EP1183402B1 - Method for producing a magnesium alloy by extrusion moulding and use of the extrusion moulded semifinished products and components - Google Patents

Abstract

Production of a magnesium alloy of high ductility comprises extruding the alloy with a deforming degree of at least 1.5. The alloy contains traces of less than 1.8 wt.% Cd, up to 0.1 wt.% Cu, up to 0.005 wt.% Ni and 0.5-20 wt.% Li, and at least 0.1 wt.% of further chemical elements. After extruding, the alloy has a breaking elongation of at least 20%, a compression strength of at least 300 MPa and an energy absorbed in fracturing of at least 70 J.

Description

The invention relates to a method for producing a magnesium alloy high Ductility etc. through extrusion and the use of extruded semi-finished products or components.

Because of their very low density, magnesium alloys are approximately in the range from 1.2 to 1.9 g / cm ³ , occasionally, especially in the case of particularly lithium-rich magnesium alloys, down to approximately 0.9 g / cm ³ as metallic construction materials of particular interest for vehicle and aircraft construction. In the future, they will be used more and more for the lightweight construction of motor vehicles and airplanes, in order to be able to compensate for the weight of additional elements due to increasing comfort and safety standards, especially in new low-emission automobiles. They are also of interest for transportable devices or systems that are particularly light-weight for other reasons. The lightweight construction enables the construction of energy-saving vehicles and planes, such as the 3-seater motor vehicle, to a particular extent. Among the manufacturing processes, die-casting and shaping, extrusion, forging, rolling and possibly subsequent forming such as stretching or deep-drawing will become increasingly important in the future, since lightweight construction components such as seats and windows can be produced using these processes - and door frames, elements of vehicle cells and vehicle outer skins, housings, floor elements, covers, tank elements, tank flaps, brackets, supports, brackets, angles, crash elements, impact absorbers, impact shields and impact carriers, small parts or corresponding components for aircraft, for which there is an increasing demand ,

The cold formability of the commercially available magnesium alloys is due to the hexagonal crystal structure and the associated low ductility limited. Polycrystalline magnesium and most magnesium alloys behave becomes brittle at room temperature. For a number of applications or for certain Manufacturing process of semi-finished products from magnesium alloys is in addition to good ones mechanical properties such as high tensile strength require ductile behavior. On improved forming, energy absorption and deformation behavior requires a higher one Ductility and possibly also higher strength and toughness. For this are To develop magnesium alloys with these properties or their To further develop manufacturing processes because many material variants match the manufacturing condition have widely varying material properties.

Ductility is the ability of a material to undergo a permanent change in shape, which, in the uniaxial state according to the stress-strain diagram, is ideally without any elastic component. This property is limited by the occurrence of the break. In general, the permanent elongation achieved in the tensile test up to fracture is considered ductility. The degree of ductility can also be seen as the constriction of fracture, impact work and notched impact work, each with a slightly different statement. These properties can be determined in accordance with EN 10 002, Part 1, or in accordance with DIN 50115 and 50116. The elongation at break A = A _plast characterizes the change in shape with its plastic part under a largely uniaxial load; in addition, according to the stress-strain diagram, the elastic part of the strain A _elast and the sum of the elastic and plastic part D = ΣA = A _elast + A _plast can be determined. A highly plastic material is called ductile.

When specifying the elongation at break and the tensile strength to different Magnesium alloys make it clear that the elongation at break is often all the higher can take if only medium high tensile strength values are achieved and that conversely, only medium-high values of elongation at break with high values of tensile strength be achieved. Very high values of tensile strength can only be achieved by comparison reach low elongation at break values.

The elasticity denotes the elastic part of the stress-strain diagram according to Hook's law, where with ideal linear-elastic relationships no permanent change in shape occurs.

Furthermore, the yield point ratio V can be specified as the ratio of the yield stress F = R _P02 to the tensile stress Z = R _m . This results in two values that characterize the elasticity, two the plasticity and two their relationship to one another for the largely uniaxial load. The ratio of the elastic to the plastic part of the stretch gives the best approximation to reality.

The impact work is above all a measure of the energy consumption of a semi-finished product and for plastic behavior, i.e. for deformability and rate of deformation. A high impact work is therefore essential for the use of deformation elements such as Crash elements, impact absorbers, impact shields and impact carriers. The stroke work measured on notched samples - is, among other things due to higher absolute values for Magnesium alloys are more meaningful than the impact energy and affects one largely uniaxial load. The impact work, which is always on notched samples is determined also indicates the susceptibility of a material to triaxial failure Burden. Their informative value is particularly low if the execution of the Notch significantly affects the values of the impact energy. The blow job and the Impact energy is measured under dynamic load and can be an indication give up on energy absorption and deformability. Tensile and compression tests are carried out in the Comparison to this under quasi-static loads. A conclusion from uniaxial on Multi-axis properties or relationships are only partially possible.

The values listed below measured on samples in a particular The state of manufacture therefore reflects the current material properties. she provide an indication of the forming behavior that previously occurred during the forming process was. In this state it is a conclusion about the characteristics and behavior of a person Semi-finished product or even a component with this semi-finished product, which may be further refined later use possible. Furthermore, there is a conclusion about the material properties formed alloys possible, e.g. by bending, pressing, pressure rolling, Stretch drawing, deep drawing, hydroforming or roll forming processed semi-finished products are to be shaped. Because the change in Material properties from cast to extruded condition similar to that Change in material properties from cast to forged, rolled or a similar reshaped state is therefore also an inference to one other forming condition possible.

For the use of lightweight components, the elastic is usually used Properties (rigidity) lifted, unless it is e.g. in the event of an accident Deformation properties and thus on the energy absorption of the element and on the plastic behavior arrives. Therefore, regarding the multiple forming especially the plastic ones and for the use the plastic ones and / or elastic ones Properties matter. These properties are typically for use on the respective ambient temperature, in extreme cases in the range from -40 ° C to +90 ° C individual points in the vehicle or plane, however, to the locally lower or higher Turn off temperatures. However, the load state is usually multi-axis. The Conclusion from uniaxial to multiaxial load conditions is all the more possible, ever more of an isotropic structure.

For the manufacture of such automotive elements, the manufacture is particularly suitable by die casting or extrusion, forging and / or rolling. requirement for the use of semi-finished products made of magnesium alloys or of or from them Components manufactured in automobiles can meet certain property profiles depending after application such as for deformation elements, seat and door frames one Tensile strength of the light material of at least 100 MPa, preferably at least 130 MPa, together with an elongation at break measured at room temperature of at least 10%, preferably at least 15%. The higher the tensile strength, Elongation at break and other properties due to high ductility and energy absorption point out, the more suitable these semi-finished products or components are generally for the Commitment. Furthermore, higher strength values and higher ductility are also one Relief and partly also a prerequisite for the forming of cast blanks or for the further forming of already formed blanks or semi-finished products. The higher these properties are in the cast state, the higher these are usually even in the deformed state. A higher ductility can the forming or the renewed Forming, especially extrusion, easier. Therefore an elongation at break of at least 10% also for the subsequent manufacturing steps to form elements Magnesium alloys helpful. Therefore, a tensile strength of at least 150 MPa measured at room temperature, preferably at least 180 MPa, or an elongation at break of at least 18%, preferably of at least 20%, particularly preferred of at least 25%, recommended. Usually this is Elongation at break in the commercially available magnesium alloys measured at Room temperature less than 12%.

With stronger substitution of other alloys by magnesium alloys to by Weight savings to save fuel or the installation of additional elements without Allowing weight gain is the advancement of the technology of the well-known Magnesium alloys and research into other magnesium alloys necessary especially regarding the combination of properties ductility - strength.

1. Eine recht begrenzte Möglichkeit dieser Steigerung ergibt sich durch Optimierung des Herstellungsprozesses in Verbindung mit Wärmebehandlungsverfahren oder/und über optimierte Herstellparameter z.B. beim Strangpressen. Wichtig ist jedoch beim Umformen z.B. durch Strangpressen, daß die auftretende dynamische Rekristallisation nicht zur Grobkombildung führt. Denn die Energieaufnahme und die mechanischen Eigenschaften einer Legierung sollten in der Regel umso größer sein, je kleiner die mittlere Korngröße ist. Ziel einer Legierungsentwicklung kann dabei eine Modifikation des Gefügeaufbaus durch Einformen von temperaturstabilen Ausscheidungen oder/und eine Stabilisierung des Gefüges durch Beeinflussung des Kornwachstums sein, um möglichst feines Kom und eine möglichst geringe Porosität zu erzeugen.

2. Beim Übergang der Kristallstruktur der Mg-Hauptphase von der hexagonal dichtesten Kugelpackung auf die kubisch raumzentrierte Kristallstruktur z.B. aufgrund einer höheren Zugabe eines Dotierungselementes wie z.B. mindestens 10,8 Gew.-% Li, um ohne weitere Dotierungselemente einen homogenen β-Lithium-Magnesium-Mischkristall zu erzeugen, tritt eine verbesserte Bruchdehnung und eine bessere Umformbarkeit bei Raumtemperatur aufgrund einer erhöhten Anzahl von Gleitsystemen auf. Allerdings können sich dabei Festigkeit und Korrosionsbeständigkeit verschlechtem.

3. Da Korngrenzen und andere Gefügeinhomogenitäten bzw. Gefügefehler wie z.B. Einschlüsse, Poren, grobe Ausscheidungen, Oxidschlieren und Seigerungen bei der Bewegung von Versetzungen als Barrieren wirken, kann eine Verfeinerung des Gefüges, eine Verkleinerung von Gefügeinhomogenitäten/-fehlern bzw. eine Vermeidung bestimmter Gefügeinhomogenitäten/-fehler zu einer Steigerung der Festigkeit, der Bruchdehnung und der Energieaufnahme führen. Die Zusammenhänge sind jedoch im Einzelfall sehr komplex. Die Komfeinung ist ein wichtiges Hilfsmittel, um weitere Verformungssysteme zu aktivieren, die ein Korngrenzengleiten und neue Fließprozesse bei Raumtemperatur erlauben und somit die Duktilität verbessern. Dies kann durch die Zugabe kornfeinender Zusätze oder/und durch heterogene Keimbildung beim Erstarren von Gußwerkstoffen aus Legierungen mit bestimmten Zusätzen erfolgen.

Basically, there are various options for increasing the ductility and thus the elongation at break in magnesium alloys and related lightweight materials:

1. A very limited possibility of this increase results from optimization of the manufacturing process in connection with heat treatment processes and / or via optimized manufacturing parameters, for example during extrusion. However, it is important when forming, for example by extrusion, that the dynamic recrystallization that occurs does not lead to coarse grain formation. Because the energy absorption and the mechanical properties of an alloy should generally be greater, the smaller the average grain size. The aim of alloy development can be a modification of the microstructure by molding temperature-stable precipitates or / and a stabilization of the microstructure by influencing the grain growth in order to produce the finest possible grain and the lowest possible porosity.

2. When the crystal structure of the Mg main phase changes from the hexagonally closest spherical packing to the cubic body-centered crystal structure, for example due to a higher addition of a doping element such as at least 10.8% by weight of Li, in order to form a homogeneous β-lithium magnesium without further doping elements -Mixing crystal, there is an improved elongation at break and better formability at room temperature due to an increased number of sliding systems. However, strength and corrosion resistance can deteriorate.

3. Since grain boundaries and other structural inhomogeneities or structural defects such as inclusions, pores, coarse precipitates, oxide streaks and segregations act as barriers when moving dislocations, a refinement of the structure, a reduction in structural inhomogeneities / defects or a avoidance of certain structural homogeneities / errors lead to an increase in strength, elongation at break and energy consumption. However, the relationships are very complex in individual cases. The refinement is an important tool to activate further deformation systems that allow grain boundary gliding and new flow processes at room temperature and thus improve ductility. This can be done by adding grain-refining additives or / and by heterogeneous nucleation when solidifying cast materials from alloys with certain additives.

Even the commercially available Mg casting alloys or wrought Mg alloys are in the cast and, if necessary, subsequently formed, in particular extruded, pressed, rolled or / and forged and possibly thereafter heat-treated condition Usually previously relatively low ductility and low Energy absorption. For the inexpensive manufacture of semi-finished products, in particular for vehicles and airplanes, there is a need for suitable alloys and simple ones Process for the production of magnesium alloys with somewhat increased strength and greatly increased ductility.

Since the interest in wrought magnesium alloys has only increased somewhat in recent years So far, only a limited number of alloys are available for large-scale use to disposal. These are alloys based on Mg-Al-Zn such as AZ31, AZ61, AZ80 and AZ81, based on Mg-Zn-Zr such as ZK40 and ZK60 or on is the extrusion of Magnesium alloys hardly used.

Haferkamp, Bach, Bohling & Juchmann (Proc. 3 ^rd Int. Magnesium Conf. Manchester April 10-12, 1996, The Institute of Materials, London 1997, ed .: GW Lorimer) or Haferkamp, Bach & Juchmann ("Stand und Development tendencies of reduced-density magnesium materials ", lecture at the advanced training event" Magnesium - Properties, Applications, Potentials "of the German Society for Materials Science Clausthal-Zellerfeld 1997) describe lithium-containing magnesium alloys based on MgLi without and with Al, AlZn, Ca, Si, SiCa, AlCa, CaAlZn or SiAlZn. For the elongation at break or tensile strength, values for MgLi40at% Al6at%, for example of 19% or about 260 MPa, and for MgLi40at% 42% or about 134 MPa are given. Due to the small laboratory extrusion press used for those experiments, however, the forming speed and the degree of forming were low.

Furthermore, Haferkamp, Bach, Bohling & Juchmann at the Magnesium Conference in Garmisch-Partenkirchen 1992 (Magnesium Alloys and Their Applications, Eds .: B. L Mordike & F. Hehmann, Oberursel 1992, 243-250) values of elongation at break and Tensile strength carried forward, that of MgLiAl, possibly with Zn, up to 25% and 239 MPa led.

NASA report N67-22072, SP-5068, Properties and current applications of magnesiumlithium alloys, 1967, indicates possibilities for increasing the strength of lithium-containing ones Magnesium alloys and reports on singular values of high elongation at break or high tensile strength, but it can be assumed that the usual at that time Manufacturing process and available raw materials high Impurities occurred that greatly affected the result and that Corrosion resistance compared to the high-purity alloys that can be produced today significantly impaired.

Dow Chemical Company's "Magnesium Wrought Products" publication of August 1994 provides an overview of commercially available extruded magnesium alloys. The The greatest elongation at break is given here for AZ61 with typically 17%.

Neite describes in Materials Science and Technology, Vol. 8, ED .: K. H. Matucha, 199 ?, in Chapter 4.3.2 Manufacturing processes and mechanical properties of typical Magnesium alloys. For extruded magnesium alloys based on AZ in shape of bars - especially increasing with the aluminum content - tensile strengths of 204 up to 340 MPa and elongations at break of 9 to 17% indicated by an artificial Aging could be increased up to a tensile strength of 380 MPa, but the Elongation at break decreased to 6 to 8%. For AZ31 250 MPa and 14 to 15% are given. Alloy M1 typically had a tensile strength in the extruded state 225 MPa and an elongation at break of 12%.

GB 2,296,256 A gives values of elongation at break of 17.2 and 18% for alloys MgAl0.5-1.1Mn0.10-0.12, which, however, had a rather low flexural strength.

Kamado et al. describe in Proc. 3 ^rd Int. Magnesium Conference April 10-12 1996, Manchester / UK, Ed .: GW Lorimer, for the alloy Al10Si1Ca0.5 values of about 170 MPa tensile strength and 2% elongation at break for the press-formed state.

By J. Becker, G. Fischer and K. Schemme, Light weight construction using extruded and forged semi-finished products made of magnesium alloys, lecture Wolfsburg 1998 for the magnesium alloy AZ31 in the extruded state values of 250 MPa Tensile strength and 14% elongation at break are communicated for the alloy M2 of 250 MPa for the Tensile strength, but only 4% for the elongation at break. The samples were therefore not up ductile material properties optimized.

In US 3,419,385 the tensile strength for individual extruded magnesium alloys with contents of Y, Zn and Zr with 248 to 352 MPa and the elongation at break with 14 to 26% each specified by composition. The chemically closest to the alloy ZE10Zr0.7 Coming alloy Zn2.1Y1.9Zr0.9 only showed an elongation at break when cast from 8% to. It can be assumed that with the then usual manufacturing processes and available raw materials, high levels of contamination occurred Result strongly influenced in this regard and the corrosion resistance compared to significantly impaired the high-purity alloys that can be produced today.

From the specialist article by Haferkamp, H et al. "State, Development and Perspectives of Lithium Containing Magnesium Alloys "in Magnesium Alloys and their Applications, 1998, Werkstoff-Informationsgesellschaft mbH, Frankfurt, pp. 157 - 162 are the alloys MgLi12Al1, MgLi12Al3, MgLi12Al8 known with a degree of deformation of 3.2 were extruded. These alloys contain 3.7% Li and 1.2% respectively 3.6% and 9.6% Al. The alloy MgLi12Al8 has a high Tensile strength of 350 MPa. However, this alloy is fragile.

There was therefore the task of a method for extruding Magnesium alloys with increased ductility and, if possible, increased energy consumption, Compressive or tensile strength and toughness by selecting the for these purposes propose the most effective parameters that have the lowest possible density and can also be produced as simply and inexpensively as possible.

The object is achieved with a method for producing a magnesium alloy high ductility and others by extrusion with the features of claim 1. Die Magnesium alloy has a Li content in the range from 0.5 to 6.8% by weight of Li. This The range of the lithium content covers both the material properties interesting 2-phase area with the hexagonal and cubic phase, as well as the Krz phase range from essentially only the cubic phase as the Li-containing phase occurs. A tensile strength of at least 200 MPa is particularly advantageous.

It has been shown that the modification of grain sizes and phase distributions over the Alloying accompanying elements such as zirconium, rare earth elements SE such as Cerium, Praseodymium, Neodymium, Samarium, Gadolinium, Ytterbium, Yttrium and Lanthanum or their Mixing is helpful in producing significantly firmer and / or more ductile Magnesium alloys. Above all an addition of at least one rare earth element including yttrium and lanthanum has proven to be beneficial for the advancement of Magnesium alloys proven.

The remaining contents of the chemical composition listed consist of Magnesium and unavoidable impurities. Levels of cadmium interfere with the Processing only because of their toxicity, but are otherwise particularly with regard to Formability is an advantage. Traces of copper, iron and nickel should be as possible be low since they affect the processing and / or the material properties impact.

It has been found that usually high ductile magnesium alloys Extrusion speeds can be achieved. There are still tests no effort has been made to achieve the highest extrusion speeds achieve, but rather there is a clear potential, even significantly higher To be able to reach speeds. The degree of deformation characterizes the degree of Reduction of cross-section during forming and is used as the natural logarithm of the Ratio of initial cross-section to cross-section specified after forming. He is therefore often correlated with the degree of dynamic recrystallization, where possible should not yet occur stronger growth of individual grains, but one if possible fine-grain structure is sought, which is high for some magnesium alloys Ductility conditional The more stable the structure of a magnesium alloy is, the more fine-grained it is the structure becomes or remains during forming. It has also been found that the degree of deformation is advantageously at least 1.5, preferably at least 2, particularly preferably at least 2.5. If the degree of deformation is less than 1.5, the dynamic Recrystallization when forming is quite low. It would also have a grade of 3.5 or more can be selected in the tests. The extrusion speed is advantageously at least 1.5 m / min, preferably at least 2.5 m / min, particularly preferably at least 5 m / min, very particularly preferably at least 7.5 m / min. It is above all due to the decreasing quality of the extruded profiles limited (see also claim 8).

It is necessary that the magnesium alloy is selected from the group of Magnesium alloys due to dynamic recrystallization and fine grain get a higher ductility. The dynamic recrystallization and structural change from the original or compacted molded body to the finished semi-finished product, component or Compounding is often not only achieved through extrusion and the associated processes thermal or mechanical influences, but they are preferred performed essentially or even mainly in extrusion.

The task is finally solved with a semi-finished product made of a magnesium alloy or with a component made of it or with it or with a composite with a such semifinished product or component that was produced according to the invention.

For the purposes of this application, semi-finished products are understood to be shaped articles which have not yet are completed and ready for use for their respective application. As components on the other hand, the molded articles are suitable for the intended purpose designated. However, both terms flow smoothly into one another, since it is the same shaped body for one purpose around a semi-finished product, but for the other can already be a component. Furthermore, for the sake of linguistic Simplification does not strictly differentiate between semi-finished products and components throughout the text or both mentioned at the same time or only spoken of magnesium alloy, although both can be meant.

The semifinished products made of magnesium alloys according to the invention or those thereof or therewith manufactured components or composites can be used as frame elements, Elements of the vehicle cell or vehicle outer skin, as a vehicle cell or Vehicle outer skin, cockpit support, cockpit skin, housing, floor element, floors, cover, Tank elements, tank flaps, brackets, supports, beams, angles, hollow profiles, pipes, Deformation elements, crash elements, crash absorbers, impact absorbers, impact shields, Impact beams, small parts, as a welded profile construction, for the vehicle body, for Seat, window or / and door frames, as semi-finished products, components or composites on or in Automobile or airplane.

Process for the production of extruded profiles:

It is preferable to start from high-purity, commercially available alloys. Possibly. these alloys are alloyed with additives. The high-purity alloys can absorb small amounts of contaminants from the crucible during the melting process. The alloys can be melted, for example, in a nickel and chromium-free steel crucible under a protective gas atmosphere, for example Ar or / and SF ₆ . Instead of a casting process, the powder-metallurgical production of green compacts, possibly with subsequent annealing, can also be used. The process steps are known in principle, but require a different modification or optimization depending on the alloy.

Prerequisite for the further processing of magnesium alloys by extrusion, Rolling and / or forging is the production of suitable materials e.g. in the form of Blocks, bolts or slabs. There are for the production of bolts for extrusion two main options:

In the first method, a bolt with a very large diameter can be cast are then turned into round bolts using a high-performance extrusion press can be pressed with a diameter that corresponds to the recipient diameter. The segregation is reduced by the thermomechanical treatment.

A less complex process than this double extrusion is the production of the Bolts by sand, mold or continuous casting with a sufficiently large size Machining allowance. However, it is important to ensure that there are no severe segregations occur that are not or only insufficient due to long homogenization times be balanced. The consequences could otherwise be a bad compressibility and a greater dispersion of the mechanical properties, in particular the ductility.

The cast bolts can first be subjected to heat treatment depending on the Alloy composition in e.g. 350 ° C homogenized in the range from 6 h to 12 h to eliminate segregations in the structure, some of which heterogeneous structure too improve and increase the pressability. Then the homogenized bolts machined to the required dimensions.

Segregations can lead to uneven deformation and critical Extrusion conditions lead to cracks or local melting, which is bad Surface qualities can cause. With less well homogenized bolts is a unnecessarily high extrusion pressure required. The homogenized bolts are then prepared for extrusion.

The extrusion of the magnesium alloys can be carried out in the same extrusion plants take place, which are used for the extrusion of aluminum alloys, both via direct as well as indirect extrusion. Only with the Tool design (die), the deformation behavior must be specifically taken into account. There are sharp-edged inlets, such as those used in aluminum alloys Avoid magnesium alloys, otherwise there is a risk of surface cracks. In many cases e.g. for matrices of round profiles an entry angle of approx. 50 ° for Magnesium alloys used. A round profile was used in the tests.

The most important parameter besides the extrusion temperature is the extrusion speed, because they have the properties and surface quality of the Extruded profiles significantly influenced. A high pressure also means a high one Extrusion speed, which is aimed for economic reasons. A high Extrusion speed is usually with an even better surface quality connected. The extrusion speed is very different from the geometry of the strand dependent. The pressability of the magnesium alloys is comparable to that heavy-duty aluminum alloys. A high extrusion speed is true Desired from an economic point of view, but is not the case with magnesium alloys always feasible. It may also be used at particularly high extrusion speeds there are no cracks or burning of the magnesium alloy. In addition, the Degree of deformation of great importance. It goes along with the change in the structure. Of a high degree of forming is therefore an advantage. However, it is not allowed with high degrees of deformation local melting occurs. Despite certain knowledge of the extrusion of Magnesium alloys usually need the parameters for extrusion in detail be worked out because there is a huge potential for optimization.

The extrusion can advantageously be followed by a heat treatment. This heat treatment is particularly suitable for the lithium-containing alloys of Interest, while the remaining extruded modified alloys through this Heat treatment cannot be greatly improved. If necessary, the semi-finished products can be straightened, e.g. by bending, pressing, pressure rolling, stretch drawing, deep drawing, hydroforming or roll forming further deformed, e.g. by cutting, drilling, milling, grinding, lapping, Polishing processed, joined and / or e.g. by etching, pickling, painting or otherwise Coating to be surface treated. With the alloys according to the invention can complete and extruded profiles in simple or complicated cross sections without problems be extruded. Here, semi-finished products can be improved, components are also manufactured.

When joining, the semi-finished product or the component made therefrom or with it can pass through at least one low-heat joining process such as Gluing, riveting, plugging, pressing, Pressing in, clinching, folding, shrinking or screwing and / or at least one heat-generating joining process such as Composite casting, composite forging, Composite extrusion, composite rolling, soldering or welding, in particular Beam welding or fusion welding, with an identical or different type Semi-finished product or component can be connected. The different semi-finished product or component can likewise essentially of a magnesium alloy or of another alloy or also consist of a non-metallic material. It can be the same or one have a different geometry than the semi-finished product or component according to the invention. The Joining methods can serve in particular to create a housing from several elements, to manufacture an apparatus, a system, a profile construction and / or a cladding.

Examples:

The following examples according to the invention represent selected embodiments, without restricting the invention.

A Al, E indicates at least one of the alloy designations used Rare earth element SE, whereby Y is also counted among the rare earth elements, M or MN Mn, S Si and Z Zn - usually with content in% by weight, unless otherwise is noted. With commonly used alloy information such as AZ31 are made by the numbers as usual for the respective alloy only in the order of magnitude specified, which can vary to a relatively wide extent as is customary in the industry. In addition, at of the starting alloy used in the examples and of those produced therewith modified alloys based on AZ have a low manganese content. All Examples showed traces of less than 0.1 wt% Cd, less than 0.05 wt% Cu, less than 0.04 wt% Fe and less than 0.003 wt% Ni.

The alloys were made as high-purity commercially available alloys or usually from high-purity starting alloys such as, for example, AM, AS or AZ alloys or by adding high-purity magnesium HP-Mg, a rare alloy containing rare earth elements with a ratio of Nd to other rare earths including yttrium of 0.92, a zirconium-containing master alloy and / or of calcium or strontium. The standard alloys contained an Mn content of up to about 0.2% by weight. The alloys were melted in a steel crucible under the protective gas atmosphere of an Ar-SF ₆ mixture. The blanks required for the subsequent extrusion were cast in a cylindrical steel mold with machining allowance. The element contents achieved were checked spectroscopically. With all alloys, care was taken to ensure that the structure of the cast body is as homogeneous and free of impurities as possible, as this can have a sensitive effect on ductility. All alloys could be melted, poured off and processed into bolts without any problems.

The bolts were then turned to a diameter of 70 mm and to a length of 120 mm brought. The bolts were then subjected to homogenization treatment in e.g. 350 ° C exposed for 4 h or 12 h to eliminate segregations in the structure and the Increase pressability. Segregations can lead to uneven deformation and critical extrusion conditions lead to cracks or local melting, which can cause poor surface qualities. With less well homogenized bolts an unnecessarily high pressing pressure is required during extrusion. The homogenized bolts were then well prepared for extrusion.

The homogenized bolts were then brought up to the respective extrusion temperature heated, warmed up and directly in a 400 t horizontal press Extrusion process extruded. The temperature of the bolt is that temperature. which the bolt has when it enters the extrusion press.

In systematic preliminary tests on the reference alloy AZ31, the suitable ones were found Extrusion parameters selected; on the extruded samples mechanical properties and the mean grain size determined (Tables 1 and 2). The The results of the preliminary tests essentially determined the test parameters of the subsequent attempts.

During the actual tests, several of the manufacturing parameters were systematically varied (Tables 3e / f). On the one hand, the die diameter was varied and became the Die speed and extrusion temperature kept constant, on the other hand the matrix geometry was kept constant and became the Die speed varied and finally the extrusion temperature varies depending on the alloy. The ram speed and the extrusion ratio gave the extrusion speed. With the help of such a parameter matrix it was possible to evaluate the influence of different forming conditions.

All alloys, both the starting alloys and those modified by additives Alloys could easily be used in a wide temperature, Form extrusion speed and extrusion ratio range. Bolts showed good compressibility with a large scope in terms of pressing force and Compression speed. The extrusion speed was not yet in the tests maxed out to the highest possible speeds and therefore can still generally be significantly increased. The lower extrusion temperature is due to the insufficient plastic deformability below a temperature in the range of about 200 to 220 ° C. conditionally, the upper extrusion temperature is limited by the proximity to eutectic temperature and possibly through the initial formation of portions of a molten phase.

Depending on the extrusion conditions, the same result Alloy composition Differences in the structure of the samples. The occurred Extrusion pressures varied depending on the alloy used and the set one Strangpreßparametern. Generally a dynamic occurred during extrusion Recrystallization depending on the extrusion parameters and the Alloy composition led to different mean grain sizes. The The composition of the magnesium alloys varied only slightly or almost not at all from the composition of the melt to the composition before or after Extrusion to the composition of the semi-finished product made from it. The The semifinished product or component according to the invention preferably consists essentially of a Magnesium alloy, which is selected from the group of alloys based on AM, AZ, or ZE with added lithium.

The strength values determined on the cast and extruded samples were much higher than expected. The deformability was also surprising of these alloys very high. It was also surprising that the material properties of the modified alloys surprisingly little depending on the Extrusion conditions varied, which is advantageous for production. Furthermore, it was Surprisingly, the impact energy of the ZE10 alloy was so high.

Finally, the course of extrusion, the sequence of extrusion in the force-displacement diagram, varied characterized with AZ, AZLi3.6 and AZLi6.8 increasing lithium content differently than expected: it was shown with a small addition of lithium poorer behavior than without or with a higher lithium content. Some of the Alloys containing lithium gave an unexpectedly strong result when the lithium content was high Dependence of the material properties on the type of heat treatment.

The extruded round profiles were processed by milling and turning into round specimens (d ₀ = 5 mm, l ₀ = 5 • d ₀ , small proportionality bar, according to DIN 50 125), pressure tests (d ₀ = 10 mm, l ₀ = 2 • d ₀ , according to DIN 50 106), impact bending tests (10 x 10 x 55 mm, according to DIN 50 116) and notched impact bending tests (according to DIN 50 115). 5 of these samples were produced and tested per alloy and test. For all samples, the longitudinal direction was chosen so that it coincided with the direction of extrusion.

In the tensile test, tensile strength R _m , yield strength = yield strength R _P0.2 and elongation at break A or, in some cases, the constriction at break at the tensile test at a tensile speed of 0.5 mm / min were determined. Values of the compressive strength R _Dm , compression limit R _D0.2 and compression A _D at a printing speed of 0.5 mm / min were obtained in the compression test. The beginning of the plastic deformation (expansion or compression limit) was determined graphically. Brinell hardness measurements were also carried out in accordance with DIN 50351. All measurements took place at room temperature. The results of the mechanical determinations are summarized in Tables 3a-c and those of the structural investigations in Table 3d.

Grindings were made on selected samples, with respect to medium grain size, Structural homogeneity as well as the type and distribution of the separated phases contained were assessed. This evaluation was used to further optimize the Manufacturing and processing parameters.

The variation of the extrusion parameters had a different influence on that Property profile of the extruded magnesium materials. Tendencies of Material properties of the different alloys depending on the manufacturing parameters can be seen from Tables 3e / f.

The measurement results of the Brinell hardness determinations did not allow any special ones Statement. The Brinell hardness of the extruded samples was found to be 7 to 22% greater than the cast samples. The hardness increased with the aluminum content.

A) Li-containing magnesium alloys:

Production of the bolts: casting in tube molds at a casting temperature of 680 to 720 ° C for larger diameters and turning to usually 70 mm in diameter. The turned bolts were heat treated at 350 ° C for 4 h (= homogenized).

Extrusion: Depending on the sample, an extrusion temperature in the range of 150 to 300 ° C and a time in the range of 50 to 110 min was set for heating and warming the bolt. Preliminary tests were carried out with the reference alloy AZ31 (Tables 1 and 2). The preliminary tests allowed the preselection of the test parameters. The specific extrusion tests were carried out in a 400 t extrusion press with direct extrusion. Depending on the sample, with a recipient diameter of 74 mm, a recipient temperature in the range from 180 to 259 ° C., a die diameter in the range from 15 to 18 mm, a compression ratio A / A ₀ in the range from 16.9 to 24.3, a degree of deformation ϕ = In (A _o / A) in the range from 2.8 to 3.2, a punch speed in the range from 191 to 419 mm / min, an extrusion speed in the range from 3.2 to 9.0 m / min, a pressing pressure at the start of the extrusion in the range from 15.2 to 24.3 MPa and a pressure at the end of the extrusion in the range from 10.0 to 14.8 MPa. Only a small part of the tests are shown in Table 3f.

The influence of extrusion parameters on the material properties of those containing lithium Alloys and their undoped base alloys were limited. He was with Tensile strength was particularly low and increased beyond the elongation at break and compressive strength something to do with the work.

The extruded alloy AM20Li3.6 showed in comparison to the extruded alloy AM20 sometimes has higher mechanical properties (Tables 3a / c). Like the other extruded alloys, the addition of lithium led to a very strong one Increase in field work. The extruded AM20 alloy had a very high one elastic and a comparatively very low plastic part of the tension in the extruded state (Table 3b). The addition of lithium doubled the corresponding plastic proportion.

The AZ31Li3.6 alloy was not subjected to tensile tests when cast characterized because the porosity of the samples was still a bit too high to be characteristic To provide statements. In the extruded state, this alloy had the highest Compressive strength values. With the AZ31 alloyed with lithium significantly higher toughness on notched impact samples as well as significantly higher Elongation at break determined as on the associated samples not alloyed with lithium, the highest values for the essentially two-phase alloy AZ31Li12.3 occurred. In contrast, the tensile strength decreased with the lithium content. The compressive strength was for the samples in the as-cast state proportional to the lithium content, for extruded ones However, samples are highest at medium lithium levels. Among the alloys in the The AZ31Li6.8 alloy showed a surprisingly high mean value at 122 MPa the yield strength. The deformability of the base grid of the AZ31 was made possible by the addition of lithium and increases the possibly modified elimination phase. The alloy AZ31Li6.8 showed a reduced tensile and compared to the alloy AZ31Li3.6 Compressive strength, but a high compression limit and high elongation at break. The The addition of lithium improved the formability.

This had an effect on the lithium-containing alloys and their starting alloys Stress under pressure is different from that under tension: different from tensile strength took the compressive strength and sometimes the compression limit from AZ31 the lithium content of the AZ31Li3.6 alloy. The alloy AZ31Li6.8 showed due their high lithium content compared to the average of all samples in this series Mean values (Table 3a) the highest compression limit and fracture compression and a very high one Compressive strength. In this series the fracture compression of the samples was in the cast Condition higher than that of the extruded samples.

The cast alloy ZE10 had a very low elastic content, but almost on average high plastic portion of the tension. With a lithium additive the elastic portion increases significantly. On the other hand, the ZE10 alloy won at Extruding an extraordinarily high elastic portion of the tension during the the plastic part remained approximately constant. For the alloys ZE10 and ZE10Li3.7 all mechanical properties of cast samples increased with the lithium content drastically. For the corresponding extruded samples, the mechanical properties with the exception of tensile strength and yield strength the lithium content. The alloy ZE10Li3.7 showed among the examined lithium-containing ones Magnesium alloys have the highest values of impact work, being due to Crash tests on deformation elements from inventive Magnesium alloys are assumed that the alloy MgLi15.5Al2.5Zn0.8 should have even higher impact and notch impact values than that Alloy ZE10Li3.7. Up to 140 J were obtained on individual samples of the ZE10Li3.7 alloy measured; other samples were taken through the abutment of the testing machine without to break completely, so that no measured value of the impact work could then be determined. The maximum applicable impact energy was 150 J.

The degree of deformation had a considerable influence on the impact work of those containing lithium Rehearse. The hammer work was with the lithium-containing magnesium alloys at one Degree of deformation ϕ of 2.83 often about 30 to 65% higher than for ϕ = 3.06 (Table 3f). at lower degrees of deformation and thus with smaller compression ratios resulted much higher values of impact work. This tendency occurred in the samples from unmodified Starting alloys and not or only with the samples alloyed with Ca or Zr weak on. The best impact work was performed on the samples containing lithium Forming temperatures of 200 to 250 ° C achieved. The forming speed (= Extrusion speed) had little effect on tensile strength and elongation at break.

The pressure-pressure curves during extrusion of the lithium-containing alloys at 200 ° C showed that with the alloy AZ31 + 12at% Li as well as AZ31, the material of the bolt did not flow until a higher pressure, for example at 16 MPa Compared to the alloys AM20 + 12at% Li, AZ31 + 21at% Li and ZE10 + 12at% Li, where the flow started at around 12.5 MPa, but also a more favorable, lower pressure was determined after a longer path. Results of the preliminary tests to determine the extrusion parameters with the AZ31 alloy at an extrusion temperature of 400 ° C, a die diameter of 16 mm, a recipient diameter of 74 mm and a compression ratio of 1:21 Compression speed Average grain diameter Tensile strength R _m Yield strength R _P0.2 Elongation at break A reduction of area m / min microns MPa MPa % % 4 8.8 277 134 12.5 29.2 5 9.3 281 141 12.7 29.3 8.4 9.0 282 137 15.6 35.2 Influence of the compression ratio on the average grain sizes and the mechanical properties from the tensile test at an extrusion temperature of 400 ° C in the preliminary tests to determine the extrusion parameters die diameter pressing ratio Compression speed average grain diameter Tensile strength R _m Yield strength R _P0.2 Elongation at break A reduction of area mm m / min microns MPa MPa % % 16 1:21 4 8.8 277 134 12.5 29.2 12 1:38 5 9.3 281 141 12.7 29.3

In tables 3, "casting" = material in the as-cast state and "extr." = Casting material which was subsequently formed by homogenization and extrusion, "B" = example according to the invention and "VB" = comparative example according to the prior art. Average values of the measurement results of the mechanical tests averaged over the various samples of the lithium-containing magnesium alloys and their starting alloys. No. alloy Tensile test Compression test Schlagvers. R _m R _P0.2 A R _Dm R _D0.2 A _D C _G C _UG MPa MPa % MPa MPa % J J B 1 AM extr. 20 274 230 18 325 129 8th 8.6 46 VB 2 AM20 + Li3.6 Molding 182 84 18 264 70 18 8.0 33 B 3 AM20 + Li3.6 extr. 229 140 21 366 130 16 12.4 83 VB 4 AZ31 Molding 192 110 9 260 80 19 7.1 27 VB 4a AZ31 extr. 276 197 17.6 375 140 12 8.8 61 VB 5 AZ31 + Li3.6 Molding nb nb nb 282 70 18 7.0 26 B 5 AZ31 + Li3.6 extr. 261 161 21 397 150 14 10.3 97 VB 6 AZ31 + Li6.8 Molding 179 122 18 308 111 25 8.9 38 B 6 AZ31 + Li6.8 extr. 227 156 26 369 165 19 11.9 102 VB 7 ZE10 Molding 88 22 17 172 20 10 7.8 13 VB 8 ZE10 + Li3.7 Molding 164 76 24 271 57 23 11.0 54 B 8 ZE10 + Li3.7 extr. 209 117 26 346 113 17 18.6 > 106 Average values of the values determined from the stress-strain diagram of the tensile tests for lithium-containing magnesium alloys and their starting alloys. F = R _P02 = yield stress = elastic part of the stress. V = yield strength ratio = F: Z. R _m = tensile stress Z = elastic + plastic part of the stress. No. alloy tensions strain flow Z - F Train- V = A _plast F Z Q: Z = A MPa MPa MPa % VB 2 AM20 + Li3.6 Molding 84 98 182 0.46 18 B 3a AM20 + Li3.6 extr. 140 89 229 0.61 21 VB 4 AZ31 Molding 110 82 192 0.57 9 VB 4a AZ31 extr. 197 79 276 0.71 17.6 VB 5 AZ31 + Li3.6 Molding nb nb nb nb nb B 5a AZ31 + Li3.6 extr. 161 100 261 0.62 21 VB 6 AZ31 + Li6.8 Molding 122 57 179 0.68 18 B 6a AZ31 + Li6.8 extr. 156 71 227 0.69 26 VB 7 ZE10 Molding 22 66 88 0.25 17 VB 8 ZE10 + Li3.7 Molding 76 88 164 0.46 24 B 8a ZE10 + Li3.7 extr. 117 92 209 0.56 26 Highest mean values of the measurement results of the mechanical properties selected from various individual samples of the lithium-containing magnesium alloys No. alloy Tensile test Compression test Schlagvers. rm R _P0.2 A R _Dm R _D0.2 A _D C _G C _UG MPa MPa % MPa MPa % J J B 3 AM20 + Li3.6 extr. 232 148 22 388 138 17 14.7 111.4 B 5 AZ31 + Li3.6 extr. 266 185 24 412 155 17 13.6 96.8 B 6 AZ31 + Li6.8 extr. 232 160 28 392 171 20 14.3 128.5 B 8 ZE10 + Li3.7 extr. 212 123 28 362 123 18 20.8 > 133 Structural components in the as-cast state after homogenization at 350 ° C for 4 h or after extrusion as well as predominantly occurring grain sizes (* = before hot aging) sample alloy Casting or homogenization structure Cast or extruded structure vorw. Grain sizes, µm VB 2 AM20 + Li3.6 cast hexagonal MgAlLi mixed crystals; individual Mn excretions; some lamellar excretions in twigs, but hardly on grain boundaries 150-200 B 3 AM20 + Li3.6 extr. barely degenerate eutectics lamellar excretory structure completely dissolved; Maintain Mn precipitates clearly recrystallized; Precipitation phase chain-like in recrystallized lamellae lined up in the extrusion direction 10-20 VB 4 AZ31 cast - hexagonal MgAl mixed crystals; individual Mn excretions; eutectics degenerate due to segregation at grain boundaries surrounded by discontinuous lamellar Mg ₁₇ Al ₁₂ excretions 200-300 VB 4a AZ31 extr. degenerate eutectics unresolved; lamellar excretions largely dissolved; Maintain Mn precipitates clearly recrystallized; Eliminations difficult to detect 5-20 VB 5 AZ31 + Li3.6 cast hexagonal MgAlLi mixed crystals; individual Mn excretions; Com borders completely surrounded by lamellar AlLi or Mg ₁₇ Al ₁₂ ; very low eutectic share on the comm boundaries 200-250 B 5 AZ31 + Li3.7 extr. degenerate eutectics unresolved; Mn excretions have been preserved; point to lamellar clearly recrystallized; Precipitation phase chain-like in the extrusion direction lined up recrystallized grains lamellar 10-20 Elimination structure around grain boundaries VB 6 AZ31 + Li6.8 cast Matrix: Mg-rich hdp-α mixed crystals and Li-rich krz-β mixed crystals; individual Mn excretions; point-shaped AlLi in krz-β mixed crystal and on grain boundaries α phase: 100-200 β phase: 50-100 B 6 AZ31 + Li6.8 extr. in krz-β mixed crystals, excretions largely dissolved; partially fine point-like re-excretions at comm boundaries; Mn excretions were retained * clearly recrystallized; Elimination phase in recrystallized grains excreted again; clear allocation of boundaries α phase: 10-40 β phase: 5-25 VB 8 ZE10 + Li3.7 cast hexagonal MgZnLi mixed crystals; Partial excretions; isolated solid precipitates in mixed crystal grains 200-250 B 8 ZE10 + Li3.7 extr. Excretions at the boundaries have been preserved clearly recrystallized; Elimination phase torn and stretched in the direction of extrusion 5-20 Process parameters and mean grain size for lithium-containing magnesium alloys and their starting alloys: sample alloy Initial _pressure p Initial _MPa Degree of deformation ϕ = In (A _o / A) Forming temperature T _{UF ° C} Pressing speed m / min number of samples B 3 AM20 + Li3.6 extr. 17.0 - 23.5 2.83 to 3.06 150-300 3.4 to 8.4 10 VB 4 AZ31 extr. 17.9 - 24.3 2.83 to 3.20 200-300 3.3 to 8.6 9 B 5 AZ31 + Li3.6 extr. 18.7 - 24.3 2.83 to 3.20 200-300 3.2 to 8.6 9 B 6 AZ31 + Li6.8 extr. 15.2 - 24.0 2.83 to 3.06 125-250 3.4 to 8.2 10 B 8 ZE10 + Li3.7 extr. 15.7-23.0 2.83 to 3.06 150-300 3.2 to 9.0 10

Claims (15)

1. Process for producing a magnesium alloy of high ductility inter alia by extrusion, in which the magnesium alloy is extruded at an extrusion rate of 1.5 to 20 m/min and with a degree of deformation of at least 1.5, being dynamically recrystallized in the process, with mean grain sizes of <= 40 µm being produced, it being possible for the alloy to contain additions or traces of Cd amounting to less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Ni, the alloy also containing Li in the range from 0.5 to 6.8% by weight, and the alloy, in addition to the Mg and Li contents, also containing at least 0.1% by weight of at least one further chemical element selected from the group consisting of manganese, aluminium, zinc and rare earths, including lanthanum and yttrium, the remaining components of the magnesium alloy consisting of magnesium and inevitable impurities, and the magnesium alloy, after extrusion, having an elongation at break of at least 20%, a compressive strength of at least 300 MPa and an impact energy, measured at unnotched specimens, of at least 70 J.
2. Process for producing a magnesium alloy of high ductility according to Claim 1, characterized in that it is a magnesium alloy based on AZ (aluminium/zinc), the magnesium alloy, after the extrusion having a compressive strength of at least 350 MPa.
3. Process for producing a magnesium alloy of high ductility according to Claim 1, characterized in that it is a magnesium alloy based on AM (aluminium/manganese) or ZE (zinc/rare earths).
4. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that after extrusion it has a tensile strength of at least 200 MPa.
5. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that after extrusion it has a plastic stress component, determined in a tensile test using the stress-strain diagram from the difference between tensile stress and yield stress, of at least 40 MPa.
6. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the shaped bodies which are to be extruded, in particular bolts, are homogenized for 2 to 24 h at temperatures in the range from 330 to 380°C.
7. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is extruded with a degree of deformation of at least 2.
8. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is extruded at an extrusion rate of from 1.5 to 18 m/min, preferably at 3 to 16 m/min, particularly preferably at 5 to 15 m/min.
9. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that after extrusion it is heat-treated or age-hardened at temperatures in the range from 80 to 250°C, preferably at 100 to 150°C.
10. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is then deformed once again or is then shaped.
11. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the semifinished product produced or the component produced from or using the semifinished product is straightened, deformed further, e.g. by bending, pressing, metal spinning, stretch-forming, deep-drawing, hydroforming or roll-forming, machined, joined and/or surface-treated.
12. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the semifinished product or the component produced from or using the semifinished product is connected to a component or semifinished product of similar or different type by means of at least one low-heat joining process, such as for example adhesive bonding, riveting, plug connection, pressing-on, pressing-in, clinching, folding, shrinking or screw connection and/or at least one heat-introducing joining process, such as for example composite casting, composite forging, composite extrusion, composite rolling, soldering or welding, in particular beam welding or fusion welding.
13. Semifinished product made from a magnesium alloy or component produced therefrom or therewith, or assembly including a component or semifinished product of this type, characterized in that it has been produced as described in at least one of the preceding claims.
14. Use of a magnesium alloy produced as described in at least one of Claims 1 to 12 as a frame element, an element of a vehicle cell or a vehicle outer skin, a vehicle cell or vehicle outer skin, a cockpit beam, a cockpit skin, a housing, a floor element, a floor, a flap, a tank element, a tank flap, a holder, a support, a beam, a corner, a hollow profiled section, a tube, a deformation element, a crash element, a crash absorber, a shock absorber, an impact shield, an impact support, a small part as a welded profiled-section structure, for the vehicle body, for seat, window and/or door frames, as a semifinished product, component or assembly on or in an automobile or aircraft.
15. Use of a semifinished product made from a magnesium alloy produced as described in at least one of Claims 1 to 12, of a component produced therefrom or therewith and/or of an assembly having at least one semifinished product and/or component of this type as a frame element, an element of a vehicle cell or vehicle outer skin, a cockpit beam, a cockpit skin, a housing, a floor element, a floor, a flap, a tank element, a tank flap, a holder, a support, a beam, a corner, a hollow profiled section, a tube, a deformation element, a crash element, a crash absorber, a shock absorber, an impact shield, an impact support, a small part, as a welded profiled-section structure, for the vehicle body, for seat, window and/or door frames, as a semifinished product, component or assembly on or in an automobile or aircraft.