EP1171643B1 - Highly ductile magnesium alloys, method for producing them and use of the same - Google Patents

Abstract

The invention relates to a magnesium alloy which can contain added quantities or traces of Cd of less than 1.8 wt. % and traces of Cu of up to 0.1 wt. %, Fe of up to 0.05 wt. % and up to 0.005 wt. % Ni. The invention is characterised in that the alloy has an AM, AS, AZ31, EM, EZ, MA, ME, MN, MZ, SA, ZE or ZM base which optionally contains quantities of Ca, Sr, Zr or/and at least one rare-earth element, including Y and La, totalling 0.1 to 12 wt. %. The invention also relates to a method for producing a magnesium alloy of this type. According to this method, a moulded or compacted form is produced and is dynamically recrystallized by forming and/or deforming. The invention also relates to a semi-finished product consisting of a magnesium alloy or a component consisting of or produced with the same or a composite structure with a semi-finished product or component of this type.

Description

The invention relates to magnesium alloys of high ductility, processes for their Production and their use, in particular those containing calcium and / or strontium Magnesium alloys.

Because of their very low density, magnesium alloys in the range from 1.2 to 1.9 g / cm ^{3 are} of great interest as metallic construction materials, above all 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-liter motor vehicle, to a particular extent. Among the manufacturing processes, die-casting and shaping, extrusion, forging, rolling and possibly subsequent shaping 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 with 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 generally for components and semi-finished products in automobiles and aircraft, for which is increasingly in need.

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 impact 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 from them or with 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 the higher these properties are in the cast or powder-compacted state are usually also in the deformed state. A higher ductility can do that Forming or reshaping, especially extrusion, easier. Therefore an elongation at break of at least 10% is also for the following ones Manufacturing steps for elements made of magnesium alloys helpful. Therefore, from tensile strength of at least 150 MPa measured for several reasons Room temperature, preferably at least 180 MPa, or an elongation at break of at least 18%, preferably at least 20%, particularly preferably of at least 25%, recommended. The elongation at break is usually commercial Common 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 Korn 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 verschlechtern.

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 Kornfeinung 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 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 main Mg phase changes from the hexagonally closest spherical packing to the body-centered cubic 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. Grain refinement is an important tool for activating further deformation systems that allow grain boundaries to slide and new flow processes at room temperature, thus improving 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 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 and AZ80, based on Mg-Zn-Zr such as ZK40 and ZK60 or based on Mg-Mn such as M1.

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%. For the ZE10 alloy in rolled and annealed dynamically recrystallized state will be 215 to 230 MPa tensile strength and 18 to 23% elongation at break specified.

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 AI10Si1Ca0.5 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.

The ductility of the samples listed in the examples, if at all, only quantified by the values of the elongation at break:

WO 89/11552 describes so-called super-plastic moldings Magnesium alloys based on ZnALSE or AlMn. The alloys were over spontaneous quenching of melt droplets obtained. The sample 5 in Table 1 said composition based on has contents of Al of 11% by weight and of Mn of 1 % By weight. It also only shows an elongation at break of 3.5%, which is comparatively low ductility, i.e. high brittleness, suggests. The highest Elongation at room temperature in all other examples is 18% and was for a magnesium alloy with the composition MgZn2Al15Nd1 was determined.

No. 5,078,962 protects magnesium alloys which contain Al, Zn, Mn, Ca or / and SE. Sample 11 of the table based on Al5Mn0.5Ca3.5 has an elongation at break of only 8%.

EP-A-0 414 620 also teaches magnesium alloys, the Al, Zn, Mn, Ca or / and SE contain. The alloys based on AlZn have significantly different compositions than AZ 31.

EP-A-0 791 662 provides information on magnesium alloys which contain Al, Mn, Ca, SE and possibly Zn contain. The alloys of the examples and comparative examples have one Elongation at break in the range from 0.3 to 6.9%.

No. 5,681,403 teaches magnesium alloys based on AlMn, which may contain SE, Ca, Cu or / and Zn contain. The diagrams show an elongation at break of less than for the alloys 12% off.

T. Ebert et al. report in Magnesium Alloys and their Applications, Eds .: B. L. Mordike and K. U. Kainer, 563ff, lectures of a conference of the same name April 28-30, 1998, in Wolfsburg, About Magnesium Alloys Made By "Spray Forming". The shown in Figure 4 mechanical room temperature properties based on AE, AS and AlCa illustrate the Direction of development towards high tensile strengths and low elongation at break. The Elongation at break is up to 11%, but 20% for the AE42 alloy.

Koushirou Hirata et al. describe the effects in Keikinzoku 47, 1997, 12, 672-678 of aluminum content and heat treatment on the tensile strength semi-solid shaped Magnesium alloys with 4 - 8% Al and possibly 2% Ca as well as with 4 - 8% Al, 1% Si and 0.5 % Approx.

US 4,675,157 protects magnesium alloys with up to 11% Al, up to 4% Zn, from 0.5 to 4% of elements selected from Si, Ge, Co, Ti and Sb, the sum of Al and Zn Is 2 to 13% and a mixed crystal phase occurs in a certain way. This Magnesium alloys were made by quenching melt droplets. The Elongation at break of various examples and comparative examples varies between 0.8 and 11%.

JP-A-09/316586 published on December 9, 1997 teaches wear and heat resistant Magnesium alloys with up to 4% SE, up to 5% Si and possibly ≤ 1% Mn, ≤ 1% Zr, ≤ 4% Ca, ≤ 10% Al, ≤ 5% Zn and ≤ 5% Ag. These alloys are characterized by high tensile strength Room temperature and at 200 ° C, but not optimized for high ductility.

EP-A-0 799 901 discloses heat-resistant magnesium alloys with good creep properties based on 2 to 6% Al and 0.5 to 4% Ca with a Ca: Al ratio of ≤ 0.8. However, the elongation at break of these samples should only be 0.8 to 7%.

US 5,071,474 carries out a process for forging magnesium alloys on the Basis of quenched melt droplets, the alloys in addition to Al and Zn Mn, Ce, Nd, Pr and Y can contain. The elongation at break of the examples and Comparative examples fluctuate between 0 and 11%.

The mechanical characteristics of magnesium alloys are disclosed in US Pat. No. 5,147,603 Basis of AlCa / Sr, Al9Zn1 and Al9Zn1Ca / Sr published. The elongation at break of the examples and comparative examples vary between 0.4 and 20%, with only the alloys Based on AlSr, AZ91 or AZ91Ca / Sr show values between 13 and 20%.

GB 831,638 describes the mechanical properties of magnesium alloys Basis of Th and Mn and, if applicable, of Zn and / or SE disclosed. The elongation at break of the Examples are only 3.5 and 4%.

JP-A-62/00348 published on July 19, 1994 teaches high-strength heat-resistant Magnesium alloys with up to 5% lanthanides and possibly ≤ 5% Ca, ≤ 1.5% Mn, ≤ 1.5 % Zr or / and contents of Ag, Al, Sc, Sr, Y or Zn. The alloys are apparently only on Tensile strength optimized at room temperature and at elevated temperature.

DE-A-42 08 504 protects machine components from a containing 2 to 8% SE Magnesium alloy, which has a high proportion of samarium and a good creep and Fatigue strength and good tensile strength at elevated temperature should. The specimens mentioned were neither reshaped nor deformed.

US 3,024,108 discloses magnesium alloys based on ZnMn, the SE and / or Th contain. The mechanical properties of the rolled samples are each for the Direction of rolling and specified transversely thereto, with averaging over all directions Elongation at break of approx. 9 to 13%.

A. Raman describes in Uses of Rare Earth Metals and Alloys in Metallurgy, Z. Metallkunde 68, 1977, 3, 163 - 172, SE-containing magnesium alloys. Even if occasionally by one Increase in ductility due to the addition of at least one rare earth element the only explicitly stated values of the elongation at break are between 2 and 8% or below Reference to JP-A-72/07973 (March 1972) for La-containing magnesium alloys at about 25%.

S. Kamado et al. report in Magnesium Alloys and their Applications, Eds .: B. L. Mordike and K. U. Kainer, 169ff, lectures of a conference of the same name April 28-30, 1998, in Wolfsburg, manufactured using magnesium alloys based on SE, Y or / and Zr, etc. by Pouring and rolling. The elongation at break was about 6 to 17% at room temperature, whereby only the alloys with 9.6% Y and 0.84% Zr and with 9.3% Gd, 4.1% Y and 0.7% Zr Values over 10% were reached.

T. Mohri et al. describe in Microstructure and mechanical properties of a Mg-4Y-3RE alloy processed by thermo-mechanical treatment in Materials Science and Engineering A257, 1998, 287-294, magnesium alloys with 4% Y, 0.41% Zr, 0.15% Li and 3.2% SE, of which 2.2% are Nd. The extruded samples showed one Elongation at room temperature of about 13% or about 20%.

WO-A-96/25529 describes magnesium alloys with a content of 2 to 6% by weight aluminum and with 0.1 to 0.8% by weight calcium. In addition to other components, the alloys can also contain up to about 0.5% by weight of manganese. These are cast alloys that are made from a magnesium-aluminum alloy and a calcium-magnesium alloy. The alloys contain the intermetallic compound Al ₂ Ca and have an increased creep resistance. Forming after casting is not intended.

Japanese patent abstract JP-A-9271919 describes heat-resistant Magnesium alloys with a content of 2 to 10 wt .-% aluminum and 1 to 10 % By weight calcium, which in addition to other elements also contains less than 2% May contain manganese. The alloys are formed from metal grains or pellets by injection molding at the liquidus temperature or by molding in the semi-melted State from a mixture between solid phase and liquid phase. It will be one Elongation at break of 14% and a tensile strength of 200 MPa are given for the products.

It was therefore the task of magnesium alloys with increased ductility and, if possible also increased energy consumption, compressive strength and toughness by choosing the one for this Propose the most likely to be effective parameters that are as low as possible Have density and also made as simple and inexpensive as possible can be.

The problem is solved with a magnesium alloy, the additives or traces of Cd less than 1.8% by weight and the traces of up to 0.1% by weight of Cu, up to 0.05% by weight of Fe and can contain up to 0.005% by weight of Ni and 0.2 to 4% by weight of Mn and 0.2 to 6 Wt .-% Ca or / and 0.1 to 6 wt .-% Sr, the remaining contents of Magnesium alloy consist of magnesium and unavoidable impurities, their compressive strength is at least 300 MPa, their impact energy measured notched specimens at least 20 J and their elongation at break measured on tensile specimens is at least 15% and it is made from high purity alloys Extrusion or forging with a degree of deformation of at least 1.5 under dynamic recrystallization and with the formation of a fine-grained structure with a average grain size of at most 25 µm.

The task is also solved with a corresponding magnesium alloy, the one Alloy based on AM (aluminum / manganese) or MA (manganese / aluminum) which is 0.5 to 10 wt .-% Al and 0.1 to 4 wt .-% Mn and 0.1 to 6 wt .-% Ca or / and Sr contains, with the remaining contents of the magnesium alloy of magnesium and unavoidable impurities, with a compressive strength of at least 320 MPa, their impact energy measured on unslotted specimens at least 40 J and their Elongation at break measured on tensile specimens is at least 16% and where it is produced is made of high purity alloys by extrusion or forging with one Degree of deformation of at least 1.5 with dynamic recrystallization and with training a fine-grained structure with an average grain size of at most 25 µm.

These magnesium alloys preferably have a plastic portion of the stress determined in the tensile test according to the stress-strain diagram from the difference of Tensile stress and yield stress of at least 40 MPa, particularly preferably of at least 60 MPa, very particularly preferably from 80 to 120 MPa.

All of these magnesium alloys can include be made by extrusion. However, there are other forming processes instead of or together with the Extrusion is an advantage, especially forging. They are preferably formed, in particular extruded and / or forged, and have a fine-grained, dynamic recrystallized structure, in particular with an average grain size of not more than 20 µm, and a precipitation phase content of not more than 5% by volume is preferred of not more than 2% by volume. You can use a structure with a medium Grain size of at most 25 microns, especially preferably of at most 15 µm, very particularly preferably of at most 8 µm. The average grain size is obtained on bevels with conventional stereometric methods certainly.

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.

The chemical 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 invention further relates to a method for producing such Magnesium alloy, in which a shaped or compacted molded body is produced and is dynamically recrystallized by shaping and / or shaping. The molded body can therefore have been produced via the melt or / and via powder. At the Forming, especially during extrusion, results in a degree of forming of at least 1.5 chosen, preferably from at least 2 or even from at least 3, to be dynamic To achieve recrystallization and a fine-grained structure. The degree of deformation characterizes the degree of cross-sectional reduction when reshaping and is considered more natural Logarithm of the ratio of the initial cross section to the cross section according to the Forming specified. It is therefore often with the degree of dynamic recrystallization correlated, where possible no stronger growth of individual grains should occur, Instead, the aim is to create a structure that is as fine-grained as possible Magnesium alloys require high ductility. The more stable the structure of one Magnesium alloy is, the more fine-grained the structure becomes or remains during the forming process. The reshaped and / or deformed shaped body can then be a semi-finished product and / or a component made from or with this semi-finished product are processed or processed. The semi-finished product or the component made from or with the semi-finished product can directed, e.g. by bending, pressing, pressure rolling, stretch drawing, deep drawing, Internal high pressure forming or roll forming further deformed, e.g. by cutting, drilling, Milling, grinding, lapping, polishing, machining, joining and / or e.g. by etching, pickling, Painting or other coating are surface treated.

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 a similar 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.

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 can be used as rims, gear housings, Steering wheel skeletons, wishbones, frame elements, elements of vehicle cells or Vehicle outer skins, vehicle cell, vehicle outer skin, cockpit support, cockpit skin, Housing, floor elements, floors, lids, tank elements, tank flaps, brackets, Supports, beams, angles, hollow profiles, pipes, deformation elements, crash elements, Crash absorbers, impact absorbers, impact shields, impact carriers, small parts such as Gears than Impellers and other types of wheels, as welded profile constructions, for the Vehicle body, for seat, window and / or door frames, as semi-finished products, components or Connections on or in the automobile or airplane.

Process for the production of extruded profiles:

The process for the production of extruded profiles from the inventive Alloys are filed on the same day by the same applicant Patent application described in detail.

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 e.g. by Extrusion, or / and forging is the production of suitable materials, e.g. in Form of blocks, bolts or slabs. For the production of bolts for There are two main options for extrusion:

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 expensive 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 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.

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 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. 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 is advantageously followed by a heat treatment. This Heat treatment is usually not of great interest since the Alloys according to the invention are usually not strong through this heat treatment be improved. If necessary, the semi-finished products can be straightened, further deformed, processed, joined or / and surface treated. With the alloys of the invention Solid and extruded profiles in simple or complicated cross sections without problems be extruded. Here, semi-finished products can be improved, components are also manufactured.

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 La and Y are also classified as rare earth elements, M or MN Mn, S Si and Z Zn - usually with content in% by weight, insofar as nothing other is noted. With commonly used alloy information such as AZ31 are only of the order of magnitude as usual for the respective alloy Levels indicated that can vary to a relatively wide extent as is customary in the industry. additionally can in the starting alloy used in the examples and the so produced 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 earth element-containing pre-alloy with a ratio of Nd to other rare earths, including yttrium of 0.92, a zirconium-containing master alloy, alloyed with 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 melt was kept and poured at a temperature in the range from 780 to 820 ° C, once at 750 ° C. The blanks required for the subsequent extrusion were cast in a cylindrical steel mold with machining allowance. 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. 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 castings were then homogenized at 350 ° C. for 12 h. By turning Bolts usually made 70 mm in diameter and 120 mm in length; with 6 samples for the AZ31Ca0.3 alloy, however, a diameter of 74 mm was chosen. The homogenized and twisted bolts were then well prepared for extrusion.

The bolts were then brought to the respective extrusion temperature in the range from 200 to Heated to 450 ° C, warmed for 60 to 150 minutes and in a 400 t horizontal press extruded. The temperature of the bolt is therefore the temperature that the bolt at Has entry into the extrusion press.

Preliminary tests were carried out with the AZ31 alloy in a 400 t extrusion press at direct Extrusion carried out (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 definition of the test parameters. In systematic preliminary tests on the AZ31 reference alloy, the appropriate extrusion parameters were selected; to the extruded samples were mechanical properties and mean Grain sizes determined (Tables 1 and 2). The results of the preliminary tests determined essentially the test parameters of the subsequent tests.

Several of the manufacturing parameters were systematically varied in the specific tests (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. 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.

In the case of the specific extrusion tests, work was also carried out in a 400 t extrusion press with direct extrusion. Extrusion temperature: 340 ° C, 365 ° C or 390 ° C each after 1 hour of heating and warming the stud. 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 3e. Depending on the sample, a recipient temperature in the range from 250 to 380 ° C., a die diameter in the range from 14 to 18 mm, a compression ratio A / A ₀ in the range from 16.9 to 27.9, and a degree of deformation were obtained with a recipient diameter of 74 mm ϕ = In (A _o / A) in the 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 pressing pressure at the start of the extrusion in the range from 8.7 to 23.5 MPa and a pressure at the end of the extrusion in the range from 7.2 to 16.5 MPa and once from 23.3 MPa.

The extrusion pressures that occurred varied depending on the alloy used and set parameters in a wide range. The final pressures reached were for Alloys without Ca, SE or Zr addition in the range around 10 ± 2 MPa Extrusion temperatures greater than 300 ° C and in the case of alloys containing Ca, SE or Zr up to 4 MPa higher. Cause for the higher extrusion pressures and thus for the increased Resistance to deformation of magnesium alloys with Ca, SE or Zr addition is a higher proportion of stable precipitates than with magnesium alloys without it Additive. For lower temperatures, extrusion pressures were generally somewhat higher determined.

All alloys, both the starting alloys and those by additives modified alloys could easily be used in a wide temperature, Form extrusion speed and extrusion ratio range. The occurred Extrusion pressures varied depending on the alloy used and the set one Strangpreßparametern. The bolts showed good compressibility with a large one Freedom in terms of pressing force and pressing speed. The lower extrusion temperature is due to the insufficient plastic deformability below a temperature in the Range of about 200 to 220 ° C conditional, the upper extrusion temperature finds its Limits by the proximity to the eutectic temperature and possibly by the first Formation of parts of a molten phase.

The extruded round profiles were processed by milling and turning into round specimens (d ₀ = 5 mm, I ₀ = 5 · d ₀ , small proportionality bar, according to DIN 50 125), pressure tests (d ₀ = 10 mm, I 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 breaking constriction BE were determined in the tensile test at a tensile speed of 0.5 mm / min. 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 average 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.

In general, dynamic recrystallization occurred during the extrusion, which in Dependence on the extrusion parameters and the alloy composition different average grain sizes. Depending on the extrusion conditions Despite the same alloy composition, there were differences in the structure of the Rehearse. The structure and the elongation at break correlated with the Deformation parameters.

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 The material properties of the modified alloys are surprisingly little dependent varied from the extrusion conditions, which is advantageous for production. Furthermore was it is surprising that the impact energy of the ZE10 alloy was so high.

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.

The tensile strength of the extruded (= extruded) alloy AM50 was at values up to 287 MPa, the compressive strength at values up to 365 MPa, the elongation at break at Values up to 21.6% and the impact work of notched specimens at values up to 85 J (Tables 3a / c). All of these material properties were therefore significantly higher than those were determined on samples in the cast state.

The extruded alloy AM20Ca0.2 and AM50Ca0.5 compared to extruded alloy AM20 or AM50 higher in compression and impact tests mechanical properties with a comparably high ductility, with the lower Alloys containing aluminum also in tensile tests. Because the examined extruded samples that have not yet had the best structural homogeneity can be found here even better properties can be achieved. For the extruded alloy AZ31Ca0.3 or AS41 Ca0.4, the results of the compressive strength were higher than for the extruded AZ31 or AS41 alloy. With these Ca-modified alloys the highest determined compressive strengths occurred. In the case of extruded alloys AM50 and AZ31 trended the mean grain sizes with the extrusion temperature e.g. in the range from 6 to 12 µm or 3.5 to 10 µm. The alloy was AM50Ca0.5 the average grain size in the range of 4.5 to 9 µm and therefore due to the addition of Ca. lower, the mean grain sizes proportional to the extrusion temperature also increased slightly.

The highest values of the tensile tests were with the extruded ME10 alloy the average tensile strength at values 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 tension, while the ratio of the elastic to the plastic component during extrusion and reversed extreme values (Table 3b). Very small average grain sizes in the range from 3 to 5 µm occurred.

The extruded alloy MN150Ca0.2 showed a very strong increase in most mechanical properties compared to the extruded alloy MN150. Adding Zr0.7 to the extruded MN150 base alloy had little effect out.

In the case of the extruded ZE10 alloy, there were fewer mechanical ones Properties determined, but these varied greatly with the temperature, so that still better mechanical properties can be achieved with an even higher temperature: The properties of the ZE10 alloy become essential from the rare earths influenced and can vary in the variation of rare earth elements including lanthanum and Yttrium and their contents can be further optimized. Occurred with the alloy ZE10 average grain sizes in the range of 6.5 to 13 microns, which again with the Extrusion temperature tend to increase; however, this alloy also warmed up increasing extrusion speed relatively strong, which at higher Extrusion speed also led to somewhat larger average grain sizes. In the extruded modified alloy ZE10Zr0.7 resulted from the Zirconium additive has much higher strength than the extruded one Starting alloy ZE10. It pointed like the extruded Zr0.7 Alloy very high values of elongation at break and impact energy. So could a heterogeneous when cooling aluminum-free zirconium-containing melts Use nucleation, which due to a grain boundary pinning to a particular fine structure. However, the striking work on unskilled specimens was due to the inhomogeneous distribution of the zirconium-containing phase in comparison. to the samples of the Alloy ZE10 partially decreased slightly. For the extruded alloy ZE14Zr0.7, the addition of zirconium stabilized the structure. It was created at Extrusion structures with average grain sizes in the range from 2.2 to 4.5 µm. This Small grain sizes were created over a wide range of extrusion parameters. At this Alloy was the small variation in grain sizes depending on the Extrusion parameters noticeable.

Adding SE0.7 or in particular Zr0.7 to the ZM21 alloy only had an effect little on the mechanical properties.

It has been found that the Hall-Petch relationship also applies to those of the invention Magnesium alloys in the trend is valid, according to the mechanical properties smaller grain sizes can be improved. In many cases, this applies above all to the train and Compressive strength, but also basically for elongation at break and impact work.

In these tests, magnesium alloys in particular were found to be suitable, in which a Ca content in the range of about 0.05 to 0.2% by weight Ca was added to each 1% by weight Al present in order to separate out the Al ₂ Ca. Phase. The Al ₂ Ca phase proved to be more temperature stable than the Mg ₁₇ Al ₁₂ phase and was therefore able to hinder the grain growth during extrusion better than the Mg ₁₇ Al ₁₂ phase. The Mg ₂ Si precipitation phase also prevented grain growth during extrusion better than the Mg ₁₇ Al ₁₂ phase. The addition of Ca to Al-free alloys led to the formation of Mg ₂ Ca or Ca ₅ Zn ₂ precipitates. It was shown that the phase Mg ₁₇ Al ₁₂ , which normally appears in magnesium alloys containing Al, does cause a 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, higher levels of Mg ₁₇ Al ₁₂ should be avoided.

The examples have shown that the magnesium alloys according to the invention are inexpensive for extrusion, but in principle, in addition or as an alternative to extrusion, they are also suitable for other types of shaping and further shaping because of their material properties. 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 strenght
R _m Stretch limit
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 medium grain diameter tensile strenght
R _m Stretch limit
R _P0.2 elongation
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

Tables 3a-f mean "casting" = material in the as-cast state and "extr." = Casting material which was subsequently formed by homogenization and extrusion (extrusion), "B" = example, "VB" = comparative example according to the prior art, example "B" according to the invention, only the alloys related to AM or MN are to be considered , 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: sample alloy Tensile test Compression test Schlagvers. BE
% R _m
MPa R _P0.2
MPa A
% R _Dm
MPa R _upset
MPa A _D
% C _G
J C _UG
J VB 10 AM20 extr. 32.5 274 230 17.9 325 129 7.8 8.6 46 B 11 AM20Ca0.2 extr. 30.9 283 233 16.6 394 168 13.9 6.8 51 VB 12 AM50 cast 14.0 178 69 11.0 338 73 26.0 6.2 13 B 13 AM50Ca0.5 extr. 30.1 287 197 18.3 373 166 15.8 7.3 66 B 13a AM50Ca1.5Sr0.2 extr. 27.6 268 186 17.8 nb nb nb 7.7 63 VB 14 AS41 extr. 19.0 292 202 14.2 355 138 9.3 5.2 52 B 15 AS41Ca0.4 extr. 18.0 275 188 13.4 406 150 16.0 4.8 51 VB 16a AZ31 extr. 33.1 282 215 17.6 342 124 8.9 10.8 65 B 17 AZ31Ca0.3 extr. 30.9 280 199 18.2 389 143 12.5 8.6 59 VB 18 ME10 cast 15.3 192 75 7.9 328 83 27.0 7.3 19 VB 19 MN150 extr. 15.2 225 177 15.2 309 119 14.1 5.1 22 B 20 MN150Ca0.2 extr. 27.3 264 242 18.3 354 194 14.6 2.5 34 Average values of the values determined from the stress-strain diagram of the tensile tests for modified 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-F
MPa Z - F
MPa Train-Z
MPa V =
Q: Z A _plast
= A% VB 10 AM20 extr. 230 44 274 0.84 17.9 B 11 AM20Ca0.2 extr. 233 50 283 0.82 16.6 VB 12 AM50 cast 69 109 178 0.39 11.0 B 13 AM50Ca0.5 extr. 197 90 287 0.69 18.3 B 13a AM50Ca1.5Sr0.2 extr. 186 82 268 0.69 17.8 VB 14 AS41 extr. 202 90 292 0.69 14.2 B 15 AS41Ca0.4 extr. 188 87 275 0.68 13.4 VB 16a AZ31 extr. 215 67 282 0.76 17.6 B 17 AZ31Ca0.3 extr. 199 81 280 0.71 18.2 VB 18 ME10 cast 75 117 192 0.39 7.9 VB 19 MN150 extr. 177 48 225 0.79 15.2 B 20 MN150Ca0.2 extr. 242 22 264 0.92 18.3 Highest mean values of the measurement results of the mechanical properties selected from various individual samples of the modified magnesium alloys: sample alloy Tensile test Compression test Schlagvers. BE
% R _m
MPa R _P0.2
MPa A
% R _Dm
MPa R _upset
MPa A _D
% C _G
J C _UG
J VB 10 AM20 extr. 36.6 278 238 20.5 352 150 8.4 9.3 50.8 B 11 AM20Ca0.2 extr. 36.0 294 254 20.8 425 209 15.6 8.0 58.0 VB 12 AM50 extr. 21.6 287 212 21.6 365 140 11.2 10.0 85.0 B 13 AM50Ca0.5 extr. 32.0 295 215 20.3 421 186 16.7 7.5 68.5 B 13a AM50Ca1.5Sr0.2 extr. 32.7 284 207 18.3 nb nb nb 11.2 68.7 VB 14 AS41 extr. 16.8 284 227 16.8 372 148 10.4 5.5 56.3 B 15 AS41Ca0.4 extr. 20.7 279 204 16.1 430 169 18.0 5.0 55.0 B 17 AZ31Ca0.3 extr. 35.3 286 214 21.8 407 162 15.3 9.0 63.7 VB 19 MN150 extr. 17.8 230 196 17.8 342 150 23.8 5.5 34.8 B 20 MN150Ca0.2 extr. 33.9 291 286 23.8 383 226 16.5 2.5 42.2 Mainly occurring grain sizes in the as-cast state after homogenization at 350 ° C for 4 h or after extrusion with the modified magnesium alloys and their starting alloys. sample alloy average grain sizes, µm VB 12 AM50 cast 95 VB 13 AM50Ca0.5 cast 124 B 13 AM50Ca0.5 extr. 4.6 - 9.2 B 13a AM50Ca1,5Sr0,2 extr. 8.9 - 17.8 VB 16 AZ31 cast 130 VB 16a AZ31 extr. 3.5 - 6.8 VB 18 ME10 cast 103 Process parameters for various samples of the modified magnesium alloys and their starting alloys. sample alloy melting temperature Temperature of the bolt Degree of deformation ϕ = In (A _o / A) Anfangspreßdruck Compression speed number of samples ° C ° C MPa m / min VB 10 AM20 extr. 780-800 340-390 2.8 - 3.3 10.7 - 15.0 4.2 - 9.9 9 B 11 AM20Ca0.2 extr. 780 200-390 2.8 - 3.1 16.7-22.2 3.5 - 9.1 11 VB 12 AM50 cast 800 1 B 13 AM50Ca0.5 extr. 780 250-340 2.8 - 3.1 15.7-23.5 3.4 - 9.2 8th B 13a AM50Ca1.5Sr0.2 extr. 780 300-400 3.1 11.4 - 18.0 3.8 - 4.5 3 VB 14 AS41 HP extr. 780 250-390 2.8 - 3.3 10.7-21.4 4.3-10.2 10 B 15 AS41 Ca0.4 extr. 780 250-340 2.8 - 3.1 15.5 - 23.0 3.4 - 9.3 8th VB 16 AZ31 cast 800 1 VB 16a AZ31 extr. 780-800 250-390 2.8 - 3.2 10.6 - 20.8 4.2 - 10.6 17 B 17 AZ31Ca0.3 extr. 780 250-365 2.8 - 3.1 15.9-21.7 3.4 - 9.1 9 B17a AZ31Ca0.5 extr. 780 250-365 2.8 - 3.1 14.7-21.2 3.5 - 9.1 9 VB 18 ME10 cast 800 340 1 VB 19 MN150 extr. 780-800 250-390 2.8 - 3.3 8.7 - 14.6 4.5 - 10.8 10 B 20 MN150Ca0.2extr. 780 250-340 2.8 - 3.1 16.4-21.5 3.2 - 8.7 8th

Claims (12)

1. Magnesium alloy which contains 0.2 to 4% by weight of Mn and 0.2 to 6% by weight of Ca and/or 0.1 to 6% by weight of Sr and may 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, and also up to 0.05% by weight of Fe and up to 0.005% by weight of Ni, the remaining components of the magnesium alloy consisting of magnesium and inevitable impurities, produced by extrusion or forging with a degree of deformation of at least 1.5 with dynamic recrystallization and with a fine-grained microstructure with a mean grain size of at most 25 µm being formed, its compressive strength being at least 300 MPa, its impact energy, measured on unnotched specimens, being at least 20 J and its elongation at break, measured on tensile specimens, being at least 15%.
2. Magnesium alloy based on AM (aluminium/manganese) or MA (manganese/aluminium), which contains 0.5 to 10% by weight of Al and 0.1 to 4% by weight of Mn as well as in each case 0.1 to 6% by weight of Ca and/or Sr, and which may 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, and also up to 0.05% by weight of Fe and up to 0.005% by weight of Ni, the remaining components of the magnesium alloy consisting of magnesium and inevitable impurities, produced by extrusion or forging with a degree of deformation of at least 1.5 with dynamic recrystallization and with a fine-grained microstructure with a mean grain size of at most 25 µm being formed, its compressive strength being at least 320 MPa, its impact energy, measured on unnotched specimens, being at least 40 J and its elongation at break, measured on tensile specimens, being at least 16%.
3. Magnesium alloy according to one of the preceding claims, characterized in that 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.
4. Magnesium alloy according to one of the preceding claims, characterized in that it has a microstructure with a mean grain size of no more than 20 µm.
5. Magnesium alloy according to one of the preceding claims, characterized in that it is deformed and has a fine-grained, dynamically recrystallized microstructure and also a precipitated phase content of no more than 5% by volume.
6. Process for producing a magnesium alloy according to at least one of the preceding claims, characterized in that a pre-shaped or compacted shaped body is produced and is dynamically recrystallized by working and/or forming.
7. Process according to Claim 6, characterized in that the formed and/or worked shaped body is machined or processed to form a semi-finished product and/or a component produced from or with this semi-finished product.
8. Process according to Claim 6 or 7, characterized in that the semi-finished product produced or the component produced from or with the semi-finished 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.
9. Process according to Claim 7 or 8, characterized in that the semi-finished product or the component produced therefrom or therewith is connected to a component or semi-finished product of similar or different type by means of at least one low-heat joining process, such as for example adhesive bonding, riveting, stretching, 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.
10. Semi-finished product made from a magnesium alloy or component produced therefrom or therewith, or assembly including a component or semi-finished product of this type, characterized in that it has been produced as described in at least one of the preceding claims.
11. Use of a magnesium alloy produced as described in at least one of Claims 6 to 9 as a rim, a transmission casing, a steering wheel skeleton, a wishbone, a frame element, an element of a vehicle cell or a vehicle outer skin, a vehicle cell or a 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 semi-finished product, component or assembly on or in an automobile or aircraft.
12. Use of a semi-finished product made from a magnesium alloy as described in one of Claims 1 to 9, of a component produced therefrom or therewith and/or of an assembly having at least one semi-finished product and/or component of this type as a rim, a transmission casing, a steering wheel skeleton, a wishbone, a frame element, an element of a vehicle cell or a vehicle outer skin, a cockpit beam, a housing, a floor element, 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 semi-finished product, component or assembly on or in an automobile or aircraft.