers to the height (W/g) of the longitudinal axis of endothermic peak that be present between 180��280 DEG C, aforementioned. For this endothermic peak height, after the position measuring temperature 150 DEG C is corrected making caloric receptivity and caloric value be 0, obtain the maximum endothermic peak height (W/g) of becoming of 180��280 DEG C of scopes. Now, measuring from the heat flow (HeatFlow) of the longitudinal axis of the heating curves (differential scanning calorimeter curve) started from room temperature is the datum line of 0.00, highly becomes the distance (W/g) of maximum endothermic peak to it. Additionally once, the transverse axis of aforementioned endothermic peak range for 180��280 DEG C also using following situation as benchmark: from the datum line phase same level that the heat flow of DSC heating curves (heavy line) with the longitudinal axis is 0.00, starting the position that declines downwards is near 180 DEG C, and the DSC heating curves (heavy line) behind the peak of aforesaid lower depression rises upward and becomes the position of phase same level with the datum line that heat flow is 0.00 of the longitudinal axis is near 280 DEG C.

In order to make the SS stricture of vagina of Al-Mg line aluminium alloy plate in the present invention improve, the height of the endothermic peak between 180��280 DEG C of this DSC heating curves is more than 5W/g. Can speculate, the Al-Mg line aluminium alloy plate of the present invention contains Cu and implements the modified of specified conditions, endothermic peak between 180��280 DEG C of this DSC heating curves represents the existence of the fine cluster based on Cu indirectly, and the height of this endothermic peak represents the amount of the fine cluster based on Cu. Therefore, it could be speculated that as long as no the endothermic peak between 180��280 DEG C of this DSC heating curves, be then absent from the fine cluster based on Cu, as long as the height of this endothermic peak is less than 5W/g, then it represents that the amount of the fine cluster based on Cu is excessively few.

Embodiment as be described hereinafter, as long as the height of the maximum endothermic peak between these 180��280 DEG C is more than 5W/g, then the �� c (limiting strain amount) of the critical strain that the zigzag on the load-deformation curve of the stretching experiment of Al-Mg system alloy sheets produces can be brought up to more than 8%, more preferably bring up to more than 10%. On the other hand, as long as no the endothermic peak between 180��280 DEG C of this DSC heating curves, as long as or the height of this endothermic peak is less than 5W/g, then improving with cannot not producing the age-hardening under room temperature and produce the critical strain that zigzag occurs, it is impossible to suppressing SS stricture of vagina to occur. Being explained, there is no particular limitation for the higher limit of the height of the maximum endothermic peak between these 180��280 DEG C, if from the limit etc. manufactured consider time, be set as about 20W/g. It addition, the upper limit of aforementioned critical strain �� c (limiting strain amount) is also without limiting especially, if from the limit etc. manufactured, being set as about 20%.

Herein, for " �� W " (microwatt) only regulation heat of regulation in aforementioned leading patent, the unit " W/g " of the height (longitudinal axis of Fig. 1) of this endothermic peak is that the weight (g) measuring test portion carries out normalized. That is, on W with " �� " or without, be only the change (10-6) of figure place of numerical value, when unit only specifies with " �� W ", the problem that can occur to consider the change of the heat of the change along with test portion weight. Therefore, in the present invention, in order to improve the precision of mensuration and repeatability, more make the regulation of the height of endothermic peak clear, have employed the heat ratio " W/g " divided by test portion weight. Differential thermal analysis field at aluminium alloy, this unit " W/g " is more general than " �� W " on the contrary, recording (use) such as, " The adds Al-Mg-Si alloy �� mono-Network Ha one De To light metal the 59th volume No. 8 (2009) 439��443 pages and Pot The nature �� high temperature givesShadow(with the addition of the natrual ageing involved by the baking hardenability of the Al-Mg-Si alloy of copper and the impact of high temperature preliminary aging) "; " Al-3%Mg-1%Cu alloy fruit and �� Na �� precipitate out light metal the 56th volume o.11 (2006) 673��679 pagesTo and Pot The Ag add shadow(impact that the Ag related in the age-hardening of Al-3%Mg-1%Cu alloy and nanometer precipitation tissue adds) "; In light metal the 52nd volume No. 2 (2002) 64��70 pages " made of Al-Cu alloy phase decomposition initial stage To �� �� Ru trace additives �� �� calculates �� �� �� �� mono-�� �� Application (behave of the trace additives that the phase decomposition of made of Al-Cu alloy is just interim and computer simulation thereof) " etc.

Can speculate, the SS stricture of vagina produced during the press molding of Al-Mg line aluminium alloy plate, the parallel band especially caused by the zigzag (vibration) on load-deformation curve is to be repeatedly performed fixing and disengaging by the free Mg atom pair transposition being solid-solubilized in aluminum matrix and produce. Hereinafter, the zigzag (vibration) on load-deformation curve the SS stricture of vagina of the parallel band caused also is referred to simply as SS stricture of vagina or SS stricture of vagina (zigzag). On the other hand, can speculate, as long as being present in the tissue of Al-Mg line aluminium alloy plate by the cluster of the Cu of the present invention that is specifically modified and that generate, free Mg atom during owing to hampering the deformation of the plate caused by press molding is to the movement of transposition, it is possible to suppress SS stricture of vagina (zigzag) to occur. And the cluster of Cu or Cu used in the present invention is nearly free from the age-hardening under the such room temperature of Zn.

Can speculate that the cluster based on this Cu is identical with the Al-Mg series intermetallic compound of aforementioned patent literature 2 etc., for the size below Nano grade. Therefore, the micro-assembly robot of the FE-TEM etc. of about 100,000 times can not differentiate and identify in observing, thus can not directly prove that it exists. Therefore, in the present invention, it is not directly limit these clusters (tissue), but limits the endothermic peak between 180��280 DEG C of aforementioned DSC heating curves.

But, in aforementioned patent literature 2,3 and the present invention, if the intermetallic compound becoming cluster is identical, then the endothermic peak of inevitable DSC heating curves is also identical. Just because of the compositions of these clusters, intermetallic compound etc. are mutually different, so the endothermic peak of DSC heating curves is different.

It addition, such as the DSC heating curves of Fig. 1, in the Al-Mg line aluminium alloy plate of the present invention, it does not have endothermic peak between 100��150 DEG C of the DSC heating curves of regulation in aforementioned patent literature 3.

Additionally once, this patent documentation 3, also same with aforementioned patent literature 2, the difference of the tissue such as the presence or absence to cluster, will utilize differential thermal analysis (DSC) even in the aforementioned heating curves of the thermal change of assay plate the endothermic peak position of ad-hoc location with highly as the identical Al-Mg line aluminium alloy plate index that also each self-organizing is different. Accordingly, the endothermic peak of the aforementioned DSC heating curves of the Al-Mg series intermetallic compound of aforementioned patent literature 2,3 is only such than lower temperature scope of the present invention between 50��100 DEG C or between 100��150 DEG C. On the other hand, the endothermic peak of the aforementioned DSC heating curves of the present invention be than 180��280 DEG C of above-mentioned higher temperature range between endothermic peak, even if the temperature range in endothermic peak can also be clearly distinguished from.

Namely, Al-Mg line aluminium alloy plate for the present invention, not there is the cluster comprising Zn etc. of regulation in Al, Mg cluster and aforementioned patent literature 3 specified in aforementioned patent literature 2, as shown in Figure 1, also without the endothermic peak in these set point of temperature regions, and, also without the endothermic peak between 180��280 DEG C of the DSC heating curves in the present invention in respective Fig. 1 of these patent documentations 2,3, so these patent documentations 2,3 do not have the cluster of the present invention.

In these patent documentations 2,3, it is alternatively that the element of property contains below the Cu1.0% of the present invention, the impurity Zn containing trace allowed in the present invention. But, even if the known one-tenth comprising these Cu is grouped into such as identical, also due to the difference of the existence of they clusters each other and organize difference, the inhibition that not only SS stricture of vagina occurs, and it is associated with the such bigger property difference of the age-hardening not produced under room temperature wanted in the present invention.

The difference of tissue (cluster) so each other can also prove from the difference of the method for making of plate each other. The Al-Mg line aluminium alloy plate of the patent documentation 3 containing Zn, as described herein, although rate of cooling control during to Quenching Treatment after solution treatment is formed in high-temperature area and carries out chilling, carries out slow cooling at low-temperature region, but, afterwards as described herein, at the temperature more than 100 DEG C, do not carry out additional anneal (artificial aging process), but only optionally carry out the additional anneal under the low temperature of 50��100 DEG C. In so low additional anneal temperature, do not generate the Cu cluster of the present invention, and as shown in Fig. 1 of patent documentation 3, it does not have the endothermic peak between 180��280 DEG C of DSC heating curves.

Additionally, the Al-Mg line aluminium alloy plate of the patent documentation 2 of Zn, below Cu1.0% is contained as selective element, as described herein, rate of cooling during Quenching Treatment after 2 stages of slow cooling being mingled with low-temperature region do not control solution treatment (final annealing), and only to the temperature range of 500��300 DEG C with 10 DEG C/S chilling carried out above. For this rate of cooling, it does not have implement be generally make productivity not reduce and carry out from less than 100 DEG C to the Slow cooling of room temperature. Therefore, can speculate in this patent documentation 2, although the rate of cooling of less than 100 DEG C is not expressly recited, but is generally the above rate of cooling of 5 DEG C/about S. And, in this patent documentation 2, only selectivity carries out the additional anneal at the temperature of 50��120 DEG C afterwards. Such modified condition does not generate the Cu cluster of the present invention, as described in Fig. 1 of patent documentation 3, it does not have the endothermic peak between 180��280 DEG C of DSC heating curves.

From the fact, the endothermic peak height between 180��280 DEG C of the DSC heating curves in the Al-Mg line aluminium alloy plate of the provable present invention is the novel cluster of other different from the cluster of regulation in the cluster containing Zn etc. specified in aforementioned patent literature 3 and aforementioned patent literature 3.

Aforementioned patent literature 2,3 and the present invention are different tissues and different clusters can also be proved from the effect difference that both reach as the situation of object. As it was previously stated, patent documentation 2 can not fully suppress the generation of stretcher strain markings. It addition, in patent documentation 3, it is impossible to suppress room-temperature aging hardening. On the other hand, in the present invention, not only inhibit room-temperature aging to harden, and can suppress by surrendering the generation stretching the random stricture of vagina caused and the generation of the parallel band being associated with the zigzag on load-deformation curve simultaneously.

The present invention is as car panel raw material plate, especially when the surface texture requirement level in the outside plate that outward appearance is critically important becomes tightened up, or from plate be fabricated onto the shaping to these panels require time for, room-temperature aging hardening during this period can not only be suppressed, and SS stricture of vagina is excellent. That is, not only suppress room-temperature aging hardening, and can suppress by the generation of the generation and the parallel band relevant to the zigzag on load-deformation curve surrendering the random stricture of vagina that extensibility causes simultaneously. This result is able to be greatly improved performance and the characteristic of car panel raw material plate.

(chemical composition composition)

The chemical composition composition of aluminum alloy hot rolling band of the present invention makes the aluminium alloy being equivalent to the JIS5000 system as Al-Mg system alloy substantially. Being explained, the % of the content of each element represents the meaning being entirely quality %.

The present invention needs to meet all characteristics such as press molding, intensity, weldability, corrosion resistance especially as car panel raw material plate. Therefore the milled sheet of the present invention, even if in 5000 line aluminium alloys, also makes and counts containing Mg:2.0��6.0%, Cu with quality %: more than 0.3% and for less than 2.0%, surplus be the Al-Mg line aluminium alloy plate of Al and inevitable impurity. Being explained, constituent content is entirely quality %.

This Al-Mg line aluminium alloy plate, as other impurity element, allow to contain respectively below Fe:0.5% (comprising 0%) in quality %, B (boron) that below Si:0.5% (comprising 0%), below Mn:0.5% (comprising 0%), below Cr:0.1% (comprising 0%), below Zr:0.1% (comprising 0%), below Ti:0.05% (comprising 0%), this Ti that encloses in the scope less than the content of Ti are easily mixed into.

And then, as previously described, because as the Zn of impurity element, be produce the reason that the age-hardening under room temperature makes bendability, press molding decline, so do not contain as far as possible. Even if if it addition, contain, being limited to less than 1.0% in quality %, it is preferable that be limited to less than 0.6%, being more preferably limited to less than 0.1%.

Mg:2.0��6.0%

Mg improves hardening energy, it is ensured that as the intensity required for car panel raw material plate, durability. It addition, make material plastic deformation equably and improve the fracture crack limit, improve formability. When the content of Mg is less than 0.5%, intensity, durability become insufficient. On the other hand, when the content of Mg is more than 7.0%, the manufacture of plate becomes difficulty, and during press molding, is susceptible to intercrystalline failure on the contrary, and press molding is remarkably decreased. Therefore, the content of Mg is set to 2.0��6.0%, it is preferable that be set to the scope of 2.4��5.7%.

Cu: more than 0.3% and be less than 2.0%

Can speculate that Cu and Zn is different, form the fine cluster based on aforesaid Cu, plate generation chamber warm hardening will not be made to harden, it is suppressed that the generation of SS stricture of vagina during press molding. When Cu is excessively less than less than 0.3%, the performance of the generation inhibition of SS stricture of vagina during press molding becomes insufficient. It addition, the growing amount of cluster based on Cu is also not enough. On the other hand, the content of Cu is if it exceeds 2.0 mass %, and thick crystal precipitate and the generation quantitative change of precipitate are many, thus easily become the starting point of destruction, make press molding decline on the contrary. The content of Cu be set to more than 0.3% and be less than 2.0% scope, it is preferred in the scope of 0.4��1.9%.

Cu/Mg:0.05��1

Herein, in order to play the aforementioned additive effect of Cu, the ratio of the Cu content relative to Mg: Cu/Mg is set to 0.05��1. This than higher limit and lower limit be between higher limit and the lower limit of aforementioned content each other or preferred ratio between higher limit and lower limit calculate, it is preferable that be set to the scope of 0.08��0.8.

Other element:

Other element illustrates Fe, Si, Mn, Cr, Zr, Ti etc. These elements are as melting raw material along with (ratio relative to aluminium ingot (�� Le �� �� system ground the gold)) increase of aluminium alloy scrap amount containing the impurity element that quantitative change is many. Namely, from the view point of the recycling of Al alloy sheets, as melting raw material, it is not only high-purity aluminium ingot, and 5000 be alloy and other Al alloyed scrap material, low-purity Al ingot etc. as melt raw material use time, the mixed volume (content) of these elements necessarily increases. And, these elements are reduced to such as detection and limit such as the following cost own to raise, it is necessary to allow containing to a certain degree. In this aspect, it is allowed to do not contain below Fe:0.5% (comprising 0%), below Si:0.5% (comprising 0%), below Mn:0.5% (comprising 0%), below Cr:0.1% (comprising 0%), Zr:0 less than 1% (comprising 0%), below Ti:0.05% (comprising 0%) with quality % score, enclose this Ti in less than the content range of Ti and the B (boron) that is easily mixed into.

(manufacture method)

The manufacture method of the plate of the present invention is carried out detailed description below.

In the present invention, before the rolling process to solution treatment, containing about the Mg4.5% of 5182,5082,5083,5056 etc., it is possible to use the manufacture method based on the common manufacturing process of shaping Al-Mg system alloy manufactures. That is, manufacture through common each manufacturing process of casting (DC casting, continuous casting process), the heat treatment that homogenizes, hot rolling, become the aluminum alloy hot rolling band that thickness of slab is 1.5��5.0mm. Can be sheet in this stage, it is also possible to be before cold rolling or cold rolling midway optionally carries out the intermediate annealing of 1 time or more than 2 times, carry out cold rolling on one side again, become the sheet of the cold-reduced sheet that thickness of slab is below 1.5mm.

Solution treatment:

In order to become the plate of the tissue with the present invention, these hot rolled plates of the required thickness of slab that such as above operation is obtained or cold-reduced sheet, first, carry out with instant heating and the solution treatment cooled down rapidly and Quenching Treatment. Carry out such solution treatment and the material of Quenching Treatment, i.e. T4 have processed material, compared with the batch anneal material along with heating and cooling more slowly, the balancing good of intensity and formability.

Herein, the fit value of solid solution temperature is different according to concrete alloy composition, it is necessary to be set in the scope of more than 450 DEG C less than 570 DEG C. It addition, within keeping under this solid solution temperature needing to be set to 180 seconds (3 minutes). When solid solution temperature is less than 450 DEG C, the solid solution of alloying element becomes insufficient, it is possible to intensity and ductility etc. decline. On the other hand, solid solution temperature is if it exceeds 570 DEG C, then excessive grain coarsening, thus the problem becoming coarse generation when formability declines and shapes. The problems the such as additionally retention time under solid solution temperature is if it exceeds 180 seconds, the coarse generation when formability producing to be caused by the excessive coarsening of crystal grain declines and shapes.

Quenching Treatment:

Rate of cooling during Quenching Treatment after solution treatment needs these 2 stages of slow cooling at the chilling of high-temperature area, low-temperature region. First, in the chilling of high-temperature area, the temperature of plate is more than 5 DEG C/sec from the rate of cooling of (scope) solid solubility temperature to 100 DEG C. When this rate of cooling is less than 5 DEG C/sec, in cooling procedure particularly in high-temperature area, generate thick precipitate, the growing amount of cluster tails off, thus suppressing the effect of the generation of SS stricture of vagina to reduce. Therefore, most soleplate is made even if applying preprocessing and annealing later, it is possible to there is SS stricture of vagina.

Plate as the present invention, after this chilling, the temperature of plate from less than 100 DEG C to the low-temperature region of room temperature the rate of cooling of (scope) be more than 5W/g to make the endothermic peak height between 180��280 DEG C of aforementioned DSC heating curves, therefore important. The cooling of this low-temperature region needs slow cooling, makes to carry out Slow cooling from less than 100 DEG C to the rate of cooling of the room temperature rate of cooling with less than 1 DEG C/min. Lower limit for slow cooling is not particularly limited, but considers preferably more than 0.01 DEG C/min the efficiency of production process.

According to such quenching condition, can speculate in the tissue of aforementioned Al-Mg system alloy sheets, generate the aggregation (cluster) of the atom based on Cu atom. Therefore, if making the cooling of this low-temperature region for the chilling speed under afore-said hot region or exceed the rate of cooling etc. of aforementioned 1 DEG C/min and make this quenching condition improper, even if then carrying out additional anneal described later, the generation of SS stricture of vagina still can not really be prevented. Namely, if can speculate that this quenching condition is improper, even if then carrying out additional anneal described later, the endothermic peak height between 180��280 DEG C of aforementioned DSC heating curves is not more than 5W/g, it is only the amount of the generation being positively prevented from SS stricture of vagina, and the cluster based on Cu can not be generated. That is, during the cooling of this low-temperature region rate of cooling more than 1 DEG C/min, become most soleplate be also possible to SS stricture of vagina even if applying prestrain later.

Apply prestrain:

In order to make the plate of the present invention, in order to eliminate the especially random stricture of vagina of SS stricture of vagina, as described in the past, after implementing these solution treatment, quenching, then plate carries out applying the cold working (preprocessing) of prestrain. These are by such as skin-pass, cold rolling or utilize the alternating bending processing etc. of roller type leveler to carry out. So adjust the increase part of yield point value and so as to be in specific scope, carry out the cold working as preprocessing, thus positively suppress the generation that surrender during press molding stretches, it is possible to positively prevent SS stricture of vagina, particularly the generation of irregular grain. Therefore, in the Al-Mg line aluminium alloy plate of the present invention, it is preferable that carry out again premised on press molding after being previously applied certain prestrain. It addition, apply such prestrain, the shape also becoming the plate after aforementioned solution treatment, Quenching Treatment controls and residual stress removing.

The applied amount of prestrain increases some such existing general preprocessings carried out for preventing irregular grain from occurring and is equal to yield point value. Such as, in the alternating bending processing utilizing roller type leveler to carry out in skin-pass in cold working, cold rolling or cold working etc., applying working modulus is the prestrain of about 1��5%. By applying such prestrain (cold working), a large amount of Zona transformans can be imported energetically in material, can positively prevent the generation that surrender stretches, even if can also stable against the generation of irregular grain in the Al-Mg system alloy sheets that crystal grain is fine. Under high working modulus above, when considering not carry out the such manufacture method of the present invention of final annealing, there is a possibility that ductility, formability reduce on the contrary, thus not preferred.

Additional anneal:

In the present invention, after this preprocessing, it is heated more than 100 DEG C and is additional anneal or the artificial aging process of 200 DEG C of temperature below. In other words, in the present invention, do not carry out generally carrying out after this preprocessing 250 DEG C are less than the instant heating at the temperature of about 550 DEG C, cool down such final annealing rapidly.

When carrying out additional anneal process (artificial aging process), plate as the present invention, really in order to the endothermic peak height between making 180��280 DEG C of aforementioned DSC heating curves is more than 5W/g, after the applying of aforementioned prestrain, higher than 100 DEG C and be carry out within the scope of 200 DEG C of temperature below. The process time of this additional anneal heats at foregoing temperature range and keeps 0.5��48 hours to carry out. Now, this additional anneal temperature more preferably above 150 DEG C and is the scope of less than 200 DEG C.

When additional anneal temperature is too low or the retention time is too short, it does not have the effect of additional anneal, do not have to generate the cluster based on Cu or growing amount deficiency in additional anneal. Therefore, only control the rate of cooling during Quenching Treatment after aforementioned solution treatment, then the cluster based on Cu is not enough, and the endothermic peak height between 180��280 DEG C of aforementioned DSC heating curves can not be more than 5W/g. The probability that its result is the generation that can not really prevent SS stricture of vagina is high.

On the other hand, when making additional anneal process carry out under the high temperature higher than 200 DEG C, there is a possibility that the endothermic peak height between 180��280 DEG C of aforementioned DSC heating curves can not be more than 5W/g on the contrary. Can speculate that its reason is to be processed by the additional anneal of high temperature, in the tissue of aforementioned Al-Mg system alloy sheets, not be the aforementioned cluster of generation but generate the reason of thicker precipitate. It addition, as too high more than 200 DEG C in aforementioned temperature or when the retention time is long, then the undesirable condition of aforesaid cluster with when carrying out the final annealing of high temperature simultaneously it is as well possible to produce to carry out the such problem of recrystallization.

From the temperature conditions of this additional anneal it can be seen that the cluster based on Cu of the present invention is compared with the cluster comprising Zn of aforementioned patent literature 3, have in the such feature of generation at higher temperature. In other words, namely return to room temperature, even if or be maintained at room temperature state, also without the cluster based on Cu generating the present invention, there is the such characteristic of the age-hardening not produced at room temperature. On the other hand, comprise the cluster of Zn owing to generating under the low temperature such as room temperature, the age-hardening under room temperature can be produced.

It addition, in the present invention, generally do not carry out carrying out after aforementioned preprocessing 250 DEG C are less than the instant heating at the temperature of about 550 DEG C, cool down such final annealing rapidly. When having carried out the final annealing of afore-said hot of more than 250 DEG C, easily become that temperature is too high, the retention time is long, rate of cooling crosses slow etc. the such condition of recrystallization that carries out, lose the effect that the SS stricture of vagina utilizing aforementioned cold working to carry out suppresses, or a part produces the coarsening of crystal grain, thus the problem of coarse grade when producing to shape. Additionally, in heating progress or in cooling process in (process), the intermetallic compound of Al-Mg system etc. easily precipitates out in a large number, can not make the endothermic peak height between 180��280 DEG C of aforementioned DSC heating curves is more than 5W/g, it is impossible to the probability positively preventing the generation of SS stricture of vagina is big. Additionally, if the intermetallic compound of Al-Mg system etc. precipitates out in a large number, then produce to comprise the coarsening of the second phase particles of the alloy addition element beyond Mg, Cu at boundary or grain etc., thus causing the decline of ductility, formability or resistance to saprophagous character, it is suppressed that the effect of SS stricture of vagina also declines.

In the present invention, by being respectively combined solution treatment condition as above, ensuing 2 stages cool down the modified of additional anneal under such special Quenching Treatment conditions and specified conditions such that it is able to make the Al-Mg line aluminium alloy plate comprising Cu become do not carry out room-temperature aging, Mg is difficult to the plate tissue that spreads. Thus, after manufacturing plate, even across more than 1 month, during counter plate press molding, the limiting strain amount also improving Al-Mg line aluminium alloy plate increases effect, it is suppressed that the zigzag on load-deformation curve, suppress the parallel band thus caused, it is possible to suppress to stretch-strain the generation of stricture of vagina. It addition, in SS stricture of vagina, additionally it is possible to prevent the generation of the random stricture of vagina caused by aforementioned surrender extensibility.

Hereinafter enumerate embodiment and the present invention is carried out more specific description, but the present invention certainly not system by following embodiment limit, can meeting the scope situation that suitable change can also be implemented in addition of order aforementioned and described later, these are all contained in the scope of technology of the present invention.

[embodiment]

Then embodiments of the invention are illustrated. Manufacture the Al-Mg system alloy sheets of each composition of the example shown in table 1, comparative example, the condition illustrated with table 2 (continued 1) carry out modified, manufacture after, the tissue of this plate after modified, mechanical property have been carried out respectively mensuration, evaluation. These results are also depicted in table 2. Being explained, the "-" labelling of the constituent content in table 1 represents that the content of this element is for below detection limit.

Each manufacture method (condition) of hot rolled plate and cold-reduced sheet and each example all adopt identical common condition to carry out. That is, at 480 DEG C, the ingot casting that the fluid origin 50mm by book mold (bookmold) casting is thick is carried out the heat treatment that homogenizes of 8 times, then starts hot rolling at 400 DEG C. Obtain the hot rolled plate that thickness of slab is 3.5mm. After this hot rolled plate is cold rolled to the thickness of slab of 1.35mm, with niter oven 400 DEG C, carry out 10 seconds obtaining intermediate annealing, then carry out cold rolling and obtain the thick cold-reduced sheet of 1.0mm.

These cold-reduced sheets solution treatment and Quenching Treatment have been carried out with each different condition as shown in table 2. This solution treatment and Quenching Treatment use continuous annealing line (CAL) etc. to carry out continuously, use forced air-cooling, spray cooling respectively, at linear velocity and their air quantity of each temperature province panel, are thus controlled rate of cooling during Quenching Treatment.

After this solution treatment and Quenching Treatment, as the cold working applying prestrain, each example is all commonly processed the skin-pass of rate 3%. Then, additional anneal or the modifier treatment carried out are carried out with the respective different condition shown in table 2.

Test film (1.0mm is thick) is cut from the plate after these modifier treatment (manufacture), after there is no the modifier treatment of impact (can ignore) of room-temperature aging within 24 hours, measure, evaluate the characteristic of the differential thermal analysis (tissue) of this test film (plate after modified), machinery respectively.

(differential thermal analysis)

Investigation as the tissue of the plate just having carried out aforementioned modifier treatment (manufacture), cut the discoid test portion of 5 diameter 3mm from the optional position of aforementioned test film, obtain the heating curves started from room temperature when utilizing differential thermal analysis (DSC) to be measured with aforesaid condition. Further, the height of the endothermic peak existed in the scope (temperature province) of the 180��280 of the present invention DEG C is obtained as the maximum of the W/g of the DSC heating curves in this region. Being explained, the height (W/g) of this endothermic peak is as the meansigma methods of the maximum of the W/g of DSC heating curves: the meansigma methods of the measurement result of 5 discoid test portions and obtain. About the collection of these data, as it was previously stated, each example is all commonly in the position measuring temperature 150 DEG C, it is corrected, so that recept the caloric and after caloric value is 0, obtaining the endothermic peak height (W/g) of existence in the scope of 180��280 DEG C. Now, measure that to play from the datum line that heat flow is 0.00 of the longitudinal axis of the heating curves (differential scanning calorimetry curve) started from room temperature be highly the distance (W/g) of maximum endothermic peak (summit).

Differential thermal analysis condition, each example all commonly carries out with following condition.

Assay device: Seiko apparatus (SeikoInstrumentsInc.) DSC220C processed,

Standard substance: fine aluminium,

Test portion container: fine aluminium,

Elevated Temperature Conditions: 15 DEG C/min,

Atmosphere encloses (in test portion container): argon (gas flow 50ml/min),

Test test portion weight: 24.5��26.5mg.

(mechanical property)

As the investigation of the mechanical property of the plate just having carried out aforementioned modifier treatment (manufacture), carry out the tension test of above-mentioned each test film, measure hot strength (MPa), extensibility (%) respectively. Experimental condition adopts No. 5 test films (25mm �� 50mmGL �� thickness of slab) relative to the JISZ2201 that rolling direction is right angle orientation, carries out tension test. Tension test, based on JISZ2241 (1980) (Tensile Testing Method of Metallic Materials), is tested room temperature 20 DEG C. Now, crosshead speed is 5mm/ minute, carries out with constant speed until test film ruptures.

The characteristic of the plate after rheological parameters' change with time under room temperature:

Additionally, in order to evaluate the rheological parameters' change with time (impact of room-temperature aging hardening) when keeping under room temperature, after aforementioned modifier treatment (manufacture), by above-mentioned each test film after room temperature keeps one-month period, carry out tension test with same condition, obtain the increase amount (room-temperature aging hardening capacity) of the hot strength just carrying out aforementioned modifier treatment (manufacture).

(SS stricture of vagina is evaluated)

Equally, in order to carry out keeping the SS stricture of vagina of press molding of plate after 1 month to evaluate as aforementioned room temperature, the dependent variable (critical strain: %) of the surrender extensibility (%) when have studied the tension test after aforementioned room temperature keeps 1 month and the jagged zigzag generation on aforesaid stresses-strain curve.

(press molding evaluation)

It addition, same, the press molding of the plate after 1 month is kept as room temperature, the extrusion molding test of the drawing sheet after aforementioned room temperature being kept 1 month carries out as the evaluation of the extrusion molding becoming problem as outside plate.

Extrusion molding test uses the bulb extrusion punching of diameter 101.6mm, test film at length 180mm, width 110mm is coated with the R-303P as lubricant, extrusion molding test is carried out, the generation state of the crackle of visualization formed products with forming speed 4mm/S, wrinkle resistant pressure loading (�� gives as security �� �� loading) 200kN. And, the not size of pipe crack, though crackle entirely without the average evaluation occurred be zero, crackle less but the average evaluation occurred for ��.

Such as table 1,2, example 1��7 controls, containing Cu, whether without Zn, to meet the Al-Mg line aluminium alloy composition regulation of the present invention. It addition, the rate of cooling condition of Quenching Treatment such as aforementioned 2 stages such solid solution and the preferred manufacturing condition of Quenching Treatment manufacture. The endothermic peak height that its result is between 180��280 DEG C of the heating curves started from room temperature utilizing that the thermal change that differential thermal analysis measures this plate obtains is more than 5W/g.

Thus, the hot strength increase amount (room-temperature aging hardening capacity) just carrying out aforementioned modifier treatment (manufacture) of each example reduces, and the press molding containing SS stricture of vagina characteristic is excellent. That is, the critical strain that the zigzag on the load-deformation curve of aluminium alloy plate occurs is more than 8%, and high critical strain is more than 10%, even if occurring also without crackle in the test of aforementioned extrusion molding. And, SS stricture of vagina characteristic or extrusion molding (being expressed as press molding in table 2) to these excellences, do not lower the excellent mechanical property level of hot strength and extensibility etc. that 5000 line aluminium alloy plates of JIS5052 alloy, JIS5182 alloy etc. do not have, additionally be able to do not have room-temperature aging to realize with hardening.

But, although the amount of allowing for, but the example 2 of the relatively large example 6 containing Zn0.6% and less content 0.02% or do not contain other the example of Zn and compare, although the scope allowed for, but room-temperature aging hardening quantitative change is big.

On the other hand, although the alloy that comparative example 8��13 and example 1 be identical forms, but such as table 2, modified condition is respectively offset from preferred scope. For comparative example 8, solid solution temperature is too low, can not carry out the cooling in aforementioned 2 stages in Quenching Treatment. For comparative example 9, in Quenching Treatment, the rate of cooling in the chilling of high-temperature area is less than 2 DEG C/sec of clocks of lower limit. For comparative example 10, in Quenching Treatment, the rate of cooling in the slow cooling of high-temperature area exceedes the upper limit 1 DEG C/sec. The additional anneal temperature of comparative example 11 is too low less than lower limit 100 DEG C. The additional anneal temperature of comparative example 12 exceedes the upper limit 200 DEG C and too high. Comparative example 13 does not carry out additional anneal.

Its result, endothermic peak height between 180��280 DEG C of the aforementioned DSC heating curves of comparative example 8��13 is less than 5W/g, although the mechanical property of intensity and extensibility etc. and example do not have big difference, but the critical strain that the zigzag on the load-deformation curve of aluminium alloy plate occurs is relatively low, being less than 8%, SS stricture of vagina characteristic significantly reduces compared with example. That is, become easily caused by aforementioned zigzag tissue.

Comparative example 14��17, such as table 1,2, although modified condition is preferred scope, but alloy Composition deviation scope of invention. Comparative example 14 does not contain Cu, and the Cu content of comparative example 15 is very few. The Mg content of comparative example 16 is too much. The Zn content of comparative example 17 is too much.

Its result, although the room-temperature aging hardening capacity of the comparative example 14,15 that the effect of Cu can not play is few, but intensity is also low, and the critical strain that the zigzag on the load-deformation curve of aluminium alloy plate occurs is low, its value is less than 8%, and SS stricture of vagina characteristic is significantly low compared with example. That is, become easily caused by aforementioned zigzag tissue.

Although the room-temperature aging hardening capacity of comparative example 16 is few, but intensity is too high, and extensibility reduces, and cracks, press molding (extrusion molding) step-down compared with example during press molding.

Comparative example 17 is too much due to Zn, and room-temperature aging hardening capacity exceedes allowed band and becomes big, cracks during press molding, press molding (extrusion molding) reduction compared with example.

From above embodiments it can be seen that SS stricture of vagina characteristic and press molding or mechanical property etc. owing to having each important document of the present invention or preferred manufacturing condition etc. concurrently, so being proved to that there is critical meaning.

[table 1]

Industry utilizes probability

As described above, according to the present invention, can provide: the new problem of the bendability reduction etc. not having generation to be caused by the age-hardening under room temperature, not only suppress to be extended the generation of the random stricture of vagina caused by aforementioned surrender, and suppress the generation of parallel band simultaneously, SS stricture of vagina can be suppressed to occur, the Al-Mg line aluminium alloy plate that the press molding of car panel is improved. Its result, towards in plate press molding a large amount of purposes of described automobile etc. of being used, expands the application of Al-Mg line aluminium alloy plate.

Claims (2)

1. the aluminium alloy plate having excellent formability, it is to count containing Mg:2.0��6.0%, Cu with quality %: more than 0.3% and for less than 2.0%, and the Al-Mg line aluminium alloy plate that surplus is Al and inevitable impurity, it is characterised in that

Utilize differential thermal analysis measure obtain from the heating curves that room temperature starts, the maximum endothermic peak height between 180��280 DEG C is more than 5W/g.

2. the aluminium alloy plate having excellent formability according to claim 1, wherein,

As the index of the formability representing described aluminium alloy plate, the zigzag critical strain of generation on the load-deformation curve of described aluminium alloy plate is more than 8%.