EP3438302A1 - Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium - Google Patents

Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium Download PDF

Info

Publication number
EP3438302A1
EP3438302A1 EP17775369.6A EP17775369A EP3438302A1 EP 3438302 A1 EP3438302 A1 EP 3438302A1 EP 17775369 A EP17775369 A EP 17775369A EP 3438302 A1 EP3438302 A1 EP 3438302A1
Authority
EP
European Patent Office
Prior art keywords
aluminum alloy
paint
alloy sheet
temperature
treatment
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP17775369.6A
Other languages
German (de)
English (en)
Other versions
EP3438302A4 (fr
Inventor
Hisao Shishido
Tomoyuki Kitamura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kobe Steel Ltd
Original Assignee
Kobe Steel Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kobe Steel Ltd filed Critical Kobe Steel Ltd
Priority claimed from PCT/JP2017/013179 external-priority patent/WO2017170835A1/fr
Publication of EP3438302A1 publication Critical patent/EP3438302A1/fr
Publication of EP3438302A4 publication Critical patent/EP3438302A4/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/05—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/12—Alloys based on aluminium with copper as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties

Definitions

  • the present invention relates to a 6000-series aluminum alloy sheet manufactured by ordinary rolling and excellent in formability and paint-bake hardenability.
  • a panel of an outer panel (outer sheet), an inner panel (inner sheet) and the like of a panel structural body such as a hood, a fender, a door, a roof, and a trunk lid out of the large body panel described above as a thin and high strength aluminum alloy sheet, Al-Mg-Si AA or JIS 6000-series (will be hereinafter simply referred to also as 6000-series) aluminum alloy sheet has been used.
  • This 6000-series (Al-Mg-Si) aluminum alloy sheet includes Si and Mg as an indispensable element.
  • bake-hard property BH property and bake-hardenability
  • the outer panel and the like of an automobile are manufactured by combiningly subjecting an aluminum alloy sheet to forming work such as stretch forming in press forming and bend forming as is well known.
  • forming work such as stretch forming in press forming and bend forming as is well known.
  • a shape of a formed product as an outer panel is obtained by press forming such as stretching, then joining work with an inner panel is executed by hem (hemming) work of a flat hem and the like of the peripheral edge part of the outer panel, and a panel structural body is formed.
  • the outer panel and the like of an automobile described above tend to be thinned further for the purpose of the weight reduction, and a high strength so as to be excellent in dent resistance is required in addition to thinning. Accordingly, such artificial temper aging hardenability (paint-bake hardenability) is required more that the proof stress of the aluminum alloy sheet is lowered further to secure the formability at the time of press forming, the aluminum alloy sheet is subjected to age hardening to improve the proof stress by heating at the time of the artificial temper aging treatment at a comparatively low temperature such as the paint-bake cycle of a panel after forming, and capable of securing a required strength even after thinning.
  • paint-bake hardenability paint-bake hardenability
  • the exothermic peak height W1 in the temperature range of 100-200°C is to be 50 ⁇ W or more and the ratio W2/W1 of the exothermic peak height W2 in the temperature range of 200-300°C and the exothermic peak height W1 is to be 20 or less.
  • Patent Literature 2 it is specified that, in the differential scanning calorimetric curve of the 6000-series aluminum alloy sheet, when the exothermic peak height in the temperature range of 230-270°C is denoted by A, the exothermic peak height in the temperature range of 280-320°C is denoted by B, and the exothermic peak height in the temperature range of 330-370°C is denoted by C in the differential scanning calorimetric curve, the exothermic peak height B is to be 20 ⁇ W/mg or more, A/B is to be 0.45 or less, and C/B is to be 0.6 or less respectively, A/B and C/B being respective ratios of the exothermic peak heights A, C to the exothermic peak height B.
  • Patent Literature 3 it is specified that, in the differential scanning calorimetric curve of a sheet that is a 6000-series aluminum alloy sheet but with the total amount of Mg and Si being 1.2% or less, only one exothermic peak is to exist or only two exothermic peak with the temperature difference between two peaks being 50°C or less are to exist within the temperature range of 230-330°C, and either the height of the only one exothermic peak or the height of the exothermic peak of one whose peak height is higher out of the only two exothermic peaks is to be in the range of 20-50 ⁇ W/mg.
  • Patent Literature 4 it is specified that, in the differential scanning calorimetric curve of a sheet that is a 6000-series aluminum alloy sheet in which to add Sn is essential, as an endothermic peak corresponding to melting of the MG-Si clusters, the peak height of the endothermic peak within the temperature range of 150-230°C is to be 8 ⁇ W/mg or less (but inclusive of 0 ⁇ W/mg), whereas as an exothermic peak corresponding to formation of the MG-Si clusters, the peak height of the exothermic peak within the temperature range of 240-255°C is to be 20 ⁇ W/mg or more.
  • an endothermic peak height of the minus in the temperature range of 150-250°C corresponding to melting of the Si/hole clusters is to be 1,000 ⁇ W or less
  • an exothermic peak height of the plus in the temperature range of 250-300°C corresponding to precipitation of the Mg/Si clusters is to be 2,000 ⁇ W or less
  • the aluminum alloy material comes to be excellent in suppressing room temperature aging and in low temperature age-hardenability.
  • the object of the present invention is to provide a 6000-series aluminum alloy sheet and a manufacturing method for the same which can provide both of an excellent formability and a high BH property even after room temperature aging for a long time, the high BH property being provided also in the conventional paint-bake hardening treatment at the low temperature described above as well as in the paint-bake hardening treatment at the high temperature described above.
  • the gist of the aluminum alloy sheet of the present invention excellent in formability and paint-bake hardenability is an aluminum alloy sheet containing, in terms of mass%, Mg: 0.3-1.5% and Si: 0.6-1.5% respectively, the total of the Mg content and the Si content being greater than 1.2%, the balance including Al and inevitable impurities, in which, in a differential scanning calorimetric curve of the aluminum alloy sheet, endothermic peaks whose height A is 3-10 ⁇ W/mg exist within a temperature range of 150-230°C, exothermic peaks whose height B is 20-50 ⁇ W/mg exist within a temperature range of 230°C or above and below 330°C, and a ratio B/A of a maximum peak height B out of the exothermic peaks to a maximum peak height A out of the endothermic peaks is greater than 3.5 and less than 15.0.
  • the gist of the manufacturing method of an aluminum alloy sheet excellent in formability and paint-bake hardenability of the present invention is that a step of subjecting an aluminum alloy cold rolled sheet to a preliminary temper aging treatment at a low temperature and for a long time is included, the aluminum alloy cold rolled sheet containing, in terms of mass%, Mg: 0.3-1.5% and Si: 0.6-1.5% respectively, the total of the Mg content and the Si content being greater than 1.2%, the balance including Al and inevitable impurities, the preliminary temper aging treatment being for holding the aluminum alloy cold rolled sheet for 5 hours or more and 500 hours or less at the temperature range of 30°C-60°C within one hour after a solution heat treatment and a quenching treatment, and that, in a differential scanning calorimetric curve before the aluminum alloy cold rolled sheet is subjected to an artificial temper aging treatment, endothermic peaks whose height A is 3-10 ⁇ W/mg are made to exist within a temperature range of 150-
  • the present inventors studied clusters that could provide both of an excellent formability and a high BH property even after room temperature aging for a long time, the high BH property being provided also in the conventional paint-bake hardening treatment at a low temperature described above as well as in the paint-bake hardening treatment at a high temperature described above.
  • the inventors also found that, even when the bake treatment temperature in the paint-bake hardening treatment might change largely from a high temperature to a low temperature, in order to obtain a high BH amount at any bake treatment temperature, clusters corresponding to the endothermic peak of the mentioned calorimetric curve were to be reduced, or clusters corresponding to the exothermic peak of the temperature range of 230°C-330°C were to be increased.
  • the inventors found that high elongation was obtained even after room temperature aging for a long time by precisely controlling the endothermic peak of the mentioned calorimetric curve within the temperature range of 150-230°C and the exothermic peak of the temperature range of 230°C-330°C, and that, even when the bake treatment temperature might change largely from a high temperature to a low temperature, a high BH property was obtained at any bake treatment temperature.
  • the inventors found that the differential calorimetric curve for obtaining a high BH property was different particularly according to the temperature of the paint-bake hardening condition (artificial temper aging treatment condition), and also found that, at a comparatively low paint-bake temperature of 175°C or below, it was required to control the differential calorimetric curve more precisely compared to a comparatively high paint-bake temperature of 180°C or above.
  • the present invention has allowed a 6000-series aluminum alloy sheet as a raw material of an automotive member to be provided with all of the elongation, the high temperature BH property, and the low temperature BH property which can be said to be contradictory to each other by executing a microstructure control of controlling the differential calorimetric curve more precisely.
  • Fig. 1 is an explanatory drawing that illustrates a differential scanning calorimetric curve of an aluminum alloy sheet of the present invention.
  • the aluminum alloy sheet (formation raw material sheet) referred to in the present invention means a raw material aluminum alloy sheet that is a rolled sheet such as a hot rolled sheet and a cold rolled sheet, is a sheet obtained by subjecting the rolled sheet to tempering (T4) such as a solution heat treatment and a quenching treatment, is before being formed into an automotive member to be used, and is before being subjected to an artificial temper aging treatment (artificial age hardening treatment) such as a paint-bake hardening treatment.
  • tempering such as a solution heat treatment and a quenching treatment
  • an artificial temper aging treatment artificial age hardening treatment
  • paint-bake hardening treatment paint-bake hardening treatment
  • the chemical composition of the aluminum alloy sheet of the present invention is determined to satisfy the formability and the paint-bake hardenability required as a raw material of the automotive members such as the automotive large body panel described above from the composition of the 6000-series aluminum alloy.
  • the chemical composition of the aluminum alloy sheet of the present invention contains, in terms of mass%, Mg: 0.3-1.5% and Si: 0.6-1.5% respectively, the total of the Mg content and the Si content is greater than 1.2%, and the balance includes Al and inevitable impurities.
  • one kind or two kinds or more out of Cu: 0.02-0.8%, Fe: 0.05-0.5%, Mn: 0.05-0.3%, Zr: 0.04-0.1%, Cr: 0.04-0.3%, V: 0.02-0.1%, Ag: 0.01-0.1%, and Zn: 0.01-0.3% may be further contained.
  • Si is an indispensable element for forming with Mg temper aging precipitates such as Mg-Si-based precipitates that contribute to solid solution strengthening and improvement of the strength at the time of the artificial temper aging treatment such as the paint-bake treatment to exert the temper aging hardenability, and securing the required strength (proof stress).
  • Mg temper aging precipitates such as Mg-Si-based precipitates that contribute to solid solution strengthening and improvement of the strength at the time of the artificial temper aging treatment such as the paint-bake treatment to exert the temper aging hardenability, and securing the required strength (proof stress).
  • the content of Si is to be made within the range of 0.6-1.5%, preferably within the range of 0.7-1.5%.
  • Mg is also an indispensable element for forming with Si temper aging precipitates such as Mg-Si-based precipitates that contribute to solid solution strengthening and improvement of the strength at the time of the artificial temper aging treatment such as the paint-bake treatment to exert the temper aging hardenability, and securing the required strength.
  • the Mg content is not sufficient, the solid solution Mg amount before the paint-bake treatment reduces, the formation amount of the Mg-Si-based precipitate becomes insufficient, therefore the BH property extremely deteriorates, and the strength becomes insufficient.
  • the Mg content is excessive, a shearing band is liable to be formed at the time of cold rolling which becomes a cause of cracking at the time of rolling a raw material sheet. Therefore, the content of Mg is to be made within the range of 0.3-1.5%, preferably within the range of 0.4-0.8%.
  • the total of the Mg content and the Si content is to be made greater than 1.2%.
  • this total is 1.2% or less as in Patent Literature 3 described above, even when the manufacturing condition of the sheet may be within the preferable range described below, the endothermic peak and the exothermic peak specified in the present invention cannot be formed, the artificial temper aging hardenability becomes insufficient, and the required strength cannot be secured.
  • the upper limit of the total of the Mg content and the Si content is determined by a limit at which the sheet can be manufactured without causing a hot rolling crack, and is to be preferably made 2.5%.
  • Cu can improve the strength by solid solution strengthening.
  • the effect is small when the content of Cu is not sufficient. Even when the content of Cu is excessive, the effect saturates, and corrosion resistance and the like are deteriorated to the contrary.
  • Fe plays the roles of forming crystallized grains, becoming nuclei of the recrystallized grains, preventing the grains from being coarsened, and improving the strength. The effect is small when the content is not sufficient. When the content is excessive, Fe forms a coarse compound and becomes an origin of breakage, and the strength and the formability deteriorate.
  • Mn, Zr, Cr, and V miniaturize the grain of the slab and the final sheet product, and contribute to improvement of the strength. Further, these elements exist as the dispersed particles, contribute to miniaturization of the grains, and also improve the formability. When the content of each element is not sufficient, the effect of improving the strength and the formability by the miniaturization of the grains becomes insufficient. On the other hand, when these elements are excessive, a coarse compound is formed, and the ductility is deteriorated.
  • Ag has effects of positively and finely precipitating temper aging precipitates that contribute to improvement of the strength by the artificial temper aging heat treatment after forming work into an automotive member, and promoting high strengthening.
  • the strength improving effect is small.
  • various properties such as the rollability and the weldability are deteriorated to the contrary, the strength improving effect saturates, and the cost increases.
  • Zn is useful in improving the artificial temper aging hardenability (BH property), and has an effect of promoting precipitation of a compound phase of the GP zone and the like into the grain of the sheet microstructure and increasing the strength in the paint-bake treatment.
  • Ti and B other than those described above are inevitable impurities. Ti forms coarse compounds with B and deteriorates the mechanical property. However, since there is also an effect of miniaturizing the grain of an aluminum alloy slab by being contained in a minute amount, containment of each element within a range specified in JIS Standards and the like as the 6000-series alloy is allowed. As an example of this allowable amount, Ti is to be made 0.1% or less, preferably 0.05% or less. B is to be made 0.03% or less. In the meantime, in the present invention, Sn that is made indispensable in Patent Literature 4 described above is not added.
  • the microstructure of the aluminum alloy sheet is defined by DSC (differential scanning calorimetric curve: DSC profile) obtained by a differential scanning thermal analysis as an indicator that indicates beforehand the existence state of the artificial temper aging precipitate in the member in which this sheet is used as a raw material.
  • DSC differential scanning calorimetric curve: DSC profile
  • the present invention is defined by DSC (differential scanning calorimetric curve: DSC profile) obtained by a differential scanning thermal analysis in order to be provided with both of an excellent formability and a high BH property even in a paint-bake hardening treatment at a comparatively low temperature as well as a high BH property in a paint-bake hardening treatment at a comparatively high temperature which is the main object even after the temper aging at a room temperature for a long time.
  • DSC differential scanning calorimetric curve: DSC profile
  • This paint-bake hardening treatment condition at a comparative high temperature means a paint-bake hardening treatment under a condition of the heating temperature of 180-230°C and the heating holding time of 10-30 minutes for example, and is differentiated in terms of the heating temperature in particular from 175°C at highest of the heating temperature of the conventional paint-bake hardening treatment of comparatively low temperature and short time.
  • both of these exothermic peak and endothermic peak are to be made to exist, in addition to each of the peak heights, the balance of both of the peak heights also becomes important. For example, when the ratio of exothermic peak/endothermic peak is too small, either the existence of the clusters corresponding to the endothermic peak is too large and the BH property become too low, or the exothermic peak is too low, clusters becoming the strengthening phase are excessive, and the elongation deteriorates.
  • an endothermic peak whose height A is 3-10 ⁇ W/mg is to exist within a temperature range of 150-230°C
  • an exothermic peak whose height B is 20-50 ⁇ W/mg is to exist within a temperature range of 230°C or above and below 330°C
  • a ratio B/A of the exothermic peak height B and the endothermic peak height A is to be greater than 3.5 and less than 15.0.
  • an endothermic peak whose height A is preferably 3-8 ⁇ W/mg is to exist within a temperature range of 150-230°C
  • an exothermic peak whose height B is preferably 20-40 ⁇ W/mg is to exist within a temperature range of 230°C or above and below 330°C
  • a ratio B/A of the exothermic peak height B and the endothermic peak height A is to be greater than 3.5 and less than 15.0.
  • the height A of the endothermic peak is 3-7 ⁇ W/mg
  • the height B of the exothermic peak is 20-35 ⁇ W/mg.
  • the fact that an endothermic peak is high on the minus side means that the clusters are molten during the differential thermal analysis, and, in other words, means that there are many clusters that correspond to the endothermic peak.
  • the height A of the peak on the minus side is as low as less than 3 ⁇ W/mg, the work hardenability deteriorates, and the formability deteriorates.
  • the height A of the peak on the minus side becomes too high beyond 10 ⁇ W/mg, the BH property at a comparatively high temperature deteriorates.
  • the height A of the peak on the minus side becomes too high beyond 7 ⁇ W/mg, the BH property at a comparatively low temperature deteriorates.
  • an exothermic peak is high means that many clusters becoming the strengthening phase or the nuclei of the strengthening phase are generated during the differential thermal analysis, and, in other words, means that there are not many clusters becoming the strengthening phase or the nuclei of the strengthening phase.
  • the height B of the exothermic peak is too high beyond 50 ⁇ W/mg, the amount of the clusters becoming the strengthening phase or the nuclei of the strengthening phase is not sufficient, and the BH property of the paint-bake hardening at a comparatively high temperature deteriorates.
  • the microstructure defined by DSC at the stage of the raw material sheet is correlated very well to the generation behavior of the precipitated phase at the time of the artificial temper aging treatment (the time of BH) of a member such as the automotive panel described above manufactured from this raw material sheet.
  • the time of BH the time of BH
  • the microstructure defined by the DSC described above at the stage of this raw material sheet possibly becomes an indicator of the formability and the BH property in a member in which this raw material sheet is used as a formation raw material.
  • Patent Literature 1 there is no endothermic peak whose height is 3-10 ⁇ W/mg within the temperature range of 150-230°C, whereas the exothermic peak exists within the temperature range of 100-200°C.
  • Patent Literature 2 described above, as illustrated in Fig. 1 thereof, there is no endothermic peak whose height is 3-10 ⁇ W/mg within the temperature range of 150-230°C.
  • Patent Literature 3 the total amount of Mg and Si is 1.2% or less, the endothermic peak and the exothermic peak specified in the present invention cannot be formed, the artificial temper aging hardenability becomes insufficient, and the required strength cannot be secured.
  • Patent Literature 4 described above, as illustrated in Fig.
  • control of the microstructure determined by the exothermic peak of DSC described above is executed by performing a preliminary temper aging treatment at a low temperature and for a long time of holding the aluminum alloy cold rolled sheet for 5 hours or more and 500 hours or less in the temperature range of 30°C-60°C within one hour after the solution treatment and the quenching treatment.
  • the 6000-series aluminum alloy sheet of the present invention is a cold rolled sheet obtained by that a slab is hot rolled after a soaking treatment and is further cold rolled, and is manufactured by an ordinary method in which tempering such as a solution heat treatment is further performed. That is, such an aluminum alloy hot rolled sheet is obtained that is manufactured through respective ordinary manufacturing steps of casting, homogenization, and hot rolling, and has the sheet thickness of approximately 2-10 mm. Then, cold rolling is performed to obtain a cold rolled sheet with the sheet thickness of 3 mm or less.
  • the molten metal of an aluminum alloy having been meltingly adjusted to within the 6000-series composition range described above is casted properly by selecting an ordinary melting casting method such as a continuous casting method, and a semi-continuous casting method (DC casting method).
  • an ordinary melting casting method such as a continuous casting method, and a semi-continuous casting method (DC casting method).
  • the average cooling rate at the time of casting is increased (made fast) as much as possible to 30°C/min or more from the liquid phase line temperature to the solid phase line temperature.
  • the aluminum alloy slab having been casted as described above is subjected to homogenization prior to hot rolling.
  • This homogenization is important for sufficiently dissolving Si and Mg in addition to homogenizing the microstructure (eliminating the segregation within the grain in the microstructure of the slab) which is an ordinary object.
  • the homogenization temperature and the homogenization (holding) time are properly selected from the range of 500°C or above and 580°C or below, and one hour or more respectively, and Si and Mg are sufficiently dissolved.
  • this homogenization temperature is low, the solid solution amount of Si and Mg cannot be secured, and the specified exothermic peak of DSC described above cannot be achieved even by the preliminary temper aging treatment (reheating treatment) after the solution heat treatment/quenching treatment described below.
  • the segregation within the grain cannot be eliminated sufficiently, the segregation acts as an origin of breakage, and therefore the formability deteriorates.
  • the hot rolling is configured of the rough rolling step and the finish rolling step of the slab according to the plate thickness to be rolled.
  • a rolling machine of the reverse type, the tandem type, and the like are used appropriately.
  • hot finish rolling with the finishing temperature being made within the range of 250-360°C is performed.
  • the soaking temperature described above and the finishing temperature of this finish rolling are too low, Mg- and Si-based compound is formed during soaking and hot rolling, the balance of solid solution Mg/Si changes, and it becomes hard to obtain the specified DSC described above.
  • Annealing before cold rolling of this hot rolled sheet is not necessary, but may be performed.
  • the hot rolled sheet described above is rolled, and is manufactured into a cold rolled sheet (including also a coil) having a desired final sheet thickness.
  • the cold rolling ratio is 60% or more, and intermediate annealing may be performed between the cold rolling passes with an aim similar to that of the annealing described above.
  • the solution heat treatment and the subsequent quenching treatment to the room temperature are performed.
  • this solution heat treatment in order to secure sufficient solid solution amount of each element such as Mg and Si, heating to the solution heat treatment temperature of 500°C or above and the melting temperature or below is preferable.
  • the average cooling rate from the solution heat treatment temperature to the quenching finish temperature that is the room temperature is made 20°C/s or more.
  • the average cooling rate of the quenching treatment to the room temperature after the solution heat treatment is low, coarse Mg 2 Si and the single body Si are formed during cooling, and the bending workability deteriorates.
  • the solid solution amount after the solution heat treatment reduces, and the BH property deteriorates.
  • air cooling such as a fan, water cooling means and conditions such as the mist, spray, and immersion are respectively selected and used.
  • this preliminary temper aging treatment is executed by performing a preliminary temper aging treatment at a low temperature for a long time for the holding of 5 hours or more and 500 hours or less in the temperature range of 30°C-60°C which are a lower temperature and a longer time compared to the ordinary method.
  • the microstructure formed with Mg-Si clusters having excellent balance of Mg and Si and determined by the peaks of DSC described above is obtained. Therefore, by the preliminary temper aging treatment at a low temperature for a long time, both of the high elongation and the BH property at a comparatively high temperature can be provided.
  • this room temperature holding time is preferable to be as short as possible, the solution heat treatment and quenching treatment and the reheating treatment may be continuous so as to almost eliminate the time difference between them, and the time of the lower limit is not set particularly.
  • the preliminary temper aging temperature described above is below 30°C or the holding time is less than 5 hours, the case becomes similar to the case of not performing this preliminary temper aging treatment, the clusters corresponding to the endothermic peak are excessively formed and the BH property is liable to deteriorate.
  • the preliminary temper aging condition described above exceeds 60°C or exceeds 500 hours, the formation amount of the clusters that become the strengthening phase corresponding to the exothermic peak and the nuclei of the strengthening phase becomes excessive, the strength in the press forming before the paint-baking becomes too high, and the formability is liable to deteriorate.
  • the processes up to the preliminary temper aging treatment at a high temperature for a short time for the holding of 5 seconds or more and 300 seconds or less in the temperature range of 100°C-300°C within one hour after the solution heat treatment and quenching treatment described above, and to perform immediately thereafter the preliminary temper aging treatment at a low temperature for a long time described above.
  • the control of DSC by the preliminary temper aging treatment at a low temperature for a long time described above can be made positive, and the endothermic peak height A within the temperature range of 150-230°C in DSC can be controlled to a preferable range of 3-8 ⁇ W/mg, and to a more preferable range of 3-7 ⁇ W/mg.
  • the exothermic peak height B within the temperature range of 230°C or above and below 330°C in DSC can be controlled to a preferable range of 20-40 ⁇ W/mg and to a more preferable range of 20-35 ⁇ W/mg.
  • the aluminum alloy sheet of the present invention manufactured to have the microstructure determined by the peaks of DSC described above is press formed into a large body panel and the like of an automobile and the like as a raw material, is painted then, and is thereafter subjected to the paint-bake hardening treatment (artificial temper aging treatment) to be high strengthened.
  • this paint-bake hardening treatment is preferable to be performed under a high temperature, and the conditions of the heating temperature of 180-230°C and the heating holding time of 10-30 minutes are exemplified.
  • the microstructure expressed by the differential calorimetric curve is required to be controlled more precisely as described above.
  • the 6000-series aluminum alloy sheets having different microstructure specified by DSC of the present invention were manufactured by separately changing the composition and the manufacturing condition.
  • the As proof stress (the proof stress before the paint-bake hardening treatment), the AB proof stress (the proof stress after the paint-bake hardening treatment), the breaking elongation, and the BH property (the paint-bake hardenability) after the holding for 100 days at the room temperature after manufacturing the sheet were respectively measured and evaluated. These results are illustrated in Tables 1, 2.
  • the preliminary temper aging treatment condition after the 6000-series aluminum alloy sheets having the composition illustrated in Table 1 were subjected to the solution heat treatment and quenching treatment was changed variously as illustrated in Table 2.
  • the indication of the content of each element in Table 1 the indication where the numerical value in each element is blank expresses that the content is the detectable limit or less.
  • the concrete manufacturing condition of the aluminum alloy sheet were made common (the same) for each example as described below with the exception of the preliminary temper aging treatment condition described above.
  • the aluminum alloy slabs having each composition illustrated in Table 1 were smelted commonly by the DC casting method.
  • the average cooling rate in casting was made 50°C/min from the liquid phase line temperature to the solid phase line temperature.
  • the slab after being subjected to surface scalping according to the necessity was subjected to the soaking treatment by 550°C ⁇ 10 hours, hot rough rolling was thereafter started at the temperature, and hot finishing rolling whose finishing temperature was between 250°C and 360°C was thereafter performed to obtain a hot rolled sheet.
  • This hot rolled sheet was cold rolled with the working rate of 67% to obtain a cold rolled sheet with the thickness of 1.0 mm.
  • each of these cold rolled sheets was subjected to the solution heat treatment for 1 minute at 550°C using a nitric furnace, and was thereafter cooled to the room temperature by performing water cooling.
  • preliminary temper aging at a high temperature for a short time using an oil bath and preliminary temper aging at a low temperature for a long time using an atmospheric furnace were performed by the temperature (°C) and the holding time (hr) illustrated in Table 2, and air cooling was performed after the preliminary temper aging treatment.
  • sample sheets 300 mm ⁇ 300 mm were cut out from the end part in the longitudinal direction and the center part in the width direction of the product, and DSC described above and the property of each sample sheet were measured and evaluated. These results are illustrated in Table 2.
  • the 0.2% proof stress (As proof stress) and the breaking elongation (%) were obtained by a tensile test.
  • the 0.2% proof stress (AB proof stress) of the sample sheet after each of these sample sheets was subjected to stretching of 2% which simulated the press forming into the automotive member described above and was thereafter subjected to respective artificial temper aging hardening treatments of 185°C ⁇ 20 min as the paint-bake hardening treatment at a high temperature and 170°C ⁇ 20 min as the paint-bake hardening treatment at a low temperature respectively commonly to each sample sheet (after BH) was obtained by a tensile test.
  • the difference of only 1% of 24% and 25% largely affects, for example, to whether or not the corner part and the outer line of the outer panel of an automobile where the shape is sharpened or complicated can be formed with a beautiful and sharp curved surface configuration without distortion and a wrinkle.
  • No. 13-A test specimen (20 mm ⁇ 80 mm GL ⁇ sheet thickness) of JIS Z 2201 was taken from each of the sample sheets described above respectively, and the tensile test was performed at the room temperature.
  • the tensile direction of the test specimen at this time was made the direction orthogonal to the rolling direction.
  • the tensile rate was made 5 mm/min up to the 0.2% proof stress, and 20 mm/min at the proof stress and onward.
  • the mechanical property was measured with the N-number of 5, and was calculated by the average value respectively.
  • the BH treatment described above was performed after applying the pre-strain of 2% to this test specimen by this tensile test machine.
  • the inventive examples 1-8 have been manufactured within the composition range of the present invention and in the preferable condition range, and have been subjected to the preliminary temper aging treatment at a low temperature for a long time in the preferable range. Therefore, each of these inventive examples conforms to what is specified in the present invention in terms of DSC as illustrated in Table 2, and are excellent in the formability and the BH property as illustrated in Table 2 even after the room temperature temper aging for a long period.
  • the inventive examples 1-8 have a high breaking elongation of 26% or more at the lowest, the BH property of a high temperature (185°C ⁇ 20 min) of 192 MPa or more at the lowest, and the BH property of a low temperature (170°C ⁇ 20 min) of 162 MPa or more at the lowest.
  • the BH property at a comparatively low temperature has become high compared to the inventive example 1 in which the preliminary temper aging treatment at a high temperature and for a short time is not performed and only the preliminary temper aging treatment at a low temperature and for a long time is performed.
  • the BH property at a comparatively low temperature has become high in average possibly depending on the alloy composition compared to the inventive examples 3, 4, and 5 in which the preliminary temper aging treatment at a high temperature and for a short time is not performed and only the preliminary temper aging treatment at a low temperature and for a long time is performed.
  • the height A of the endothermic peak within the temperature range of 150-230°C in DSC has been capable of being controlled more precisely to the preferable range (3-8 ⁇ W/mg) and the more preferable range (3-7 ⁇ W/mg)
  • the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C in DSC has been capable of being controlled more precisely to the preferable range (20-40 ⁇ W/mg) and the more preferable range (20-35 ⁇ W/mg) in a similar manner.
  • the comparative examples 1-6 of Table 2 use the alloy example 1 that is the same as the inventive example.
  • the manufacturing conditions such as the temperature and the holding time of the preliminary temper aging treatment deviate from the preferable condition.
  • DSC deviates from the range specified in the present invention, either the BH property or the formability after the room temperature temper aging for a long period is inferior compared to the inventive example 1 that has the same alloy composition, and it has not been possible to have both of the BH property and the formability.
  • the BH property at a high temperature (185°C ⁇ 20 min) has become less than 190 MPa even when the breaking elongation is 26% or more, or the breaking elongation has become less than 25% even when the BH property at a high temperature (185°C ⁇ 20 min) is 190 MPa or more, and the acceptance criteria described above have not been satisfied.
  • the preliminary temper aging treatment is not performed. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak exceeds 10 ⁇ W/mg and is too high, and the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C also exceeds 50 ⁇ W/mg and is too high.
  • the time of the preliminary temper aging treatment on the low temperature side is too short. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak exceeds 10 ⁇ W/mg and is too high, and the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C also exceeds 50 ⁇ W/mg and is too high.
  • the temperature of the preliminary temper aging treatment on the low temperature side is too high. Therefore, even though the endothermic peak with the height A of 3-10 ⁇ W/mg exists within the temperature range of 150-230°C, the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C is less than 20 ⁇ W/mg and is too low.
  • the time of the preliminary temper aging treatment on the low temperature side is too long. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak is less than 3 ⁇ W/mg and is too low, and also the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C is less than 20 ⁇ W/mg and is too low.
  • the time of the preliminary temper aging treatment on the high temperature side is too long. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak is less than 3 ⁇ W/mg and is too low, and also the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C is less than 20 ⁇ W/mg and is too low.
  • the temperature of the preliminary temper aging treatment on the low temperature side is too high. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak is less than 3 ⁇ W/mg and is too low, and the ratio B/A to the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C exceeds 15.0 and is too large.
  • the BH property at a high temperature is approximately 138-146 MPa at the most
  • the BH property at a low temperature is approximately 133-139 MPa at the most.
  • the comparative example 7 is formed of the alloy 7 of Table 1, the amount of Mg is too small, and also the amount of the total content of Mg and Si is too small. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak is less than 3 ⁇ W/mg and is too low, and also the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C is less than 20 ⁇ W/mg and is too low.
  • the comparative example 8 is formed of the alloy 8 of Table 1, the amount of Si is too small, and also the total content of Mg and Si is too small. Therefore, even though the endothermic peak exists within the temperature range of 150-230°C, the height A of the endothermic peak is less than 3 ⁇ W/mg and is too low, and the height B of the exothermic peak within the temperature range of 230°C or above and below 330°C is also less than 20 ⁇ W/mg and is too low.
  • Fig. 1 DSC selected from these inventive examples and comparative examples is illustrated in Fig. 1 .
  • the unit of the vertical axis written as "Heat Flow" is ⁇ W/m
  • the bold solid line represents the inventive example 1 of Table 2
  • the bold dotted line represents the inventive example 2
  • the narrow dotted line represents the comparative example 3.
  • the present application is based on the Japanese Patent Application ( JP-A No. 2016-067007) applied on March 30, 2016 and the Japanese Patent Application ( JP-A No. 2016-213789) applied on October 31, 2016 , and the contents of them are hereby incorporated as the reference into the present application.
  • a 6000-series aluminum alloy sheet which is provided with both of the excellent formability and the high BH property even after the room temperature temper aging for a long time and with the paint-bake hardening treatment at a high temperature. That is, both of the excellent formability even after the room temperature temper aging for a long time and the high BH property even in the conventional paint-bake hardening treatment at a low temperature described above as well as in the paint-bake hardening treatment at a high temperature described above can be provided.
  • application of the 6000-series aluminum alloy sheet can be expanded as an automotive member including a panel material.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Laminated Bodies (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
EP17775369.6A 2016-03-30 2017-03-30 Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium Withdrawn EP3438302A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2016067007 2016-03-30
JP2016213789A JP6306123B2 (ja) 2016-03-30 2016-10-31 アルミニウム合金板及びアルミニウム合金板の製造方法
PCT/JP2017/013179 WO2017170835A1 (fr) 2016-03-30 2017-03-30 Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium

Publications (2)

Publication Number Publication Date
EP3438302A1 true EP3438302A1 (fr) 2019-02-06
EP3438302A4 EP3438302A4 (fr) 2020-01-15

Family

ID=60045398

Family Applications (1)

Application Number Title Priority Date Filing Date
EP17775369.6A Withdrawn EP3438302A4 (fr) 2016-03-30 2017-03-30 Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium

Country Status (4)

Country Link
US (1) US20190127825A1 (fr)
EP (1) EP3438302A4 (fr)
JP (1) JP6306123B2 (fr)
CN (1) CN108884524B (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7473423B2 (ja) * 2020-08-24 2024-04-23 株式会社神戸製鋼所 成形性に優れたＡｌ－Ｍｇ－Ｓｉ系アルミニウム合金板
CN116103548A (zh) * 2022-12-20 2023-05-12 吉林大学 一种高时效硬化响应的Al-Mg-Si系铝合金及其制备方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003105471A (ja) * 2001-09-28 2003-04-09 Sumitomo Light Metal Ind Ltd アルミニウム合金板およびその製造方法
JP5278494B2 (ja) * 2004-01-07 2013-09-04 新日鐵住金株式会社 塗装焼付け硬化性に優れた６０００系アルミニウム合金板の製造方法
JP5498069B2 (ja) * 2009-07-10 2014-05-21 株式会社Ｕａｃｊ 冷間プレス成形用アルミニウム合金板ブランクの製造方法、およびそれによる冷間プレス成形方法および成形品
JP5709298B2 (ja) * 2010-08-12 2015-04-30 株式会社Uacj 塗装焼付硬化性および成形性に優れたＡｌ−Ｍｇ−Ｓｉ系アルミニウム合金板の製造方法
JP6227222B2 (ja) * 2012-02-16 2017-11-08 株式会社神戸製鋼所 焼付け塗装硬化性に優れたアルミニウム合金板
JP6429519B2 (ja) * 2014-07-14 2018-11-28 株式会社Uacj Ａｌ−Ｍｇ−Ｓｉ系合金圧延板の温間成形方法

Also Published As

Publication number Publication date
US20190127825A1 (en) 2019-05-02
EP3438302A4 (fr) 2020-01-15
JP6306123B2 (ja) 2018-04-04
CN108884524B (zh) 2021-06-08
JP2017186641A (ja) 2017-10-12
CN108884524A (zh) 2018-11-23

Similar Documents

Publication Publication Date Title
US9453273B2 (en) Aluminum alloy sheet with excellent paint-bake hardenability
JP5918158B2 (ja) 室温時効後の特性に優れたアルミニウム合金板
CN107709590B (zh) 具有高机械强度的用于机动车辆车身的金属板
JP4939091B2 (ja) 曲げ加工性に優れたアルミニウム合金板の製造方法
CA2941997C (fr) Plaque en alliage d'aluminium presentant une excellente aptitude au moulage et d'excellentes proprietes de durcissement a la cuisson
JP2016141843A (ja) 高強度アルミニウム合金板
JP6810508B2 (ja) 高強度アルミニウム合金板
JP2016141842A (ja) 高強度アルミニウム合金板
US20170114431A1 (en) Aluminum alloy sheet having good formability
JP5643479B2 (ja) 曲げ性に優れたＡｌ−Ｍｇ−Ｓｉ系アルミニウム合金板
WO2016031937A1 (fr) Tôle d'alliage d'aluminium pour formage
CN112981191B (zh) 汽车结构构件用铝合金板及其制造方法和汽车结构构件
JP3833574B2 (ja) 曲げ加工性とプレス成形性に優れたアルミニウム合金板
EP3438302A1 (fr) Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium
JP3740086B2 (ja) 室温時効後のヘム加工性に優れた、張出成形後にヘム加工されるアルミニウム合金板の製造方法
JP6315582B2 (ja) 成形用アルミニウム合金板
WO2017170835A1 (fr) Feuille d'alliage d'aluminium et procédé de fabrication de feuille d'alliage d'aluminium
JP2004238657A (ja) アウタパネル用アルミニウム合金板の製造方法
JP4238019B2 (ja) フラットヘム加工用アルミニウム合金パネル
JP3766334B2 (ja) 曲げ加工性に優れたアルミニウム合金板
JP4694770B2 (ja) 曲げ加工性に優れたアルミニウム合金板
JP2003247040A (ja) フラットヘム加工性に優れたアルミニウム合金板およびその製造方法
JP4588338B2 (ja) 曲げ加工性とプレス成形性に優れたアルミニウム合金板
JP2001003129A (ja) 耐食性に優れた輸送機用アルミニウム合金板
JP2017179469A (ja) アルミニウム合金板およびアルミニウム合金構造部材

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20181018

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
REG Reference to a national code

Ref country code: DE

Ref legal event code: R079

Free format text: PREVIOUS MAIN CLASS: C22C0021020000

Ipc: C22C0021080000

A4 Supplementary search report drawn up and despatched

Effective date: 20191213

RIC1 Information provided on ipc code assigned before grant

Ipc: C22C 21/08 20060101AFI20191209BHEP

Ipc: C22C 21/12 20060101ALI20191209BHEP

Ipc: C22F 1/00 20060101ALI20191209BHEP

Ipc: C22C 21/02 20060101ALI20191209BHEP

Ipc: C22F 1/05 20060101ALI20191209BHEP

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20200723

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20221001