EP1165848B1 - USE OF AN ALUMINUM ALLOY OF THE AlMgSi TYPE AS SAFETY PART IN VEHICLES - Google Patents

Abstract

An alloy of the AlMgSi type which is suited for producing structural components which are highly capable of absorbing kinetic energy by means of plastic deformation contains silicon provided in a wt. % ranging from 0.45 to 0.85, magnesium in a wt. % ranging from 0.35 to 1.0, copper in a wt. % ranging from 0.05 to 0.30, iron in a wt. % ranging from 0.05 to 0.25, vanadium in a maximum wt. % of 0.25, manganese in a maximum wt. % of 0.10, as well as impurities which result during production in a maximum wt. % of 0.05 individually and 0.15 in total, and aluminum as the remainder wt. %. The structural component is manufactured from a rolled strip or sheet of the alloy. Components made of this alloy are suited as safety parts used in the construction of vehicles. The alloy is also suited for producing vehicle body parts which comprise a high degree of flexibility without the occurrence of cracking and orange peel effects, in particular, for producing two-sheet structures such as an engine hood, door, and trunk lid of a passenger car. These structural components and vehicle body parts can be easily recycled together.

Description

The invention relates to the use of an aluminum alloy of the type AlMgSi.

Crash behavior is an increasingly important aspect in vehicle construction; this applies to road traffic as well as to rail traffic. Manufacturer of road and rail vehicles are moving more and more, special ones Dimension components or even entire assemblies of the vehicle so that they absorb as much energy as possible in a collision, to reduce the risk of injury to passengers. Next The structural design of these so-called crash elements are the mechanical ones Properties of the materials and joining zones used by of crucial importance. The aim is the greatest possible absorption of energy before breaking. This can be due to a low ratio from yield strength to strength. An important material characteristic is also a high stretch. The requirements for are also to be observed the finished component. In terms of construction, for example, a certain one Strength level, certain minimum values of elongation, corrosion resistance or other essential parameters are specified.

The growing importance of manufacturing lighter automobiles to save energy has developed a large number of aluminum alloys led for automotive applications. A single aluminum alloy would be ideal that could be used for various parts in automotive engineering. Especially with regard to the recycling of scrap or the recyclability of so-called space frame structures in automotive engineering, it would be desirable the frame parts manufactured today from extruded profiles, the Body panels as well as the structural components from one and the same To be able to manufacture alloy. Different components in one automobile however, often require different properties. For example an aluminum alloy should be very easy to form for exterior sheet metal applications to allow stretching, deep drawing and bending at the same time but achieve high strength after baking the paint. in particular Sheets for the production of two-sheet structures such as bonnets, Doors and trunk lids should have a high flexibility without cracking and Orange peel formation, as these components are often flared get connected.

EP-A-0805219 discloses a structural component made of an AlMgSi alloy for use in vehicle construction. The structural component is made in a conventional manner manufactured by extrusion.

EP-A-0 801 139 discloses one for the production of im Components from a hollow body used in vehicle construction by means of AlMgSi alloy suitable for internal high pressure forming.

The alloy disclosed by document EP-A-0 801 139 contains in% by weight: 0.3-1.6 Si; 0.3-1.3 mg; ≤0.9 Cu; ≤0.5 Fe; 0.05-0.3 V; ≤0.5 Mn; ≤0.3 Co; ≤0.3 Cr; ≤0.8 Ni; ≤0.3 Zr; as well as further alloy elements individually max. 0.05, max. 0.15 and Al as Rest.

Document EP-A-0 808 911 discloses a component and a safety part in US Pat Vehicle construction from an alloy in% by weight: 0.3-1.6 Si; 0.3-1.3 mg; ≤0.9 Cu; ≤0,5 Fe; 0.05-0.3 V; ≤0.5 Mn; ≤0.3 Co; ≤0.3 Cr; ≤0.8 Ni; ≤0.3 Zr; as well as others Alloy elements individually max. 0.05, max. 0.15 and Al as the rest.

Document EP-A-0 714 993 A discloses rolled sheets made of an alloy suitable for the production of deep-drawn automobile body parts, which in% by weight contain the alloy elements Mg and Si by means of the trapezoid ABCDE with the coordinates: Si mg A 0.50 0.35 B 0.50 0.60 C 0.95 0.60 D 0.95 0.40 e 0.80 0.35 and 0.05-0.4 Cu; ≤0.25 Fe; ≤0.15 Mn; 0.05-0.2 V as an optional element; as well as further alloy elements individually max. 0.05, max. 0.15 and Al as the rest.

Document EP-A-0 811 700 discloses rolled sheets made of an alloy suitable for the production of deep-drawn automobile body parts, which in% by weight contain the alloy elements Mg and Si by means of the trapezoid ABCDE with the coordinates: Si mg A 0.50 0.35 B 0.50 0.60 C 0.95 0.60 D 0.95 0.40 e 0.80 0.35 and 0.15-0.45 Cu; 0.25-0.55 Fe; 0.05-0.20 Mn; 0.05-0.50 Zn; 0.05-0.2 V as an optional element; as well as further alloy elements individually max. 0.10, total max. 0.30 and Al as the rest.

The document US-A-4 525 326 discloses rolled sheets of an alloy which are described in US Pat % By weight: 0.3-1.2 Si; 0.3-1.0 mg; ≤0.4 Cu; 0.1-0.5 Fe; 0.05-0.2 V; 1 / 2Fe to 2 / 3Fe Mn; and Al as the rest. In particular, document US-A-4 525 326 discloses one Alloy in% by weight: 0.60 Si; 0.55 mg; 0.17 Cu; 0.21 Fe; 0.10 V; 0.06 Mn; and Al as the rest.

The invention has for its object a structural component to create which with extruded structural components achieved requirements with regard to crash behavior. In addition, the Alloy used for structural components also for the production of body parts can be used.

Use according to the invention has the features of claim 1.

The structural component has a formed from sheet metal and part connected to a tubular part or hollow body. The tubular part is preferably rectangular in cross section, but can in principle have any cross-sectional shape. The tubular part is further expanded by hydroforming reshaped.

The connection of the sheet to a tubular part can be done by any Connection type, for example by welding, gluing rivets or screwing.

The alloy used for the structural component can also be used for production of body parts, in particular in the form of a two-sheet structure such as a bonnet, Door and trunk lid of a passenger car are used, what is the scrap recycling or recyclability of structural components and body panels significantly simplified.

The structural component is used as a safety part in vehicle construction, especially in the automotive sector.

The alloy can be processed in the usual way by continuous casting or strip casting, hot and / or cold rolling to form sheet metal or strip. To achieve optimum properties with regard to crash and bending behavior, it has proven to be particularly advantageous if solution annealing is carried out in a continuous belt furnace in a temperature range from 520 ° C. to 580 ° C. with subsequent quenching. Quenching can be carried out in the usual way, usually with water or with air, depending on the sheet thickness. When solution annealing, care must be taken to ensure that all soluble constituents such as Si and Mg ₂ Si pass into solid solutions and are in the supersaturated state after cooling. The cooling rate can have a significant effect on the mechanical properties, because Si and Mg ₂ Si precipitate at the grain boundaries if the cooling rate is too slow and thus significantly deteriorate the crash and bending behavior. In addition, the hardenability and the corrosion behavior are impaired.

The structural components and body parts are preferred in the heat-cured state, especially in the heat treatment state T6, used. This state of heat treatment can affect body parts generated during a paint baking cycle.

Those for the production of structural components and body parts The strips or sheets used are preferably in a thickness range from 0.8 to 4 mm.

The strips and sheets can also be chemically treated before they are finished or pretreated electrochemically and / or with a dry lubricant coating be provided.

Other advantages, features and details of the manufacture of the Structural components and body parts used alloy sheets emerge from the description below more preferred Embodiments.

example 1

An alloy of the composition (% by weight)
0.59 Si
0.55 mg
0.15 Fe
0.07 Cu
0.10 V
0.08 mn
and a standard alloy AA 6016 used for automotive applications as a comparative alloy was processed in the usual way by continuous casting, hot and cold rolling to a sheet with a thickness of 1.5 mm. The solution was annealed at 540 ° C with subsequent quenching in water. Status R _m MPa R _p0.2 MPa A ₁₀ % n _5% r f = r _i / t crashworthiness invention T4 222 113 25.8 00:30 00:57 <0.1 3 invention T6 263 229 11.5 - - 00:25 3 AA 6016 T4 254 138 28.5 00:29 00:59 00:30 3 AA 6016 T6 295 258 14.2 - - 0.60 1

The results of Table 1 clearly show the better crash behavior of the alloy according to the invention in comparison to the standard alloy AA 6016, especially when thermoset.

Example 2

An alloy of the composition (% by weight)
0.60 Si
0.53 mg
0.20 Fe
0.14 Cu
0.15 V
0.07 mn
and a standard alloy AA 6016 used for automotive applications as a comparative alloy were processed in the usual way by continuous casting, hot and cold rolling to a sheet with a thickness of 1.5 mm. Solution annealing was carried out at 560 ° C. with subsequent quenching in water. Status R _m MPa R _p0.2 MPa A ₁₀ % n _5% r f = r _i / t crashworthiness invention T4 212 112 26.4 00:28 00:52 00:15 3 invention T6 243 199 13.8 - - 00:25 3 AA 6016 T4 232 124 27.6 00:29 0.61 00:40 2 AA 6016 T6 283 211 17.9 - - 0.65 1

The results clearly show the better crash behavior of the inventive Alloy compared to the standard alloy AA 6016, in particular in the hardened state.

Example 3

An alloy of the composition (% by weight)
0.57 Si
0.53 mg
0.18 Fe
0.07 Cu
0.006 V
0.07 mn
and a standard alloy AA 6016 used for automotive applications as a comparison alloy was processed in the usual way by continuous casting, hot and cold rolling to a sheet with a thickness of 2.0 mm. Solution annealing was carried out at 560 ° C. with subsequent quenching in water. Status R _m MPa R _p0.2 MPa A ₁₀ % n _5% r f = r _i / t crashworthiness invention T4 191 120 24.4 00:22 00:50 00:10 3 invention T6 257 226 11.5 - - 00:30 3 AA 6016 T4 215 131 24.8 00:24 00:58 00:40 2 AA 6016 T6 297 223 12.8 - - 0.70 1

The results of Table 3 clearly show the better crash behavior of the alloy according to the invention in comparison to the standard alloy AA 6016, especially when thermoset.

T4

Wärmebehandlungszustand Lösungsglühen, Abschrecken

T6

Wärmebehandlungszustand Lösungsglühen, Abschrecken, Warmauslagerung 210°C/30 min (T6 kann auch während eines Lackeinbrennzyklus erreicht werden)

R_m

Zugfestigkeit

R_p0.2

Streckgrenze

A₁₀

Dehnung

n_5%

Verfestigungsexponent n bei 5% Dehnung

r

r-Wert = mittlere senkrechte Anisotropie

f = n / t

Biegefaktor (r_i minimaler Innenradius, t Blechdicke)

In the preceding examples 1 to 3 mean

T4

Heat treatment condition solution annealing, quenching

T6

Heat treatment condition solution annealing, quenching, heat aging 210 ° C / 30 min (T6 can also be achieved during a paint baking cycle)

R _m

tensile strenght

R _p0.2

Stretch limit

A ₁₀

strain

n _5%

Solidification exponent n at 5% elongation

r

r-value = mean vertical anisotropy

f = n / t

Bending factor (r _i minimum inner radius, t sheet thickness)

The crash behavior was determined in a quasi-static compression test with notes rated from 1 to 3, with 3 being the top grade. The quasi-static compression test is used to assess energy-absorbing components. The wished Behavior is characterized by regular folding without Cracking. The appearance of the compressed samples was compared with the Notes 3 (no cracking, even folding), 2 (roughened, slightly torn), and 1 (crack formation).

Claims (3)

1. Use of an aluminium alloy of the AlMgSi type having the composition (in % by weight) silicon 0.50 to 0.60 magnesium 0.40 to 0.65 copper 0.05 to 0.20 iron 0.05 to 0.20 vanadium max. 0.20 manganese max. 0.10 as well as impurities due to production individually to a maximum of 0.05 and altogether to a maximum of 0.15, with the remainder aluminium, for a component formed from rolled sheet or strip, joined to a tubular part or hollow body and formed further by internal high-pressure forming used as a safety component in vehicle construction.
2. Use according to claim 1, characterised in that the strip or sheet is produced by continuous casting or strip casting, hot and/or cold rolling and solution annealing in a belt kiln at a temperature within the range of 520°C to 580°C with subsequent quenching.
3. Use according to claim 1 or claim 2 in the artificially aged state, in particular in the heat-treatment state T6.