EP1183402A1

EP1183402A1 - Method for producing a magnesium alloy by extrusion moulding and use of the extrusion moulded semifinished products and components

Info

Publication number: EP1183402A1
Application number: EP00917040A
Authority: EP
Inventors: Wolfgang Sebastian; Heinz Haferkamp; Peter Juchmann; Karl Ulrich Kainer
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 1999-04-03
Filing date: 2000-04-03
Publication date: 2002-03-06
Anticipated expiration: 2020-04-03
Also published as: WO2000060133A1; ATE255170T1; EP1295957A3; EP1295957A2; DE50004572D1; EP1183402B1; DE19915276A1

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

Process for producing a magnesium alloy by extrusion and use of the extruded semi-finished products and components

The invention relates to a method for producing a magnesium alloy of high ductility and others. 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 of 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, particularly in new low-emission automobiles. They are also of interest for portable 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-liter motor vehicle, to a particular extent. Among the manufacturing processes, die casting and, during shaping, extrusion, forging, rolling and possibly subsequent shaping such as stretching or deep drawing will become increasingly important in the future, since lightweight parts such as seats and windows can be produced with these processes - and door frames, elements of vehicle cells and vehicle outer skins, housings, floor elements, lids, tank elements, tank flaps, holders, sockets, supports, angles, crash elements, impact dampers, impact shields and impact carriers, small parts or corresponding components for aircraft, for which there is an increasing demand .

The cold formability of commercially available magnesium alloys is limited due to the hexagonal crystal structure and the associated low ductility. Polycrystalline magnesium and most magnesium alloys behave brittle at room temperature. In addition to good mechanical properties such as high tensile strength, ductile behavior is necessary for a number of applications or for certain manufacturing processes for semi-finished products made of magnesium alloys. An improved forming, energy absorption and deformation behavior requires a higher one Ductility and, if necessary, higher strength and toughness. Magnesium alloys with these properties must be developed for this, or their manufacturing processes developed further, because many material variants have widely varying material properties.

Ductility is the ability of a material to undergo a permanent change in shape, which in the uniaxial state is ideally without any elastic component according to the stress-strain diagram. This property is limited by the occurrence of the break. In general, the permanent elongation achieved in the tensile test until fracture is considered ductility. The measure of the ductility can also be considered to be the break line, impact work and notch 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 _p ι _as , 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 ^ _ast and the sum of the elastic and plastic part D = ΣA = A _e , _ast + A _p ι _as , can be determined. A highly plastic material is called ductile.

When specifying the elongation at break and the tensile strength for various magnesium alloys, it is clear that the elongation at break can often be all the higher if only medium-high values of the tensile strength are achieved and that conversely only medium-high values of the elongation at break are achieved with high values of the tensile strength Tensile strength can only be achieved with comparatively low elongation at break values.

The elasticity refers to the elastic part of the stress-strain diagram according to Hook's law, where under ideal linear-elastic conditions there is still no permanent change in shape

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 gives two the elasticity, two the plasticity and two values that characterize 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 of plastic behavior, i.e. of the deformability and rate of deformation. A high impact work is therefore essential for the use of deformation elements such as crash elements, impact dampers, impact shields and impact carriers. The impact work - measured on notched specimens - is more meaningful than the notched impact work due to higher absolute values for magnesium alloys and affects a largely uniaxial load. The impact energy, which is always determined on notched specimens, also characterizes the susceptibility of a material to failure under three-axis loading. Their significance is particularly low if the execution of the notch significantly influences the values of the impact energy. The impact work and the notch impact work are measured under dynamic load and can give an indication of the energy absorption and deformability. In comparison, tensile and compression tests are carried out under quasi-static loads. A conclusion from uniaxial to multiaxial properties or relationships is only partially possible.

The values listed below measured on samples in a certain manufacturing condition therefore reflect the current material properties. They provide an indication of the forming behavior that previously occurred during the forming process. In this state, it is possible to draw a conclusion about the properties and behavior of a semi-finished product or even a component with this semi-finished product, which may be further refined, in later use. Furthermore, a conclusion can be drawn about the material properties of formed alloys, e.g. by bending, pressing, pressure rolling, stretch drawing, deep drawing, hydroforming or roll profiling to be processed into semi-finished products. Since the change in the material properties from the cast to the extruded state is similar to the change in the material properties from the cast to the forged, rolled or a similar formed state, it is therefore also possible to draw a conclusion about another formed state.

For the use of lightweight components, the elastic properties (rigidity) are usually emphasized, as long as the deformation properties and thus the energy absorption of the element and the plastic behavior are not important, as in an accident. Therefore, multiple forming may play a role in particular the plastic and, for use, the plastic and / or elastic properties play a role. For use, these properties are generally based on the respective ambient temperature, in extreme cases in the range from -40 ° C to +90 ° C, but at individual points in the vehicle or plane at the locally even lower or higher temperatures. However, the load state is usually multi-axis. The conclusion from uniaxial to multiaxial load states is all the more possible the more an isotropic structure is present.

For the production of such automotive elements, the production by die casting or extrusion, forging and / or rolling is particularly suitable. Prerequisite for the use of semi-finished products made of magnesium alloys or of components or parts made from them in automobiles may be the fulfillment of certain property profiles depending on the application, e.g. in the case of deformation elements, seat and door frames, a tensile strength of the light material of at least 100 MPa, preferably of at least 130 MPa, together with an elongation at break measured at room temperature of at least 10%, preferably of at least 15%. The higher the tensile strength, elongation at break and other properties that indicate high ductility and energy consumption, the more suitable these semi-finished products or components are generally for use. Furthermore, higher strength values and a higher ductility are also a relief and in some cases also a prerequisite for the forming of cast blanks or for the further forming of blanks or semi-finished products that have already been formed. The higher these properties are in the cast state, the higher these are usually also in the formed state. A higher ductility can facilitate the forming or the renewed forming, in particular the extrusion. Therefore, an elongation at break of at least 10% is also helpful for the subsequent manufacturing step to elements made of magnesium alloys. A tensile strength of at least 150 MPa measured at room temperature, preferably of at least 180 MPa, or an elongation at break of at least 18%, preferably of at least 20%, particularly preferably of at least 25%, is therefore recommended for several reasons. The elongation at break in the commercially available magnesium alloys measured at room temperature is usually less than 12%.

With stronger substitution of other alloys by magnesium alloys, in order to save fuel by saving weight or the installation of additional elements without Allowing weight gain is the advancement of the technology of the well-known

Magnesium alloys and the research of other magnesium alloys are necessary, especially with regard to the combination of properties ductility - strength.

Basically, there are various options for increasing the ductility and thus the elongation at break for 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 or / and via optimized manufacturing parameters e.g. during extrusion. However, it is important when forming e.g. by extrusion that the dynamic recrystallization occurring 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 forming 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 body-centered cubic crystal structure e.g. due to a higher addition of a doping element such as e.g. at least 10.8% by weight of Li, in order to produce a homogeneous β-lithium-magnesium mixing chamber without further doping elements, 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 excretions, oxide streaks and segregations act as barriers when moving dislocations, refinement of the structure, reduction in structural homogeneity errors or avoidance of certain structural homogeneity errors can lead to an increase strength, elongation at break and energy consumption. However, the relationships are very complex in individual cases. Grain refinement is an important tool to activate further deformation systems that allow grain boundary sliding 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 made of alloys with certain additives. Even the commercially available Mg casting alloys or wrought magnesium alloys have usually been relatively low in ductility and have a low energy consumption in the cast and, if appropriate, subsequently formed, in particular extruded, pressed, rolled or / and forged and, if appropriate, subsequently heat-treated, condition. For the inexpensive manufacture of semi-finished products, in particular for vehicles and airplanes, there is a need for suitable alloys and simple processes 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. 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 extrusion of magnesium alloys is hardly used.

Haferkamp, Bach, Bohling & Juchmann (Proc. 3 ^ Int. Magnesium Conf. Manchester April 10-12, 1996, The Institute of Materials, London 1997, ed .: GW Lorimer) or Haferkamp, Bach & Juchmann ("Stand und Trends in the development of density-reduced magnesium materials ", lecture at the advanced training event" Magnesium - Properties, Applications, Potentials "of the German Society for Material Science Clausthal-Zellerfeld 1997) describe lithium-containing magnesium alloys based on MgLi without and with AI, AlZn, Ca, Si, SiCa , AICa, CaAlZn or SiAIZn. For the elongation at break or tensile strength, values for Mgü40at% AI6at% e.g. of 19% or about 260 MPa and for Mgü40at% 42% or about 134 MPa. 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 presented values of elongation at break and tensile strength at the magnesium conference in Garmisch-Partenkirchen 1992 (Magnesium Alloys and Their Applications, Eds .: BL Mordike & F Hehmann, Oberursel 1992, 243-250), which led to values of up to 25% and 239 MPa for MgüAI, possibly with Zn. NASA report N67-22072, SP-5068, Properties and current applications of magnesium-lithium alioys, 1967, indicates possibilities for increasing the strength of lithium-containing magnesium alloys and reports on singular values of high elongation at break or high tensile strength, but it is It can be assumed that high impurities occurred in the production processes and starting materials available at that time, which greatly influenced the result in this regard and significantly impaired the corrosion resistance compared to the high-purity alloys that can be produced today.

The Dow Chemical Company publication "Magnesium Wrought Products" from August 1994 provides an overview of commercially available extruded magnesium alloys. The greatest elongation at break is specified 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 the form of rods, tensile strengths of 204 to 340 MPa and elongations at break of 9 to 17% are specified - especially with increasing aluminum content - which could be increased to tensile strength of 380 MPa by artificial aging, 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 of 225 MPa and an elongation at break of 12% in the extruded state.

GB 2,296,256 A gives values of the elongation at break of 17.2 and 18% for alloys MgAI0.5-1.1 MnO.10-0.12, which, however, had a rather low flexural strength.

Kamado et al. describe in Proc. 3 "* Int. Magnesium Conference April 10-12 1996, Manchester / UK, Ed .: G.W. Lorimer, for the alloy AI10Si1Ca0.5 values of about 170 MPa tensile strength and 2% elongation at break for the press-molded state.

By J. Becker, G. Fischer and K. Schemme, Light weight construction using extruded and forged semi-finished products made of magnesium alioys, lecture Wolfsburg 1998, values for the magnesium alloy AZ31 in the extruded state were 250 MPa tensile strength and 14% elongation at break 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 optimized for ductile material properties.

In US 3,419,385 the tensile strength for individual extruded magnesium alloys with contents of Y, Zn and Zr is given with 248 to 352 MPa and the elongation at break with 14 to 26% depending on the composition. The alloy Zn2.1 Y1.9Zr0.9, which chemically comes closest to the ZE10Zr0.7 alloy, only had an elongation at break of 8% in the cast state. It can be assumed that high impurities occurred in the manufacturing processes and starting materials available at that time, which greatly influenced the result in this regard and significantly impaired the corrosion resistance compared to the high-purity alloys that can be produced today.

The object was therefore to propose a method for extruding magnesium alloys of increased ductility and, if possible, also increased energy absorption, compressive or tensile strength and toughness, by selecting the parameters which are most likely to work for these purposes and which have the lowest possible density and moreover also possible can be produced easily and inexpensively.

The object is achieved with a method for producing a magnesium alloy of high ductility, inter alia by extrusion, which is characterized in that the alloy is extruded with a degree of deformation of at least 1.5 so that it contains additives or traces of Cd less than 1.8% by weight. -% and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain Li in the range of 0.5 contains up to 20% by weight that, in addition to the contents of Mg and Li and possibly Al or / and Si, it contains at least one further chemical element of at least 0.1% by weight and that after extrusion it contains a Elongation at break of at least 20%, a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 70 J. This further chemical element is preferably Mn, Zn or / and at least one rare earth element SE including La and Y. The magnesium alloy preferably has an ü content in the range from 3 to 18% by weight of Li, preferably from 6 to 14% by weight. % Li. This wide range of lithium content covers both the 2-phase range with the hexagonal and cubic phase, which is interesting in terms of material properties, as well as the krz phase range, in which essentially only the cubic phase appears as a phase containing g. A tensile strength of at least 150 MPa is particularly advantageous.

The task is still solved with a method for producing a magnesium alloy of high ductility, among others. by extrusion, in which the alloy is extruded with a degree of deformation of at least 1.5, with additions or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to Can contain 0.05% by weight of Fe and up to 0.005% by weight of Ni, it having a Ca content in the range from 0.1 to 6% by weight and, after extrusion, an elongation at break of at least 16%, a Compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 50 J. In a variant of advantageous embodiments, the weight fraction of the Ca contained is in the range from 2 to 30%, preferably in the range from 5 to 20%, by weight of the aluminum contained or, if no aluminum occurs, manganese. The Ca content is in particular 0.15 to 4% by weight, preferably 0.2 to 1.5% by weight. The proportion of Ca can be partially replaced by Sr, even though Sr usually behaves differently from Ca.

The object is also achieved with a corresponding method, in which the magnesium alloy has a Sr content in the range from 0.1 to 6% by weight and, after extrusion, an elongation at break of at least 17.5% and an impact energy measured on non-notched samples of has at least 50 J. In a variant of advantageous embodiments, the weight fraction of the Sr contained is in the range from 2 to 30%, preferably in the range from 5 to 20%, of the weight fraction of aluminum contained or, if no aluminum occurs, manganese. The Sr content is in particular 0.15 to 4% by weight, preferably 0.2 to 1.5% by weight. The proportion of Sr can be partially replaced by Ca.

The object is also achieved with a corresponding process in which the magnesium alloy has a Zr content in the range from 0.1 to 10% by weight and, after extrusion, an elongation at break of at least 18%, a compressive strength of at least 300 MPa and impact energy measured at least 20 J on unslotted samples. The Zr content is in particular 0.15 to 6% by weight, preferably 0.2 to 3% by weight, particularly preferably 0.3 to 1.5% by weight. The object is also achieved with a corresponding process in which the magnesium alloy contains at least one rare earth element SE including La and Y in the range of 0.1 to 10% by weight in total and, after extrusion, has an elongation at break of at least 18% Compressive strength of at least 300 MPa and an impact work measured on notched samples of at least 50 J, the total content of rare earth elements in alloys with lithium is only up to 1 wt .-%. The total content of SE in alloys with lithium is in particular 0.15 to 0.9% by weight, preferably 0.2 to 0.8% by weight, particularly preferably 0.3 to 0.75% by weight. In the case of magnesium alloys without the addition of lithium, the total content of rare earth elements is in particular 0.15 to 8% by weight, preferably 0.2 to 6% by weight, particularly preferably 0.3 to 4% by weight, very particularly preferably 0, 4 to 3% by weight.

It has been shown that the modification of grain sizes and phase distributions by alloying with accompanying elements such as lithium, zirconium, rare earth elements SE such as e.g. Cerium, praseodymium, neodymium, samarium, gadolinium, ytterbium, yttrium and lanthanum or their mixtures or the alkaline earth metals - in particular Ca, Sr, Ba - is helpful in producing significantly stronger and / or more ductile magnesium alloys. In particular, the addition of lithium, calcium, strontium, zirconium or at least one rare earth element including yttrium and lanthanum has proven to be beneficial for the further development of magnesium alloys.

The object is also achieved with a method for producing a magnesium alloy with high ductility, among others. by extrusion, which is characterized in that the alloy is dynamically recrystallized during extrusion, in that it contains additions or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0 , 05 wt .-% Fe and up to 0.005 wt .-% Ni may contain that it is a magnesium alloy based on AM, AS, EM, EZ, MA, ME, SA, ZA or ZE and that after extrusion a Elongation at break of at least 17.5%, a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 45 J.

The object is also achieved with a corresponding process in which the magnesium alloy based on AZ with at least one addition of Ca, Sr, Li, SE or / and Zr is in each case at least 0.1% by weight and in which it is after extrusion a Elongation at break of at least 17.5%, a compressive strength of at least 350 MPa and an impact energy measured on notched specimens of at least 50 J. The

The proportion by weight of the respective additive can be in particular 0.15 to 6% by weight, preferably 0.2 to 4% by weight, particularly preferably 0.25 to 2% by weight.

In addition, other additions can occur, preferably those that are dynamic

Reinstallation behavior and affect the graininess.

The object is also achieved with a corresponding process in which the magnesium alloy based on MN contains at least 1% by weight of Mn and with the addition of Ca, Sr, Li, SE or / and Zr in each case at least 0.1% by weight. % and in which, after extrusion, it has an elongation at break of at least 15%, a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 20 J. The Mn content is preferably at least 1.3% by weight. The proportion by weight of the particular additive can be in particular 0.15 to 6% by weight, preferably 0.2 to 4% by weight, particularly preferably 0.25 to 2% by weight .-%. In addition, other additives can occur, preferably those that influence the dynamic reinstallation behavior.

The object is also achieved with a corresponding method in which the magnesium alloy is based on MZ or ZM, which can contain an addition of in particular Ca, Sr, Li, SE or / and Zr in each case of at least 0.1% by weight, and in which, after extrusion, it has an elongation at break of at least 15%, a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 40 J. After extrusion, the alloy preferably has a plastic portion of the stress determined in the tensile test according to the stress-strain diagram from the difference between tensile stress and yield stress of at least 40 MPa.

The remaining contents of the chemical composition mentioned consist predominantly or essentially of magnesium. The contents of cadmium interfere with processing only because of their toxicity, but are otherwise of particular advantage in terms of formability. Trace levels of copper, iron and nickel should be as low as possible, since they have a negative effect on processing and / or material properties. It has been shown that high extrusion speeds can usually be achieved with the ductile magnesium alloys. No efforts have yet been made in the tests to achieve the highest extrusion speeds, but rather there is clear potential to be able to achieve significantly higher speeds. The degree of forming characterizes the degree of cross-sectional reduction during forming and is given as the natural logarithm of the ratio of the starting cross-section to the cross-section after the forming. It is therefore often correlated with the degree of dynamic recrystallization, whereby if possible no stronger growth of individual grains should occur, but a fine-grained structure is sought, which requires a high ductility in some magnesium alloys. The more stable the structure of a magnesium alloy, the more fine-grained the structure will remain during forming. Furthermore, it has been found that the degree of deformation is advantageously at least 1.5, preferably at least 2, particularly preferably at least 2.5. With a degree of shaping of less than 1.5, the dynamic recrystallization during shaping is quite low. A degree of deformation of 3.5 or more could also have been 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 limited above all by the decreasing quality of the extruded profiles.

It is necessary for the magnesium alloy to be selected from the group of magnesium alloys which are given a higher ductility due to the dynamic recrystallization and fine grain. The dynamic recrystallization and structural change from the preformed or compacted shaped body to the finished semi-finished product, component or composite will often not only be caused by the extrusion and the associated thermal or mechanical influences, but they are preferably carried out essentially or even mainly during the extrusion.

The object is finally achieved with a semifinished product made of a magnesium alloy or with a component made therefrom or with a composite or with a composite with such a semifinished product or component which was produced according to the invention. The semi-finished 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, AS, AZ, EZ, MA, SA, ZA or ZE with added lithium, EM, EZ, ME, MN, MZ, ZE and ZM containing at least one rare earth element AM, AS, AZ, MA, MN, MZ, SA, ZA or ZM with calcium or / and strontium addition or EZ, MN or ZE with zirconium addition.

For the purposes of this application, semi-finished products are understood to be shaped bodies which have not yet been completed and are ready for use for their respective application. On the other hand, components are those which are suitable for the intended purpose. However, both terms flow smoothly into one another, since the same molded body can be a semi-finished product for one purpose, but can already be a component for the other. Furthermore, for reasons of language simplification, there is no strict distinction between semi-finished product and component throughout the text or both mentioned at the same time or only spoken of magnesium alloy, although both can be meant.

The semi-finished products made of magnesium alloys according to the invention or the components or composites made therefrom or used therewith 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, floor, lid, tank elements, tank flaps, holders , Sockets, supports, angles, hollow profiles, pipes, deformation elements, crash elements, crash absorbers, impact dampers, impact shields, impact supports, small parts, as welded profile construction, for the vehicle body, for seat, window and / or door frames, as semi-finished products, components or composites on or in the automobile or airplane.

Process for the production of extruded profiles:

The magnesium alloys, in particular the lithium or calcium, strontium, zirconium and / or magnesium alloys containing at least one rare earth element, which can be formed according to the invention by extrusion, are described in detail in two patent applications filed on the same day by the same applicant; those registrations are considered to be fully included in this registration by name. 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.

A 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 two main options for the production of bolts for extrusion:

In the first method, a bolt with a very large diameter can be cast, which can then be pressed using a high-performance extrusion press into round boices 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 machining allowance. However, care must be taken to ensure that there are no major segregations that are not or only insufficiently compensated for by long homogenization times. Otherwise, the consequences could be poor compressibility and a greater spread of the mechanical properties, in particular the ductility.

The cast bolts can first be homogenized by heat treatment depending on the alloy composition at, for example, 350 ° C. in the range from 6 h to 12 h in order to eliminate segregations in the structure, to improve the heterogeneous structure in some cases and to increase the pressability. Then the homogenized bolts can be machined to the required dimensions. Segregations can lead to uneven deformation and, in the case of critical extrusion conditions, to cracks or local melting, which can result in poor surface qualities. If the bolts are not homogenized well, an unnecessarily high compression pressure is required during extrusion. The homogenized bolts are then prepared for extrusion.

The extrusion of the magnesium alloys can be carried out in the same extrusion plants that are used for the extrusion of aluminum alloys, both via direct and indirect extrusion. The deformation behavior must only be specifically taken into account when designing the mold (die). Sharp-edged inlets, such as those used with aluminum alloys, should be avoided with magnesium alloys, otherwise there is a risk of surface cracks. In many cases e.g. an inlet angle of approx. 50 ° is used for matrices of round profiles for magnesium alloys. A round profile was used in the tests.

The most important parameter besides the extrusion temperature is the extrusion speed, because it significantly influences the properties and the surface quality of the extrusion profiles. A high pressure also requires a high extrusion speed, which is sought for economic reasons. A high extrusion speed is usually associated with an even better surface quality. The extrusion speed is very dependent on the geometry of the strand. The pressability of the magnesium alloys is comparable to that of hard-pressed aluminum alloys. A high extrusion speed is desirable from an economic point of view, but is not always feasible with magnesium alloys. In addition, cracks and burning of the magnesium alloy must not occur at particularly high extrusion speeds. The degree of deformation is also of great importance. It goes along with the change in the structure. A high degree of forming is therefore an advantage. At high degrees of deformation, however, local melting must not occur. Despite certain knowledge of the extrusion of magnesium alloys, the parameters for the extrusion usually have to be worked out in detail, since there is a great 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 other extruded modified alloys according to the invention are not greatly improved by this heat treatment. The semi-finished products can optionally be straightened, for example further deformed by bending, pressing, pressure rolling, stretch drawing, deep drawing, hydroforming or roll profiling, for example by cutting, drilling, milling, grinding, lapping, polishing, joining and / or for example by etching, pickling, Painting or other coating are surface treated. With the alloys according to the invention, solid and extruded profiles in simple or complicated cross sections can be extruded without problems. In this case, semi-finished products can be improved or components can be produced from them or, if necessary, from them.

When joining, the semi-finished product or the component made therefrom or with it can be produced using at least one low-heat joining process, e.g. Gluing, riveting, inserting, pressing on, pressing in, clinching, folding, shrinking or screwing and / or at least one heat-generating joining process such as e.g. Composite casting, composite forging, composite extrusion, composite rolling, soldering or welding, in particular beam welding or fusion welding, are connected with a similar or different type of semi-finished product or component. The different semi-finished product or component can also consist essentially of a magnesium alloy or of another alloy or also of a non-metallic material. It can have the same or a different geometry as the semi-finished product or component according to the invention. The joining process can be used in particular to produce a housing, an apparatus, a system, a profile construction and / or a cladding from several elements.

Examples:

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

In the alloy designations used, A AI, E denotes at least one rare earth element SE, with Y also being counted among the rare earth elements, M or MN Mn, S Si and Z Zn - usually with content in% by weight, unless stated otherwise. In the case of generally used alloy specifications, such as AZ31, the numbers, as is customary for the respective alloy, only indicate amounts of the order of magnitude which can vary to a relatively wide extent, as is customary in the industry. In addition, at the starting alloy used in the examples and the modified AZ-based alloys produced therewith 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 earth element-containing master alloy 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, since 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 brought to a length of 120 mm. The bolts were then subjected to homogenization treatment in e.g. Exposed to 350 ° C for 4 h or 12 h to remove segregations in the structure and to increase the pressability. Segregations can lead to uneven deformation and, under critical extrusion conditions, to cracks or local melting, which can lead to poor surface qualities. If the bolts are not homogenized well, an unnecessarily high compression pressure is required during extrusion. The homogenized bolts were then well prepared for extrusion.

The homogenized bolts were then heated to the respective extrusion temperature, warmed through and extruded in a 400 t hollow press using the direct extrusion process. The temperature of the billet is the temperature that the billet has when it enters the extrusion press. The appropriate tests were carried out in systematic preliminary tests on the AZ31 reference alloy

Extrusion parameters selected; The mechanical properties and the average grain sizes were determined on the extruded samples (Tables 1 and 2).

The results of the preliminary tests essentially determined the test parameters of the subsequent tests.

During the actual tests, several of the manufacturing parameters were varied systematically (Tables 3e / f and 4e / f). On the one hand the die diameter was varied and the die speed and extrusion temperature were kept constant, on the other hand the die geometry was kept constant and the die speed was varied and finally the extrusion temperature was varied depending on the alloy. The ram speed and the extrusion ratio gave the extrusion speed. With the help of such a parameter matrix, an assessment of the influence of different forming conditions was possible.

All alloys, both the starting alloys and the alloys modified by additives, could easily be formed in a wide range of temperatures, extrusion speeds and extrusion ratios. The bolts showed good compressibility with a large scope in terms of pressing force and pressing speed. The extrusion speed has not yet been pushed to the highest possible speeds in the tests and can therefore generally be increased significantly. The lower extrusion temperature is due to the insufficient plastic deformability below a temperature in the range of about 200 to 220 ° C, the upper extrusion temperature is limited by the proximity to the eutectic temperature and possibly by the first formation of parts of a molten phase.

Depending on the extrusion conditions, there were differences in the structure of the samples despite the same alloy composition. The extrusion pressures that occurred varied depending on the alloy used and the extrusion parameters set. In general, dynamic recrystallization occurred during extrusion, which led to different average grain sizes depending on the extrusion parameters and the alloy composition. 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 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, AS, AZ, EZ, MA, SA, ZA or ZE with lithium addition, EM, EZ, ME, MN, MZ , ZE and ZM with a content of at least one rare earth element AM, AZ, MA, MN, MZ, ZA or ZM with calcium or / and strontium addition or EZ, MN or ZE with zirconium addition.

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

Finally, the course of the extrusion, which characterizes the course of the extrusion in the force-displacement diagram, varied differently than expected for the alloys AZ, AZÜ3.6 and AZü ^' 6.8 with increasing lithium content: poorer behavior was found with a small addition of lithium than without or with a higher lithium content. Some of the lithium-containing alloys showed an unexpectedly strong dependence of the material properties on the type of heat treatment when the lithium content was high.

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 _mi yield strength = yield strength R _P0 , ₂ and elongation at break A or, in some cases, the constriction of the fracture in the tensile test at a tensile speed of 0.5 mm / min. In the compression test, values of the compressive strength R _Dm , compression limit Roo. ₂ and compression A _{D obtained} at a printing speed of 0.5 mm / min. The beginning of plastic deformation (expansion or Compression limit) was determined graphically. Brinell hardness measurements were also carried out

DIN 50351 carried out. All measurements took place at room temperature. The results of the mechanical determinations are in Tables 3a-c and 4a-c and those of

Structural studies compiled in Tables 3d and 4d.

Grindings were produced on selected samples, which were assessed with regard to average grain size, structural inhomogeneities and the type and distribution of the phases separated out. This evaluation was used to further optimize the manufacturing and processing parameters.

The variation of the extrusion parameters had a different influence on the property profile of the extruded magnesium materials. Trends in the material properties of the different alloys depending on the manufacturing parameters can be seen in Tables 3e / f and 4e / f.

The measurement results of the Brinell hardness determinations made no special statements possible. The Brinell hardness of the extruded samples was found to be 7 to 22% greater than that of the cast samples. The hardness increased with the aluminum content.

A) Li-Haltiqe magnesium alloys:

Production of the bolts: casting in tubular molds at a casting temperature of 680 to 720 ° C to 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 heating 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, a recipient temperature in the range of 180 to 259 ° C, a die diameter in the range of 15 to 18 mm, a compression ratio A / Ao in the range of 16.9 to 24.3, a degree of deformation φ was at a recipient diameter of 74 mm = ln (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 compression pressure at the start of extrusion in the range from 15.2 to 24.3 MPa and a compression pressure at the end of 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 the extrusion parameters on the material properties of the lithium-containing alloys and their undoped base alloys was limited. It was particularly low in tensile strength and increased somewhat over the elongation at break and compressive strength up to the impact work.

The extruded AM20U3.6 alloy sometimes had higher mechanical properties than the extruded AM20 alloy (Tables 3a / c). As with the other extruded alloys, the addition of lithium led to a very strong increase in impact work. The extruded AM20 alloy had a very high elastic and a comparatively very low plastic part of the tension in the extruded state (Table 3b). The corresponding plastic portion doubled due to the addition of lithium.

The alloy AZ31U3.6 was not characterized in the cast state in the tensile test, since the porosity of the samples was still somewhat too high to allow characteristic statements. In the extruded state, this alloy had the highest compressive strength values. In the case of AZ31 alloyed with lithium, significantly higher toughness values were determined on notched impact specimens and significantly higher elongations at break than on the associated samples not alloyed with lithium, the highest values occurring with the essentially two-phase AZ31U12.3 alloy. In contrast, the tensile strength decreased with the lithium content. The compressive strength was in the cast state proportional to the lithium content, but the highest in extruded samples at medium lithium contents. Among the alloys in the as-cast state, the AZ31Li6.8 alloy showed an astonishingly high mean yield strength of 122 MPa. The deformability of the base grid of the AZ31 was increased by the addition of lithium and the possibly modified excretion phase. The AZ31U6.8 alloy showed a lower tensile and compressive strength than the AZ31U3.6 alloy, but a high compression limit and high elongation at break. The addition of lithium improved the formability. This had an effect on the lithium-containing alloys and their starting alloys

Stress under pressure differs from that under tension: In contrast to tensile strength, the compressive strength and in some cases also the compression limit increased from AZ31 with the lithium content to AZ31 L.3.6 alloy. Due to its high lithium content, the alloy AZ31 U6.8 had 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 ZE10 alloy had a very low elastic component, but an almost average high plastic component of the stress. The elastic content could be increased significantly by adding lithium. On the other hand, the ZE10 alloy gained an extraordinarily high elastic part of the tension during extrusion, while the plastic part remained approximately constant. With the ZE10 and ZE10U3.7 alloys, all mechanical properties of samples in the as-cast state with the lithium content increased dramatically. In the corresponding extruded samples, the mechanical properties, with the exception of tensile strength and yield strength, increased significantly with the lithium content. The alloy ZE10U3.7 showed the highest values of the impact work among the examined lithium-containing magnesium alloys, whereby due to crash tests on deformation elements from the invention

Magnesium alloys are assumed that the alloy MgLi15.5AI2.5Zn0.8 should have even higher values of impact energy and notched impact energy than the alloy ZE10U3.7. Up to 140 J were measured on individual samples of the ZE10U3.7 alloy; other samples were taken through the abutment of the testing machine without breaking 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 the lithium-containing samples. The impact energy for the lithium-containing magnesium alloys with a degree of deformation φ of 2.83 was often about 30 to 65% higher than for φ = 3.06 (Table 3f). With lower degrees of deformation and thus with smaller compression ratios, the impact energy was much higher. This tendency did not occur or only weakly in the samples from unmodified starting alloys and in the samples alloyed with Ca or Zr. 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 Comparison to the alloys AM20 + 12at% Li, AZ31 + 21at% ü and ZE10 + 12at% Li, where the flow started at about 12.5 MPa, but also a more favorable, lower pressure was determined after a longer path.

B) Ca, Sr, SE, and / or Zr-containing magnesium alloys:

Casting the bolts: The melt was kept and cast at a temperature in the range of 780 to 820 ° C, once also at 750 ° C. Depending on the test, the mold had a diameter of 90 or 110 mm and a mold temperature in the range from 80 to 320 ° C. The element contents achieved were checked spectroscopically.

The castings were homogenized at 350 ° C. over 12 h. As a rule, bolts of 70 mm in diameter and 120 mm in length were produced; for 6 samples of the alloy AZ31CaO, 3, however, a diameter of 74 mm was chosen. Depending on the sample, an extrusion temperature in the range from 200 to 450 ° C. and a time for heating and soaking in the range from 60 to 150 min were set.

Extrusion: Preliminary tests were carried out with AZ31 alloy in a 400 t extrusion press with direct extrusion (Tables 1 and 2). With a recipient diameter of 74 mm, a wide range of parameters could be successfully examined. The preliminary tests allowed the test parameters to be defined.

The specific extrusion tests were carried out in a 400 t extrusion press with direct extrusion. Extrusion temperature: 340 ° C, 365 ° C and 390 ° C respectively after 1 hour of heating and warming the bolt. Press dies with a diameter of 15, 16 or 18 mm and a compression ratio of 1:24.3, 1:21, 4 and 1:16.9 were predominantly used. The pressing speed was 3.8 - 4.5, 5.0 - 5.5, 5.8 - 6.5 and 9.5 - 10 m / min. Only a small part of the extrusion tests are shown in Table 4f. Depending on the sample, a recipient diameter of 74 mm, a recipient temperature in the range from 250 to 380 ° C., a die diameter in the range from 14 to 18 mm, a press ratio A Ao in the range from 16.9 to 27.9, a degree of deformation φ = ln (AJA) im Range from 2.8 to 3.3, a punch speed in the range from 145 to 508 mm / min, an extrusion speed in the range from 3.2 to 10.8 m / min, a pressure at the start of extrusion in the range of 8.7 to 23.5 MPa and a compression pressure at the end of the extrusion in the range from 7.2 to 16.5 MPa and once from 23.3 MPa.

The parameter spectrum showed a good compressibility with a large scope in terms of pressing force and pressing speed. The structure and the elongation at break correlated with the deformation parameters. Comparatively high strength values were achieved.

The extrusion pressures that occurred varied in a wide range depending on the alloy used and the parameters set. The final pressures reached were for alloys without Ca, Sr, SE or Zr addition in the range around 10 ± 2 MPa at extrusion temperatures above 300 ° C and for Ca, Sr, SE or Zr-containing alloys by up to 4 MPa higher. The reason for the higher extrusion pressures and thus for the increased deformation resistance of magnesium alloys with Ca, Sr, SE or Zr addition is a higher proportion of stable precipitates than with magnesium alloys without this addition. For lower temperatures, somewhat higher extrusion pressures were generally determined.

In the case of the extruded (= extruded) alloy AM50, the tensile strength was up to 287 MPa, the compressive strength up to 365 MPa, the elongation at break up to 21.6% and the impact energy of notched specimens up to 85 J ( Tables 4a / c). All of these material properties were therefore significantly higher than those determined on samples in the cast state.

In the case of the extruded alloy AM20Ca0.2 and AM50Ca0.5, compared to the extruded alloy AM20 and AM50, the mechanical and compression tests showed higher mechanical properties with a comparably high ductility, and in the case of the low aluminum alloys, the tensile tests. Since the extruded samples examined did not yet have the best structural homogeneity, here even better properties can be achieved. For the extruded alloy

AZ31Ca0.3 or AS41Ca0.4, the results of the compressive strength were higher than for the extruded AZ31 or AS41 alloy. The highest determined compressive strengths occurred with these Ca-modified alloys. In the case of extruded alloys

AM50 and AZ31 trended the mean grain sizes with the extrusion temperature e.g. in the range of 6 to 12 μm or 3.5 to 10 μm. In the case of the alloy AM50CaO.5, the average grain size was in the range from 4.5 to 9 μm and thus smaller due to the addition of Ca, the average grain sizes also increasing somewhat in proportion to the extrusion temperature.

In the case of the extruded ME10 alloy, the highest values for the tensile tests with the average tensile strength were up to 336 MPa and the average yield strength at values up to 327 MPa. The cast ME10 alloy showed a very high plastic part of the stress, while the ratio of the elastic to the plastic part was reversed during extrusion and led to opposite extreme values (Table 4b). Very small average grain sizes in the range from 3 to 5 μm occurred.

With the extruded alloy MN150Ca0.2 there was a very strong increase in most mechanical properties compared to the extruded alloy MN150. The addition of Zr0.7 to the extruded starting alloy MN150 had little effect.

Lower mechanical properties were determined for the extruded ZE10 alloy, but these varied greatly with the temperature, so that even better mechanical properties can be achieved with an even higher temperature: The properties of the ZE10 alloy are significantly influenced by the rare earths and can the variation of the rare earth elements including yttrium and their contents can be further optimized. Average grain sizes in the range from 6.5 to 13 μm occurred in the ZE10 alloy, which increased again with the extrusion temperature; however, this alloy heated relatively strongly with increasing extrusion speed, which also led to somewhat larger average grain sizes at higher extrusion speed. The zirconium addition of the modified ZE10ZrO, 7 alloy resulted in much higher strengths than the ZE10 extruded starting alloy. She pointed like that additionally extruded alloy containing Zr0.7 has very high values of elongation at break and notch impact energy. When cooling aluminum-free melts containing zirconium, heterogeneous nucleation could start, which led to a particularly fine structure due to grain boundary pinning. However, due to the inhomogeneous distribution of the zirconium-containing phase, the impact work on ungrooved samples had decreased slightly in comparison to the samples of the ZE10 alloy. The zirconium additive stabilized the structure of the extruded ZE10ZrO.7 alloy. During extrusion, microstructures with average grain sizes in the range of 2.2 to 4.5 μm were created. These small grain sizes were created over a wide range of extrusion parameters. The slight variation in grain size depending on the extrusion parameters was striking with this alloy.

Adding RE0.7 to the extruded ZM21 alloy had little effect on the mechanical properties.

It has been found that the trend of the Hall-Petch relationship is also valid for the magnesium alloys according to the invention, according to which the mechanical properties are improved with smaller grain sizes. In many cases, this applies above all to tensile and compressive strength, but also in principle to elongation at break and impact work.

Magnesium alloys in particular were found to be suitable, in which a Ca content in the range of approximately 0.05 to 0.2% by weight Ca was added to each 1% by weight Al present in order to eliminate the Al ₂ Ca phase to enable. The phase AI ₂ Ca proved to be more temperature stable than the phase Mg ₁₇ AI ₁₂ and was therefore able to hinder the grain growth during extrusion better than the phase Mg _i7 AI ₁₂ . The precipitation phase Mg Si also hindered the grain growth during extrusion better than the phase Mg ₁₇ Alι ₂ . The addition of Ca to Al-free alloys led to the formation of Mg ₂ Ca or CasZn _∑ precipitates. It was found that the phase Mgι ₇ AI ₁₂ , which normally appears in the case of aluminum alloys containing magnesium, does cause somewhat increased strength, but is also responsible for a lower elongation at break. Since this phase is even more brittle than the pure hexagonal Mg phase, larger contents of Mgι ₇ AI ₂ should be avoided. Table 1: 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

Table 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

Tables 3 and 4 mean "casting" = material in the as-cast state and "extr." = Casting material which was subsequently formed by homogenization and extrusion (extrusion), "B" = example according to the invention and "NB" = comparative example according to the prior art.

Table 3a: 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.

Table 3b: 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.

Table 3c: Highest mean values of the measurement results of the mechanical properties selected from various individual samples of the lithium-containing magnesium alloys

Table 3d: 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)

Table 3e: Process parameters and average grain size for the lithium-containing magnesium alloys and their starting alloys:

Table 3f: Manufacturing parameters and material properties of individually selected extruded samples of the lithium-containing alloys and their starting alloys: bolts - length 120 mm, diameter 70 mm; Mold diameter usually 90 mm.

Table 4a: Average values of the measurement results of the mechanical tests on various samples of the CA. Magnesium alloys containing Sr, SE and Zr and their starting alloys:

Table 4b: Average values of the values that can be determined from the stress-strain diagram of the tensile tests for modified lithium-free magnesium alloys and their starting alloys. F = R _P02 = yield stress = elastic part of the stress. V = yield strength ratio = F. Z. R _m = tension Z = elastic + plastic part of the tension.

Table 4c: Highest mean values of the measurement results of the mechanical properties selected from various individual samples of the modified magnesium alloys:

B 25 ZM21Zt0.7 extr. 254 193 16.9 nbnbnb 10.7 62.0

Table 4d: Mainly occurring grain sizes in the as-cast state after homogenization at 350 ° C for 4 h or after extrusion with the modified lithium-free magnesium alloys and their starting alloys.

Table 4e: Process parameters for various samples of the modified lithium-free magnesium alloys and their starting alloys.

Table 4f: Manufacturing parameters and material properties of individually selected extruded samples of the modified lithium-free alloys and their starting alloys: length of bolt 120 mm, diameter of bolt 70 mm. Mold diameter usually 90 mm.

C!

Claims

PATENT CLAIMS

1.Method for producing a high ductility magnesium alloy, etc. by extrusion, characterized in that the alloy is extruded with a degree of deformation of at least 1.5, that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain Li in the range from 0.5 to 20% by weight, in addition to the contents of Mg and Li and optionally AI or / and Si contains at least one further chemical element of at least 0.1% by weight and that after extrusion they measured an elongation at break of at least 20%, a compressive strength of at least 300 MPa and an impact energy on notched specimens of at least 70 J.

2.Method for producing a high ductility magnesium alloy, etc. by extrusion, characterized in that the alloy is extruded with a degree of deformation of at least 1.5, that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain Ca in the range from 0.1 to 6% by weight and, after extrusion, an elongation at break of at least 16% , has a compressive strength of at least 300 MPa and an impact energy measured on ungraded samples of at least 50 J.

3. A process for producing a magnesium alloy of high ductility, inter alia by extrusion, characterized in that the alloy is extruded with a degree of deformation of at least 1.5, that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni may contain Sr in the range from 0.1 to 6% by weight and, after extrusion, has an elongation at break of at least 17.5% and an impact energy measured on notched specimens of at least 50J.

4.Procedure for producing a high ductility magnesium alloy, etc. by extrusion, characterized in that the alloy is extruded with a degree of deformation of at least 1.5, that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain Zr in the range from 0.1 to 10% by weight and, after extrusion, an elongation at break of at least 18% , has a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 20 J.

5.Method for producing a magnesium ductility of high ductility and others by extrusion, characterized in that the alloy is extruded with a degree of deformation of at least 1.5, that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight of Ni can contain at least one rare earth element SE including La and Y in the range from 0.1 to 10% by weight in total and after the extrusion has an elongation at break of at least 18%, a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 50 J, the total content of rare earth elements in lithium-containing alloys being only up to 1% by weight.

6.Method for producing a high ductility magnesium alloy, etc. by extrusion, characterized in that the alloy is dynamically recrystallized during extrusion, in that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 Wt .-% Fe and up to 0.005 wt .-% Ni may contain that it is a magnesium alloy based on AM, AS, EM, EZ, MA, ME, SA, ZA or ZE and that it has an elongation at break after extrusion at least 17.5%, a compressive strength of at least 300 MPa and an impact energy measured on notched specimens of at least 45 J.

7. A method for producing a magnesium alloy of high ductility, inter alia by extrusion, characterized in that the alloy during extrusion it is dynamically recrystallized to contain additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and up to 0.005% by weight. -% Ni may contain that it is a magnesium alloy based on AZ with at least one addition of Ca, Sr, Li, SE or / and Zr of at least 0.1 wt .-%, and that it has an elongation at break after extrusion has at least 17.5%, a compressive strength of at least 350 MPa and an impact energy measured on notched specimens of at least 50 J.

8.Procedure for producing a high ductility magnesium alloy, etc. by extrusion, characterized in that the alloy is dynamically recrystallized during extrusion, in that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 % By weight of Fe and up to 0.005% by weight of Ni can contain a magnesium alloy based on MN with at least 1% by weight of Mn and with the addition of Ca, Sr, Li, SE or / and Zr in each case is at least 0.1% by weight and that, after extrusion, it has an elongation at break of at least 15%, a compressive strength of at least 300 MPa, and an impact energy measured on notched specimens of at least 20J.

9.Method for producing a high ductility magnesium alloy, etc. by extrusion, characterized in that the alloy is dynamically recrystallized during extrusion, in that it contains additives or traces of Cd less than 1.8% by weight and traces of up to 0.1% by weight of Cu, up to 0.05 % By weight of Fe and up to 0.005% by weight of Ni can be such that it is a magnesium alloy based on MZ or ZM, which in particular contains Ca, Sr, Li, SE or / and Zr in each case at least 0.1 Can contain wt .-%, and that after extrusion it has an elongation at break of at least 15%, a compressive strength of at least 300 MPa and an impact work measured on unc notched samples of at least 40 J.

10. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it has a tensile strength of at least 200 MPa after extrusion.

11. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it has a compressive strength of at least 300 MPa after the extrusion.

12. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it has a plastic portion of the stress determined after the extrusion in the tensile test according to the stress-strain diagram from the difference between tensile stress and yield stress of at least 40 MPa.

13. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the extruded articles, in particular bolts, are homogenized at temperatures in the range from 330 to 380 ° C for 2 to 24 h.

14. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is extruded at a degree of deformation of at least 2.

15. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is extruded at an extrusion speed in the range from 0.5 to 20 m / min, preferably at 1 to 18 m / min, particularly preferably at 3 to 16 m / min, very particularly preferably at 5 to 15 m / min.

16. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is heat-treated or aged after extrusion at temperatures in the range from 80 to 250 ° C, preferably at 100 to 150 ° C.

17. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that it is subsequently shaped again or is subsequently shaped.

18. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the semi-finished product or the component made from or with the semi-finished product is directed, e.g. is further deformed, processed, joined and / or surface treated by bending, pressing, pressure rolling, stretch drawing, deep drawing, hydroforming or roll profiling.

19. A method for producing a magnesium alloy according to at least one of the preceding claims, characterized in that the semi-finished product or the component produced therefrom or with it by at least one low-heat joining process such as e.g. Gluing, riveting, inserting, pressing on, pressing in, clinching, folding, shrinking or screwing and / or at least one heat-generating joining process such as e.g. Composite casting, composite forging, composite extrusion, composite rolling, soldering or welding, in particular beam welding or fusion welding, is connected to a similar or different type of semi-finished product or component.

20. Semi-finished product made of a magnesium alloy or a component or composite made therefrom or composite with such a semi-finished product or component, characterized in that it was produced according to at least one of the preceding claims.

21. Use of a magnesium alloy, produced according to at least one of claims 1 to 19 as a frame element, element of vehicle cell or vehicle outer skin, vehicle cell or vehicle outer skin, cockpit support, cockpit skin, housing, base element, base, cover, tank element, tank flap, holder, support, support, Angle, hollow profile, tube, deformation element, crash element, crash absorber, impact damper, impact shield, impact beam, small part, as a welded profile construction, for the vehicle body, for seat, window or / and door frames, as a semi-finished product, component or composite on or in the automobile or aircraft.

22. Use of a semi-finished product made of a magnesium alloy, a component made therefrom or with it and / or a composite with at least one such a semi-finished product and / or component as a frame element, element of the vehicle cell or vehicle outer skin, as a vehicle cell or vehicle outer skin, cockpit support, cockpit skin, housing, floor element, floor, cover, tank element, tank flap, holder, support, support, angle, hollow profile, tube, deformation element, Crash element, crash absorber, impact absorber, impact shield, impact carrier, small part, as a welded profile construction, for the vehicle body, for seat, window or / and door frames, as a semi-finished product, component or composite on or in the automobile or aircraft.