DE102020001116A1 - Cold extrusion component and cold extrusion process - Google Patents

Abstract

The invention relates to a cold-extruded component made from a hardenable aluminum alloy. According to the invention, a first relationship is provided between the Brinell hardness [HB] based on work hardening and precipitation hardening components and the corrosion penetration depth KE in [µm] of g (HB, KE) ≥ L with g (HB, KE) = (HB-4) / [ 1 + ℓn ((20 + KE) / 20)], and L = 30 and / or a second relationship between this Brinell hardness and the sum Σ3 of magnesium, silicon and double the copper content of the aluminum alloy in percent by weight of HB - (Δ1 + Δ2) / 2 ≥ tanh (z) · (Δ1-Δ2) / 2, with Δ1 = K0 + K1ℓn [1 + 2.3 | Σ3-0.9 |], Δ2 = K2 + (Σ3-0, 45) · (K0-K2) / 0.45, z = 30 (Σ3-0.9) and K0 = 60, K1 = 25 and K2 = 46.

Description

The invention relates to a special field of massive forming of metallic materials, namely the cold extrusion of hardenable aluminum alloys.

DE 10 2017 001 384 A1 discloses an aluminum alloy with up to 1.3% by weight silicon and up to 1.2% by weight magnesium and thus also hardenable aluminum alloys, and also relates to the cold extrusion of slugs from such alloys. This document teaches that the range of application of cold extrusion can then also be expanded favorably to non-rotationally symmetrical basic shapes, even for cup-shaped parts, if the curvature ratios and wall thickness ratios described in this document are observed.

WO 2017/093304 discloses alloys with, inter alia, 0.30 to 0.6% by weight silicon and 0.35 to 0.6% by weight magnesium, or also with 0.2 to 0.6% by weight silicon and 0.45 up to 0.9% by weight magnesium, and teaches extrusion processes for various applications, such as building structures. For this purpose, the material is brought to a forming temperature of 520 ° C by means of induction heating using an 800 ton vertical press and, after the extrusion, is subjected to a heat treatment in which the extruded profiles are brought to a temperature of 195 ° C. According to this document, it is important that the alloy components Cu and Zn lie in a specifically defined window in the Cu-Zn diagram.

WO 2018/080710 A1 provides information on how aluminum alloys can be produced from a casting process to aluminum alloys that are hot-rolled at 250 ° C to 500 ° C, optionally cold-rolled, hot-rolled again and, if necessary, solution-annealed and aged. Such starting materials brought into flat shapes by rolling are, however, less suitable as starting material for the cold extrusion according to the invention, since slugs produced by cutting are more easily obtained in other ways from cylindrical or beam-like configurations.

In L. Marzoli et al. Light Metals 2017 , P. 343 ff from The Minerals, Metals & Materials Series explains that, in addition to the discontinuous manufacturing steps just described, via casting, extrusion and / or rolling, the wound material can also be produced via a continuous casting and rolling process, and cold drawing processes are also described and on the favorable possibility of determining corrosion properties according to Volkswagen AG group standard PV 1113, 2007-10, class no. 53312 and explained this.

For an in CN 109628860 For the production process described for a starting material, cast alloys are extruded at temperatures of up to 560 ° C, quenched and ideally aged at 165 ° C to 170 ° C.

EP 3 214 191 A1 suggests an Mn content of 0.7-0.8% for Al-Mg-Si alloys.

U.S. 5,507,888 A discloses tubular structures made of aluminum alloys which are produced by hot extrusion above 260 ° C.

Extrusion processes are also the subject of the article Metals, 2018, 8, 51. It determines that an Al alloy with (wt .-%) 0.5 Si, 0.5 Mg, 0.2 Cu and 0.2 Fe is more favorable Properties obtained if the extrusion is not carried out at artificial aging temperatures of 170 ° C, but at a temperature of 120 ° C.

Trans. Nonferrous Met. Soc. China 22 (2012) 2072-2079 is also about age-hardenable aluminum alloys, here with an Mg content of 0.9 wt% and an Si content of 0.41 wt%, this article deals with cold rolling for a reduction in thickness of 20, 40 or 60 % and further deals with the question of how an intermediate aging process, also inserted between two cold rolling processes, at 180 ° C for half an hour, affects the end product.

Similar to this article, Materials Science Forum Vols. 794-796 (2014), pp. 605-610 , Cold rolling (73%) as a massive forming process. According to this article, heat treatments are carried out at 175 ° C to demonstrate which mechanisms underlying the Nes model best agree with the observations obtained from it, but do not come to the same conclusions as E. Nes in Acta metall. mater. Vol. 43, No. 6, pp. 2189-2207, 1995 .

In Material Science and Engineering A 759 (2019) 520-529 cold-rolled sheets are considered and the β '' phase is described as the relevant phase of precipitation hardening of hardenable aluminum alloys. It is taught to carry out the aging process at 185 ° C, but to carry out "pre-aging" if the time between solution annealing and artificial aging is too long.

This β ″ phase and the so-called GPI and GPII zones as strength-generating are also described in Materials Characterization 49 (2003) 193-202 addressed, in which cold rolling as a solid Forming process is proposed. An artificial aging hardness achieved for an aging temperature of 210 ° C requires an aging time of 500 minutes at the lowest specified aging temperature of 160 ° C.

In the product catalog “Extrusion is our world” from Neuman Aluminum, AT, the path taken during extrusion from the butt to the extruded part is also shown for hardenable aluminum alloys. The slugs are delivered in a soft-annealed condition, extruded, solution-annealed and artificially aged (artificially aged), in accordance with the professional approach, as e.g. in the lecture FT II Forming Technology WS 2015/16 on page 27.

Example 8 of the EP 0 676 480 A1 discloses a cold-extruded component according to the preamble of claim 1 made of a hardenable aluminum alloy with, inter alia, a Si content of 0.91, a Cu content of 0.78 and an Mg content of 1.41, each weight%. By solution annealing the cold-extruded container with water quenching and artificial aging for approx. 16 hours, the precipitation hardening achieved during artificial aging achieves increased strength values compared to, for example, the 6060 aluminum alloys.

Usually, in cold extrusion processes, an alloy selection and process parameters adapted to the specific requirements of the components to be manufactured are determined.For example, it must be ensured that the process forces depending on the degree of deformation can be carried by the extrusion tool and the alloy composition without excessive wear / tear / risk of destruction. For example, if the aim is to achieve the highest possible strength and hardness, for example a 6XXX aluminum alloy will be selected and the Si and Mg content or Cu content increased to increase the desired strength potential.

The invention is based on the object of providing cold-extruded components which, even in the case of diverse requirements, are a good compromise solution with properties that are still per se satisfactory for each individual.

For this purpose, the invention provides a cold-pressed component made of a hardenable aluminum alloy, which is essentially characterized by a first relationship between the Brinell hardness [HB] based on work hardening and precipitation hardening components and the maximum corrosion penetration depth KE in [µm] of g (HB, KE) ≥ L with g (HB, KE) = (HB-4) / [1 + ℓn ((20 + KE) / 20)], and L = 30 and / or a second relationship between this Brinell hardness and the sum Σ ₃ made of magnesium, silicon and double the copper content of the aluminum alloy in percent by weight of HB - (Δ ₁ + Δ ₂ ) 2 ≥ tanh (z) · (Δ ₁ -Δ ₂ ) / 2 with Δ ₁ = K ₀ + K ₁ tn [1 + 2.3 | Σ ₃ -0.9 |], Δ ₂ = K ₂ + (Σ ₃ -0.45) · (K ₀ -K ₂ ) / 0.45, z = 30 (Σ ₃ -0.9) and K ₀ = 60, K ₁ = 25 and K ₂ = 46, preferably also with K ₀ = 70, in particular also with K ₀ = 80.

The cold-extruded components according to the invention show a good compromise between, on the one hand, properties of mechanical hardness and other properties, such as corrosion protection, which are usually negatively influenced by measures to increase hardness.

A type 6XXX alloy is preferably used as the base material of the alloy. It goes without saying that with cold extrusion numerous and otherwise common structures that can, but need not be symmetrical to the press axis, areas with greater deformation and areas with less deformation (degree of deformation) are created, and in such cases a strain hardening proportion in the lower deformed areas, eg floor areas compared to wall areas of cup-like structures, is relatively less. The component is therefore to be understood in such a way that it in any case has areas in which the first relationship and / or the second relationship applies. In both relationships ℓn denotes the natural logarithmic function to the base e, and tanh is the tangent hyperbolic function.

For the purposes of this disclosure, the IGC test PV1113 (Volkswagen) already cited above with an exposure time of 2 hours is the decisive method for determining the maximum corrosion penetration depth. Furthermore, the relevant reference DIN EN ISO 6506 HBW 2.5 / 62.5 is specified for the Brinell hardness, and the hardness value HB relates to this.

In a further preferred embodiment, L is greater than 33, in particular greater than 36, in the first relationship. More preferably, values of greater than 38, even 40, can also exist for L.

For the relationship between Brinell hardness and the sum Σ ₃ , it is further preferred that the second relationship also _{applies with K 0} = 83, further also K ₀ = 86, in particular K ₀ = 88 and / or also with K ₁ = 27 consists.

Furthermore, the second relationship preferably also applies with K ₂ = 56, K ₂ = 60 and even for K ₂ = 64, K ₂ = 68 or K ₂ = 72.

In preferred embodiments, the first or second relationship preferably applies with an inverse limitation to the effect that in these relationships the “≥” is replaced by a “<”, in which case L = 60, more preferably L = 55, then applies. especially L = 48. Furthermore, it is provided in reverse limitation that K ₀ = 120, preferably equal to 112, in particular equal to 108, and / or K _{2 is} 98, preferably 94, in particular 90. In this way, the processes for manufacturing the component can be carried out more easily and with more leeway.

In a likewise preferred embodiment, the second relationship applies cumulatively or alternatively also with Σ ₂ (= Mg + Si content in% by weight) instead of Σ ₃ .

In a particularly preferred embodiment, the aluminum alloy has an Si content in% by weight of at least 0.25, preferably at least 0.33, in particular at least 0.4, and / or lower than 1.4, preferably than 1.1, especially 0.9.

In a particularly preferred embodiment, the aluminum alloy has an Mg content in% by weight of at least 0.2, preferably at least 0.28, in particular at least 0.35, and / or lower than 1.3, preferably than 1.0, especially 0.8.

In a particularly preferred embodiment, the aluminum alloy has an Mn content in% by weight of at most 1.1, preferably at most 0.7, in particular at most 0.3, or at most 0.15.

In a particularly preferred embodiment, the aluminum alloy has a Cu content in% by weight of less than 1.3, preferably less than 0.8, in particular less than 0.4, even less than 0.2, in particular less than 0.1 .

The aluminum alloy may contain minor iron constituents for technical reasons or intentionally (eg scrap recycling), the weight percent of which, however, should not be greater than 0.8, preferably than 0.5, more preferably than 0.4, in particular than 0.3.

Cr, Zn, Ti can be contained in the usual amounts, preferably not more than 0.35% by weight individually and not more than 0.75% by weight in total.

In a particularly preferred embodiment, the aluminum alloy has the sum Σ ₂ of Si and Mg content in% by weight of greater than 0.45, preferably than 0.5, in particular 0.6, and / or of lower than 2.7, preferably than 2.4, more preferably than 2.0, in particular than 1.7.

In a further preferred embodiment, the sum Σ ₃ of Si and Mg and double the Cu content in% by weight is more than 0.5, preferably more than 0.6, also more than 0.7, in particular more than 0 , 8, and / or less than 2.8, preferably less than 2.4, more preferably less than 2.1, in particular less than 1.8.

Precipitations are preferably present in the β ″ phase, in particular at least 10%, preferably at least 20%, in particular at least 40% of the Si, Mg constituents.

In a further preferred embodiment, the cold-extruded component also has a dislocation density in [m ^-2 ] of greater than 10 ^{14 in areas} , preferably 5 · 10 ¹⁴ , in particular 10 ¹⁵ , which can be determined, for example, via TEM recordings and their customary evaluation. These values relate to the finished part (ie to the state after the final heat treatments that are part of the production process).

Forward and backward extrusion are contemplated and combined, including to form wall-like structures. In particular, it is preferred that the cold-extruded component has wall regions formed by backward hollow extrusion and / or backward cup extrusion. In this context, it is also preferably provided that the cold-extruded component has a cup-shaped basic shape.

In a further preferred embodiment, the wall thickness of at least some of the wall areas of the cold-extruded component is less than 8 mm, further less than 5 mm, in particular less than 3 mm, but it is particularly provided that this wall thickness is even greater than 0.5 mm, preferably as 1 mm, in particular as 1.5 mm.

In a further preferred embodiment, the cold-extruded component has a degree of deformation higher than 0.1, preferably higher than 0.4, in particular higher than 1. However, the degree of deformation (in the maximum deformed area) should preferably be less than 10, preferably than 8, especially than 5.

Furthermore, the cold-extruded component is preferably a component produced by mechanical extrusion or hydraulic extrusion with pressing times of less than 20, in particular less than 6 seconds. Furthermore, it is provided that the cold-extruded component is artificially aged, with the increase in dislocation density brought about by the cold-forging process in any case still partially present, preferably at least 20% thereof, preferably at least 30% thereof, in particular at least 40% thereof.

In terms of process engineering, the invention is achieved by a method of producing a component from a hardenable component Aluminum alloy by massive forming of a slug by means of a discontinuous process, namely cold extrusion, in which the cold-extruded component is still subjected to a heat treatment, which is essentially characterized in that the heat treatment begins to act on a structure that can be heat-aged.

In contrast to the conventional extrusion of slugs made of hardenable aluminum alloys, which only creates a structure condition capable of artificial aging through the heat treatment, namely the solution heat treatment, the heat treatment begins when the microstructure is already capable of artificial aging. This is achieved by a further heat treatment of the solution heat treatment (e.g. at 520 to 550 ° C, at which preferably at least 80%, in particular at least 90% of the alloy components Mg, Si go into solution) in addition to a water quenching in particular already takes place before the cold extrusion . It goes without saying that the alloy properties disclosed above are also considered to be preferred for the method according to the invention.

In a preferred embodiment, no stabilization annealing takes place between quenching and cold extrusion, even if there is a period of more than two days, in particular also more than a week or more than two weeks, between quenching and cold extrusion.

In a preferred embodiment, the heat treatment includes artificial aging and in particular consists essentially of artificial aging, in which a reduction in the dislocation density generated during cold extrusion is at least partially counteracted by temperature control that does not exhaust the precipitation hardening potential of the structural state. In this way, it is possible to obtain a portion of the work hardening generated that is lost with artificial aging typically used for such components. The temperature (course) control includes the temperature and duration of artificial aging.

In this context, it is preferably provided that a temperature [in ° C] of the artificial aging of the heat treatment is a threshold temperature in [in ° C] at which the loss of work hardening associated with a reduction in the dislocation density exceeds the gain in strength through precipitation hardening at 8 hours of aging does not exceed 8%, preferably does not exceed 4%, in particular is outsourced below this threshold temperature.

The threshold temperature itself will depend, for example, on the alloy composition of the cold-extruded component and slightly on the degree of deformation of the cold-forging, but can be easily determined experimentally by initially using the strength, in particular the Brinell hardness, as a zero reference in a series of experiments as a function of the aging temperature Component is determined as cold extrusion, and this measurement is repeated after 2 hours of artificial aging at the respective aging temperature. Hardening effects of precipitation hardening occur above the threshold temperature, but the resulting recovery and thus reduction in the dislocation density means a strain hardening loss that overcompensates the gain in precipitation hardening.

In a particularly preferred embodiment of the method it is provided that between the artificial aging time t _w in [h] and the artificial aging temperature T _w in [° C.] the relationship (ℓn t _w ) / [1-α (T _w -T ₀ ) / T ₀ ] ≤ β, with T ₀ = 120 ° C, α = (6ℓn 2.4) / (2 ℓn 2.4 + ℓn 10), β = 2 ℓn 2.4 + ℓn 10, where t _{w is} preferably greater than 2 hours and / or not longer than 24 hours. Furthermore, it is preferably provided that this relationship also applies to α = (6 ℓn 2.5) / (2 ℓn 2.5 + ℓn 8) and β = ℓn 8 + 2 ℓn 2.5, in particular also for α = 6 ℓn (8/3) / 2 ℓn (8/3) + ℓn 6 and β = ℓn 6 + 2 tn (8/3). Furthermore, it can be provided that this relationship also applies to α = 6 ℓn 3.5 / (2 ℓn 3.5 + ℓn 4) and β = tn 4 + 2 ℓn 3.5. In this way, an even more favorable interplay of retained work hardening and still achieved precipitation hardening is obtained.

In a further preferred embodiment of the method it is provided that between the artificial aging time t _w in [h] and the artificial aging temperature T _w in [° C] the relationship δ ≤ (ℓn t _w ) / [1-γ (T _w -T ₀ ) / T ₀ ], with T ₀ = 120 ° C, γ = 6 ℓn (8/3) / (2 ℓn (8/3) + ℓn 1,5), δ = 2 ℓn (8/3) + ℓn 1 , 5, where t _{w is} preferably greater than 2 h and / or not greater than 24 h. It is also provided that this relationship with γ = 6 tn 3 / ℓn 2 + 2 ℓn 3) and δ = ℓn 2 + 2 ℓn 3 applies, and in particular that this relationship with γ = 2.4 and β = 5 ℓn 2 is applicable. This means that counteracting the reduction in work hardening does not reduce the gain in precipitation hardening too much.

In a preferred embodiment, aging takes place at an aging temperature of 156 ° C. or less, in particular 152 ° C. or less. This beneficially delays the healing of dislocations. In a further preferred embodiment, the artificial aging time is even 148 ° C. or less, in particular 144 ° C. or less. This delays the healing of the Dislocations even further and thus retains a greater proportion of work hardening.

In addition, it is preferred that the artificial aging time is less than 24 hours, in particular less than 22 hours. Furthermore, artificial aging times of preferably less than 18 hours, in particular 16 hours, are taken into account. In an embodiment which is also preferred in terms of process organization, the artificial aging time is not greater than 12 hours, in particular not greater than 10 hours.

A method is preferred in which _{the (third) relationship between the sum Σ 3} of magnesium and silicon and twice the copper content of the aluminum alloy in% by weight, the degree of deformation ρ during extrusion and the time Δt between quenching and cold extrusion the following applies: ρ / 3 · [135 + x (1 + 0.25 [1 + tanh (x)] log (1 + Δt))] ≤ K, x = 30 (Σ ₃ -1.5) and K = 110 , the cold extrusion preferably taking place with a mechanical press.

A method is also preferred in which between the sum Σ ₃ of magnesium and silicon and twice the copper content of the aluminum alloy in% by weight, the degree of deformation ρ during extrusion and the time Δt between quenching and cold extrusion the (fourth) The relationship is: ρ / 3 · [135 + x (1 + 0.25 [1 + tanh (x)] log (1 + Δt))] ≤ Kf (τ), x = 30 (Σ ₃ -1.5) and K = 110, where f (τ) = 1 + 0.4 [1 + 2 / π · arctan (τ-5)] and the forming time τ in [s] is preferably less than 20s, more preferably than 6s, in particular than 4s.

In a likewise preferred embodiment, the third and / or fourth relationship (claim 14 or 15) applies cumulatively or alternatively also with Σ ₂ (= Mg + Si content in% by weight) instead of Σ ₃ .

In addition, it is preferred that the component created with the method has the properties described in claims 1 to 10 and / or the above with reference to the component.

• 1 ein beispielhaftes fließgepresstes Bauteil zeigt,
• 2 eine schematische Darstellung der Prozessschritte des erfindungsgemäßen Kaltfließpressens zeigt,
• 3a mechanische Eigenschaften eines fließgepressten Bauteils zu verschiedenen Auslagerungszeiten zeigt,
• 3b mechanische Eigenschaften eines fließgepressten Bauteils zu verschiedenen Legierungszusammensetzungen zeigt und
• 4a), b) und c) TEM-Aufnahmen mit Versetzungen und Ausscheidungen zeigen.

Further features, details and advantages of the invention emerge from the following description with reference to the accompanying figures, of which

• 1 shows an exemplary extruded component,
• 2 shows a schematic representation of the process steps of cold extrusion according to the invention,
• 3a shows mechanical properties of an extruded component at different aging times,
• 3b shows mechanical properties of an extruded component for different alloy compositions and
• 4a), b ) and c) show TEM images with dislocations and precipitations.

1 shows an embodiment of a cold-extruded component 100 that is a floor area 10 and a surrounding wall area 20th having. The component is produced by backward cup extrusion (pressing axis X), but the invention is not restricted either by this cup shape or by this specific subtype of cold extrusion.

In the specific example, the component was cold-extruded using a toggle press. However, the invention is not limited to this method, mechanical presses being preferred over hydraulic extrusion presses.

However, hydraulic presses with, in particular, a high number of items per minute are also suitable. Even then, the forming time of cold extrusion is preferably not more than 10,000 ms, more preferably not more than 3000 ms.

The wall thickness of the wall areas 2 is 2.5 mm in this embodiment, however, in this regard, the invention is not limited to these wall thicknesses, but can also have different wall thicknesses in the case of relatively small wall thicknesses relative to the transverse dimension, in particular in the range specified above.

The degree of deformation ρ of the cold extrusion in the present exemplary embodiment is 2 here, but the invention is not limited to precisely these values of degrees of deformation, the ranges given above for degrees of deformation being preferred.

The material of the component 100 is an aluminum alloy with, in this first exemplary embodiment, components of Si = 0.47, Mg = 0.38, Fe = 0.22, Cu = 0.01, Mn = 0.05, these figures in% by weight , with residual aluminum apart from unavoidable impurities of individually less than 0.05% by weight and less than 0.15% by weight in total.

However, this alloy composition is only exemplary and not restrictive; preferred values for individual components of the alloy are given above.

The component has a Brinell hardness value of 93.9 HB. The maximum corrosion penetration depth according to IGC PV1113 (Volkswagen) is 40 µm.

Tensile strength measurements showed, for example, 300 MPa for example 1 and 280 MPa for example 4.

Further exemplary embodiments have the same alloy composition as the first example given above, and essentially the same corrosion penetration depth of the above example, but have different Brinell hardness values, namely 92.4 HB (example 2), 90.6 HB (example 3), 89.9 HB (Example 4), 89.4 HB (Example 5), 88.3 HB (Example 6), 88.2 HB (Example 7), 86.4 HB (Example 8), 84.4 HB ( Example 9) and 81.3 HB (Example 10).

An alloy according to the first exemplary embodiment is used as a first comparative example, extruded from the soft-annealed state and thereby work-hardened to 57 HB. A pressed part with a hardness value of 76 HB based on precipitation hardening serves as the second comparative example, with the same alloy composition as in Examples 1 to 10 and at this corrosion penetration depth.

In a further exemplary embodiment, the sum of the magnesium and silicon content is increased to 1.3% by weight compared to the first exemplary embodiment, the other alloy components are unchanged. In this example 11, the maximum corrosion penetration depth is 60 µm, and the hardness 120 HB.

In a further exemplary embodiment (example 12) the alloy composition is as in example 11, and also the maximum corrosion penetration depth as in example 11, the hardness value is 115 HB. In yet another exemplary embodiment (example 13), the alloy composition and the maximum corrosion penetration depth are the same as in example 11, the hardness value is 110 HB.

In further exemplary embodiments 14th , 15th and 16 the sum of magnesium and silicon content was increased to 1.8% by weight with the alloy composition otherwise being the same as in the other examples. The hardness values of these working examples were 135 HB (example 14), 130 HB (example 15) and 125 HB (example 16), with a respective maximum corrosion penetration depth of 150 μm. The degree of deformation in these exemplary embodiments 14th , 15th and 16 is 1.6.

In yet further exemplary embodiments, the total Mg + Si content was increased again to 2.3% by weight, with a degree of deformation of 1.2 and other alloy components that remained the same. Here the maximum corrosion penetration depth is 200 μm, the hardness values being 140 HB (Example 17), or 135 HB (Example 18) and 130 HB (Example 19).

With a reduced Mg + Si content to the sum of 0.5% by weight according to further examples, the corrosion penetration depth is 30 µm, and the hardness values are 87 HB (example 20), 86 HB (example 21) and 85 HB (example 22) . For examples 1, 2, 4 and 11 to 22 see also 3b .

From the TEM images of 4th ( 4b is a detailed representation of 4a top left and 4c a further, considerably enlarged representation) clearly shows that in the examples both considerable dislocations (clearly visible in 4a , 4b) as well as considerable excretions (clearly recognizable in 4c ) are present that have formed along dislocation lines.

The following is with reference to 2 a production method is described with which cold-extruded components of the above embodiments were produced.

In a first step S1 slugs made of an aluminum alloy with, for example, the above-mentioned compositions are provided, preferably made of wrought alloys, and brought into the form of a slug (blank) by a cutting process that is well known to the person skilled in the art.

In one step S2 the slugs are solution annealed in a furnace and then quenched. In the present exemplary embodiment, a solution annealing temperature of 535 ° C. is maintained for 40 minutes, and (water) quenched at a quenching rate in the range between 20 and 100 K / s to a temperature of approx. 50 ° C. or lower. However, these detailed values are only to be understood as exemplary and do not restrict the invention; rather, values from ranges customary in the art for solution annealing and quenching can be used for the invention.

In the present example, the holding temperature of the solution annealing is selected so high that the Mg + Si components completely dissolve, as already explained above, this is also not absolutely necessary, the lower values given above can also dissolve without this changes something in the basic principle of the invention.

According to the invention, this heat treatment is in contrast to the soft annealing which is usually carried out before cold extrusion. The slugs are preferably not increased in temperature after quenching and before forming exposed above 80 ° C, preferably 60 ° C, in particular 35 ° C.

In one step S3 Preparatory measures for cold extrusion are carried out, such as cleaning processes known to the person skilled in the art (if desired) and the application of a lubricant, for example in the in DE 10 2017 001 384 A1 described way.

The procedural step S4 includes the massive forming of cold extrusion itself. In the specific embodiment, a degree of deformation of 2 was used for the areas of greatest deformation, as already mentioned above, but it goes without saying that the degree of deformation depends on the desired component end geometry and therefore also in some process variants may appear as a predetermined size.

Between the steps S2 and S4 Time may well pass, in the present exemplary embodiment this was 2 weeks. Periods of this order of magnitude allow intermediate storage and give time leeway in the processing chain. In principle, however, it is also conceivable to design a process chain with shorter intermediate times, for example when the overall process is in a plant S1 until S4 is set up in a continuous process chain.

After the step S2 the slug is in an unstable state, as it is susceptible to cold aging. In a preferred embodiment like the present one, this state is consciously accepted, since a stabilization treatment avoiding cold aging occurs in the form of stabilization annealing in the method step S4 would have a more negative impact. The 2 week period between procedural steps S2 and S4 is also only to be understood as an exemplary embodiment and not as a mandatory restriction, rather other times are conceivable and preferably the times indicated above and / or the relationship indicated above between aluminum alloy, the degree of deformation and this intermediate time Δt.

Cold extrusion in step S4 takes place, in accordance with a particularly preferred embodiment, in this embodiment at room temperature. It goes without saying, however, that the slugs could, if necessary, also be heated to a temperature Ti of preferably not more than 100.degree. C., particularly in the case of comparatively high degrees of deformation. In this case, it should preferably be ensured that, due to the heated slugs, the temperature rise generated during forming does not lead to excessive temperatures (of e.g. 170 ° C or higher) in the material, for example by observing the relationships of claim 14 or 15 with a reduction in the Parameter value for K by the factor (170-Ti [° C]) / 170.

In a further process step S5 the cold-extruded components are subjected to a heat treatment by artificially aging them. The heat treatment can, but does not have to, immediately follow the process step S4 take place, as a temperature increase associated with the extrusion process produces an effect comparable to that of stabilization annealing and thus avoids the risk of reducing the positive effect of artificial aging through previous cold aging. This time interval could easily be on the order of weeks, or less.

• Im ersten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 140°C bei einer Auslagerungszeit von 14 Stunden. Im zweiten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 150°C bei einer Auslagerungszeit von 9 Stunden. Im dritten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 140°C bei einer Auslagerungszeit von 24 Stunden. Im vierten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 160°C bei einer Auslagerungszeit von 4 Stunden. Im fünften Ausführungsbeispiel betrug die Warmauslagerungstemperatur 150°C bei einer Auslagerungszeit von 14 Stunden. Im sechsten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 160°C bei einer Auslagerungszeit von 9 Stunden. Im siebten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 140°C bei einer Auslagerungszeit von 9 Stunden. Im achten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 150°C bei einer Auslagerungszeit von 4 Stunden. Im neunten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 160°C bei einer Auslagerungszeit von 14 Stunden. Im zehnten Ausführungsbeispiel betrug die Warmauslagerungstemperatur 140°C bei einer Auslagerungszeit von 4 Stunden.

For the above exemplary embodiments (see 3a) the following parameters of artificial aging are observed:

• In the first exemplary embodiment, the artificial aging temperature was 140 ° C. with an aging time of 14 hours. In the second exemplary embodiment, the artificial aging temperature was 150 ° C. with an aging time of 9 hours. In the third exemplary embodiment, the artificial aging temperature was 140 ° C. with an aging time of 24 hours. In the fourth exemplary embodiment, the artificial aging temperature was 160 ° C. with an aging time of 4 hours. In the fifth exemplary embodiment, the artificial aging temperature was 150 ° C. with an aging time of 14 hours. In the sixth exemplary embodiment, the artificial aging temperature was 160 ° C. with an aging time of 9 hours. In the seventh embodiment, the artificial aging temperature was 140 ° C. with an aging time of 9 hours. In the eighth exemplary embodiment, the artificial aging temperature was 150 ° C. with an aging time of 4 hours. In the ninth embodiment, the artificial aging temperature was 160 ° C. with an aging time of 14 hours. In the tenth exemplary embodiment, the artificial aging temperature was 140 ° C. with an aging time of 4 hours.

In the second comparative example of the soft-annealed cold-extruded slug, after subsequent solution heat treatment and quenching, the compact was artificially aged at 170 ° C. customary in the industry for 8 hours; in the first comparative example, such a heat treatment was no longer carried out

in the 11 . Embodiment were the conditions of artificial aging as in the first embodiment, as well as those of the 14th, 17th and 20th embodiment.

in the 12th . In the exemplary embodiment, the artificial aging conditions were as in the second exemplary embodiment, and also in the 15th, 18th and 21st exemplary embodiments as in the second exemplary embodiment.

in the 13th . The exemplary embodiment were the conditions of artificial aging as in the fourth exemplary embodiment, also in the 16th, 19th and 22nd exemplary embodiments.

The hardness values given above for this are on the one hand higher than without heat treatment, and also in the range of or even higher than in conventional processes in which an optimized precipitation hardening is achieved, but no more work hardening contributions are present.

The invention is not limited to the specifications described in the above examples. Rather, the features of the above description and the following claims can be essential individually and in combination for the implementation of the invention in its various embodiments.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102017001384 A1 [0002, 0078]
• WO 2017/093304 [0003]
• WO 2018/080710 A1 [0004]
• CN 109628860 [0006]
• EP 3214191 A1 [0007]
• US 5507888 A [0008]
• EP 0676480 A1 [0015]

Non-patent literature cited

• L. Marzoli et al. Light Metals 2017 [0005]
• Trans. Nonferrous Met. Soc. China 22 (2012) 2072-2079 [0010]
• Similar to this article, Materials Science Forum Vols. 794-796 (2014), pp. 605-610 [0011]
• E. Nes in Acta metall. mater. Vol. 43, No. 6, pp. 2189-2207, 1995 [0011]
• In Material Science and Engineering A 759 (2019) 520-529 [0012]
• This β ″ phase and the so-called GPI and GPII zones as strength-generating are also described in Materials Characterization 49 (2003) 193-202 [0013]

Claims (15)

Cold-extruded component made from a hardenable aluminum alloy, characterized by a first relationship between the Brinell hardness based on work hardening and precipitation hardening components [HB] and corrosion penetration depth KE in [µm] of g (HB, KE) ≥ L with $$\text{G}\left(\text{HB}\text{, KE}\right)=\left(\text{HB}-\mathrm{4th}\right)\text{/}\left[1+\mathcal{l}\text{n}\left(\left(\mathrm{20th}+\text{KE}\right)\text{/}\mathrm{20th}\right)\right],\text{and L}=\mathrm{30th}$$

and / or a second relationship between this Brinell hardness and the sum Σ ₃ of magnesium, silicon and double the copper content of the aluminum alloy in percent by weight of $$\text{HB}-\left({\mathrm{\Delta }}_1+{\mathrm{\Delta }}_2\right)\text{/ 2}\ge \text{tanh}\left(z\right)\cdot \left({\Delta }_1+{\Delta }_2\right)\text{/ 2}$$

with $${\mathrm{\Delta }}_1={\text{K}}_{\text{0}}+{\text{K}}_1\mathcal{l}\text{n}\left[1+2.3\text{|}{\displaystyle {\sum }_3-0.9\text{|}}\right]$$

$${\mathrm{\Delta }}_2={\text{K}}_{\text{2}}+\left({\displaystyle {\sum }_3-0.45}\right)\cdot \left({\text{K}}_{\text{0}}-{\text{K}}_{\text{2}}\right)\text{/}0.45$$

$$\text{z}=\mathrm{30th}\left({\displaystyle {\sum }_3-0.9}\right)$$

and K ₀ = 60, K ₁ = 25 and K ₂ = 46 Cold-extruded component after Claim 1 , with a sum Σ ₂ of magnesium and silicon content less than 2.7, preferably less than 2.4, in particular less than 1.7 and / or greater than 0.45, preferably greater than 0.5, in particular greater than 0 , 6. Cold-extruded component after Claim 1 or 2 , with an Fe content of less than 0.8, in particular less than 0.5, an Mn content of less than 1.1, in particular less than 0.3 and / or a Cu content of less than 1.3, in each case in percent by weight , in particular less than 0.4. Cold-extruded component according to one of the preceding claims, with an aluminum content of the aluminum alloy of greater than 94% by weight, preferably greater than 96% by weight, in particular greater than 98% by weight. Cold-extruded component according to one of the preceding claims, with a degree of deformation of greater than 0.1, preferably greater than 0.4, in particular greater than 1. Cold-extruded component according to one of the preceding claims, with a wall structure which has areas with wall thicknesses thinner than 8 mm, preferably thinner than 5 mm, in particular thinner than 3 mm. Cold-extruded component according to one of the preceding claims, with an elongation at break (A 5,65) of greater than 4%, preferably greater than 6%, in particular greater than 8%. Cold-extruded component after Claim 1 , with Σ ₃ less than 2.8, preferably less than 2.1, in particular less than 1.8 and / or higher than 0.5, preferably higher than 0.8, in particular higher than 0.7. Cold-extruded component with a tensile strength in [MPa] of greater than 200, preferably greater than 220, in particular greater than 240. Method of manufacturing a component from a hardenable aluminum alloy by massive forming of a slug by means of cold extrusion, in which the cold extrusion component is subjected to a heat treatment, characterized in that the heat treatment begins to act on a structure that can be heat-aged. Procedure according to Claim 10 , in which the heat treatment includes artificial aging, in which a reduction in the dislocation density generated during cold extrusion is at least partially counteracted by a temperature control that does not exhaust the precipitation hardening potential of the structural state. Procedure according to Claim 10 or 11 , where between the artificial aging time t _w in [h] and the artificial aging temperature T _w in [° C] the relationship $$\left(\mathcal{l}\text{n tw}\right)\text{/}\left[1-\mathrm{\alpha }\left({\text{T}}_{\text{w}}-{\text{T}}_{\text{0}}\right)/{\text{T}}_{\text{0}}\right]\le \mathrm{\beta }$$

consists, with T ₀ = 120 ° C, α = (6 ℓn 2.4) / (2 ℓn 2.4 + ℓn 10), β = 2 ℓn 2.4 + ℓn 10, where t _{w is} preferably greater than 2 h and / or is not longer than 24 hours. Method according to one of the Claims 10 until 12th , where between the artificial aging time t _w in [h] and the artificial aging temperature T _w in [° C] the relationship $$\delta \le \left(\mathcal{l}{\text{n t}}_{\text{w}}\right)\text{/}\left[1-\gamma \left({\text{Tw-T}}_{\text{0}}\right){\text{/ T}}_0\right]$$

exists, with T ₀ = 120 ° C, γ = 6 ℓn (8/3) / (2 ℓn (8/3) + ℓn 1.5), δ = 2 ℓn (8/3) + ℓn 1.5, where t _{w is} preferably greater than 2 hours and / or not greater than 24 hours. Method according to one of the Claims 10 until 13th , in which between the sum Σ ₃ of magnesium and silicon and double copper content of the aluminum alloy in% by weight, the degree of deformation ρ during extrusion and the time Δt in [min] between quenching and cold extrusion, the relationship applies $$\mathrm{\rho \; /}3\left[135+\text{x}\left(1+0.25\left[1+\text{tanh}\left(\text{x}\right)\right]\text{log}\left(1+\mathrm{\Delta }\text{t}\right)\right)\right]\le \text{K}$$

with x = 30 (Σ ₃ -1.5) and K = 110, the cold extrusion preferably being carried out with a mechanical press. Method according to one of the Claims 10 until 13th , in which the relationship applies between the sum Σ ₃ of magnesium and silicon and double the copper content of the aluminum alloy in% by weight, the degree of deformation ρ during extrusion and the time Δt in [min] between quenching and cold extrusion $$\mathrm{\rho \; /}3\left[135+\text{x}\left(1+0.25\left[1+\text{tanh}\left(\text{x}\right)\right]\text{log}\left(1+\mathrm{\Delta }\text{t}\right)\right)\right]\le \text{Kf}\left(\mathrm{\tau }\right)$$

with x = 30 (Σ ₃ -1.5) and K = 110, where f (τ) = 1 + 0.4 [1 + 2 / π · arctan (τ-5)] and the forming time τ in [s] is preferably less than 20s, more preferably than 6s, in particular than 4s.

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