EP2662461A1 - Iron-chromium-manganese-nickel alloy - Google Patents

Abstract

Nickel-chromium-manganese alloy comprises 0.005-0.07 wt.% of carbon, 20.5-23 wt.% of chromium, 0.05-1.5 wt.% of silicon, 1.5-6 wt.% of manganese, 1.7-3 wt.% of nickel, 0.15-0.30 wt.% of nitrogen, 0.1-0.8 wt.% of molybdenum, 0.05-4.5 wt.% of copper, up to 0.3 wt.% of cobalt, up to 0.04 wt.% of phosphorus, up to 0.04 wt.% of sulfur, up to 0.2 wt.% of niobium, up to 0.2 wt.% of vanadium, up to 0.2 wt.% of zirconium, up to 0.2 wt.% of tungsten, up to 0.2 wt.% of tantalum, up to 0.1 wt.% of lead, up to 0.1 wt.% of bismuth, up to 0.1 wt.% of tin, and up to 0.1 wt.% of zinc. Nickel-chromium-manganese alloy comprises 0.005-0.07 wt.% of carbon, 20.5-23 wt.% of chromium, 0.05-1.5 wt.% of silicon, 1.5-6 wt.% of manganese, 1.7-3 wt.% of nickel, 0.15-0.30 wt.% of nitrogen, 0.1-0.8 wt.% of molybdenum, 0.05-4.5 wt.% of copper, up to 0.3 wt.% of cobalt, up to 0.04 wt.% of phosphorus, up to 0.04 wt.% of sulfur, up to 0.2 wt.% of niobium, up to 0.2 wt.% of vanadium, up to 0.2 wt.% of zirconium, up to 0.2 wt.% of tungsten, up to 0.2 wt.% of tantalum, up to 0.1 wt.% of lead, up to 0.1 wt.% of bismuth, up to 0.1 wt.% of tin, up to 0.1 wt.% of zinc, up to 0.1 wt.% of selenium, up to 0.1 wt.% of arsenic, up to 0.1 wt.% of titanium, up to 0.05 wt.% of % aluminum, up to 0.05 wt.% of calcium, up to 0.05 wt.% of magnesium, up to 0.05 wt.% of barium, up to 0.05 wt.% of lanthanum, up to 0.05 wt.% of cerium, up to 0.05 wt.% of yttrium, up to 0.05 wt.% of rhenium, up to 0.05 wt.% of oxygen, up to 0.05 wt.% of boron and balance iron including impurities caused by smelting. Independent claims are included for: (1) a component made from the alloy, having at least one mechanical properties at room temperature, where the mechanical properties have >= 420 N/mm 2> of proof stress (0.2%), a tensile strength of >= 620 N/mm 2>, an elongation of greater 20%, and a notched impact strength of >= 60J; (2) method-I for preparing the alloy, comprising melting the alloy constituents in an induction furnace and then deoxidizing by pan aggregates; and (3) method-II for producing the component, comprising performing the method for producing a cast alloy, and casting the component.

Description

The invention relates to a nickel-chromium-manganese alloy, a component, a method for producing an alloy, a method for producing a component and the use of nickel-chromium-manganese alloys.

Duplex steels are known from the prior art. Duplex steel refers to a steel that has a two-phase structure consisting of a ferrite matrix with intercalated austenite. Duplex steels have established themselves as engineering materials in many areas of engineering due to the interplay of good mechanical properties and very good corrosion properties. A disadvantage of duplex steels is that they can only be machined with great effort. Furthermore, the higher proportion of nickel and the high proportion of molybdenum are disadvantageous to duplex materials known from practice, since this makes the materials relatively expensive. Furthermore, the currently known production methods for duplex steels are expensive, so that standard for the production of duplex steels AOD / VOD converter (argon Oxygen Decarburisation- / Vacuum Oxygen Decarburisation converter) are used with appropriate secondary metallurgical possibilities. A foundry does not usually have such converters.

Out EP 1 327 008 B1 An alloy is known. This alloy has a relatively low nickel content and a relatively high manganese content. This has the disadvantage that the embrittlement tendency of the alloy increases due to the low nickel content and high manganese content.

Furthermore, it is off US 6,096,441 an alloy is known which has a very low nickel content and average manganese content. This alloy is almost impossible to image by casting.

Out US 3,736,131 An alloy is known which has a very low nickel content and high manganese content. According to current requirements, this alloy has too low austenite content and insufficient toughness.

Against this background, the object of the invention was to propose a nickel-chromium-manganese alloy which has good mechanical properties, good corrosion resistance and good machinability and which can preferably be produced in a cost-efficient manner in a foundry without special melt-metallurgical treatment. A further object of the invention is to propose a component, a method for producing an alloy, a method for producing a component, and a use of nickel-chromium-manganese alloys.

This object is achieved by the alloy according to claim 1, the component according to claim 8, the method for producing an alloy according to claim 9, the method for producing a component according to claim 11 and the use according to claim 14. Advantageous embodiments are given in the subclaims and the following description.

The invention is based on the idea of producing good machinability by substituting nickel with one or more of the alloying elements manganese, nitrogen and copper. During processing, it is assumed that nickel leads to hardening of the chip, adhesion of the chips to the tool and unfavorable chip breaking behavior. It has been found that these negative properties can be reduced by the substitution of nickel with copper and / or manganese. Thus it has been shown that the hardening and the tendency to stick can be significantly reduced in this substitution. This leads advantageously to low tool wear and higher cutting values. The substitution with nitrogen serves in conjunction with manganese to set a favorable ferrite-austenite ratio and to improve the chip breakage.

The invention proposes a nickel-chromium-manganese alloy with 0.005 to 0.07% by weight of carbon, 20.5 to 23.0% by weight of chromium, 0.05 to 1.5% by weight of silicon, 1.5 to 6, 0 wt% manganese, 1.7 to 3.0 wt% nickel, 0.15 to 0.30 wt% nitrogen, 0.1 to 0.8 wt% molybdenum, 0.05 to 4.5 wt% copper, to 0.3 wt% cobalt, up to 0.04 wt% phosphorus, up to 0.04 wt% sulfur, up to 0.2 wt% niobium, up to 0.2 wt% vanadium, up to 0.2 wt% zirconium, up to 0, 2% by weight of tungsten, up to 0.2% by weight of tantalum, up to 0.1% by weight of lead, up to 0.1% by weight of bismuth, up to 0.1% by weight of tin, up to 0.1% by weight of zinc, up to 0.1% by weight % Selenium, up to 0.1% by weight arsenic, up to 0.1% by weight of titanium, up to 0.05% by weight of aluminum, up to 0.05% by weight of calicum, up to 0.05% by weight of magnesium, up to 0.05% by weight of barium, up to 0.05% by weight of lanthanum, up to 0 , 05% by weight of cerium, up to 0.05% by weight of yttrium, up to 0.05% by weight of rhenium, up to 0.05% by weight of oxygen, up to 0.05% by weight of boron and the remainder of iron, including impurities caused by melting.

Particularly preferred is an alloy, however, individually or side by side more than 0.005 and less than 0.07 wt% carbon, more than 20.5 and less than 23.0 wt% chromium, more than 0.05 and less than 1.5 Wt% silicon, more than 1.5 and less than 6.0 wt% manganese, more than 1.7 and less than 3.0 wt% nickel, more than 0.15 and less than 0.30 wt% nitrogen, more as 0.1 and less than 0.8% by weight of molybdenum, more than 0.05 and less than 4.5% by weight of copper.

As impurities caused by melting, the alloying elements which are not explicitly mentioned in connection with the present invention description are understood, which find their way into the alloy when the alloy is melted. In a particularly preferred embodiment, the invention has no such impurity-causing impurities and thus only the alloying element mentioned in connection with the present invention description; the remainder in this preferred embodiment would therefore only be iron.

In a preferred embodiment, the alloy according to the invention has as little or no constituents as possible of the following alloying elements: cobalt, phosphorus, sulfur, niobium, vanadium, zirconium, tungsten, tantalum, lead, bismuth, tin, zinc, selenium, arsenic, titanium, aluminum , Calcium, magnesium, barium, lanthanum, cerium, yttrium, rhenium, oxygen, boron. More preferably, the alloy has less than 0.1% by weight of niobium (Nb), vanadium (V), zirconium (Zr), tantalum (Ta) up. It has been recognized that the grain sizes produced during casting and the resulting solidification times in nitrogen-alloyed steels can cause embrittlement and thus a significant drop in impact strength, since, unlike in continuous casting with subsequent hot working, the alloying of the abovementioned micro-alloying elements for the accumulation of nitrides and Carbonitrides can lead in the ferritic matrix and thus leads to embrittlement of the ferrite. It is therefore preferred to keep the contents of the aforementioned micro-alloying elements particularly low.

In a preferred embodiment of the alloy, the oxygen content is minimized, preferably to less than 0.04 wt%. This has a toughening effect. In other manufacturing processes, this can be achieved by degassing metallurgical measures, the success of which can not be guaranteed in the casting process. Therefore, attention should be paid to the lowest possible oxygen content when adjusting the alloy. In a preferred embodiment, only the minimum amount required used on nickel (ie amounts of ≥ 1.7 wt% Ni), thereby achieving the optimized mechanical processing and good mechanical properties.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention has 0.005 to 0.05 wt.% Carbon. It has been found that reducing the potential carbon content from 0.07 wt.% To 0.05 wt.% Minimizes carbide formation and increases resistance to intergranular corrosion.

In a preferred embodiment, the nickel-chromium-manganese alloy has 21.2 to 22.5% by weight of chromium, particularly preferably 21.4 to 22% by weight of chromium. It has been found that by increasing the lower range limit for chromium from 20.5% by weight to 21.2% and 21.4% by weight, respectively, and decreasing the upper range limit for chromium from 23.0% by weight to 22% , 5 or 22.0 wt.% An advantageous composition of the ferrite-austenite ratio is achieved, which leads to the positive mechanical properties of the alloy.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention has 0.25 to 1.0 wt.% Or 0.2 to 1.0 wt.% Silicon. It has been found that by increasing the lower range limit for silicon from 0.05 to 0.25, or 0.2% by weight and by decreasing the upper range limit for silicon from 1.5% by weight to 1.0 Wt.% In particular, the advantage is achieved that the oxygen still present in the melt is set by the silicon, without the ferrite-austenite ratio is adversely affected.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention has only up to 0.03% by weight of phosphorus and / or only up to 0.015% by weight of sulfur. It has been found that by lowering the upper range limit for phosphorus from 0.04 wt% to 0.03 wt% and / or lowering the upper range limit for sulfur from 0.04 wt% to 0.015 wt%. the advantage is achieved that exude no technologically relevant embrittling phases.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention comprises 2.0 to 2.7 wt.% Nickel. It has been found that by increasing the lower range limit for nickel from 1.7 to 2.0 wt.% And by reducing the upper range limit for nickel from 3.0 wt.% To 2.7 wt The advantage is achieved that the mechanical properties of the material with minimum nickel content can be reliably achieved without embrittlement. It is considered that embrittlement of the material occurs at nickel contents of less than 1.7% by weight. This could be demonstrated by a decreasing impact strength on materials with nickel contents of less than 1.7% by weight.

It has also been found that nickel contributes to the formation of austenite and leads to a reduction in the solubility of nitrogen in the ferrite. Therefore, a minimum content of nickel in the alloy for austenite formation is helpful. Furthermore, limiting the maximum to limit the decreasing solubility of the nitrogen in the ferrite is advisable.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention comprises 0.2 to 0.25% by weight of nitrogen. It has been found that by increasing the lower range limit for nitrogen from 0.15 to 0.2 wt.% And reducing the upper range limit for nitrogen from 0.3 wt.% To 0.25 wt Advantage is achieved that the material has a structure of 30-50% ferrite content with optimum mechanical properties.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention has 0.3 to 0.7% by weight of molybdenum. It has been found that by increasing the lower range limit for molybdenum from 0.1 to 0.3% by weight, and by reducing the upper range limit for molybdenum from 0.8% by weight to 0.7% by weight, in particular Advantage is achieved that a significantly increased resistance to intergranular corrosion and an increase in strength occurs without disadvantages in mechanical processing.

The nickel-chromium-manganese alloy according to the invention can be carried out in a preferred embodiment with relatively low copper contents. In this preferred embodiment, the invention comprises only 0.3 to 1.0 wt% copper. This provides the advantage that the material has improved machinability with a stable ferrite-austenite ratio.

In continuation of this preferred embodiment, but also as an independent measure, the alloy according to the invention may contain 3.5 to 5.0% by weight of manganese, particularly preferably 3.5 to 4.5% by weight of manganese. By increasing the lower range limit from 1.5 wt% manganese to 3.5 wt% manganese and lowering the upper range limit from 6.0 wt% manganese to 5.0 wt% or 4.5 wt% Manganese can achieve the advantage that the material possesses optimum machinability without embrittlement of the ferritic matrix occurring.

In a supplementary or alternative embodiment, the desired good mechanical processing and the desired high strength can be achieved by alloying copper. In a preferred embodiment, therefore, copper contents of greater than 3 wt .-% are used to meet the casting requirements of the material. Particular preference is given to using copper contents of from 3.0 to 4.5% by weight of copper. In a preferred embodiment, at high copper levels the manganese content is lowered, preferably to values of less than 3.0% by weight and at least 1.5% by weight. In a preferred embodiment, the ferrite-austenite ratio with adjusted heat treatment is set at 45-70% austenite.

In a preferred embodiment, the manganese content of the alloy in weight percent is less than three times the nickel content of the alloy in weight percent. Most preferably, the ratio of the manganese content of the alloy in weight percent to the nickel content of the alloy in weight percent is between 1.5 and 3 times, preferably between 1.5 and 2.5 times. It has been recognized that setting such a ratio results particularly well in the desired mechanical properties and improved machinability. It is assumed that a Mn content / Ni content of greater than 3 leads to embrittlement of the material. It is believed that lowering the Mn content / Ni content below 1.5 results in a decrease in strength as well as poorer machinability.

It has been recognized that manganese is a weak austenite former which has the property of increasing the solubility of nitrogen in the alloy. This seems to apply to both the austenitic and ferritic phases. This entails the danger of nitrogen supersaturation of the ferrite and consequent waste of the material toughness. Therefore, it is advisable to limit the manganese content as well as to determine this depending on the nickel content.

In an alternative preferred embodiment, the sum of the manganese content and the copper content of the alloy in weight percent is less than three times the nickel content of the alloy in weight percent. More preferably, the ratio of this sum to the nickel content of the alloy in weight percent is between 1.5 and 3.5 times, preferably between 1.8 and 3.0 times. It has been recognized that setting such a ratio results in the desired mechanical properties and improved machinability. A deviation below this ratio may result in a non-preferred ferrite content <30% and lower strength properties. A deviation above this ratio can lead to low toughness properties.

It has been recognized that an increased level of copper in combination with manganese can be used to substitute nickel. At low levels (up to 1% by weight), copper leads to an increase in the strength of the alloy without any noticeable effect on the ferrite-austenite ratio. In higher contents of greater than or equal to 3% by weight, the copper has a weak austenite-forming effect. In the middle alloy range between 1 and 3 wt.% Copper, these effects cancel each other out, which leads to an unnecessary increase in the cost of the alloy. The copper content of the alloy should therefore be tuned with the manganese and nickel content.

In a preferred embodiment, the alloy has a ferrite content of the total structure of 30 to 55%, particularly preferably 35 to 55%. It has been shown that particularly good mechanical properties are achieved with such a ferrite component. In a preferred embodiment, the remainder of the microstructure is austenite.

• 0,2% - Dehngrenze (Rp0,2) ≥ 420 N/mm2,
• Zugfestigkeit (Rm) ≥ 620 N/mm2,
• Dehnung (A5) ≥ 20% und
• Kerbschlagzähigkeit (Charpy - V) ≥ 60J,
  wobei die Dehnung (Bruchdehnung) durch das in DIN EN ISO 6892-1 beschriebene Verfahren "Zugversuch" ermittelt wird und die Kerbschlagzähigkeit (Charpy - V) die in DIN EN ISO 148-1 genannten "verbrauchte Schlagenergie" ist.

The component according to the invention consists at least in part, preferably completely, of the alloy according to the invention. In a preferred embodiment, this component has at least one, preferably all of the mechanical properties listed below at room temperature:

• 0.2% - yield strength (Rp0.2) ≥ 420 N / mm2,
• Tensile strength (Rm) ≥ 620 N / mm 2,
• Elongation (A5) ≥ 20% and
• Notched impact strength (Charpy - V) ≥ 60J,
  wherein the elongation (elongation at break) is determined by the method "tensile test" described in DIN EN ISO 6892-1 and the notched impact strength (Charpy - V) is the "consumed impact energy" specified in DIN EN ISO 148-1.

The inventive method for producing the alloy according to the invention provides that the alloy components are melted in an induction furnace and deoxidized by means of Pfannenzuchlägen. It has been shown that the alloy according to the invention can be produced particularly easily in this way.

In a preferred embodiment, the melting of the alloying constituents is carried out in a medium frequency crucible furnace without subsequent secondary metallurgy such as ladle degassing.

The inventive method for producing the component according to the invention provides for carrying out the inventive method for producing the alloy according to the invention, thereby to produce a casting alloy and then provides the casting of the component according to the invention from this casting alloy.

In a preferred embodiment, the casting of the component takes place under normal atmosphere, ie without a vacuum or inert gas atmosphere.

In a preferred embodiment, preferably no subsequent forming takes place after the casting of the component. In a preferred embodiment, at least no rolling and / or forging takes place. A transformation leads to a reduction of the grain size. Although this often leads to an improvement of the mechanical properties. However, the method according to the invention preferably dispenses with a Forming to save this operation. It was recognized that in thick-walled areas, ie areas with a wall thickness of more than 20 mm, grain sizes of more than 1.5 mm are increasingly found, which are also retained over the entire life cycle of the component. Grain sizes of more than 1.5 mm can not be avoided with cast components, which is why the alloy should already be adjusted from the outset so that it achieves the required properties without deformation.

In a preferred embodiment, the cast component is subjected to a heat treatment at a temperature of 1,000 to 1,250 ° C with accelerated cooling. This makes it possible to set a ferrite-austenite ratio of preferably 45-55% ferrite, balance austenite.

In a particularly preferred embodiment, when carrying out the process according to the invention, the manganese, nickel and copper contents are adjusted so that the alloy remains pourable and exhibits optimum cutting values and good mechanical-technological properties after solidification. This is achieved in particular by the manganese content in the following limits: 1.5 to 6.0% by weight, the nickel content within the following limits: 1.7 to 3.0% by weight and the copper content. Content within the following limits: 0.05 to 4.5Gew% is selected.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention is used as cast alloy. Here, a cast alloy is understood in particular to mean an alloy which is produced in a primary molding process without subsequent transformation. By using the nickel-chromium-manganese alloy according to the invention as cast alloy, a large design spectrum is available for the production method for the component according to the invention. By casting both thin-walled and thick-walled component geometries can be generated. It has been found that both thin-walled and thick-walled components can be produced by casting from the nickel-chromium-manganese alloy according to the invention.

In a preferred embodiment, the nickel-chromium-manganese alloy according to the invention is adjusted so that it already meets the mechanical requirements required for the use of the component consisting of this alloy without after-treatment, or at least alone with subsequent heat treatment.

Furthermore, limiting the maximum to limit the decreasing solubility of the nitrogen in the ferrite is advisable.

Particularly preferably, the alloy according to the invention is used as a duplex material. The alloy according to the invention is particularly preferably used in order to use it for components for general mechanical engineering, in particular for components in the separation technique, for example, the decanter or centrifuge or for components used in mixers, pumps, valves, valves and / or piping.

Table 1 below shows, as examples of the alloy according to the invention, alloys 1 to 18. Further, Table 1, which is incorporated herein by reference, shows as alloys (alloys not belonging to the invention) alloys which are similar to the alloy types 22Cr-5Ni (material number 1.4470) and 23Cr-4Ni, respectively (Material number 1.4362) were produced. The table shows the carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), nickel (Ni), molybdenum (Mo), nitrogen (N), aluminum (Al) and copper (Cu) wt .-% of the respective alloy, the remainder were each iron and unavoidable impurities. Further, the table shows the ratio of the Mn content to the Ni content and the ratio of the sum of manganese and copper contents to nickel content (* = reference alloys). <b> Table 1: </ b> Ex. C Si Mn P S Cr Ni Not a word N al Cu (Mn + Cu) / Ni Mn / Ni 1 0.03 0.73 4.95 0.028 0.001 21.59 1.57 0.54 0.215 0,012 0.19 3.27 3.15 2 0,025 0.87 5.41 0,015 0,003 21.28 1.6 0.52 0.22 0,015 0.25 3.54 3.38 3 0.027 0.8 3.69 0,021 0.005 20.7 2.2 0.2 0,186 0.005 0.6 1.95 1.68 4 0.03 0.69 4.8 0,015 0,004 21.6 2.6 0.83 0.225 0,029 0.51 2.04 1.85 5 0.03 0.62 4.77 0,018 0.001 21.1 2.28 0.47 0,241 0.011 0.3 2.22 2.09 6 0.028 0.86 4.46 0.08 0.005 21.08 1.74 0.53 0,228 0,014 0.23 2.70 2.56 7 0,035 0.4 4.2 0.02 0,003 21.5 2.3 0.4 0.23 0.01 0.6 2.09 1.83 8th 0,025 0.6 3.8 0.02 0,003 21.76 2.34 0.7 0.24 0.011 0.4 1.79 1.62 9 0.03 0.56 4.13 0.019 0,004 21.62 2.21 0.34 0.21 0,018 0.63 2.15 1.87 10 0.028 0.72 4.18 0,022 0,006 21.43 2.17 0.45 0.23 0.02 0.38 2.10 1.93 11 0,035 0.8 3.68 0,017 0,003 21.4 2.03 0.52 0,228 0.009 0.59 2.10 1.81 12 0.027 0.47 4.26 0,025 0,003 22,01 2.48 0.39 0.236 0,014 0.57 1.95 1.72 13 0,035 0.34 4.42 0.02 0,002 22.41 2.46 0.33 0.207 0,014 0.81 2.13 1.80 14 0,035 0.31 2.8 0.02 0,002 21.2 2.85 0.41 0,179 0.016 0.15 1.04 0.98 15 0,035 0.23 2.3 0,012 0,003 21,25 2.57 0.39 0.221 0.001 3.34 2.19 0.89 16 0,015 0.33 1.83 0,006 0.04 21.63 2.12 0.4 0.226 0.01 3.31 2.42 0.86 17 0,025 0.53 3.87 0.019 0,003 21.51 2.21 0.41 0.25 0.034 0.79 2.1 1.75 18 0,035 0.5 2 0.02 0,003 22 2.3 0.5 0.22 0.01 3.5 2.39 0.87 19 * 0.023 0.68 0.98 0.019 0.001 23.54 4.64 0.47 0.22 0.019 0.27 0.27 0.21 20 * 0.023 0.68 0.89 0.02 0.001 23.27 4.79 0.49 0,205 0,017 0.25 0.24 0.19 21 * 0.02 0.62 1.18 0,018 0.001 23.47 4.61 0.45 0.23 0.02 0.29 0.32 0.26 22 * 0,022 0.67 1.11 0.02 0,002 23.45 4.37 0.54 0.213 0,018 0.23 0.31 0.25 23 * 0.028 0.74 1.12 0.023 0,006 22.67 6 2.59 0.16 0.016 0.1 0.20 0.19

Table 2 below shows the mechanical-technological parameters determined for the abovementioned alloys. <b> Table 2: </ b> Ex. Rp0.2 rm A ISO-V (RT) Tooling Values fulfilled (Mn + Cu) / Ni Mn / Ni 1 477 636 36.4 46.2 133 1 3.27 3.15 2 459.7 638 42.8 49.5 132 1 3.54 3.38 3 445 625.5 42.4 180.5 130 2 1.95 1.68 4 441.3 639 42.2 148 nb 2 2.04 1.85 5 450 649 44.7 205 128 2 2.22 2.09 6 457.5 641 43.3 93.7 125 2 2.70 2.56 7 448 641 40.3 185 130 2 2.09 1.83 8th 457 648 39.3 170.6 127 2 1.79 1.62 9 445 643 38.6 156 nb 2 2.15 1.87 10 451 637 43.2 192.3 135 2 2.10 1.93 11 462 642 41.2 173 130 2 2.10 1.81 12 473 660 44.6 201.3 131 2 1.95 1.72 13 468 653 43.7 178.5 131 2 2.13 1.80 14 438 597 48.7 180 118 1 1.04 0.98 15 425 650 42 218 nb 2 2.19 0.89 16 441 635 40 154 124 2 2.42 0.86 17 441 640 43.8 189 nb 2 2.11 1.75 18 475 665 35.7 125 nb 2 2.39 0.87 19 * 465.3 660 42.1 197 100 2 0.27 0.21 20 * 455.7 647.3 41.3 196.3 100 2 0.24 0.19 21 * 458.3 668 42.6 179 102 2 0.32 0.26 22 * 513 653 39 209 99 2 0.31 0.25 23 * 484 681 38.3 239 89 2 0.20 0.19

The Fig. 1 indicates the degree of compliance with the desired mechanical properties 0.2% proof stress (Rp0.2) ≥ 420 N / mm2, tensile strength (Rm) ≥ 620 N / mm2, elongation (A5)> 20% and notched impact strength (Charpy - V) ≥ 60J.

It can be seen that setting the Mn / Ni content results in a material which covers the entire requirement profile and additionally has better machinability ( Fig. 2 ). While falling below this ratio, a failure to achieve the mechanical-technological values (strength or toughness) or when it falls below a lower machinability can be seen.

The Fig. 2 shows the machinability of the experimental analyzes based on Mo-poor reference alloys as a function of the Mn / Ni ratio. One recognizes the improved machinability at higher Mn / Ni ratios.

The Fig. 3, 4 and 6 show typical structures of the Ni-Cr-Mn duplex alloy according to the invention according to the alloy composition defined in detail in the table above according to Example 5, 10 and 15. It can be seen the typical balanced two-phase structure of the duplex steels.

The Fig. 5 shows the representative gap fracture at unfavorable Mn-Ni ratio of alloy composition no. 1. The ratio is too high, a decrease in toughness can be seen.

Claims (15)

Nickel-chromium-manganese alloy with 0.005 to 0.07 wt% carbon 20.5 to 23.0% by weight of chromium 0.05 to 1.5% by weight of silicon 1.5 to 6.0% by weight manganese 1.7 to 3.0% by weight nickel 0.15 to 0.30 wt% nitrogen 0.1 to 0.8% by weight of molybdenum 0.05 to 4.5% by weight of copper to 0.3% by weight of cobalt to 0.04 wt% phosphorus to 0.04 wt% sulfur to 0.2% by weight of niobium to 0.2% by weight of vanadium to 0.2% by weight zirconium to 0.2% by weight tungsten up to 0.2% by weight tantalum up to 0.1% by weight of lead to 0.1% by weight of bismuth to 0.1% by weight of tin to 0.1% by weight of zinc to 0.1% by weight of selenium up to 0.1% by weight of arsenic to 0.1% by weight of titanium to 0.05% by weight of aluminum to 0.05% by weight of calicum up to 0.05% by weight of magnesium to 0.05% by weight of barium to 0.05% by weight of lanthanum to 0.05% by weight of cerium to 0.05% by weight of yttrium up to 0.05% by weight of rhenium to 0.05% by weight of oxygen to 0.05% by weight boron Remaining iron, including impurities caused by melting. An alloy according to claim 1, but individually or side by side 0.005 to 0.05% by weight of carbon 21.2 to 22.5 wt% chromium 0.25 to 1.0% by weight of silicon 3.5 to 5.0% by weight of manganese 0.3 to 1.0% by weight of copper up to 0.03% by weight phosphorus to 0.015% by weight of sulfur contains. An alloy according to claim 2, but which individually or side by side 21.4 to 22.0 wt% chromium 3.5 to 4.5% by weight of manganese 2.0 to 2.7% by weight nickel 0.2 to 0.25% by weight of nitrogen 0.3 to 0.7% by weight of molybdenum contains. An alloy according to claim 1, but individually or side by side 0.005 to 0.05% by weight of carbon 21.2 to 22.5 wt% chromium 0.2 to 1.0% by weight of silicon 1.5 to 3.0% by weight of manganese 3.0 to 4.5% by weight copper up to 0.03% by weight phosphorus to 0.015% by weight of sulfur contains. Alloy according to claim 4, characterized by 21.4 to 22.0% by weight of chromium 2.0 to 2.7% by weight nickel 0.2 to 0.25% by weight of nitrogen 0.3 to 0.7% by weight of molybdenum contains. Alloy according to one of claims 1 to 5, characterized in that the manganese content of the alloy in wt.% Is less than three times the nickel content of the alloy in wt.% And higher than 1.5 times the nickel content of the alloy in wt. %. Alloy according to one of claims 1 to 6, characterized in that the ratio of the sum of the copper content and the manganese content in% by weight to the nickel content of the alloy in% by weight is between 1.5 and 3.5. Alloy according to one of claims 1 to 7, characterized in that the alloy has a ferrite content of 30 to 55% of the total structure. Component of an alloy according to one of claims 1 to 8, characterized in that the component has at least one of the following mechanical properties at room temperature: 0.2% proof stress (Rp0.2) ≥420 N / mm2, Tensile strength (Rm) ≥ 620 N / mm 2, Elongation (A5)> 20% and Impact strength (Charpy - V) ≥ 60J. A process for producing an alloy according to any one of claims 1 to 8, characterized in that the alloy components are melted in an induction furnace and deoxidized by means of Pfannenzuchlägen. A method according to claim 10, characterized in that the alloying components are melted in a medium frequency crucible furnace without further secondary metallurgy. Method for producing the component according to Claim 9, characterized by carrying out the method according to one of Claims 8 or 9 for producing a cast alloy and casting the component. A method according to claim 12, characterized in that the component is not rolled or forged after casting. A method according to claim 12 or 13, characterized in that a heat treatment of the cast component takes place at a temperature of 1000 to 1250 ° C. Use of the alloy according to one of claims 1 to 8 as duplex steel.

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