WO2009090231A1 - Parts made of austenitic cast iron having an increased carbon content, methods for the production thereof, and use thereof - Google Patents

Abstract

The invention relates to parts made of austenitic cast iron that has an increased carbon content, has TRIP/TWIP properties, and contains more than 0.15 percent and up to 0.6 percent of carbon, more than 0.1 percent and up to 0.5 percent of nitrogen, more than 2 percent and up to 22 percent of manganese, 0 to 4 percent of nickel, more than 2 percent and up to 14 percent of chromium, 0.5 to 4 percent of molybdenum, more than 0 percent and up to 2 percent of aluminum, more than 0.5 percent and up to 4 percent of silicon, 0 to 2 percent of niobium, 0 to 1 percent of tantalum, 0 to 3 percent of titanium, 0 to 1 percent of vanadium, 0.01 to 0.5 percent of zirconium, and a total of 0 to 0.8 percent of the rare earth metals yttrium, cerium, and/or lanthanum, the remainder consisting of iron and steel production-related impurities. The part has a TRIP effect under stress such that a phase transition occurs when the part is deformed or damaged, said phase transition resulting in an increased tensile strength, breaking elongation, and notched bar impact work. The invention further relates to methods for producing said parts as well as the use thereof.

Description

 Components of high-carbon austenitic cast steel, process for their preparation and their use

The invention relates to components of high-carbon austenitic cast steel with TRIP / TWIP properties, processes for their production and their use for armor, parts of plant and refrigeration, load-bearing structures, vehicle parts or foamed parts.

Components made of commercially available austenitic stainless steel have maximum contents of 0.1 to 0.15% carbon content. The carbon content is limited mainly because of its resistance to intercrystalline corrosion (IC) and its associated good weldability [1, 2]. The dissolved carbon content in the steel can by the addition of carbide-forming elements such. As niobium or titanium can be reduced. This is characteristic of stabilized stainless steels [2].

High-strength austenitic austenitic CrMnCN steels based on wrought alloys and containing up to 1.07% carbon and nitrogen and having a chromium content of 14.7% to 21% are described in [3] for the phases and precipitates that occur, as well as corrosive and mechanical properties at room temperature. Thereafter, such steels have 0.2% yield strengths greater than 490 MPa, tensile strengths greater than 950 MPa, uniform elongations greater than 60%, and impact strengths greater than 650 J / cm ² . By rapid cooling, the formation of carbides and nitrides can be prevented, so that no intergranular corrosion or embrittlement effects occur. Comparable results for stainless austenitic CrMnCN cast steel with similar chemical composition are not available.

Austenitic steels with more than 0.15% carbon are more prone to chromium carbide formation. As a result, the corrosion resistance to intergranular corrosion is reduced and the use of austenitic steel is limited [2].

The addition of nitrogen can counteract this negative effect. The presence of dissolved nitrogen causes the formation of Chromium carbide precipitates in austenitic steels is delayed. This restricts the tendency for intergranular corrosion. The formation of chromium-containing nitrides, however, is less critical and time-delayed in austenitic steels [2]. The improvement of the corrosion properties with respect to hole and crevice corrosion by adding nitrogen is used technically in stainless steels [1, 2].

Dissolved nitrogen also causes an increase in austenite strength due to solid solution. Nitrogen-alloyed austenitic steels therefore have higher 0.2-yield strengths and tensile strengths compared to similarly alloyed austenitic steels without nitrogen [1, 2].

Dissolved nitrogen and carbon cause austenite stabilization against ferrite and martensite formation. The formation of ferrite is suppressed and the formation of martensite is made more difficult [2].

The lowering of the chromium and molybdenum content in stainless steels causes a general deterioration of the passivation and thus of the corrosion properties. Stainless steels with lowered chromium and molybdenum content can not counteract corrosive corrosion by correspondingly necessary corrosion resistance. The applications of such stainless steels are therefore limited [2].

Manganese is an element which, like nickel, stabilizes the austenitic phase. Increasing levels of manganese and nickel lead to an increase in austenite stability over the formation of martensitic phases. The positive influence of manganese on the corrosion properties of austenitic stainless steels is weaker than that of nickel. Especially for cost reasons, manganese has proved to be a substitution material for nickel in stainless austenitic steels in many applications [1, 2].

If the sum content of chromium and molybdenum falls below 12 to 13%, then no passivation of the steel surface takes place and the steel rusts. The steel is then usually corrosion resistant. Characteristic of this is the formation of a tight-fitting Surface layer of iron mixed oxides [2]. The rate of corrosion is a measure of corrosion inertia. The lower the total content of chromium and molybdenum, the higher the rate of corrosion is [2]. Corrosion steels Austenitic steels with TRIP / TWIP effect and chromium contents of less than 12% and with carbon contents of not more than 0.15% are described in the patent DE 10 2005 024 029 A1 [4]. These are austenitic steels alloyed with aluminum and silicon.

Stainless nitrogen-coated austenitic steels exhibit metastable austenite in the microstructure and thus have special mechanical properties. These properties are significantly influenced by a TRIP / TWIP effect. The TRIP effect induces a strain-induced martensite formation when the steels are exposed to external stress. In contrast, the TWIP effect induces a deformation-induced twinning. The TRIP / TWIP effect is largely determined by the chemical composition of the steel.

The TRIP / TWIP effect in austenitic and austenitic-martensitic CrMnNi lightweight steels is influenced by the austenite stability and used technically to improve the properties, such as the patents DE 10 2005 024 029 Al [4] and DE 10 2005 030 413 B3 [5] demonstrate.

The influence of the austenite strength on the TRIP / TWIP effect has not been systematically investigated. There is therefore a lack of information on the influence of the different strengthening mechanisms on the TRIP / TWIP effect in steels. This involves solid solution strengthening, or precipitation and particle solidification, or secondary phase consolidation or grain refining or the like. Only in the patent DE 10 2005 024 029 Al [4] and DE 10 2005 030 413 B3 [5] the effect of AlN precipitation on the increase in strength of austenite is described. It highlights the positive impact of AlN precipitates on the TRIP / TWIP effect. It leads to an improvement of the mechanical properties and is used technically. The patent DE 10 2005 030 413 B3 [5] additionally emphasizes the influence of a martensitic second phase in the austenitic basic structure. Here, too, it can be seen that an increase in strength of the steel leads to an increased TRIP / TWIP effect and can be used technically insofar as the austenite stability is matched to this condition. Steel castings exposed to low temperatures require cold-tough behavior. To ensure component safety, the steels must not become brittle. Cast steels with ferritic fine grain structure fulfill this requirement only partially. For this reason, steels with an austenitic or, under certain circumstances, austenitic-ferritic structure are preferably used for use at low temperatures. These are preferably stainless steels.

The cold toughness of stainless steels is significantly influenced by the stability of the austenite. That is, the metastable austenite tends to convert into hexagonal ε-martensite and / or cubic-centered α'-martensite during deep-freezing. This Abkühlmartensit leads to an increase in strength and a decrease in the toughness properties and thus to a deterioration of the cold toughness. If, on the other hand, such spontaneous martensite formation is avoided, a cold-tough austenitic microstructure exists at low temperatures.

If metastable austenitic steels are exposed to external stresses and plastically deformed at low temperatures, deformation-induced martensite may form. In this case, a TRIP effect can be observed. This TRIP effect results in an increase in tensile strength, elongation at break and impact energy. Austenitic wrought alloys with TRIP effect are therefore characterized by steels without TRIP effect by a higher tensile strength, a higher elongation at break and a higher impact energy. They have a high strength and elongation reserve at low temperatures and therefore less prone to embrittlement. They are cold-tough.

For use at low temperatures, the austenitic steel is preferably used. The toughness properties are correspondingly high in the low temperature region. To what extent the temperature profile of the impact energy work is influenced by a TRIP effect is not known.

Ferritic-austenitic microstructure states are usually thermally stable. As a rule, no spontaneous martensite formations are observed in the low-temperature region, which has a positive effect on the cold toughness. But at the same time, the formation of ferrite is associated with undesirable loss of toughness. So for example, the deteriorates Cold toughness of steels with increasing ferrite content. In the published patent application DE 34 05 078 Al a stainless austenitic-ferritic cast steel is described. It is preferred because of its high corrosion resistance at low temperatures for nitrogen liquefaction plants. The steel has a ferrite content of 10 to 40%, a carbon content of up to 0.08%, a silicon content of up to 2%, a manganese content of up to 2%, a chromium content of 18 to 26%, a nickel content of 5 to 14% and a molybdenum content of 0.5 to 5%.

The influence of manganese on the notch impact work is shown for stainless austenitic CrNi wrought alloys in the textbook Werkstoffkunde Stahl, Volume 2 [6]. Accordingly, depending on the manganese content in the concentration range of about 10 to about 15% manganese, a maximum of the impact energy in the low temperature area is registered. The maximum shifts to lower values as the temperature falls. The effect is due to the manganese-changing austenite stability. The influence of manganese on the notch impact work of austenitic CrNi cast steel alloys is not known in contrast to the wrought alloys.

A disadvantage of the prior art is the non-use of the TRIP / TWIP effect in components made of cast steel. In addition, so far the positive influence of carbon in combination with nitrogen, which leads to an increase in the TRIP / TWIP effect in stainless or corrosion-resistant steels, is not used technically.

The invention has for its object to provide components of higher carbon, austenitic, cold-tough steel cast with TRIP effect.

According to the invention, the object is achieved by a component made of higher-carbon, austenitic, cold-tenable cast steel with a

- carbon content greater than 0,15 to 0,6%,

Nitrogen content greater than 0.1 to 0.5%,

Manganese content greater than 2 to 22%,

- Nickel content from 0 to 4%

Chromium content greater than 2 to 14%,

Molybdenum content of 0.5 to 4%, - Aluminum content greater 0 to 2%

- silicon content greater than 0.5 to 4%

Niobium content from 0 to 2%,

Tantalum content from 0 to 1%,

Titanium content from 0 to 3%

- Vanadium content from 0 to 1%

- Zirconium content of 0.01 to 0.5% and

a total amount of rare earth elements yttrium, cerium or lanthanum between 0.01 to 0.8%,

-Rest of iron and steel tendons caused by fusion, whereby the component has a TRIP effect under load, so that upon deformation or destruction a phase transformation occurs, which leads to an increase of the tensile strength, the elongation at break and impact energy.

Surprisingly, it was found that in austenitic CrMnNi cast steel components, whose carbon contents are above 0.15% and their chromium contents are below 14% and which are alloyed with rare earths, a strong TRIP / TWIP effect due to external stress at room temperature and low temperatures can be forced. The elements of the rare earths cause an increase in the TRIP / TWIP effect and, moreover, a lowering of the IK susceptibility. The IC susceptibility of stainless steels is lowered by the addition of nitrogen, carbide-forming elements and rare earth elements. In the same way, the corrosion behavior of the cast steel according to the invention is retarded with chromium contents below 12%. The TRIP / TWIP effect results in a high-strength and at the same time very ductile cast steel. Because of the excellent combination of properties of high strength and sometimes extremely high ductility, the inventive cast steel has a high energy absorption capacity in the solution-annealed state, which is not achieved by conventional austenitic cast steel.

The inventive components made of stainless and corrosion-resistant cast steel are inexpensive to manufacture and for special applications, preferably in the cryogenic field suitable. In particular, the cast steel according to the invention or the components according to the invention for extreme stresses, as they must withstand armor of military vehicles and wear and crash-stressed parts are suitable. In addition, particularly thin-walled components with wall thicknesses of up to 3 - 5 mm can be produced if the steel casting has manganese contents of more than 4%. With increasing manganese content, the castability of the steel improves.

At room temperature and low temperatures, the components according to the invention or the cast steel according to the invention have a 0.2% proof strength of more than 300 MPa, a tensile strength of 700 to 1600 MPa, an elongation at break of 50 to 90% and an impact strength of more than 40 J. on. The stainless or corrosion-resistant cast steel is alloyed with inexpensive elements and therefore inexpensive to produce. The cast steel of the invention or the components according to the invention are characterized by a high energy absorption capacity.

The components of the invention have improved strength and toughness and wear properties. This applies both to temperatures above room temperature and to low temperatures and thus also to the use of a cold-tough austenitic steel having carbon contents of 0.15 to 0.6% and chromium contents of 2 to 14% and nickel contents of 0 to 4%.

Components with higher carbon austenitic cast steel alloy, which are additionally alloyed with rare earth elements to increase the TRIP / TWIP effect, have not heretofore been used in practice. Such components are due to their property profile of high strength at the same time high elongation and thus due to their high energy absorption capacity particularly suitable for crash-stressed components and armor. In addition, as a result of martensite and twin formation during mechanical stress, high wear resistance is achieved which protects the material from abrasion.

According to an advantageous embodiment of the invention, the component according to the invention comprises a cast steel with a composition

- carbon content of 0,15 to 0,25%,

Nitrogen content from 0.2 to 0.4%,

- Nickel content from 0 to 2%

Manganese content of 5 to 10%,

Chromium content from 8 to 14%, Molybdenum content of 0.5 to 4%,

- aluminum content from 0 to 0.15%,

- silicon content of 0.5 to 2%

Niobium content from 0 to 2%,

Tantalum content from 0 to 1%,

Titanium content from 0 to 3%

- Vanadium content from 0 to 1%

- Zirconium content of 0.01 to 0.5% and

-Sum content of the rare earth elements yttrium, cerium or lanthanum between 0.01 to 0.3% remainder of iron as well as melting-related accompanying elements

Preferably, the cast steel alloy according to the present invention has a content by mass percentage of Nb 0.05-2%, Ta 0.01-1%, Ti 0.01-3% and V 0.01-1%. A content in percent by weight of Nb is preferably between 0.1 and 1%, on Ta between 0.05 and 0.5%, on Ti between 0.1 and 1% and on V between 0.05 and 0.5%. Particularly preferred is a content of Nb and Ti of 0.1 to 0.5%.

The invention also includes components in which the cast steel according to the invention consists of cast steel foam and can be produced in a known manner.

Defective accompanying elements, such. B. S, P, O but also impurities are due to the process and are not added to the invention Stahlformguss.

The components according to the invention can be produced by melting the alloy, casting into a finished casting mold and demolding. A separate after-treatment except the usual surface treatment or deburring is not required. For certain applications, a heat treatment, for. As a solution annealing at 1000 to 1050 ° C / lh / H ₂ O advantageous.

The method according to the invention for the production of components from cast steel comprises the following steps: a) melting of an alloy with a composition in mass percent - carbon content greater than 0,15 to 0,6%,

Nitrogen content greater than 0.1 to 0.5%,

Manganese content greater than 2 to 22%,

- Nickel content from 0 to 4%

Chromium content greater than 2 to 14%,

Molybdenum content of 0.5 to 4%,

- Aluminum content greater 0 to 2%

- silicon content greater than 0.5 to 4%

Niobium content from 0 to 2%,

Tantalum content from 0 to 1%,

Titanium content from 0 to 3%

- Vanadium content from 0 to 1%

- Zirconium content of 0.01 to 0.5% and

a total amount of rare earth elements yttrium, cerium or lanthanum between 0.01 to 0.8%,

- Remainder of iron and melting-related steel accompanying elements

b) Casting the cast steel into a mold

c) demolding and, if necessary, machining while maintaining the cast structure.

The cast components can be subjected to a heat treatment to improve the strength and toughness in a further step, according to an advantageous embodiment of the method according to the invention. In this case, the steel casting before and / or after the manufacture of the components of an approximately one hour annealing at 1000 to 1050 ⁰ C subjected before subsequently a water, oil or air cooling takes place.

Preferably, an alloy having the composition wherein, by mass percent, the carbon content is from 0.15 to 0.25%,

- the nitrogen content of 0.2 to 0.4%,

- the nickel content of 0 to 2%

the manganese content of 5 to 10%,

the chromium content of 8 to 14%,

the molybdenum content is from 0.5 to 4%, - the aluminum content of 0 to 0.15%,

- the silicon content of 0.5 to 2% and

- the niobium content from 0 to 2%,

- the tantalum content from 0 to 1%,

- the titanium content from 0 to 3%

- the vanadium content from 0 to 1%

- the zirconium content of 0.01 to 0.5% and

- The Summengehalt of the rare earth elements yttrium, cerium or lanthanum is between 0,01 to 0,3% amounts, remainder iron and fusion-related steel accompanying elements, melted.

Preferably, the cast steel alloy of the present invention is melted to have a content by mass percentage of Nb 0.05-2%, Ta 0.01-1%, Ti 0.01-3%, V 0.01-1%. A content in percent by weight of Nb is preferably between 0.1 and 1%, on Ta between 0.05 and 0.5%, on Ti between 0.1 and 1% and on V between 0.05 and 0.5%. Particularly preferred is a content of Nb and Ti of in each case between 0.1 to 0.5%.

Melting accompanying elements, such. B. S, P, O but also impurities are due to the process and are not added to the invention Stahlformguss.

The mechanical properties and processing properties for the steel casting shown in the invention are achieved by a vote of the austenite stability on the one hand and by the acting hardening mechanisms on the other hand, which determine the strength of the austenite. By means of the chemical composition of austenite and by means of a heat treatment, the necessary tuning can take place. A heat treatment is not absolutely necessary, but can be advantageous.

The elements Nb, Ti, Ta and V form carbides, nitrides and carbonitrides, respectively, which reduces the IK susceptibility in stainless steels. However, the precipitates also contribute to the precipitation strengthening and grain concentration of the austenite. Associated with this is an increase in the strength of austenite. Strength increases of austenite have a positive influence on the TRIP / TWIP effect, in that the austenite stability remains the same compared to the martensite or twin formation or is compensated by other measures.

The influence of the rare elements yttrium, zirconium, cerium or lanthanum on the TRIP / TWIP effect and the associated use and processing properties is not yet known. Rare earths (cerium, lanthanum) are added, for example, in nickel-base alloys to improve oxidation resistance. On the other hand, yttrium, zirconium and cerium or their oxides are added in ODS alloys (oxides dispersion strengthened) in order to ensure the strength of the material, especially at high temperatures.

Due to the advantageous properties of the components according to the invention, these can be used for armouring vehicles and components or for components in plant and refrigeration technology or for components for the transport and extraction of gases and for liquefying and fractionating gases or for load-bearing components or components subject to crash become.

The components of the invention are characterized by excellent strength and toughness combined with high energy absorption capacity and are particularly suitable for crash-stressed components and stiffening structural components, chassis components, wear and strength components.

The invention therefore also includes energy absorption components made of cast steel according to the invention. With the same space, these allow higher energy intake.

The energy absorption components according to the invention are suitable, for example, as bumper carriers, as frame parts (eg sills) or the like in vehicles, for example in motor vehicles for absorbing kinetic energy in the event of an impact, for example as a result of an accident. They have a high deformability while ensuring a sufficient static strength.

The invention will be explained in more detail with reference to the following embodiments. Embodiment 1

In an induction furnace, an alloy with the chemical composition carbon content of 0.58%, a silicon content of 1.16%, a manganese content of 8.5%, a chromium content of 13.1%, a molybdenum content of 5%, a nickel content of 5.11%, a nitrogen content of 0.25% (in percent by mass), balance iron and common steel accompanying elements, melted and poured into a finished ready-made mold for a pipe. After the casting no solution annealing took place. During use of the pipe under stress conditions, deformation-induced martensite and deformation twins are formed on the surface. As a result, the hardness and the wear resistance are significantly increased, which has a significant increase in the life result.

Embodiment 2

A cast component in the form of a sheet with a carbon content of 0.20%, a silicon content of 1.16%, a manganese content of 7.0%, a chromium content of 13.1%, a molybdenum content of 3.63%, is melted Nickel content of 3.17%, a nitrogen content of 0.12% (in mass percent). The rest are iron and the usual steel accompanying elements. After a solution annealing at 1050 ° C / lh / H ₂ θ, the cast steel part shows an austenitic basic structure with a pronounced TRIP / TWIP effect at room temperature and low temperatures. The cast steel has a 0.2% proof stress of more than 360 MPa at room temperature, a tensile strength of 740 MPa, an elongation at break of greater than 58% and an impact strength of 50 J. The energy absorption capacity at room temperature is over 30 J / mm ³ for this steel casting. The same austenitic cast steel has a 0.2% yield strength of 435 MPa, a tensile strength at 830 MPa and an impact energy of 55 J at -78 ⁰ C. The cast steel achieves a maximum elongation of 67%. The energy absorption capacity increases to approx. 35 J / mm ³ .

This means that, for example, in the case of a sudden stress, as in the case of a crash, the steel casting is solidified and deformed at the same time, without breaking. Therefore, the steel is particularly suitable for components and armor of vehicles subject to crash, especially at temperatures below room temperature, the strength and toughness reserves be improved.

Therefore, the steel casting according to the invention is used for crash-stressed, thin-walled components, such as the A and B or C pillar of a motor vehicle. But also armor of protective vehicles guarantee a lightweight construction and increased protection of the occupants. In addition, steel casting is used in plant and refrigeration technology, for machine components, fittings, housings, lids, brackets and as a component that is exposed to low temperatures. In addition, the cast steel is to be used for foamed parts.

literature

Stahlschlüssel 2004, Verlag Stahlschlüssel WEGST GmbH [2] Stainless steels, volume 493, expert-Verlag, Esslingen [3] Berns, H., V.G. Gavriljuk, S. Riedner and A. Tyshchenko: Steel research int. 78 (2007) 9,

Pp. 714-719

[4] White, A., H. Gutte and P.R. Scheller DE 102005 024 029 A1 [5] Weiß, A., H. Gutte and P.R. Scheller DE 102005 030 413 B3 [6] Material Science Steel, Volume 2: Applications, Springer-Verlag Berlin Heidelberg New York

Tokyo, 1985, p.288

Claims

claims 1. Component of high-carbon, austenitic, cold-cast steel casting with a composition in mass percent - carbon content greater than 0,15 to 0,6%, Nitrogen content greater than 0.1 to 0.5%, Manganese content greater than 2 to 22%, - Nickel content from 0 to 4% Chromium content greater than 2 to 14%, Molybdenum content of 0.5 to 4%, - Aluminum content greater 0 to 2% - silicon content greater than 0.5 to 4% Niobium content from 0 to 2%, Tantalum content from 0 to 1%, Titanium content from 0 to 3% - Vanadium content from 0 to 1% - Zirconium content of 0.01 to 0.5% and - a total amount of rare earth elements yttrium, cerium and / or lanthanum between 0.01 to 0.8%, - remainder of iron and melting-related steel accompanying elements, wherein the component under stress has a TRIP effect, so that upon deformation or destruction, a phase transformation occurs, which leads to an increase in the tensile strength, the elongation at break and impact energy. 2. Component according to claim 1, characterized in that it is under load a 0.2% - yield strength of more than 300 MPa, a tensile strength of 700 to 1600 MPa, an elongation at break of 50 to 90%, a notch impact of more than 40 J. having. 3. Component according to claim 1 or 2, characterized in that the - the carbon content of 0.15 to 0.25%, - the nitrogen content of 0.2 to 0.4%, - the nickel content of 0 to 2% the manganese content of 5 to 10%, the chromium content of 8 to 14%, the molybdenum content is from 0.5 to 4%, - the aluminum content of 0 to 0.15%, - the silicon content of 0.5 to 2% and - The Summengehalt of the rare earth elements yttrium, cerium and / or lanthanum is between 0.01 to 0.3%. 4. Component according to one of claims 1 to 3, characterized in that the cast steel is a cast steel foam. 5. A process for producing a component from a high-carbon, austenitic, cold-worked steel casting alloy with TRIP or TWIP effect with the following steps: a) melting an alloy with a composition in mass percent - carbon content greater than 0,15 to 0,6%, Nitrogen content greater than 0.1 to 0.5%, Manganese content greater than 2 to 22%, - Nickel content from 0 to 4% Chromium content greater than 2 to 14%, Molybdenum content of 0.5 to 4%, - Aluminum content greater 0 to 2% - silicon content greater than 0.5 to 4% Niobium content from 0 to 2%, Tantalum content from 0 to 1%, Titanium content from 0 to 3% - Vanadium content from 0 to 1% - Zirconium content of 0.01 to 0.5% and a total amount of rare earth elements yttrium, cerium and / or lanthanum between 0 to 0.8%, - Remainder of iron and melting-related steel accompanying elements b) Casting the cast steel into a mold c) demolding and, if necessary, machining while maintaining the cast structure. 6. The method according to claim 5, characterized in that the cast component is subjected to a heat treatment. Method according to claim 5 or 6, characterized in that - the carbon content is from 0.15 to 0.25%, - the nitrogen content of 0.2 to 0.4%, - the nickel content of 0 to 2% the manganese content of 5 to 10%, the chromium content of 8 to 14%, the molybdenum content is from 0.5 to 4%, - the aluminum content of 0 to 0.15%, - the silicon content of 0.5 to 2% and - The Summengehalt the rare earth elements elements yttrium, cerium and / or lanthanum is between 0.01 to 0.3%. 8. Use of a component according to one of claims 1 to 7 for armouring of vehicles and components or for components in plant and refrigeration technology or for components for the transport and recovery of gases and for liquefaction and fractionation of gases or for bearing or wear or crash-impacted components or for energy absorption components.