EP3765647A1 - Procédé de fabrication d'un produit de type tôle d'alliage d'al-mg-si - Google Patents

Procédé de fabrication d'un produit de type tôle d'alliage d'al-mg-si

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Publication number
EP3765647A1
EP3765647A1 EP19705361.4A EP19705361A EP3765647A1 EP 3765647 A1 EP3765647 A1 EP 3765647A1 EP 19705361 A EP19705361 A EP 19705361A EP 3765647 A1 EP3765647 A1 EP 3765647A1
Authority
EP
European Patent Office
Prior art keywords
ageing
sheet
temperature
aluminium alloy
sheet product
Prior art date
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Granted
Application number
EP19705361.4A
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German (de)
English (en)
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EP3765647B1 (fr
Inventor
Mehdi LALPOOR
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.)
Aleris Aluminum Duffell BVBA
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Aleris Aluminum Duffell BVBA
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Publication of EP3765647A1 publication Critical patent/EP3765647A1/fr
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Classifications

    • 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
    • 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

Definitions

  • the invention relates to a method of manufacturing an AA6000-series alu- minium alloy sheet product, which is particularly suitable for use in the production of automotive body parts, and to an aluminium alloy sheet product of the AA6000- series, produced by this method.
  • US 2016/0348225 A1 discloses a method of preparing a AA6000-series alu- minium alloy sheet product, which includes solution heat treating and then quench- ing the AA6000-series aluminium alloy sheet product, followed by exposure of the sheet product to a temperature range of 30-60°C for 0.2-300 seconds. Afterwards, the sheet product is coiled and then placed in an ambient environment. By this method, the AA6000-series aluminium alloy sheet product may realise more con- sistent strength and ductility.
  • EP 0 805 879 B1 discloses a process of producing an aluminium alloy sheet material, which comprises subjecting hot-or cold-rolled aluminium alloy sheets to solution heat treatment followed by quenching and, before substantial age-harden- ing has taken place, subjecting the alloy sheet material to one or more subsequent heat treatments involving heating the material to a peak temperature in the range of 100-300°C, preferably 130-270°C, holding the material at the peak temperature for a period of time less than about 1 min, and cooling the alloy from the peak tempera- ture to a temperature of 85°C or less.
  • US 2016/0222491 A1 discloses an AA6000-series aluminium alloy sheet product with good bendability, which is produced by solution heat treatment, fol lowed by quenching. After quenching, the sheet is subjected to pre-aging within 1 hr.
  • the pre-aging treatment consists of holding the sheet at 60-120°C for ten hours to 40 hours.
  • CN 107254646 discloses a heat treatment method for 6000 aluminium series alloys including solution heat treatment and quenching to 40-60°C, soaking for 5-20 min, and then rapidly heating to 100-120°C, and holding at this temperature for 2-5 min.
  • the pre-aging treatments known from the prior art mostly have the objective of stabilizing the paint-bake response, i.e. the increase in yield strength induced by a paint bake cycle.
  • the prior art has focused merely on the paint- bake response, without paying attention also to the bending behaviour and related hemming performance of the pre-aged sheet product. It is therefore an object of the invention to provide a method for manufacturing an 6000-series aluminium alloy sheet product ideally for use in the production of automotive body parts, which, after significant naturpal aging up to e.g. 6 months after pre-ageing treatment, has an excellent hemming performance in T4P temper, in combination with a good paint-bake response.
  • all aluminium alloy designations and temper designations refer to the designations by the Alumi- num Association as published e.g. in“International Alloy Designations and Chemical Composition Limits for Rolled Aluminum and Rolled Aluminum Alloys” in January 2018.
  • sheet or “sheet product” refers to a rolled product having up to 4.0 mm in thickness.
  • the yield strength after a paint-bake simulation consisting of 2% pre-strain and holding at 185°C for 20min is significantly stabilized by using a higher pre-aging temperature than was normally applied in the industrial scale process, namely by using a pre-aging temperature in the range of 65-1 10°C, preferably 80-1 10°C, more preferably 85 to 105°C, wherein the most effective range was found to be between 90-100°C.
  • the T4P temper here refers to a material that has been solution heat treated and quenched and then subjected to a pre-ageing treatment and then natural aged to provide said T4P temper.
  • the natural ageing occurs as a result of storing at am- bient (room) temperature, typically for about 72 hours up to 6 months, until forming or shaping into an automotive body panel, in particular into a three-dimensional au- tomotive panel.
  • the T64 temper here refers to a T4P temper material that has been deformed in tension by 2% pre-strain followed by a 20 minutes treatment at 185°C to represent the forming plus paint curing treatment typically experienced by automotive panels.
  • the difference in strength between T64 and T4P is often referred to as the paint-bake response.
  • the pre-aging temperature of the invention is particularly advantageous because it leads to the formation of a particular type of nano-clusters, named C2-clusters, which enhance the formation of the “-phase during the paint-bake treatment, and therefore increase the paint bake response.
  • C2-clusters a particular type of nano-clusters
  • the precipitation of the “-phase is be- lieved to be responsible for the strengthening of the subject aluminium alloy sheet during paint-baking.
  • These advantageous C2 clusters form between 60-130°C. Therefore, pre-ageing temperatures in this range are advantageous.
  • the pre-ageing temperatures in the range 80-1 10°C appear to require shorter soak times (e.g. less than 60 min. or even less than 45min.), which is advantageous in an industrial context. Owing to the for- mation of detrimental Si-rich C1 clusters in the range 30°C ⁇ T ⁇ 60°C, it appears ad- vantageous to avoid short stay of the material at such temperatures.
  • the pre-aging time is limited to 20-70 min according to the invention, preferably 25 to 60min.
  • a preferred lower limit is about 25 min, and more preferably about 30 min, and most preferably about 35 min.
  • a preferred upper- limit is 60 min., more preferably 55 min., and most preferably 45 min.
  • the higher pre-aging temperature may lead to a deterioration in hemming performance.
  • it has been found that it is advantageous to cool the sheet product from the pre-aging temperature at a relatively high cooling rate of more than 3°C/h.
  • the sheet product is directly coiled after the pre-aging step and placed in an ambient environment. If on an industrial-scale a coil of aluminium alloy sheet, which weighs up to about 10t, is left to cool down in natural air cooling, the cooling rate will be very slow, e.g. around or even below 1 °C/h, as is disclosed for example in patent document US 2016/0047021 A1 .
  • water cooling is used after the pre- aging treatment, which results in cooling rates of >50°C/h, preferably in a range of 60-150°C/h, more preferred in a range of 80-120°C/h, most preferred in a range of 90-1 10°C/h.
  • a possible reason for the advantage of using a forced cooling after pre- aging rather than natural cooling, is that the detrimental temperature zone between 30-60°C, in which the C1 clusters form, is passed through relatively quickly, avoiding long dwell times in this temperature range.
  • the sheet product is cooled from the pre-aging temperature with the above-described cooling rate down to below 35°C, preferably to below 30°C or to ambient temperature. Thereby, holding of the sheet product in the temperature range where C1 clusters form is avoided.
  • the cooling time from pre-aging temperature should be less than 20h, preferably less than 10h, more preferred less than 5h. Such shorter cooling time will also result in an improvement in the hemming performance in the T4P con- dition after natural aging for a significant amount of time.
  • the hemming performance in T4P condition may be further improved by modifying also the quenching step after solution heat treatment, namely by pursuing the quench/cooling of the sheet to below 45°C, preferably to below 35°C, more pre- ferred to below 30°C and most preferred to ambient temperature or room tempera- ture.
  • the quench/cooling of the sheet to below 45°C, preferably to below 35°C, more pre- ferred to below 30°C and most preferred to ambient temperature or room tempera- ture.
  • CAL continuous annealing line
  • the quench rate has no signif- icant influence on mechanical properties as long as the exit temperature of the quenching operation is sufficiently low, namely below 45°C, preferably below 35°C. Also here, this may be related to the formation of adverse C1 clusters in the tem- perature range of 30-80°C, which is significantly reduced by quenching down to be- low 45°C. It has been found that using such extended quenching has a positive effect on the hemming behaviour in T4P after natural aging for 6 months.
  • quenching from solution heat treatment temper- ature is done by water-quenching, which allows cooling to the desired low tempera- tures.
  • the method steps (b) to (d) are preferably performed on a continuous an- nealing line (“CAL”), i.e. the rolled aluminium alloy is provided in the coiled state, and is passed through the CAL.
  • CAL an- nealing line
  • the sequential steps of solution heat treatment, quenching and pre-aging are performed not batch-wise but in-line in a continuous processing line.
  • the sheet product is coiled after passing the continuous annealing line, and wherein the cooling step of the aluminium sheet is thus performed in the coiled state.
  • the quenched sheet will be sub- jected to levelling and/or etching and/or passivation prior to the pre-aging step. Since these process steps take some time, in most embodiments, there will be a time delay between quenching and the pre-aging step. But this delay should be as short as possible, since the natural aging will start directly after quenching.
  • the pre-aging step is preferably started within 30 minutes, more preferably within 20 minutes after quenching, more preferred after 15 minutes and most pre- ferred within 5-12 minutes following the quenching step.
  • the aluminium alloy sheet is passed through the con- tinuous annealing line at a line speed of up to 120 m/min, wherein the higher line speeds are preferred, preferably in a range of 50 to 100 m/min, more preferably 50 to 90 m/min, as experiments have shown that better hemming performance in com- bination with good bake response can be realized at relative high line speeds.
  • the reason may be the reduced natural aging time between quenching and pre-aging.
  • the method according to the invention guarantees the properties at both extreme speed limits.
  • solution heat treatment is performed at a temperature in a range of 510°C to 580°C, preferably 520-565°C, more preferred about 530°C to 560°C, wherein a solution heat treatment temperature of about 550 ⁇ 5°C is most preferred.
  • a relatively high solution heat treatment temperature has been found useful, since it leads to a more complete solid dissolution of elemental excess Si as well as Mg2Si, and this will result in the good hardening response of the alu- minium alloy during paint-baking.
  • the AISiMg- or AIMgSiCu-alloy can be provided as an ingot or slab for fabrica- tion into rolling feedstock using casting techniques regular in the art for cast prod- ucts, e.g. DC-casting, EMC-casting, and preferably having an ingot thickness in a range of about 220 mm or more, e.g. 400 mm, 500 mm or 600 mm.
  • thin gauge slabs resulting from continuous casting e.g. belt casters or roll casters, also may be used, and having a thickness of up to about 40 mm.
  • the thick as-cast ingot is commonly scalped to remove segregation zones near the cast surface of the ingot.
  • the cast ingots are subjected to a homogenization treatment by heating the ingot to a temperature of above 540°C, but at a temperature lower than the solidus temperature of the subject alloy; maintaining the ingot at this temperature for at least about 4 hours, and preferably for at least about 10 hours.
  • the ingots are hot-rolled and subsequently cold-rolled.
  • the rolled sheet has a final thickness of usually 0.5 to 4.0 mm, and preferably in a range of 0.7 mm to 2.0 mm, for example a thickness of about 1 .0 mm or about 1 .2 mm.
  • the cold-rolled band or sheet is then further processed according to the method of this invention.
  • the provided rolled aluminium alloy sheet product comprising an AA6000-series has a chemical composition closely associated with the known AA6016 or AA6016A series, or modifications thereof.
  • the rolled aluminium sheet may comprise a single layer of the AA6000-series alloy.
  • the rolled aluminium sheet may comprise sev- eral layers. At least one layer is made of an aluminium alloy of the AA6000-series, and preferably having the following composition, in weight %:
  • Mg 0.2-0.8 preferably 0.25-0.7, most preferred 0.4 -0.60,
  • Cu ⁇ 0.40, preferably ⁇ 0.25, more preferably ⁇ 0.20,
  • the sheet product according to the invention preferably has a Si content of at least 0.75%, preferably 0.8%, preferably at least 0.9%, and most preferred at least 1 .0%.
  • a preferred upper limit for the Si content is 1 .4%, more preferred 1 .30%.
  • the Mg content should be at least 0.2%, preferably at least 0.25% and more preferred at least 0.4%, in order to provide sufficient strength to the sheet product after the paint-bake cycle.
  • a preferred upper-limit for the Mg-content is 0.7%, and more preferably 0.60%.
  • the amount of iron (Fe) is carefully controlled in order to provide an improved hemming performance compared to aluminium alloys with higher Fe levels, and having otherwise the same composition.
  • the Fe content in the alloy sheet product is preferably ⁇ 0.35%, more preferred ⁇ 0.3% and most preferred 0.10-0.3%.
  • Cu can be purposively present in the sheet product to a level of ⁇ 0.40, but preferably should not exceed 0.25 in order to maintain a good corrosion perfor- mance.
  • Cu is present up to 0.20%, more preferred up to 0.15%.
  • Cu is purposefully added to be present in a range of 0.05-0.20%, preferably 0.05-0.17%. It appears that Cu is affecting the precipitation sequence of the hardening Mg2Si phase, leading to a favourable stabilisation of the pre-aging properties and a higher paint-bake response.
  • Mn is added to the alloy sheet product for grain size control to improve the formability of the sheet product.
  • the Mn level should be present in a range of up to 0.25%, preferably up to 0.20%, and more preferably in a range of 0.01 % to 0.15%.
  • a preferred lower-limit for the Mn content is about 0.03%, and more prefer- ably about 0.05%.
  • Cr can be present up to 0.10%. Cr is preferentially avoided in the sheet product as it may prevent full recrystallization of the sheet product. Preferably it is tolerated up to 0.04%, and is preferably less than 0.03%, and more preferably less than 0.02%.
  • the sheet product generally includes not greater than 0.03% V and not greater than 0.03% Zr.
  • the sheet product includes V only up to 0.02%.
  • the sheet product includes Zr only up to 0.02%.
  • Zn may optionally be included in the alloy, and in an amount up to about 0.25%. Zinc may be present in scrap, and its removal may be costly.
  • the alloy includes not greater than 0.10% Zn, and in a preferred embodiment the alloy includes not greater than 0.05% Zn.
  • Ti can be added to the sheet product amongst others for grain refiner purposes during casting of the alloy ingots.
  • the addition of Ti should not exceed 0.10%, and preferably it should not exceed about 0.05%.
  • a preferred lower limit for the Ti addi- tion is about 0.008%, and can be added as a sole element or with either boron or carbon as known in the art serving as a casting aid, for grain size control.
  • Unavoidable impurities may be present up to 0.05% each, and in total up to 0.25%, preferably up to 0.15%, and the balance being aluminium.
  • the provided rolled aluminium alloy sheet comprising an AA6000-series alloy has a composition consisting of:
  • Mg 0.2-0.8 preferably 0.25-0.7, most preferred 0.4 -0.60,
  • Cu ⁇ 0.40, preferably ⁇ 0.25, more preferably ⁇ 0.20,
  • the al- loy may have preferred narrower compositional ranges as herein described and claimed.
  • the invention is also directed to an aluminium alloy sheet product, particularly suitable for use in the production of automotive body parts, and which has been manufactured by the herein described and claimed method according to the inven- tion or one of its embodiment.
  • Such sheet product has been found to have a hem- ming performance of 3 or more, preferably 3 1 ⁇ 2 or more after six months of natural aging, which corresponds to the T4P temper. Once this 6 months naturally aged sheet has been subjected to a simulated paint-baking cycle of 2% pre-strain and heating at 185°C for 20 minutes, it exhibits a paint bake response of 80 MPa or more, preferably of 85 MPa or more.
  • the aluminium alloy sheet product produced according to the invention has excellent forming, and in particular hemming properties after extended natural aging for more than two months and therefore can easily be processed by or for an automobile manufacturer into an automotive body part by means of forming (e.g. by deep-drawing, pressing, or stamping).
  • the product of the invention can advantageously be used as an automotive panel, ideally an outer panel, with guaranteed paint-bake response, hemming and bending performance for 6 months after CAL-treatment, pre-ageing and natural age- ing.
  • Fig. 1 is a flow-diagram of the usual process steps used in manufacturing a Al- SiMg alloy rolled sheet product for use in the production of automotive body parts;
  • Fig 2 is a schematic temperature vs. time diagram, illustrating the heat treat- ments of the CAL according to the invention.
  • Figure 1 illustrates an embodiment of the processing steps used in the man- ufacturing of AA6000-series aluminium alloys to produce automotive body sheets according to the invention.
  • ingots are cast using DC or EMC casting.
  • the alloy is pref- erably of the AA6016-series, although the invention may also find use for e.g. AA6014, AA6081 , AA6451 , or AA6005A-type of alloys.
  • the cast ingots are subject to scalping and a usual homogenization treatment in step 4.
  • the homogenized ingot is hot-rolled in step 6, and the hot-rolled plate is passed to the cold-rolling mill.
  • a first cold-rolling step 8 is followed by an intermedi- ate annealing step 10 and afterwards, a second and final cold rolling step 12 is performed.
  • the sheet is in the form of a band having a thickness of e.g. 0.5-4.0 mm, typically 0.8-1 .5mm.
  • the rolled aluminium alloy sheet provided to the solution heat-treatment and pre-aging treatment according to this invention will usually be made of one monolithic layer, but the invention is equally applicable to multi-layered sheet products, wherein one or all of the layers are of the AA6000-series.
  • the rolled aluminium sheet is typically supplied to a continuous annealing line (“CAL”).
  • CAL continuous annealing line
  • the steps of solution heat treatment and quench- ing to below 35°C are performed in step 14.
  • the quenched sheet product is subjected to levelling and in useful embodiments also to etching and passivation in step 16.
  • the sheet product is heated to the pre-aged tempera- ture in step 18, preferably coiled at pre-aging temperature, soaked at the pre-aging temperature for the prescribed pre-aging time, and subjected to a controlled cooling step resulting in a cooling rate of >3°C/h in step 18.
  • Fig. 2 shows a temperature profile of a continuous annealing line according to an embodiment of the invention.
  • the rolled sheet product is heated up to preferably above 540°C in the solution heat treatment step.
  • Such high temperature is advantageous as it results in the highest possible rate of dissolution of Mg2Si and Si.
  • the shaded area 24 between 400-540°C shows the temperature range in which Si is dissolved in solid solution. In the range 22 between 400-480°C Mg2Si is dis solved. In the temperature range between 300-400°C, which is dotted and marked with 26, Mg2Si and Si are dissolved in the cold-rolled material. It follows that above 540°C, the dissolution of Mg2Si and Si is complete.
  • the material is held at the SHT-temperature for a short time, e.g. for less than 1 minutes, preferably less than 30 seconds, and quenched 28 preferably by water quenching, in this illustrative example to below 30°C.
  • the quenching rate is as usual in the art, namely about 200-400°C/s.
  • Fig.2 The advantage of quenching to below 45°C and more preferably to below 35°C or even below 30°C is illustrated in Fig.2 by the various zones 38-46, in which the C1 and C2 clusters form: in the temperature range 46 between 30-80°C, the C1 clusters tend to form, which are detrimental to the paint bake response, since they delay precipitation p“-phase. This effect is believed to be strongest in the middle of this range, between about 45°C and 60°C. Hence, this temperature range may be called the“unsafe zone”. Accordingly, it is advantageous to quench to below 45°C in step 28.
  • the C2 clusters form which have been shown to have a positive effect on the properties of the sheet after natural aging, including paint-bake response (PBR).
  • the zone 44 be- tween 80-130°C, in which only C2 clusters form, is designated as“safe zone”, and is a useful temperature range for the pre-ageing treatment.
  • the zone 40 between 60-80°C is characterised by the formation of both C1 and C2 clusters, and therefore may still be used with advantageous effects for pre-ageing. At these comparatively low temperatures, longer soak times are preferred according to the invention, e.g. around 40 min or 50 min to 70 min.
  • the sheet product After quenching, the sheet product is held at ambient temperature 30 for less than 30 minutes, while additional process steps such as levelling, etching and/or passivation are performed. These process steps typically take place at a tempera- ture of e.g. between 20-30°C. After completion of these steps, and as soon as fea- sible after quenching, the sheet product is heated to the pre-aging temperature, in this case between 80-1 10°C in step 32. The sheet product is held there in step 34 for a pre-aging time of 20 min or more, however, preferably less than 70 min, wherein the holding at pre-aging temperature may take place in the uncoiled or al- ready coiled state.
  • additional process steps such as levelling, etching and/or passivation are performed. These process steps typically take place at a tempera- ture of e.g. between 20-30°C.
  • the sheet product After completion of these steps, and as soon as fea- sible after quenching, the sheet product
  • the sheet After the soaking time at pre-aging temperature, the sheet, usu- ally the coiled sheet, is subjected to forced convection cooling 36 to ambient tem- perature, resulting in a cooling rate of 3-150°C/h, and a cooling time of 20 hours or less.
  • the solution heat treatment temperature was 540°C for comparison sample C2 and otherwise 550°C.
  • the quench type is either standard or extended, wherein standard relates to the standard quenching procedure wherein the quench exit tem- perature is above 60°C.
  • the extended quench type relates to an embodiment of the inventive quenching step with an exit temperature after quenching of below 30°C.
  • the usual passivation step was performed.“PAT” stands for pre- aging temperature, and“PA-time” for the holding time at PAT.
  • the cooling rate stands for the cooling rate from the pre-ageing temperature after the PA-time.
  • coils #4 and #5 and coiled sheet product samples S3 and S4 which were cooled at a cooling rate of 3.2°C/h and 3.8°C/h, respectively, were cooled in a forced convec- tion cooling chamber, whereas coil #3 and samples S1 and S2 having a cooling rate of about 100°C/h were cooled by water spraying.
  • the mechanical properties of the materials are listed in Table 2.
  • the yield strength Re was always measured in the transverse direction and is given in T4 temper after the pre-aging treatment followed by 25 days of natural aging (25d), and 6 months of natural aging (6m).
  • the hemming performance in L-direction (rolling direction) was measured also in T4P condition after 6 months of natural aging.
  • the hemming performance was tested via a flat hemming test, by bending the samples 180° with a bending radius of 0.0mm as described in ASTM Norm E290-97-A and followed by a visual assessment. A score was given according to the following rat- ing:
  • Rating "5" represents no visual defects, "4" mild surface roughening, "3" se- vere surface roughening, "2" small surface cracks, and "1” represents continuous surface cracks, and whereby a further sub-rating of for example 3 1 ⁇ 4, 31 ⁇ 2 and 33 ⁇ 4 is used. A rating of 21 ⁇ 2 or below is unacceptable for the preferred intended application as an automotive outer panel.
  • the samples were subjected to a simulated paint-bake cycle, which con- sisted of 2% stretch and soaking at 185°C for 20min, resulting in a T64 temper.
  • the tensile tests in T64 temper were done in transverse direction and the increase in Re during the paint-bake cycle is given as the paint-bake response (PBR).
  • Coil #1 with sample C1 represents a sheet product produced with the normal state-of-the-art processing conditions, including a standard quench and a pre-aging treatment at 60°C for 60 minutes, followed by the usual natural convection cooling in the coiled state, and which results in a slow cooling rate of 1 -1 .5°C/h.
  • the C1 sample has a low Re-T6 and low paint-bake response.
  • the Re-T6 drops significantly by 24MPa during the 6 months aging.
  • the hemming performance at 2 is not acceptable.
  • Coil #3 and sample S1 were processed according to the invention, with a standard quench and a cooling rate of 100°C after pre-ageing.
  • the pre-ageing treat- ment was done at 96°C for 30 minutes.
  • the hemming performance is significantly improved to 3 1 ⁇ 4 in comparison with sample C2, while the PBR is even higher at 87 MPa.
  • the drop of Re-T64 in the 5 months between the two measurements (Re-T64 (25d) and Re-T64 (6 m)) is negligible at 1 MPa.
  • this process results in an excellent stability in mechan- ical properties, in particular of the PBR, in combination with a very good hemming performance in T4P condition after significant natural ageing.
  • Sample S2 of the same coil was processed in the same way as sample S1 , with the exception that an extended quench was used. As can be seen in Table 2, this leads to a further improvement of the hemming performance in T4P condition from 3 1 ⁇ 4 to 3 1 ⁇ 2.
  • sample S3 and S4 demonstrate that forced convection cooling is adequate to achieve a cooling rate after pre-ageing which is sufficient to realize the advantages of the invention.
  • sample C2 shows that natural cooling, however, will not produce satisfactory results, as the cooling rate after pre-ageing is too low.
  • raising the pre-ageing tem- perature from 60°C to above 65°C to 1 10°C, preferably to 80-1 10°C, while adjusting the PA-time is shown to improve the stability of the mechanical properties during natural ageing, in a particular Re-T64 and PBR.

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Abstract

L'invention concerne un procédé de fabrication d'un produit de type tôle d'alliage d'Al-Mg-Si(Cu) particulièrement approprié pour être utilisé dans la production de parties de carrosserie d'automobile, le procédé comprenant les étapes consistant à (a) utiliser une tôle d'alliage d'aluminium laminée comprenant un alliage de la série AA6000 ; (b) traiter thermiquement en solution la tôle d'alliage d'aluminium laminée ; (c) tremper ladite tôle ; (d) faire pré-vieillir ladite tôle en le soumettant à un traitement thermique à une température de pré-vieillissement de 65°C à 110°C, pendant une durée de pré-vieillissement de 20 à 70 min ; et (e) refroidir la tôle pré-vieillie à partir de la température de pré-vieillissement à une vitesse de refroidissement supérieure à 3 °C/h.L'invention concerne également un produit de type tôle d'aluminium produit par ce procédé.
EP19705361.4A 2018-03-15 2019-02-19 Procédé de fabrication d'un produit de feuille d'alliage almgsi Active EP3765647B1 (fr)

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CN113528900B (zh) * 2021-07-20 2022-05-27 中铝瑞闽股份有限公司 一种短流程高导电6系铝合金板带材及其制备方法

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JP5918158B2 (ja) 2013-02-26 2016-05-18 株式会社神戸製鋼所 室温時効後の特性に優れたアルミニウム合金板
JP5882380B2 (ja) 2013-04-09 2016-03-09 株式会社神戸製鋼所 プレス成形用アルミニウム合金板の製造方法
JP2016141843A (ja) 2015-02-02 2016-08-08 株式会社神戸製鋼所 高強度アルミニウム合金板
CN107667184B (zh) 2015-05-29 2020-03-06 奥科宁克公司 6xxx铝合金及其制备方法
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