Use of a Precipitation-Hardening or Solid-Solution-Strengthening, Biocompatible Cobalt-Based Alloy and Method for Producing Implants or Prostheses by Means of Material-Removing Machining

Abstract

The invention shows possibilities which allow simplified production of implants or prostheses, specifically of dental implants or prostheses, by applying subtractive processes. For this purpose, the invention proposes the use of a precipitation-hardening or solid-solution-strengthening, biocompatible cobalt-based alloy for the production of blanks. Such blanks are provided in the soft state. Subsequently, each component (implant or prosthesis) is produced from the soft blank by means of material-removing machining. Subsequently, a heat-treatment of the implant or prosthesis then takes place to adjust the hardness thereof by means of precipitation hardening or solid-solution formation.

Claims

1. An implant or prosthesis comprising a precipitation-hardening or solid-solution-strengthening, biocompatible cobalt-based alloy wherein the implant or prosthesis is carved out of a soft blank of the precipitation-hardening or solid-solution-strengthening biocompatible cobalt-based alloy and heat treated to adjust a final hardness by precipitation hardening or solid-solution strengthening.

2. A method for producing an implant or a prosthesis, comprising: providing a soft blank, comprising a precipitation-hardening or solid-solution-strengthening, biocompatible cobalt-based alloy; carving an implant or a prosthesis out of the soft blank using material-removing machining; and heat-treating the implant or the prosthesis to adjust a final hardness by precipitation hardening or solid-solution strengthening.

3. The method according to claim 2, wherein the blank is a disc from which each implant or each prosthesis is carved by milling.

4. The method according to claim 2, wherein the cobalt-based alloy comprises (in % by weight), C: up to 0.5%, Si: up to 2.5%, Cr: 22-29%, Mn: up to 1%, Ni: up to 3%, Fe: up to 3%, Ce: up to 1%, Ga: up to 5%, and B: up to 2.5%, and in each case at least one hardening precipitation or solid-solution-forming element is selected from the group consisting of Mo, W, Nb, Al, and Ti, wherein for the concentrations of these elements, where present, the following proportions apply Mo: 3-9%, W: 3-9%, Nb: 3-9%, Al: 0.1-6%, and Ti: 0.1-6%, and wherein the remainder is Co and unavoidable impurities resulting from production.

5. The method according to claim 4, wherein the C concentration of the cobalt-based alloy is at most 0.1% by weight.

6. The method according to claim 4, wherein the Si concentration of the cobalt-based alloy is 0.8-2.0% by weight.

7. The method according to claim 4, wherein the Cr concentration of the cobalt-based alloy is 23-27% by weight.

8. The method according to claim 4, wherein, for the concentrations of the hardening precipitation or solid-solution-forming elements present in the cobalt-based alloy, the following proportions apply (in % by weight): Mo: 4-6%, W: 4-6%, Nb: 4-6%, Al: 2-4%, and Ti: 1-3%.

9. The method according to claim 4, wherein (in % by weight) the Mn concentration of the cobalt-based alloy is at most 0.5%, or the Ni concentration of the cobalt-based alloy is at most 0.1%.

10. The method according to claim 4, wherein in each case at least two elements forming hardening precipitates are present in the cobalt-based alloy.

11. The method according to claim 2, wherein the blanks are solution-annealed before the material-removing machining thereof at a temperature of from 1050-1300 C. over a period of from 15-600 min.

12. The method according to claim 11, wherein, after the solution-annealing, the blanks are cooled to room temperature at a cooling speed of from 5-1000 K/min.

13. The method according to claim 2, wherein the implants or prostheses are heat treated at an ageing temperature of from 600-1000 C. for an ageing period of at least 5 min and at most 600 min in order to adjust the hardness thereof.

14. The method according to claim 13, wherein the ageing temperature is at least 700 C.

15. The method according to claim 13, wherein the ageing period is from 5-150 min.

Description

[0018] Advantageous embodiments of the invention are indicated in the dependent claims and will be explained in greater detail below, together with the general inventive concept.

[0019] The invention accordingly proposes the use of a precipitation-hardening or solid-solution-strengthening, biocompatible cobalt-based alloy for the production of blanks which are provided so that, in the soft state thereof, implants or prostheses are carved out of said blanks by means of cutting machining, which implants or prostheses are subjected to a heat treatment after the cutting machining in order to adjust the final hardness of the implants or prostheses by means of precipitation hardening or solid-solution formation.

[0020] The invention also proposes, to produce an implant, carrying out at least the following work steps: [0021] providing a soft blank, which consists of a precipitation-hardening or solid-solution-strengthening, biocompatible cobalt-based alloy, [0022] carving an implant or the prosthesis out of the soft blank by means of cutting machining, [0023] heat-treating the implant or the prosthesis to adjust the hardness by means of precipitation hardening or solid-solution formation.

[0024] What the use according to the invention and the method according to the invention have in common is thus that each blank from which each implant or prosthesis component is to be manufactured is produced from a precipitation-hardening or solid-solution-strengthening Co-based material, which, in the initial state thereof, i.e. the state in which it is provided for the material-removing machining, has not yet achieved the final hardness thereof, but rather is designed in such a way that said material reaches the final hardness thereof only after a final heat treatment as a result of the precipitations forming in the structure of the material.

[0025] The soft structure of the blank provided according to the invention, which is characterised by low hardness, can be adjusted in particular by subjecting the blank to solution-annealing before the material-removing machining, in which solution-annealing process the hardness of said blank is reduced by triggering the break-up of intermetallic phases and grain growth.

[0026] The production of the blank can be carried out in a conventional manner by casting or by applying powder-metallurgy processes which are likewise known per se. Examples include casting, casting and shaping, precision casting, powder and hot isostatic pressing.

[0027] Due to the low hardness of the blank provided according to the invention by comparison with the final hardness of each component, said blank can be machined with low tool wear and at a greater speed. Material is typically removed by means of cutting processes, in particular by means of milling. However, all other processes which allow effective removal of material whilst utilising the low hardness present in a blank provided according to the invention are also suitable for this purpose.

[0028] The mechanical properties required from the finished implant or prosthesis component are adjusted according to the invention by a heat treatment which is carried out after the material-removing, shaping machining. This heat treatment brings about the precipitation hardening or solid-solution formation and, as a consequence thereof, adjusts the high strengths that the implants should have in particular for the dental sector. Precipitation hardening and solid-solution formation can of course occur in combination and jointly contribute to increasing hardness. By adjusting the respective alloys, the effect of precipitation hardening can exceed that of solid-solution formation and vice versa.

[0029] Typically, the blanks provided according to the invention are discs from which each implant is carved by means of milling. Such discs are also referred to in technical terminology as milling discs.

[0030] In this case, the invention is particularly suitable for producing dental implants which are introduced as fixing means for dentures or directly as dentures or as aids for fixing dentures in the jaw, or for dental prostheses which are attached to the jaw as or for a denture.

[0031] Co-based alloys, of the type provided by the invention for use as a material for blanks from which implants or prostheses, in particular dental implants or prostheses, are produced by removing material, are known per se from the prior art (e.g. EP 1 972 321 B1). However, in said document, said alloys are used for other uses or other production processes.

[0032] Only the invention has recognised that these alloys, which are known per se, can be combined or heat treated in such a way that, as a blank, they have optimised properties for material-removing machining and, by means of a final heat treatment following the material-removing machining, can be brought into line with the mechanical properties required by the respective implant or prostheses components.

[0033] An alloy specification which is suitable for the purpose according to the invention accordingly provides that the cobalt-based alloy consists of (in % by weight) [0034] C: up to 0.5% [0035] Si: up to 2.5% [0036] Cr: 22-29%, [0037] Mn: up to 1%, [0038] Ni: up to 3%, [0039] Fe: up to 3%, [0040] Ce: up to 1%, [0041] Ga: up to 5%, [0042] B: up to 2.5%
and in each case at least one of the elements forming hardening precipitations or solid solutions from the group comprising Mo, W, Nb, Al, Ti, in which, for the concentrations of these elements, where present, the following proportion applies [0043] Mo: 3-9%, [0044] W: 3-9%, [0045] Nb: 3-9%, [0046] Al: 0.1-6%, [0047] Ti: 0.1-6%,
and as residue, Co and unavoidable impurities resulting from production.

[0048] Carbon can be present in the cobalt-based alloy used according to the invention in concentrations of up to 0.5% by weight. Carbon is generally an undesirable impurity since, as a result of precipitation of Cr-rich carbides, corrosion resistance is reduced. Optimally, therefore, the C concentration is limited to up to 0.1% by weight, in particular to less than 0.1% by weight.

[0049] Silicon can be present in the cobalt-based alloy used according to the invention in concentrations of up to 2.5% by weight. By adding silicon, the melting point and the viscosity of the molten mass are reduced. At the same time, silicon has the positive effect that the adhesion of a ceramic veneer which is optionally attached to the implant is improved by forming oxides or oxide compounds. To make use of this effect, the Si concentration of the Co alloy can be at least 0.8% by weight. Above 2% by weight, Si has no more property-improving effects.

[0050] In the cobalt-based alloy used according to the invention, chromium can be present in concentrations of from 22-29% by weight, in particular more than 22.00% by weight to less than 29.00% by weight. Chromium is required for corrosion resistance and is also involved in the solid-solution strengthening which is used according to the invention for the final adjustment of the hardness of each implant. Cr provides an optimal effect in the Co alloy used according to the invention when the Cr concentration is at least 23% by weight, in particular more than 23% by weight. At the same time, it has been shown that Cr concentrations of at most 27% by weight, in particular less than 27.00% by weight, ensure sufficient corrosion resistance specifically for regular use in the oral cavity.

[0051] Manganese in concentrations of up to 1% by weight, similarly to silicon, influences the viscosity of the molten mass and the adhesion to the veneer. In addition, sulphur is set by forming Mn sulphides. The positive effect of Mn in the Co alloy according to the invention can be used in particular when the Mn concentration is at least 0.01% by weight. Above 1% by weight, Mn has no more property-improving effects, the presence of Mn having an optimised effect when the Mn concentration is at most 0.5% by weight.

[0052] The nickel concentration in Co alloys used according to the invention is at most 3% by weight, but for use in particular in the oral cavity can be limited to concentrations of up to 0.1% by weight, in particular less than 0.1% by weight, in order to safely avoid allergic reactions. However, Co-based alloys having higher Ni concentrations can be suitable for knee or hip implants in order to achieve the mechanical properties of the material which are required for this intended use.

[0053] Iron ends up in the Co alloy used according to the invention as a result of the production process but is to be limited to at most 3% by weight, in particular less than 3.0% by weight, so as not to impair the corrosion resistance of the material. Negative effects of the present of Fe can be avoided particularly safely when the Fe concentration is limited to at most 0.5% by weight, in particular less than 0.1% by weight.

[0054] Cerium can be added to the alloy used according to the invention in concentrations of up to 1% by weight, since it greatly improves the bonding to the ceramic veneer by means of oxide formation.

[0055] Gallium can be present in the cobalt-based alloy used according to the invention in concentrations of up to 5% by weight. Gallium is also involved in the solid-solution strengthening and contributes to reducing the coefficient of thermal expansion.

[0056] In concentrations of up to 2.5% by weight, boron has comparable effects to Si. In addition, boron influences the oxide colour and, by forming boride precipitations, brings about an increase in hardness and strength. Concentrations above 2.5% by weight should be avoided, since otherwise the material would become very brittle.

[0057] In order to bring about the precipitation formation used according to the invention to adjust the hardness of the implant obtained after carrying out a subtractive process, the Co-based alloy used according to the invention contains at least one precipitation-forming element from the group comprising Mo, W, Nb, Al, Ti, said elements being able to be present not only in isolation, but of course also in combination with one another in the Co alloy. For example, in each case two or more elements from the group of precipitation-forming elements provided according to the invention can be contained in the Co alloy.

[0058] Molybdenum in concentrations of from 3-9% by weight firstly increases corrosion resistance, but also brings about pronounced solid-solution strengthening and, as a consequence thereof, an effective increase in the hardness and strength of the Co alloy. At the same time, Mo contributes to reducing the coefficient of thermal expansion. The positive influence of Mo can be used particularly safely when the Mo concentration is at least 4% by weight. Practical trials have proven that, to use the positive influence of Mo, it is generally sufficient for the Mo concentration to be limited to at most 6% by weight.

[0059] In the Co alloy used according to the invention, tungsten in concentrations of from 3-9% by weight has a similar effect to molybdenum and thus firstly increases corrosion resistance, but also brings about pronounced solid-solution strengthening and, as a consequence thereof, an effective increase in the hardness and strength of the Co alloy. At the same time, W contributes to reducing the coefficient of thermal expansion. The positive influence of W can be used particularly safely when the W concentration is at least 4% by weight. Practical trials have proven that, to use the positive influence of W, it is generally sufficient for the W concentration to also be limited to at most 6% by weight.

[0060] Niobium can also be present in the Co alloy used according to the contested patent in concentrations of from 3-9% by weight. Niobium firstly leads to increased formation of Nb carbides provided that carbon is present. Unavoidable carbon impurities are thus set, with the consequence that the production of Cr and/or Mo carbides, which would reduce corrosion resistance, is prevented. The presence of Nb in the concentrations given thus indirectly leads to an increase in corrosion resistance. In other respects, the effect of Nb corresponds to that of tungsten or molybdenum. The positive influence of Nb can be used particularly safely when the Nb concentration is at least 4% by weight. Practical trials have proven that, to use the positive influence of Nb, it is generally sufficient for the Nb concentration to also be limited to at most 6% by weight.

[0061] Aluminium and titanium are equally involved in the formation of intermetallic phases and thus support precipitation hardening. With respect to the atomic percent thereof, they are interchangeable at a ratio of 1:1, where necessary. If present, the Al concentration of the Co alloy used according to the invention is 0.1-6% by weight, and the Ti concentration is 0.1-6% by weight, in particular up to 5% by weight, Al concentrations of at least 2% by weight or Ti concentrations of at least 1% by weight having proven to be particularly effective. At the same time, it has been shown that Al concentrations of a maximum of 4% by weight or Ti concentrations of a maximum of 3% by weight are regularly sufficient for the purposes according to the invention.

[0062] If necessary, before the cutting machining, the blank used and provided in each case according to the invention can be subjected to a heat treatment in which said blank is solution-annealed for a duration of from 15-600 min at a temperature of from 1050-1300 C. Optimal solution-annealing results are achieved when the solution period is at least 60 min, a maximum duration of the solution-annealing of at most 480 min having also been proven with respect to optimising the annealing result. It also contributes to optimising the result of the solution-annealing when the solution-annealing temperature is at least 1150 C., solution-annealing temperatures of a maximum of 1250 C. having also proven themselves in terms of optimisation. The solution-annealing brings about a reduction in hardness by triggering the break-up of intermetallic phases and grain growth so that the blanks have a hardness which is optimal for the material-removing machining.

[0063] The heating rate of the solution-annealing treatment should be at least 5 K/min and at most 20 K/min and thus be in the range typical for conventional solution-annealing furnaces. By means of the heating taking place in such a way, sufficient through-heating is ensured. Moreover, the heating rate has no effect on the resulting properties of the products produced according to the invention. After the solution-annealing, the blanks can be cooled to room temperature at a cooling rate of from 5-1000 K/min. When the cooling rate is slower, precipitations and recrystallisation are possible. The consequence would be an increase in hardness, which is undesirable in this work step. When cooling takes place considerably more fastly, warpage and even cracks could occur as a result of the thermal stresses. In this case, the cooling rates are to be selected within the limitations of the invention according to the cross section, and more specifically in each case so that the required cooling is achieved even in the core region.

[0064] The solution-annealing can be carried out conventionally under normal atmospheric conditions. In an equally conventional manner, the quenching after the solution-annealing can take place with air or water.

[0065] However, should the costs for the removal of the scale produced during the conventional solution-annealing under normal atmospheric conditions be avoided, then the solution-annealing treatment can be carried out under vacuum. The solution-annealing under vacuum prevents the oxidation and scaling of the respective blanks so that otherwise necessary secondary machining processes for removing scale or oxides can be minimised, and measurements required for the secondary machining can be avoided. The quenching can then be carried out by means of pressurised nitrogen in order to thereby also avoid oxidation and scale formation.

[0066] The optimal hardness for the material-removing machining is typically in the range of up to 35 HRC, in particular up to 28 HRC.

[0067] The hardness in HRC is conventionally determined in accordance with the processes defined in DIN EN ISO 6508-1.

[0068] To adjust the hardness thereof, the implants obtained by means of material-removing machining of the blanks can be kept at an ageing temperature of from 600-1000 C., in particular of up to 950 C., for an ageing duration of at least 5 min, in particular at least 60 min, and at most 600 min. Ageing temperatures of at least 700 C., above which the precipitation processes used according to the invention ensue particularly safely, have especially proven themselves in this case. In particular, for this purpose, the ageing temperature can be set to at least 750 C.

[0069] In this case, it has been shown that an ageing duration of from 5-150 min, in particular 5-120 min, is generally sufficient to bring about the precipitation processes used according to the invention. Depending on the respective alloy variants, good increases in hardness can already be achieved in the case of ageing durations of at most 20 min; in other alloy variants, ageing durations of at least 80 mins have proven to be advantageous in this respect. The heating rate should again be at least 5 K/min and at most 20 K/min in this case in order to reliably achieve proper through-heating using conventional furnaces. After the ageing, the blanks can be cooled to room temperature at a cooling rate of from 5-20 K/min.

[0070] In applications in the field of dental technology, no additional measures are generally required to achieve the hardness and strength levels sought for each use. In other cases, for example for the production of fastening components to be installed in or on the body, such as splints, screws, braces and the like, it can be expedient, however, to subject each product to work-hardening by means of cold deformation in order to increase the hardness and strength levels. Generally, the work-hardening takes place before the ageing, since then the blanks or the products formed therefrom are still soft and thus offer maximum hardening potential. Deformation processes which are carried out at temperatures of less than 200 C. are offered as an option for cold deformation for the work-hardening. These include processes in which deformations are produced by tension, compression or bending. These processes include swaging, drawing, straightening, stretching and the like. Typical degrees of deformation are up to 80% in this case. In this way, increases in hardness of up to 300% are possible (for example from 20 HRC in the initial state to 60 HRC in the cold-work-hardened state).

[0071] In the case where the implant is to be provided with a ceramic veneer, the temperature of the ageing can be selected in such a way that the ageing temperature corresponds to the baking temperature of the respective ceramic layers. Then the process of the precipitation hardening or solid-solution strengthening and the baking of the ceramic veneer can be combined with one another so that no additional process step is required, and the baking of the veneer has no additional effect on the precipitation hardening or solid-solution strengthening and the properties of the implant that are adjusted thereby.

[0072] This is possible by means of a specially adjusted combination of the chemical composition, the temperature and the duration of the heat treatment. However, the veneering can also be carried out retrospectively. The alloy according to the invention makes it possible in this case to coordinate the heat treatment and the process parameters of the veneering by means of a wide range of possible variations. The optimal functional properties can thus be adjusted without complicating the processing.

[0073] In order to demonstrate the feasibility of the invention disclosure, eleven different alloy systems Variant I-Variant XI were produced by means of casting. Starting from a CoCrSi base alloy, the alloy elements Mo, W, Nb, Al and Ti were varied.

[0074] In Tables 1-11, for each of the Variants 1-XI, a general alloy specification, the alloy specification which is considered to be optimal in the context of the general alloy specification, the analysis of the specifically examined sample, and a soft and a hard version of the alloy specification are indicated. The softer and harder versions are adjusted primarily by varying the concentrations of the alloy elements Al and Ti, since the effect of said alloy elements on the precipitation hardening is the most pronounced.

[0075] By contrast, varying Mo, W and Nb has an effect primarily on the solid-solution strengthening, as a result of which, the solution-annealing hardness changes. Mo, W and Nb, especially in combination with Al or Ti, bring about pronounced precipitation hardening. Without Al or Ti, precipitation hardening is still possible, but not as pronounced.

[0076] Except for the concentrations of Ti and Al, the concentrations of the respective alloy components of the samples specifically examined in each case were determined in a manner known per se using a spark spectrometer. The concentrations of Al and Ti were determined in each case in a manner likewise known per se using wet chemistry.

[0077] All samples were firstly solution-annealed at 1250 C. for eight hours in a vacuum. The heating took place at a heating rate of approx. 10 K/min. The quenching following the solution-annealing was carried out using nitrogen at 3.5 bar, which corresponded to a cooling rate of from 30-50 K/min in the trials carried out here.

[0078] In practice, after the solution-annealing, the material-removing machining of the blank would follow for the production of the implant.

[0079] The subsequent ageing tests were carried out in the temperature range of from 500-1000 C. (in steps of 100 C.) for ten hours in each case. The heating and cooling rates were approx. 10 K/min in each case. After each heat treatment, the hardness was measured in HRC. In Tables 1-11, for the specifically examined analyses, the average values from at least five individual measurements are indicated. In this case, Variant V does not correspond to the invention, since said variant does not contain any of the elements from the group provided according to the invention which bring about precipitation hardening or solid-solution strengthening.

[0080] The results shown in Tables 1-11 demonstrate that in particular the alloys containing Al and Ti tend towards pronounced precipitation hardening when the ageing is carried out in the temperature range of approximately 800 C.

[0081] Although Variants III and V show only a relatively low increase in hardness after the ageing treatment, said variants are suitable in particular for increasing hardness by means of work-hardening. In this way, it was possible to show that in Variants III and V, an increase in hardness of up to 60 HRC can be achieved by means of work-hardening of the samples.

[0082] Based on the samples from Variants VII-XI which were specifically examined, additional ageing tests were carried out in order to investigate the increase in hardness according to the ageing time. The ageing time was varied in steps of 20 min up to a total of 120 minutes. The tests also started from the state which was reached after the solution-annealing at 1250 C. which has already been explained. The rest of the parameters of the heat treatment were also not changed.

[0083] The results of the ageing tests are shown in Table 12. It should be noted that ageing times of more than 60 minutes already bring about a considerable increase in hardness. In Variants VII-X, after ageing for 120 minutes at 800 C., the hardness is already the same as after ageing for 10 hours.

[0084] The invention thus shows possibilities which allow simplified production of implants or prostheses, specifically of dental implants or prostheses, by applying subtractive processes. For this purpose, the invention proposes the use of a precipitation-hardening or solid-solution-strengthening, biocompatible cobalt-based alloy for the production of blanks. Such blanks are provided in the soft state in the course of the method according to the invention. Subsequently, each component (implant or prosthesis) is produced from the soft blank by means of material-removing machining. Subsequently, a heat-treatment of the implant or prosthesis then takes place to adjust the hardness thereof by means of precipitation hardening or solid-solution formation.

TABLE-US-00001 TABLE 1 VARIANT I C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 3.0-9.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 4.0-6.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 3.0-5.0 3.0-5.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 5.0-7.0 5.0-7.0 <0.5 <0.1 <0.5 Examined example *) 0.032 0.99 24.61 5.08 4.98 <0.01 <0.01 0.06 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 18.3 2.0 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 19.5 2.7 Trial 2 10 h 600 C. 19.4 2.6 Trial 3 10 h 700 C. 22.7 2.2 Trial 4 10 h 800 C. 31.2 3.1 Trial 5 10 h 900 C. 28.5 1.8 Trial 6 10 h 1000 C. 21.8 1.0 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00002 TABLE 2 VARIANT II C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 3.0-5.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 5.0-7.0 <0.5 <0.1 <0.5 Examined example *) 0.005 1.01 24.01 5.02 <0.01 <0.01 0.06 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 21.9 2.3 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 24.3 1.5 Trial 2 10 h 600 C. 25.3 1.5 Trial 3 10 h 700 C. 22.6 1.8 Trial 4 10 h 800 C. 22.7 1.6 Trial 5 10 h 900 C. 25.8 1.8 Trial 6 10 h 1000 C. 21.3 1.7 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00003 TABLE 3 VARIANT III C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 3.0-5.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 5.0-7.0 <0.5 <0.1 <0.5 Examined example *) 0.011 0.96 24.89 5.16 <0.01 <0.02 0.06 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 22.1 2.1 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 22.8 0.5 Trial 2 10 h 600 C. 23.3 2.5 Trial 3 10 h 700 C. 23.3 3.2 Trial 4 10 h 800 C. 20.7 2.7 Trial 5 10 h 900 C. 21.7 1.7 Trial 6 10 h 1000 C. 22.9 3.1 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00004 TABLE 4 VARIANT IV C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 3.0-5.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 5.0-7.0 <0.5 <0.1 <0.5 Examined example *) 0.005 1.02 25.27 5.46 <0.01 <0.02 0.07 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 32.1 0.9 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 30.0 1.1 Trial 2 10 h 600 C. 30.3 1.3 Trial 3 10 h 700 C. 43.3 1.5 Trial 4 10 h 800 C. 46.0 1.0 Trial 5 10 h 900 C. 42.1 1.8 Trial 6 10 h 1000 C. 36.1 1.6 *) Information in % by weight, residue Co and unavoidable impurities;

TABLE-US-00005 TABLE 5 VARIANT V not according to the invention C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 <0.5 <0.1 <0.5 Examined example *) 0.011 0.96 24.89 <0.01 <0.02 0.07 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 18.6 1.7 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 21.5 1.7 Trial 2 10 h 600 C. 20.6 2.7 Trial 3 10 h 700 C. 20.0 1.4 Trial 4 10 h 800 C. 19.8 1.7 Trial 5 10 h 900 C. 22.7 2.3 Trial 6 10 h 1000 C. 22.5 2.4 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00006 TABLE 6 VARIANT VI C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 0.1-6.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 2.0-4.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 0.1-3.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 3.0-6.0 <0.5 <0.1 <0.5 Examined example *) 0.005 1.02 25.27 3.58 <0.01 <0.02 0.07 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 19.3 2.0 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 19.0 1.4 Trial 2 10 h 600 C. 19.0 1.8 Trial 3 10 h 700 C. 20.7 2.2 Trial 4 10 h 800 C. 25.1 2.6 Trial 5 10 h 900 C. 30.1 2.3 Trial 6 10 h 1000 C. 24.4 1.1 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00007 TABLE 7 VARIANT VII C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 0.1-6.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 2.0-4.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 4.0-6.0 0.1-3.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 4.0-6.0 3.0-6.0 <0.5 <0.1 <0.5 Examined example *) 0.019 1.23 25.06 4.76 3.62 <0.01 <0.01 0.11 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 20.4 1.5 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 17.3 2.3 Trial 2 10 h 600 C. 17.5 2.7 Trial 3 10 h 700 C. 20.3 1.4 Trial 4 10 h 800 C. 41.8 2.6 Trial 5 10 h 900 C. 43.4 1.7 Trial 6 10 h 1000 C. 35.7 1.1 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00008 TABLE 8 VARIANT VIII C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 0.1-6.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 2.0-4.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 4.0-6.0 0.1-3.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 4.0-6.0 3.0-6.0 <0.5 <0.1 <0.5 Examined example *) 0.036 1.26 25.29 4.92 3.4 <0.01 0.03 0.07 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 21.6 1.2 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 18.7 1.4 Trial 2 10 h 600 C. 17.3 1.2 Trial 3 10 h 700 C. 18.4 2.1 Trial 4 10 h 800 C. 29.6 2.1 Trial 5 10 h 900 C. 36.1 1.3 Trial 6 10 h 1000 C. 31.4 1.5 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00009 TABLE 9 VARIANT IX C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 0.1-6.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 2.0-4.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 4.0-6.0 0.1-3.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 4.0-6.0 3.0-6.0 <0.5 <0.1 <0.5 Examined 0.019 1.40 25.39 5.73 3.50 <0.01 0.04 0.08 example *) Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 27.0 1.5 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 26.6 2.6 Trial 2 10 h 600 C. 29.3 3.1 Trial 3 10 h 700 C. 29.0 2.8 Trial 4 10 h 800 C. 46.1 1.8 Trial 5 10 h 900 C. 43.5 1.6 Trial 6 10 h 1000 C. 39.3 1.8 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00010 TABLE 10 VARIANT X C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 3.0-9.0 0.1-6.0 <1.0 <3.0 <3.0 Optimal *) <0.1 0.8-2.0 23-27 4.0-6.0 4.0-6.0 2.0-4.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 4.0-6.0 4.0-6.0 0.1-3.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 4.0-6.0 4.0-6.0 3.0-6.0 <0.5 <0.1 <0.5 Examined example *) 0.045 1.35 25.02 4.85 4.83 3.46 <0.01 0.05 0.07 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 34.0 1.2 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 30.7 2.7 Trial 2 10 h 600 C. 33.0 1.4 Trial 3 10 h 700 C. 34.9 1.5 Trial 4 10 h 800 C. 53.7 1.3 Trial 5 10 h 900 C. 51.7 2.1 Trial 6 10 h 1000 C. 47.1 1.7 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00011 TABLE 11 VARIANT XI C Si Cr Mo W Nb Al Ti Mn Ni Fe General *) <0.5 2.5 22-29 3.0-9.0 0.1-5.0 <0.1 <3.0 <3.0 Optimal *) <1.0 0.8-2.0 23-27 4.0-6.0 1.0-3.0 <0.5 <0.1 <0.5 Soft variant *) <0.1 0.8-2.0 23-27 4.0-6.0 0.1-2.0 <0.5 <0.1 <0.5 Hard variant *) <0.1 0.8-2.0 23-27 4.0-6.0 2.0-5.0 <0.5 <0.1 <0.5 Examined example *) 0.005 1.97 25.02 5.07 1.86 <0.01 0.03 0.08 Solution-annealing Duration Temperature Hardness in HRC after solution-annealing 8 1250 25.2 0.4 Ageing Duration Temperature Hardness in HRC after ageing Trial 1 10 h 500 C. 22.0 1.9 Trial 2 10 h 600 C. 27.0 1.8 Trial 3 10 h 700 C. 30.9 1.8 Trial 4 10 h 800 C. 48.0 2.5 Trial 5 10 h 900 C. 44.2 2.0 Trial 6 10 h 1000 C. 40.8 2.9 *) Information in % by weight, residue Co and unavoidable impurities

TABLE-US-00012 TABLE 12 Variant: VII VIII IX X XI Hardness in 20.4 1.5 21.6 1.2 27.0 1.5 34.0 1.2 25.2 0.4 HRC after solution- annealing: Ageing Temperature/ Duration Hardness in HRC after ageing: 800 C./20 min 20.2 1.2 18.3 0.5 27.5 2.9 32.8 1.3 21.3 1.4 800 C./40 min 21.0 1.9 19.0 2.0 30.6 4.0 33.2 0.8 23.8 1.8 800 C./60 min 21.0 2.2 17.8 1.0 32.8 2.5 35.3 2.1 24.0 2.4 800 C./80 min 31.7 3.4 23.4 2.3 40.8 2.8 50.3 2.2 35.0 1.6 800 C./100 min 41.3 1.5 29.3 2.2 43.7 0.8 50.3 2.2 35.0 1.6 800 C./120 min 42.8 1.9 29.0 1.7 46.0 1.1 52.8 2.0 36.4 1.5 800 C./10 h 41.8 2.6 29.6 2.1 46.1 1.8 53.7 1.3 48.0 2.5