EP0657556A1 - Austenitic alloys and their applications - Google Patents
Austenitic alloys and their applications Download PDFInfo
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- EP0657556A1 EP0657556A1 EP94118682A EP94118682A EP0657556A1 EP 0657556 A1 EP0657556 A1 EP 0657556A1 EP 94118682 A EP94118682 A EP 94118682A EP 94118682 A EP94118682 A EP 94118682A EP 0657556 A1 EP0657556 A1 EP 0657556A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
Definitions
- the invention relates to high-chromium, corrosion-resistant, austenitic alloys and their use.
- Table A shows, by way of example, the metallic materials which are possible according to the prior art for the handling of oxidizing acids (nickel alloys and high-alloy special stainless steels, 2nd edition, Expert Verlag, 1993). With the exception of superferrite, they are so-called austenitic alloys, i.e. around those with a cubic surface-centered lattice structure.
- the alloys according to the prior art shown in Table A are within a range of between about 17 and 29% by weight for the main alloy element chromium. With regard to the corrosion resistance to max.
- already relatively low-alloyed materials can be used with 67% nitric acid.
- a suitable material is Cronifer 1809 LCLSi, with the addition LSi indicating a restricted silicon content (low silicon).
- Nickel-rich materials such as Nicrofer 6030, which is also listed in Table A, offer advantages if halogen compounds are present or if nitric acid / hydrofluoric acid mixtures are used, such as when reprocessing nuclear reactor fuel elements.
- the molybdenum-containing material Nicrofer 3127 hMo (1.4562) according to EP 0 292 061 with its chromium content of 26 to 28% is of interest where, in addition to the relatively high resistance to nitric acid, particular importance is attached to high resistance to pitting and crevice corrosion.
- a typical removal rate in boiling azeotropic nitric acid (Huey test) for this material is approx. 0.11 mm / year.
- the Cronifer 1815 LCSi (1.4361) alloyed with about 4% silicon shows excellent resistance up to the boiling point of the nitric acid.
- the materials that can be used to produce urea have a composition similar to that of steels that are particularly corrosion-resistant to nitric acid.
- the Nicrofer 2509 Si7 steel alloyed with 7% silicon has been developed in accordance with EP-A 0516 955 for working with hot, highly concentrated sulfuric acid.
- the superferrite Cronifer 2803 Mo (1.4575) also has a special interest. Because of their limited processability, superferrites are only suitable for small wall thicknesses, which are usually 2 mm and below.
- Alloys with, for example, about 31% chromium and about 46% chromium have been found in nitric acid-hydrofluoric acid mixtures for their corrosion resistance examined ("Materials and Corrosion" 43 , (1992) pp. 191-200). These alloys with high chromium contents could no longer be produced as austenitic materials and could only be processed using special processes such as powder metallurgy.
- British Patent 1 114 996 claims alloys with 14 to 35% chromium and 0 to 25% iron.
- EP-A 0 261 880 describes alloys with 27 to 31% chromium, 7 to 11% iron and the rest essentially nickel.
- Alloys with chromium contents of more than 30% Cr can no longer be produced homogeneously and austenitically. In practice, chrome contents of max. 29% set.
- the Superferrite 1.4575 with a chromium content of 26 to 30% is a ferritic alloy.
- EP-A 0 130 967 describes the suitability of nickel alloys and stainless steels for hot sulfuric acid of 99% -101% at> 120 ° C in heat exchangers.
- the alloys are selected according to the following formula: 0.35 (Fe-Mn) + 0.70 (Cr) + 0.30 (Ni) - 0.12 (Mo)> 39.
- the above-mentioned molybdenum-containing stainless steels have a maximum of 28% chromium on.
- molybdenum-free chromium and nickel alloys consisting of 21-35% chromium, 30-70% iron, 2-40% nickel and 0-20% manganese as well as usual accompanying elements are used as materials for objects that are against Sulfuric acid above 96% to 100% and are resistant to oleum.
- EP-A 249 792 claims the use of alloys consisting of 21 to 55% chromium, 0 to 30% iron, 0 to 5% tungsten and 45 to 79% Ni in concentrated sulfuric acid.
- DE-A 2 154 126 describes the use of austenitic nickel alloys with 26-48% nickel, 30-34% chromium, 4-5.25% molybdenum, 4-7.5% cobalt, 3-2.5% iron , 1-3.5% manganese etc. as a resistant material for objects in hot sulfuric acid above 65%.
- high chromium contents are important for the resistance of nickel-chromium-iron alloys to alkali-induced stress corrosion cracking in hot alkaline solutions.
- the chromium content should be at least 18%, preferably at least 26 to 27%, up to max. 35% and the iron content to max. 7% be restricted.
- the alloy 690 with 29% chromium and 9% iron is particularly resistant to alkali-induced stress corrosion cracking.
- US 4,853,185 describes in the high temperature range corrosion-resistant alloys consisting of approximately 30% to 45% nickel, approximately 12 to 32% chromium, at least one of the elements niobium with 0.01% to 2.0%, tantalum with 0.2 to 4 , 0% and vanadium with 0.05 to 1.0%, further up to 0.20% carbon, approximately 0.05 to 0.50% nitrogen, an addition of titanium of up to 0.20, which is effective for high-temperature strength %, Balance iron and impurities, where the sum of free carbon and nitrogen (C + N) F must be> 0.14 and ⁇ 0.29.
- EP-A 340 631 describes a high-temperature-resistant steel tube with a low silicon content, which is not more than 0.1% by weight of carbon, not more than 0.15% by weight silicon, not more than 5% by weight manganese, 20 to 30% by weight chromium, 15 to 30% by weight nickel, 0.15 to 0.35% by weight nitrogen, 0.1 to 1.0% by weight of niobium and not more than 0.005% by weight of oxygen, at least one of the metals aluminum and magnesium in an amount of 0.020 to 1.0% by weight and 0.003 to 0.02, respectively % By weight and the rest iron and unavoidable impurities.
- the object of the present invention was to provide alloys which can be used in a variety of ways and can be processed without problems and whose corrosion rates are low.
- alloys according to the invention are high in chromium and still easy to process. They have only a low molybdenum content or no molybdenum and, contrary to expectations, have high corrosion resistance in hot, oxidizing acids.
- the invention relates to austenitic, corrosion-resistant chromium, nickel and iron alloys of the following composition: 32-37 wt% chromium 28-36 wt% nickel Max. 2% by weight of manganese Max. 0.5% by weight silicon max 0.1% by weight aluminum Max. 0.03 wt% carbon Max. 0.01 wt% sulfur Max. 0.025 wt% phosphorus Max. 2% by weight molybdenum Max. 1% by weight copper as well as usual manufacturing-related admixtures and impurities and the rest as iron, which are characterized in that the alloys additionally contain 0.3-0.7% by weight of nitrogen.
- Austenitic alloys with the following composition are also preferred: 32-35 wt% chromium 28-36 wt% nickel Max. 2% by weight of manganese Max. 0.5% by weight silicon Max. 0.1% by weight aluminum Max. 0.03 wt% carbon Max. 0.01 wt% sulfur Max. 0.025 wt% phosphorus Max. 2% by weight molybdenum Max. 1% by weight copper as well as usual manufacturing-related admixtures and impurities and the rest as iron, which are characterized in that the alloys additionally contain 0.4-0.6% by weight of nitrogen.
- These preferred alloys are preferably used as wrought materials for the production of semi-finished products, e.g. Sheets, strips, rods, wires, forgings, pipes, used.
- Austenitic alloys with the following composition are also preferred: 35-37 wt% chromium 28-36 wt% nickel Max. 2% by weight of manganese Max. 0.5% by weight silicon Max. 0.1% by weight aluminum Max. 0.03 wt% carbon Max. 0.01 wt% sulfur Max. 0.025 wt% phosphorus Max. 2% by weight molybdenum Max. 1% by weight copper as well as usual manufacturing-related admixtures and impurities and the rest as iron, which are characterized in that the alloys additionally contain 0.4-0.7% by weight of nitrogen.
- These preferred alloys are preferably used as materials for the production of castings, e.g. Pumps and fittings.
- Austenitic alloys with the following composition are also preferred 32.5-33.5 wt% chromium 30.0-32.0 wt% nickel 0.5-1.0% by weight of manganese 0.01-0.5% by weight silicon 0.02 - 0.1 weight aluminum Max. 0.02 wt% carbon Max. 0.01 wt% sulfur Max. 0.02 wt% phosphorus 0.5-2% by weight molybdenum 0.3-1% by weight copper 0.35-0.5% by weight nitrogen or 34.0-35.0 wt% chromium 30.0-32.0 wt% nickel 0.5-1.0% by weight of manganese 0.01-0.5% by weight silicon 0.02-0.1% by weight aluminum Max. 0.02 wt% carbon Max. 0.01 wt% sulfur Max.
- the alloys can contain up to 0.08% by weight of rare earths, up to 0.015% by weight of calcium and / or up to 0.015% by weight of magnesium as admixtures due to the manufacturing process .
- the alloys according to the invention can also be used as materials for articles which, compared to mixtures of sulfuric acid and sodium dichromate and / or chromic acid, contain 0.1 to 40% by weight, preferably 0.3 to 20% by weight, nitric acid and 50 to 90% by weight .-% sulfuric acid up to 130 ° C or from 0.01 to 15% by weight hydrofluoric acid and 80-98% by weight sulfuric acid up to 180 ° C or from up to 25% by weight nitric acid and up to 10% by weight hydrofluoric acid are resistant up to 80 ° C.
- the alloys according to the invention Compared to organic acids, e.g. Formic acid and acetic acid, the alloys according to the invention have sufficient resistance and stability.
- the alloys according to the invention can also be used as materials for objects which are resistant to cooling water up to boiling temperature and to sea water up to 50 ° C.
- the alloys according to the invention are used as a material for the production of components for use in marine engineering systems, in environmental technology, space travel, reactor technology and in chemical process technology.
- the alloys according to the invention can be produced in the available plants of the stainless steel producers by the known methods and show good processability.
- the overall corrosion behavior of the alloys according to the invention is excellent. Expensive alloy elements such as tungsten, niobium, tantalum can be dispensed with without sacrificing good properties.
- the alloys according to the invention also offer the advantage of an unusually universal corrosion resistance.
- the alloys are exposed to acids on one side of the apparatus and on the other side of the apparatus with chloride-containing cooling and heating media, such as in heat exchangers. Two completely different corrosion resistances are therefore required at the same time, namely acid resistance on the one hand and pitting, crevice and stress crack corrosion resistance on the other hand.
- the extraordinary resistance profile is achieved with a comparatively economical alloy budget, which is otherwise only achieved with expensive NiCrMo alloys (see Table B) or selectively on the acid side only with the highest alloyed, specially developed materials for special applications (see Table C).
- the alloys according to the invention are distinguished by an unusual elimination inertia under thermal stress in comparison to materials from the prior art.
- This behavior is in the production of semi-finished products and their further processing, e.g. the design of bobbin lace and the production of welded connections are extremely positive. This is particularly evident from the time-temperature sensitization diagrams (Fig. 1, 2).
- This material property is also important for the behavior of welds that are not subjected to a final heat treatment after the apparatus has been manufactured, and for the production of molded parts.
- the mechanical-technological values for the various alloy variants claimed in example 1 show a further engineering benefit which can be implemented in the form of a cost advantage.
- high strength values (example 1) can be implemented, for example, in offshore and reactor technology with regard to component dimensioning, which means that savings can be realized through lower material consumption.
- Example 2 shows the corrosion behavior in sulfuric acid (98-99.1% H2SO4) for different temperatures.
- the alloys according to the invention have excellent corrosion resistance up to 200 ° C. Under flowing conditions, which dominate in operational practice, even lower corrosion rates are determined (example 12).
- the alloy according to the invention In alkaline media, e.g. in 70% sodium hydroxide solution at 170 ° C., the alloy according to the invention also shows excellent corrosion resistance. As can be seen from Example 3, it is practically equivalent to that of the high nickel-containing materials Alloy 201, 400, 600 and 690 (17, 15, 16, 11), while the material 12 (Alloy G-30) drops sharply here. Even at lower alkali concentrations and temperatures, the alloys according to the invention stand out positively from the known ones (example 13).
- the copper-nickel alloys CuNi30MnlFe (18) have proven to be very stable according to the prior art, more resistant than many of the tried and tested high-alloyed steels and nickel-chromium-molybdenum Alloys.
- the alloys according to the invention also have a corrosion behavior superior to that of the prior art.
- another advantage of the alloys according to the invention is their higher strength, which makes them more suitable for the pressure vessel application mentioned here.
- Example 5 the mass loss rates determined in boiling azeotropic nitric acid are compared with one another. It can be seen that the alloys according to the invention suffer only very little corrosion removal. This is lower than that of the well-known materials AISI 310 L (4) and Alloy 28 (7). In super-azeotropic nitric acids, the corrosion behavior of the invention Alloys cheaper than the behavior of "HNO3 special alloys" (Example 14).
- the alloys according to the invention according to Example 6 show a high resistance in the so-called iron (III) chloride test at a pitting corrosion temperature of 60 ° C. This corresponds to that of the alloy 28 (7).
- the alloys according to the invention show a clear superiority, which can be used immediately in this combination when using plants for producing azeotropic nitric acid. The same applies to the alloy Alloy G-30 (12).
- Example 7 shows the corrosion behavior in mixed acids from sulfuric acid and nitric acid.
- the alloy according to the invention is superior to the known alloys both at low and at high H2SO4 contents.
- Example 8 shows a comparison of the mass loss rates in sulfuric acid-hydrofluoric acid solutions.
- the alloys according to the invention are compared in high-chromium alloyed materials AISI 310 L (4), Alloy 28 (7), Alloy G-30 (12) and 1.4465 (5). It can be seen that the alloys according to the invention have less corrosion removal than the materials corresponding to the prior art.
- Example 9 A comparison of the mass loss rates was also made in phosphoric acid solutions. The results obtained are shown in Example 9.
- the alloys according to the invention are compared with materials which, according to the prior art, are used specifically for handling phosphoric acid solutions. While in solution 1 the material Alloy 904 L (3) corresponding to the state of the art can be regarded as sufficient, in solution 2 this is not the case.
- the corrosion resistance of the alloys according to the invention is not significantly different from that of the material Alloy G-30 (12), but the low corrosion removal with the alloys according to the invention is achieved with significantly less expenditure on expensive alloy additives.
- Example 10 shows the corrosion behavior in nitric acid / hydrofluoric acid mixtures.
- the alloys according to the invention are far superior to the prior art.
- Example 15 demonstrates the favorable corrosion behavior of the alloys according to the invention compared to known alloys in chromic acid.
- the alloy 2 'according to the invention is also resistant to intergranular corrosion after a thermal load of up to 8 hours in the temperature range between 600 and 1000 ° C, both in the case of a test in accordance with SEP 1877 II and in Huey -Test.
- alloys according to the invention are widely applicable, and they can preferably be used in the following areas:
- the steels in Table 1 were melted on a 100 kg scale from raw materials known per se and cast into blocks.
- the blocks were formed into 5 (12) mm thick sheets.
- the final solution annealing was carried out at at least 1120 ° C. with subsequent quenching. There was a fully austenitic, excretion-free, homogeneous structure.
- the mechanical properties of the alloys indicate good cold formability.
- the materials 17, 15, 16 are typical materials for this application.
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Abstract
Description
Die Erfindung betrifft hochchromhaltige, korrosionsbeständige, austenitische Legierungen und deren Verwendung.The invention relates to high-chromium, corrosion-resistant, austenitic alloys and their use.
Tabelle A zeigt beispielhaft die nach dem Stand der Technik für die Handhabung von oxidierenden Säuren in Frage kommenden metallischen Werkstoffe (Nickellegierungen und hochlegierte Sonderedelstähle, 2. Auflage, Expert Verlag, 1993). Mit Ausnahme des Superferrits handelt es sich bei ihnen um sogenannte austenitische Legierungen, d.h. um solche mit kubischflächenzentrierter Gitterstruktur. Die Legierungen gemäß dem in Tabelle A gezeigten Stand der Technik liegen innerhalb einer sich zwischen etwa 17 und 29 Gew.-% erstreckenden Bandbreite für das Hauptlegierungselement Chrom. Im Hinblick auf die Korrosionsbeständigkeit gegenüber max. 67 %iger Salpetersäure sind schon verhältnismäßig niedriglegierte Werkstoffe brauchbar. Ein entsprechender Werkstoff ist Cronifer 1809 LCLSi, wobei der Nachsatz LSi auf einen eingeschränkten Silizium-gehalt (low silicon) hinweist.Table A shows, by way of example, the metallic materials which are possible according to the prior art for the handling of oxidizing acids (nickel alloys and high-alloy special stainless steels, 2nd edition, Expert Verlag, 1993). With the exception of superferrite, they are so-called austenitic alloys, i.e. around those with a cubic surface-centered lattice structure. The alloys according to the prior art shown in Table A are within a range of between about 17 and 29% by weight for the main alloy element chromium. With regard to the corrosion resistance to max. Already relatively low-alloyed materials can be used with 67% nitric acid. A suitable material is Cronifer 1809 LCLSi, with the addition LSi indicating a restricted silicon content (low silicon).
Nickelreiche Werkstoffe wie der gleichfalls in Tabelle A eingetragene Nicrofer 6030 bieten Vorteile, sofern Halogenverbindungen anwesend sind bzw. mit Salpetersäure / Flußsäuremischungen gearbeitet wird, wie beispielsweise bei der Wiederaufarbeitung von Kernreaktor-Brennelementen.Nickel-rich materials such as Nicrofer 6030, which is also listed in Table A, offer advantages if halogen compounds are present or if nitric acid / hydrofluoric acid mixtures are used, such as when reprocessing nuclear reactor fuel elements.
In "Werkstoffe und Korrosion" 43, 191-200 (1992), "Korrosion nichtrostender Stähle und Nickelbasislegierungen in Salpetersäure-Flußsäure-Gemischen" werden verschiedene molybdänhaltige Chrom-Nickel-Eisen-Stähle mit bis 29 % Chrom, bis 39 % Nickel und bis 6,5 % Molybdän beschrieben. Bei erhöhten Molybdängehalten verbessert sich die Beständigkeit in Salpetersäure-Flußsäure-Gemischen.In "Materials and Corrosion" 43 , 191-200 (1992), "Corrosion of stainless steels and nickel-based alloys in nitric acid-hydrofluoric acid mixtures", various molybdenum-containing chromium-nickel-iron steels with up to 29% chromium, up to 39% nickel and bis 6.5% molybdenum described. With increased molybdenum contents, the resistance in nitric acid-hydrofluoric acid mixtures improves.
In "Werkstoffe und Korrosion" 44, 83-88 (1993), "Avesta 654 SMO TM-A new nitrogen-enhanced superaustenitic stainless steel" werden austenitische Edelstähle mit bis 22 % Nickel, bis 25 % Chrom und Stickstoffgehalten von 0,2 bis 0,5 Gew.-% beschrieben.In "Materials and Corrosion" 44 , 83-88 (1993), "Avesta 654 SMO TM-A new nitrogen-enhanced superaustenitic stainless steel" austenitic stainless steels with up to 22% nickel, up to 25% chromium and nitrogen contents from 0.2 to 0.5 wt .-% described.
Der molybdänhaltige Werkstoff Nicrofer 3127 hMo (1.4562) gemäß EP 0 292 061 ist mit seinem Chromgehalt von 26 bis 28 % dort von Interesse, wo neben verhältnismäßig großer Salpetersäurebeständigkeit besonderer Wert auf hohe Beständigkeit gegenüber Loch- und Spaltkorrosion gelegt wird. Eine typische Abtragsrate in siedender azeotroper Salpetersäure (Huey-Test) für diesen Werkstoff ist ca. 0,11 mm/Jahr.The molybdenum-containing material Nicrofer 3127 hMo (1.4562) according to EP 0 292 061 with its chromium content of 26 to 28% is of interest where, in addition to the relatively high resistance to nitric acid, particular importance is attached to high resistance to pitting and crevice corrosion. A typical removal rate in boiling azeotropic nitric acid (Huey test) for this material is approx. 0.11 mm / year.
Beim Arbeiten mit mehr als 67 %iger Salpetersäure oder unter sonst äußerst stark oxidierenden Bedingungen zeigt der mit etwa 4 % Silizium legierte Cronifer 1815 LCSi (1.4361) eine ausgezeichnete Beständigkeit bis zum Siedepunkt der Salpetersäure. Die für die Harnstofferzeugung in Frage kommenden Werkstoffe haben ähnliche Zusammensetzung wie die gegen Salpetersäure besonders korrosionsbeständigen Stähle.When working with more than 67% nitric acid or under otherwise extremely strongly oxidizing conditions, the Cronifer 1815 LCSi (1.4361) alloyed with about 4% silicon shows excellent resistance up to the boiling point of the nitric acid. The materials that can be used to produce urea have a composition similar to that of steels that are particularly corrosion-resistant to nitric acid.
Für das Arbeiten mit heißer, hochkonzentrierter Schwefelsäure ist der mit 7 % Silizium legierte Stahl Nicrofer 2509 Si7 gemäß EP-A 0516 955 entwickelt worden. Hier hat gemäß der Lehre von DE-OS 38 30 365 auch der Superferrit Cronifer 2803 Mo (1.4575) ein spezielles Interesse. Superferrite kommen wegen ihrer eingeschränkten Verarbeitbarkeit allerdings nur für geringe Wanddicken in Frage, die in der Regel bei 2 mm und darunter liegen.The Nicrofer 2509 Si7 steel alloyed with 7% silicon has been developed in accordance with EP-A 0516 955 for working with hot, highly concentrated sulfuric acid. According to the teaching of DE-OS 38 30 365, the superferrite Cronifer 2803 Mo (1.4575) also has a special interest. Because of their limited processability, superferrites are only suitable for small wall thicknesses, which are usually 2 mm and below.
Legierungen mit beispielsweise etwa 31 % Chrom und etwa 46 % Chrom wurden im Hinblick auf ihre Korrosionsbeständigkeit in Salpetersäure-Flußsäuregemischen untersucht ("Werkstoffe und Korrosion" 43, (1992) S. 191-200). Diese Legierungen mit hohen Chromgehalten konnten nicht mehr als austenitische Werkstoffe hergestellt werden und nur mittels Sonderverfahren, wie z.B. der Pulvermetallurgie verarbeitet werden.Alloys with, for example, about 31% chromium and about 46% chromium have been found in nitric acid-hydrofluoric acid mixtures for their corrosion resistance examined ("Materials and Corrosion" 43 , (1992) pp. 191-200). These alloys with high chromium contents could no longer be produced as austenitic materials and could only be processed using special processes such as powder metallurgy.
In der Britischen Patentschrift 1 114 996 werden Legierungen mit 14 bis 35 % Chrom und 0 bis 25 % Eisen beansprucht.British Patent 1 114 996 claims alloys with 14 to 35% chromium and 0 to 25% iron.
Die EP-A 0 261 880 beschreibt Legierungen mit 27 bis 31 % Chrom, 7 bis 11 % Eisen und dem Rest im wesentlichen Nickel.EP-A 0 261 880 describes alloys with 27 to 31% chromium, 7 to 11% iron and the rest essentially nickel.
Legierungen mit Chromgehalten von mehr als 30 % Cr sind nicht mehr ohne weiteres homogen und austenitisch darstellbar. In der Praxis werden daher Chromgehalte von max. 29 % eingestellt. Bei dem Superferrit 1.4575 mit Chromgehalten von 26 bis 30 % handelt es sich um eine ferritische Legierung.Alloys with chromium contents of more than 30% Cr can no longer be produced homogeneously and austenitically. In practice, chrome contents of max. 29% set. The Superferrite 1.4575 with a chromium content of 26 to 30% is a ferritic alloy.
In EP-A 0 130 967 wird die Eignung von Nickellegierungen und Edelstählen für heiße Schwefelsäure von 99 %-101 % bei > 120°C in Wärmetauschern beschrieben. Die Auswahl der Legierungen erfolgt nach folgender Formel: 0,35 (Fe-Mn) + 0,70 (Cr) + 0,30 (Ni) - 0,12 (Mo) > 39. Die genannten molybdänhaltigen Edelstähle weisen maximal 28 % Chrom auf.EP-A 0 130 967 describes the suitability of nickel alloys and stainless steels for hot sulfuric acid of 99% -101% at> 120 ° C in heat exchangers. The alloys are selected according to the following formula: 0.35 (Fe-Mn) + 0.70 (Cr) + 0.30 (Ni) - 0.12 (Mo)> 39. The above-mentioned molybdenum-containing stainless steels have a maximum of 28% chromium on.
In EP-A 0 200 862 werden molybdänfreie Chrom-, Nickel-Legierungen bestehend aus 21-35 % Chrom, 30-70 % Eisen, 2-40 % Nickel und 0-20 % Mangan sowie üblichen Begleitelementen als Werkstoffe für Gegenstände, die gegen Schwefelsäure oberhalb 96 % bis 100 % und gegen Oleum beständig sind, beansprucht.In EP-A 0 200 862, molybdenum-free chromium and nickel alloys consisting of 21-35% chromium, 30-70% iron, 2-40% nickel and 0-20% manganese as well as usual accompanying elements are used as materials for objects that are against Sulfuric acid above 96% to 100% and are resistant to oleum.
EP-A 249 792 beansprucht die Verwendung von Legierungen bestehend aus 21 bis 55 % Chrom, 0 bis 30 % Eisen, 0 bis 5 % Wolfram und 45 bis 79 % Ni in konzentrierter Schwefelsäure.EP-A 249 792 claims the use of alloys consisting of 21 to 55% chromium, 0 to 30% iron, 0 to 5% tungsten and 45 to 79% Ni in concentrated sulfuric acid.
In US 4 410 489 wird für die Handhabung von Phosphorsäure eine Legierung bestehend aus 26-35 % Chrom, 2-6 % Molybdän, 1-4 % Wolfram, 0,3-2 % (Niob+Tantal), 1-3 % Kupfer, 10-18 % Eisen, bis 1,5 % Mangan, bis 1 % Silizium, Rest im wesentlichen Nickel vorgeschlagen. Vorzugsweise soll der Chromgehalt bei 30 % liegen.In US 4,410,489, an alloy consisting of 26-35% chromium, 2-6% molybdenum, 1-4% tungsten, 0.3-2% (niobium + tantalum), 1-3% copper is used for handling phosphoric acid , 10-18% iron, up to 1.5% manganese, up to 1% Silicon, rest essentially nickel suggested. The chromium content should preferably be 30%.
In DE-A 2 154 126 wird die Verwendung austenitischer Nickel-Legierungen mit 26-48 % Nickel, 30-34 % Chrom, 4-5,25 % Molybdän, 4-7,5 % Kobalt, 3-2,5 % Eisen, 1-3,5 % Mangan etc. als widerstandsfähiger Werkstoff für Gegenstände in heißer Schwefelsäure oberhalb 65 % beansprucht.DE-A 2 154 126 describes the use of austenitic nickel alloys with 26-48% nickel, 30-34% chromium, 4-5.25% molybdenum, 4-7.5% cobalt, 3-2.5% iron , 1-3.5% manganese etc. as a resistant material for objects in hot sulfuric acid above 65%.
In US 4 853 185 werden Edelstähle mit 25-45 % Nickel, 12-32 % Chrom, 0,1 bis 2 % Niob, 0,2 bis 4 % Tantal, 0,05 bis 1 % Vanadium und 0,05-0,5 % Stickstoff neben weiteren Bestandteilen beschrieben. Die Legierungen sollen gegenüber CO, CO₂ und Schwefelverbindungen resistent sein.In US 4,853,185 stainless steels with 25-45% nickel, 12-32% chromium, 0.1 to 2% niobium, 0.2 to 4% tantalum, 0.05 to 1% vanadium and 0.05-0, 5% nitrogen is described along with other ingredients. The alloys are said to be resistant to CO, CO₂ and sulfur compounds.
Hohe Chromgehalte sind gemäß der US-Patentschrift 3 565 611 für die Beständigkeit von Nickel-Chrom-Eisen-Legierungen gegenüber laugeninduzierter Spannungsrißkorrosion in heißen alkalischen Lösungen von Bedeutung. Dabei soll der Chromgehalt wenigstens 18 %, vorzugsweise wenigstens 26 bis 27 %, bis max. 35 % betragen und der Eisengehalt auf max. 7 % eingeschränkt sein. Die Legierung 690 ist mit 29 % Chrom und 9 % Eisen besonders beständig gegenüber laugeninduzierter Spannungsrißkorrosion.According to US Pat. No. 3,565,611, high chromium contents are important for the resistance of nickel-chromium-iron alloys to alkali-induced stress corrosion cracking in hot alkaline solutions. The chromium content should be at least 18%, preferably at least 26 to 27%, up to max. 35% and the iron content to max. 7% be restricted. The alloy 690 with 29% chromium and 9% iron is particularly resistant to alkali-induced stress corrosion cracking.
US 4 853 185 beschreibt im Hochtemperaturbereich korrosionsbeständige Legierungen, bestehend aus ungefähr 30 % bis 45 % Nickel, ungefähr 12 bis 32 % Chrom, wenigstens einem der Elemente Niob mit 0,01 % bis 2,0 %, Tantal mit 0,2 bis 4,0 % und Vanadium mit 0,05 bis 1,0 %, ferner bis zu 0,20 % Kohlenstoff, ungefähr 0,05 bis 0,50 % Stickstoff einem für die Hochtemperaturfestigkeit wirkungsvollen Zusatz von Titan in Höhe von bis zu 0,20 %, Rest Eisen und Verunreinigungen, wobei die Summe an freiem Kohlenstoff und Stickstoff (C + N)F > 0,14 und < 0,29 sein muß. Der Ausdruck (C + N)F ist dabei definiert als:
EP-A 340 631 beschreibt ein hochtemperaturbeständiges Stahlrohr mit niedrigem Siliziumgehalt, welches nicht mehr als 0,1 Gew.-% Kohlenstoff, nicht mehr als 0,15 Gew.-% Silizium, nicht mehr als 5 Gew.-% Mangan, 20 bis 30 Gew.-% Chrom, 15 bis 30 Gew.-% Nickel, 0,15 bis 0,35 Gew.-% Stickstoff, 0,1 bis 1,0 Gew.-% Niob und nicht mehr als 0,005 Gew.-% Sauerstoff, mindestens eines der Metalle Aluminium und Magnesium in einer Menge von 0,020 bis 1,0 Gew.-% bzw. 0,003 bis 0,02 Gew.-% und Rest Eisen und unvermeidbare Verunreinigungen aufweist.US 4,853,185 describes in the high temperature range corrosion-resistant alloys consisting of approximately 30% to 45% nickel, approximately 12 to 32% chromium, at least one of the elements niobium with 0.01% to 2.0%, tantalum with 0.2 to 4 , 0% and vanadium with 0.05 to 1.0%, further up to 0.20% carbon, approximately 0.05 to 0.50% nitrogen, an addition of titanium of up to 0.20, which is effective for high-temperature strength %, Balance iron and impurities, where the sum of free carbon and nitrogen (C + N) F must be> 0.14 and <0.29. The expression (C + N) F is defined as:
EP-A 340 631 describes a high-temperature-resistant steel tube with a low silicon content, which is not more than 0.1% by weight of carbon, not more than 0.15% by weight silicon, not more than 5% by weight manganese, 20 to 30% by weight chromium, 15 to 30% by weight nickel, 0.15 to 0.35% by weight nitrogen, 0.1 to 1.0% by weight of niobium and not more than 0.005% by weight of oxygen, at least one of the metals aluminum and magnesium in an amount of 0.020 to 1.0% by weight and 0.003 to 0.02, respectively % By weight and the rest iron and unavoidable impurities.
Aufgabe der vorliegenden Erfindung war es, Legierungen zur Verfügung zu stellen, die vielfältig einsetzbar und problemlos verarbeitbar sind und deren Korrosionsraten niedrig sind.The object of the present invention was to provide alloys which can be used in a variety of ways and can be processed without problems and whose corrosion rates are low.
Diese Aufgabe konnte mit den erfindungsgemäßen Legierungen gelöst werden. Diese Legierungen sind hochchromhaltig und trotzdem gut verarbeitbar. Sie weisen nur einen geringen Molybdängehalt bzw. kein Molybdän auf und haben wider Erwarten eine hohe Korrosionsbeständigkeit in heißen, oxidierenden Säuren.This object could be achieved with the alloys according to the invention. These alloys are high in chromium and still easy to process. They have only a low molybdenum content or no molybdenum and, contrary to expectations, have high corrosion resistance in hot, oxidizing acids.
Gegenstand der Erfindung sind austenitische, korrosionsbeständige Chrom-, Nickel-, Eisen-Legierungen folgender Zusammensetzung:
32-37 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,025 Gew.-% Phosphor
max. 2 Gew.-% Molybdän
max. 1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, welche dadurch gekennzeichnet sind, daß die Legierungen zusätzlich 0,3-0,7 Gew.-% Stickstoff enthalten.The invention relates to austenitic, corrosion-resistant chromium, nickel and iron alloys of the following composition:
32-37 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
max 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.025 wt% phosphorus
Max. 2% by weight molybdenum
Max. 1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, which are characterized in that the alloys additionally contain 0.3-0.7% by weight of nitrogen.
Bevorzugt sind Legierungen mit 0,5 bis 2 Gew.-% Molybdän und 0,3 bis 1 Gew.-% Kupfer.Alloys with 0.5 to 2% by weight of molybdenum and 0.3 to 1% by weight of copper are preferred.
Weiterhin bevorzugt sind austenitische Legierungen mit folgender Zusammensetzung:
32-35 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max. 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,025 Gew.-% Phosphor
max. 2 Gew.-% Molybdän
max. 1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, welche dadurch gekennzeichnet sind, daß die Legierungen zusätzlich 0,4-0,6 Gew.-% Stickstoff enthalten.Austenitic alloys with the following composition are also preferred:
32-35 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
Max. 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.025 wt% phosphorus
Max. 2% by weight molybdenum
Max. 1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, which are characterized in that the alloys additionally contain 0.4-0.6% by weight of nitrogen.
Diese bevorzugten Legierungen werden vorzugsweise als Knetwerkstoffe zur Herstellung von Halbzeug, wie z.B. Blechen, Bändern, Stangen, Drähten, Schmiedeteilen, Rohren, eingesetzt.These preferred alloys are preferably used as wrought materials for the production of semi-finished products, e.g. Sheets, strips, rods, wires, forgings, pipes, used.
Weiterhin bevorzugt sind austenitische Legierungen mit folgender Zusammensetzung:
35-37 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max. 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,025 Gew.-% Phosphor
max. 2 Gew.-% Molybdän
max. 1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, welche dadurch gekennzeichnet sind, daß die Legierungen zusätzlich 0,4-0,7 Gew.-% Stickstoff enthalten.Austenitic alloys with the following composition are also preferred:
35-37 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
Max. 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.025 wt% phosphorus
Max. 2% by weight molybdenum
Max. 1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, which are characterized in that the alloys additionally contain 0.4-0.7% by weight of nitrogen.
Diese bevorzugten Legierungen werden vorzugsweise als Werkstoffe zur Herstellung von Gußteilen eingesetzt, wie z.B. Pumpen und Armaturen.These preferred alloys are preferably used as materials for the production of castings, e.g. Pumps and fittings.
Weiterhin bevorzugt sind austenitische Legierungen mit folgender Zusammensetzung
32,5 - 33,5 Gew.-% Chrom
30,0 - 32,0 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
0,5-2 Gew.-% Molybdän
0,3-1 Gew.-% Kupfer
0,35 - 0,5 Gew.-% Stickstoff oder
34,0 - 35,0 Gew.-% Chrom
30,0 - 32,0 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
0,4 - 0,6 Gew.-% Stickstoff oder
35,0 - 36,0 Gew.-% Chrom
30,0 - 32,0 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
0,4 - 0,6 Gew.-% Stickstoff oder
36,0 - 37,0 Gew.-% Chrom
30,0 - 32,0 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
0,4 - 0,7 Gew.-% Stickstoff
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen.Austenitic alloys with the following composition are also preferred
32.5-33.5 wt% chromium
30.0-32.0 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02 - 0.1 weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
0.5-2% by weight molybdenum
0.3-1% by weight copper
0.35-0.5% by weight nitrogen or
34.0-35.0 wt% chromium
30.0-32.0 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
0.4-0.6% by weight nitrogen or
35.0 - 36.0 wt% chromium
30.0-32.0 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
0.4-0.6% by weight nitrogen or
36.0-37.0 wt% chromium
30.0-32.0 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
0.4-0.7% by weight nitrogen
as well as usual manufacturing-related admixtures and impurities and the rest as iron.
Zur Schmelzbehandlung mit dem Ziel einer ausreichenden Desoxidation und Entschwefelung können die Legierungen bei Bedarf bis zu 0,08 Gew.-% Seltene Erden, bis zu 0,015 Gew.-% Calcium und/oder bis zu 0,015 Gew.-% Magnesium als herstellungsbedingte Beimengungen enthalten.For melt treatment with the aim of adequate deoxidation and desulfurization, the alloys can contain up to 0.08% by weight of rare earths, up to 0.015% by weight of calcium and / or up to 0.015% by weight of magnesium as admixtures due to the manufacturing process .
Die erfindungsgemäßen Legierungen werden als Werkstoff für Gegenstände verwendet, die gegenüber
- a) Natronlauge oder Kalilauge einer Konzentration von 1 bis 90 Gew.-%, vorzugsweise 1 bis 70 Gew.-%, bei Temperaturen bis 200°C, insbesondere 170°C,
- b) Harnstofflösungen einer Konzentration von 5 bis 90 Gew.-%,
- c) Salpetersäure einer Konzentration von 0,1 bis 70 Gew. -%, bei Temperaturen bis zum Siedepunkt und bis 90 Gew.-% bei Temperaturen bis 75°C und > 90 Gew.-% bei Temperaturen bis 30°C,
- d) Flußsäure einer Konzentration von 1 bis 40 Gew.-%, vorzugsweise 1 bis 25 Gew.-%,
- e) Phosphorsäure einer Konzentration bis 85 Gew.-%, vorzugsweise von 26-52 Gew.-%, bei Temperaturen bis zu 120°C bzw. bis zu 300°C bei Konzentrationen <10 Gew.-%,
- f) Chromsäure einer Konzentration bis 40 Gew.-%, vorzugsweise bis 30 Gew.-%,
- g) Oleum einer Konzentration bis 100 Gew.-%, vorzugsweise 20 bis 40 Gew.-% bei Temperaturen bis zur jeweiligen Siedetemperatur oder
- h) Schwefelsäure einer Konzentration von 80 bis 100 Gew.-%, vorzugsweise 85 bis 99,7 Gew.-%, besonders bevorzugt 95 bis 99 Gew.-% bei hohen Temperaturen bis zu 250°C beständig sind.
- a) sodium hydroxide solution or potassium hydroxide solution in a concentration of 1 to 90% by weight, preferably 1 to 70% by weight, at temperatures up to 200 ° C., in particular 170 ° C.,
- b) urea solutions with a concentration of 5 to 90% by weight,
- c) nitric acid at a concentration of 0.1 to 70% by weight, at temperatures up to the boiling point and up to 90% by weight at temperatures up to 75 ° C. and> 90% by weight at temperatures up to 30 ° C.,
- d) hydrofluoric acid in a concentration of 1 to 40% by weight, preferably 1 to 25% by weight,
- e) phosphoric acid of a concentration of up to 85% by weight, preferably of 26-52% by weight, at temperatures up to 120 ° C or up to 300 ° C at concentrations <10% by weight,
- f) chromic acid in a concentration of up to 40% by weight, preferably up to 30% by weight,
- g) oleum in a concentration of up to 100% by weight, preferably 20 to 40% by weight at temperatures up to the respective boiling point or
- h) sulfuric acid at a concentration of 80 to 100 wt .-%, preferably 85 to 99.7 wt .-%, particularly preferably 95 to 99 wt .-% are stable at high temperatures up to 250 ° C.
Die erfindungsgemäßen Legierungen sind auch als Werkstoffe für Gegenstände einsetzbar, die gegenüber Mischungen aus Schwefelsäure und Natriumdichromat und/oder Chromsäure, aus 0,1 bis 40 Gew.-%, vorzugsweise 0,3 bis 20 Gew.-% Salpetersäure und 50 bis 90 Gew.-% Schwefelsäure bis 130°C oder aus 0,01 bis 15 Gew.-% Flußsäure und 80-98 Gew.-% Schwefelsäure bis 180°C oder aus bis 25 Gew.-% Salpetersäure und bis 10 Gew.-% Flußsäure bis 80°C beständig sind.The alloys according to the invention can also be used as materials for articles which, compared to mixtures of sulfuric acid and sodium dichromate and / or chromic acid, contain 0.1 to 40% by weight, preferably 0.3 to 20% by weight, nitric acid and 50 to 90% by weight .-% sulfuric acid up to 130 ° C or from 0.01 to 15% by weight hydrofluoric acid and 80-98% by weight sulfuric acid up to 180 ° C or from up to 25% by weight nitric acid and up to 10% by weight hydrofluoric acid are resistant up to 80 ° C.
Gegenüber organischen Säuren, wie z.B. Ameisensäure und Essigsäure, weisen die erfindungsgemäßen Legierungen eine ausreichende Beständigkeit und Stabilität auf.Compared to organic acids, e.g. Formic acid and acetic acid, the alloys according to the invention have sufficient resistance and stability.
Die erfindungsgemäßen Legierungen können auch als Werkstoffe für Gegenstände eingesetzt werden, die gegenüber Kühlwasser bis Siedetemperatur und gegenüber Meerwasser bis 50°C beständig sind.The alloys according to the invention can also be used as materials for objects which are resistant to cooling water up to boiling temperature and to sea water up to 50 ° C.
Aufgrund der guten Verarbeitbarkeit und Korrosionsbeständigkeit werden die erfindungsgemäßen Legierungen als Werkstoff zur Herstellung von Bauteilen für den Einsatz in meerestechnischen Anlagen, in der Umwelttechnik, Raumfahrt, Reaktortechnik und in der chemischen Prozeßtechnik verwendet.Because of the good processability and corrosion resistance, the alloys according to the invention are used as a material for the production of components for use in marine engineering systems, in environmental technology, space travel, reactor technology and in chemical process technology.
Die erfindungsgemäßen Legierungen sind in den verfügbaren Anlagen der Edelstahlerzeuger nach den bekannten Verfahren herstellbar und zeigen gute Verarbeitbarkeit.The alloys according to the invention can be produced in the available plants of the stainless steel producers by the known methods and show good processability.
Das Korrosionsverhalten der erfindungsgemäßen Legierungen ist insgesamt hervorragend. Auf teure Legierungselemente wie Wolfram, Niob, Tantal kann ohne Einbuße der guten Eigenschaften verzichtet werden.The overall corrosion behavior of the alloys according to the invention is excellent. Expensive alloy elements such as tungsten, niobium, tantalum can be dispensed with without sacrificing good properties.
Die erfindungsgemäßen Legierungen bieten weiterhin den Vorteil einer ungewöhnlich universellen Korrosionsbeständigkeit. So werden die Legierungen auf der einen Apparateseite durch Säuren beaufschlagt und auf der anderen Apparateseite mit chloridhaltigen Kühl- und Heizmedien, wie z.B. in Wärmetauschern. Es werden also gleichzeitig zwei völlig verschiedene Korrosionsbeständigkeiten gefordert, nämlich Säurebeständigkeit einerseits und Loch-, Spalt- und Spannungsrißkorrosionsbeständigkeit andererseits.The alloys according to the invention also offer the advantage of an unusually universal corrosion resistance. The alloys are exposed to acids on one side of the apparatus and on the other side of the apparatus with chloride-containing cooling and heating media, such as in heat exchangers. Two completely different corrosion resistances are therefore required at the same time, namely acid resistance on the one hand and pitting, crevice and stress crack corrosion resistance on the other hand.
Gleichzeitig wird das außergewöhnliche Beständigkeitsprofil mit einem vergleichsweise sparsamen Legierungshaushalt erzielt, das ansonsten nur mit teuren NiCrMo-Legierungen (s. Tabelle B) oder punktuell auf der Säureseite nur mit höchstlegierten, speziell entwickelten Werkstoffen für Spezialanwendungen erreicht wird (s. Tabelle C).At the same time, the extraordinary resistance profile is achieved with a comparatively economical alloy budget, which is otherwise only achieved with expensive NiCrMo alloys (see Table B) or selectively on the acid side only with the highest alloyed, specially developed materials for special applications (see Table C).
Zusätzliche Vorteile sind:
- a) Schonung der Rohstoffressourcen an Ni und Mo im Vergleich zu den vorgenannten höchstlegierten Werkstoffen,
- b) Kostenersparnisse bei der Legierungsherstellung durch geringe Gehalte teurer Legierungsbestandteile sowie bei der Apparateherstellung durch leichte Verarbeitbarkeit.
- a) Conservation of raw material resources in Ni and Mo in comparison to the aforementioned high-alloy materials,
- b) Cost savings in the production of alloys due to the low content of expensive alloy components and in the manufacture of the apparatus due to easy processability.
Hinsichtlich der Verarbeitbarkeit zeichnen sich die erfindungsgemäßen Legierungen im Vergleich zu Werkstoffen aus dem Stand der Technik durch eine ungewöhnliche Ausscheidungsträgheit bei thermischer Belastung aus. Dieses Verhalten ist bei der Herstellung von Halbzeugen und deren Weiterverarbeitung, z.B. der Formgebung von Klöpperböden und dem Herstellen von Schweißverbindungen ausgesprochen positiv. Dies geht insbesondere aus den Zeit-Temperatur-Sensibilisierungs-Diagrammen (Abb. 1, 2) hervor. Bedeutungsvoll ist diese Werkstoffeigenschaft auch für das Verhalten von Schweißnähten, die keiner abschließenden Wärmebehandlung nach der Apparatefertigung unterzogen werden sowie für die Herstellung von Gußformteilen.With regard to processability, the alloys according to the invention are distinguished by an unusual elimination inertia under thermal stress in comparison to materials from the prior art. This behavior is in the production of semi-finished products and their further processing, e.g. the design of bobbin lace and the production of welded connections are extremely positive. This is particularly evident from the time-temperature sensitization diagrams (Fig. 1, 2). This material property is also important for the behavior of welds that are not subjected to a final heat treatment after the apparatus has been manufactured, and for the production of molded parts.
Aus den in Beispiel 1 dargestellten mechanisch-technologischen Werten für die verschiedenen beanspruchten Legierungsvarianten geht ein weiterer ingenieurtechnischer Nutzen, der sich in Form eines Kostenvorteiles umsetzen läßt, hervor. Die im Vergleich zu Standardausteniten hohen Festigkeitskennwerte (Beispiel 1) lassen sich z.B. in der Offshore- und Reaktortechnik vorteilhaft in Bezug auf die Bauteildimensionierung umsetzen, d.h., es läßt sich ein Einsparpotential durch geringeren Materialverbrauch realisieren.The mechanical-technological values for the various alloy variants claimed in example 1 show a further engineering benefit which can be implemented in the form of a cost advantage. The Compared to standard austenites, high strength values (example 1) can be implemented, for example, in offshore and reactor technology with regard to component dimensioning, which means that savings can be realized through lower material consumption.
Beispiel 2 zeigt das Korrosionsverhalten in Schwefelsäure (98-99,1 % H₂SO₄) für verschiedene Temperaturen. Die erfindungsgemäßen Legierungen weisen bis 200°C eine ausgezeichnete Korrosionsbeständigkeit auf. Unter strömenden Bedingungen, wie sie in der betrieblichen Praxis dominieren, werden noch geringere Korrosionsgeschwindigkeiten ermittelt (Beispiel 12).Example 2 shows the corrosion behavior in sulfuric acid (98-99.1% H₂SO₄) for different temperatures. The alloys according to the invention have excellent corrosion resistance up to 200 ° C. Under flowing conditions, which dominate in operational practice, even lower corrosion rates are determined (example 12).
In alkalischen Medien, wie z.B. in 70 %iger Natronlauge bei 170°C zeigt die erfindungsgemäße Legierung gleichfalls eine hervorragende Korrosionsbeständigkeit. Wie aus Beispiel 3 ersichtlich, ist sie derjenigen der hochnickelhaltigen Werkstoffe Alloy 201, 400, 600 und 690 (17, 15, 16, 11) praktisch gleichwertig, während der Werkstoff 12 (Alloy G-30) hier stark abfällt. Auch bei niedrigeren Laugenkonzentrationen und -temperaturen heben sich die erfindungsgemäßen Legierungen von den bekannten positiv ab (Beispiel 13).In alkaline media, e.g. in 70% sodium hydroxide solution at 170 ° C., the alloy according to the invention also shows excellent corrosion resistance. As can be seen from Example 3, it is practically equivalent to that of the high nickel-containing materials Alloy 201, 400, 600 and 690 (17, 15, 16, 11), while the material 12 (Alloy G-30) drops sharply here. Even at lower alkali concentrations and temperatures, the alloys according to the invention stand out positively from the known ones (example 13).
In Ethanol-Wassergemischen mit Zusatz von Phosphorsäure in Druckbehältern bei hohen Temperaturen haben sich die Kupfer-Nickel-Legierungen CuNi30MnlFe (18) gemäß dem Stand der Technik als sehr beständig erwiesen, beständiger als zahlreiche der erprobten sehr hochlegierten Stähle und Nickel-Chrom-Molybdän-Legierungen. Wie Beispiel 4 zeigt, weisen die erfindungsgemäßen Legierungen auch hier ein diesem Stand der Technik überlegenes Korrosionsverhalten auf. Im Vergleich zu dem Kupferwerkstoff ist als weiterer Vorteil der erfindungsgemäßen Legierungen deren höhere Festigkeit zu berücksichtigen, welche sie für die hier angesprochene Druckbehälteranwendung geeigneter macht.In ethanol-water mixtures with the addition of phosphoric acid in pressure vessels at high temperatures, the copper-nickel alloys CuNi30MnlFe (18) have proven to be very stable according to the prior art, more resistant than many of the tried and tested high-alloyed steels and nickel-chromium-molybdenum Alloys. As example 4 shows, the alloys according to the invention also have a corrosion behavior superior to that of the prior art. Compared to the copper material, another advantage of the alloys according to the invention is their higher strength, which makes them more suitable for the pressure vessel application mentioned here.
In Beispiel 5 werden die in siedender azeotroper Salpetersäure ermittelten Massenverlustraten miteinander verglichen. Man erkennt, daß die erfindungsgemäßen Legierungen einen nur sehr geringen Korrosionsabtrag erleiden. Dieser liegt niedriger als der der bekannten Werkstoffe AISI 310 L (4) und Alloy 28 (7). In überazeotropen Salpetersäuren ist das Korrosionsverhalten der erfindungsgemäßen Legierungen günstiger als das Verhalten von "HNO₃-Speziallegierungen" (Beispiel 14).In Example 5, the mass loss rates determined in boiling azeotropic nitric acid are compared with one another. It can be seen that the alloys according to the invention suffer only very little corrosion removal. This is lower than that of the well-known materials AISI 310 L (4) and Alloy 28 (7). In super-azeotropic nitric acids, the corrosion behavior of the invention Alloys cheaper than the behavior of "HNO₃ special alloys" (Example 14).
In vielen Fällen ist für die Werkstoff-Anwendung nicht nur die Beständigkeit gegenüber gleichförmigem Korrosionsabtrag durch z.B. Salpetersäure ausschlaggebend, sondern es wird beispielsweise kühlwasserseitig zugleich auch eine hohe Beständigkeit gegen Lochkorrosion gefordert. Hier zeigen die erfindungsgemäßen Legierungen gemäß Beispiel 6 im sogenannten Eisen(III)chlorid-Test bei einer Lochkorrosionstemperatur von 60°C eine hohe Beständigkeit. Diese entspricht derjenigen der Legierung Alloy 28 (7). Die erfindungsgemäßen Legierungen zeigen jedoch in der Kombination ihrer Lochkorrosionsbeständigkeit mit der Beständigkeit gegenüber gleichförmigem Korrosionsabtrag in siedender azeotroper Salpetersäure als typischer oxidierender Säure eine deutliche Überlegenheit, was sich bei Verwendung von Anlagen zur Herstellung azeotroper Salpetersäure in dieser Kombination sofort nutzen läßt. Das gleiche gilt auch für die Legierung Alloy G-30 (12). Diese ist zwar in ihrer Lochkorrosionsbeständigkeit den erfindungsgemäßen Legierungen etwas überlegen, im Hinblick auf ihre Beständigkeit gegenüber gleichförmigem Korrosionsabtrag in siedender azeotroper Salpetersäure aber sehr schlecht. In neutralen chloridhaltigen Lösungen, wie Kühlwässern, kommt bei elektrochemischen Korrosionsversuchen die sehr gute Lochkorrosionsbeständigkeit der erfindungsgemäßen Legierungen zum Ausdruck (Beispiel 11).In many cases, it is not only the resistance to uniform corrosion removal, e.g. Nitric acid is crucial, but it is also required, for example, a high resistance to pitting corrosion on the cooling water side. Here, the alloys according to the invention according to Example 6 show a high resistance in the so-called iron (III) chloride test at a pitting corrosion temperature of 60 ° C. This corresponds to that of the alloy 28 (7). However, in the combination of their pitting corrosion resistance with the resistance to uniform corrosion removal in boiling azeotropic nitric acid as typical oxidizing acid, the alloys according to the invention show a clear superiority, which can be used immediately in this combination when using plants for producing azeotropic nitric acid. The same applies to the alloy Alloy G-30 (12). Although its pitting corrosion resistance is somewhat superior to the alloys according to the invention, it is very poor in terms of its resistance to uniform corrosion removal in boiling azeotropic nitric acid. In neutral chloride-containing solutions, such as cooling water, the very good pitting corrosion resistance of the alloys according to the invention is expressed in electrochemical corrosion tests (Example 11).
Beispiel 7 zeigt das Korrosionsverhalten in Mischsäuren aus Schwefelsäure und Salpetersäure. Die erfindungsgemäße Legierung ist sowohl bei niedrigen wie auch bei hohen H₂SO₄-Gehalten den bekannten Legierungen überlegen.Example 7 shows the corrosion behavior in mixed acids from sulfuric acid and nitric acid. The alloy according to the invention is superior to the known alloys both at low and at high H₂SO₄ contents.
Beispiel 8 zeigt einen Vergleich der Massenverlustraten in Schwefelsäure-Flußsäurelösungen. Die erfindungsgemäßen Legierungen sind hoch in Chrom legierten Werkstoffen AISI 310 L (4), Alloy 28 (7), Alloy G-30 (12) und 1.4465 (5) gegenübergestellt. Man erkennt, daß die erfindungsgemäßen Legierungen einen geringeren Korrosionsabtrag aufweisen als die dem Stand der Technik entsprechenden Werkstoffe.Example 8 shows a comparison of the mass loss rates in sulfuric acid-hydrofluoric acid solutions. The alloys according to the invention are compared in high-chromium alloyed materials AISI 310 L (4), Alloy 28 (7), Alloy G-30 (12) and 1.4465 (5). It can be seen that the alloys according to the invention have less corrosion removal than the materials corresponding to the prior art.
Ein Vergleich der Massenverlustraten wurde auch in Phosphorsäure-Lösungen vorgenommen. Die erhaltenen Ergebnisse sind in Beispiel 9 wiedergegeben. Die erfindungsgemäßen Legierungen werden mit Werkstoffen, welche gemäß dem Stand der Technik speziell für den Umgang mit Phosphorsäure-Lösungen verwendet werden, verglichen. Während in Lösung 1 der dem Stand der Technik entsprechende Werkstoff Alloy 904 L (3) als ausreichend betrachtet werden kann, ist dies in Lösung 2 nicht der Fall. Die Korrosionsbeständigkeit der erfindungsgemäßen Legierungen ist von derjenigen des Werkstoffs Alloy G-30 (12) zwar nicht wesentlich verschieden, der geringe Korrosionsabtrag bei den erfindungsgemäßen Legierungen wird aber mit wesentlich weniger Aufwand an teuren Legierungszusätzen erreicht.A comparison of the mass loss rates was also made in phosphoric acid solutions. The results obtained are shown in Example 9. The alloys according to the invention are compared with materials which, according to the prior art, are used specifically for handling phosphoric acid solutions. While in solution 1 the material Alloy 904 L (3) corresponding to the state of the art can be regarded as sufficient, in solution 2 this is not the case. The corrosion resistance of the alloys according to the invention is not significantly different from that of the material Alloy G-30 (12), but the low corrosion removal with the alloys according to the invention is achieved with significantly less expenditure on expensive alloy additives.
Beispiel 10 zeigt das Korrosionsverhalten in Salpetersäure/Flußsäuregemischen. Die erfindungsgemäßen Legierungen sind dem Stand der Technik weit überlegen.Example 10 shows the corrosion behavior in nitric acid / hydrofluoric acid mixtures. The alloys according to the invention are far superior to the prior art.
Beispiel 15 belegt das günstige Korrosionsverhalten der erfindungsgemäßen Legierungen im Vergleich zu bekannten Legierungen in Chromsäure.Example 15 demonstrates the favorable corrosion behavior of the alloys according to the invention compared to known alloys in chromic acid.
Die erfindungsgemäße Legierung 2' ist gemäß Abb. 1 und 2 auch nach einer bis zu 8 h gehenden thermischen Beanspruchung im Temperaturbereich zwischen 600 und 1000°C beständig gegen interkristalline Korrosion, und zwar sowohl im Fall einer Prüfung gemäß SEP 1877 II als auch im Huey-Test.The alloy 2 'according to the invention is also resistant to intergranular corrosion after a thermal load of up to 8 hours in the temperature range between 600 and 1000 ° C, both in the case of a test in accordance with SEP 1877 II and in Huey -Test.
Aufgrund der obigen Versuchsergebnisse wird deutlich, daß die erfindungsgemäßen Legierungen breit anwendbar sind, wobei sie bevorzugt in folgenden Bereichen eingesetzt werden können:On the basis of the above test results, it is clear that the alloys according to the invention are widely applicable, and they can preferably be used in the following areas:
Herstellung von Schwefelsäure, insbesondere im Bereich der Absorbtionen,
Verarbeitung von Schwefelsäure, z.B. Sulfierung, Sulfonierung und Nitrierung sowie Konzentrierung,
Herstellung von azeotroper Salpetersaure und Verarbeitung sowie Lagerung von Salpetersaure,
Herstellung von Flußsäure aus Schwefelsäure und Flußspat sowie Verarbeitung der Flußsäure und Verfahren, bei denen Flußsäure als Katalysator eingesetzt wird,
Anwendung von Flußsäure-, Schwefelsäure-, Salpetersäure-haltigen Ätzbädern, z.B. für Nickellegierungen und nichtrostende Stähle bzw. in der Galvanotechnik, Herstellung von Chromsäure aus Schwefelsäure oder Oleum und Natriumdichromat,
Einsatz in Kühlwassersystemen und Anlagen zur Luftreinhaltung,
Lagerung und Eindampfung von Alkalien, z.B. Herstellung von Natronlauge-Perlen,
Verwendung heißer Alkalien bei chemischen Prozessen sowie als Elektrodenmaterialien in elektrolytischen Prozessen, ferner für Beizbäder in der Stahl- und Metallindustrie.Production of sulfuric acid, especially in the area of absorption,
Processing of sulfuric acid, eg sulfonation, sulfonation and nitration as well as concentration,
Production of azeotropic nitric acid and processing and storage of nitric acid,
Production of hydrofluoric acid from sulfuric acid and fluorspar, processing of hydrofluoric acid and processes using hydrofluoric acid as a catalyst
Use of etching baths containing hydrofluoric acid, sulfuric acid, nitric acid, for example for nickel alloys and stainless steels or in electroplating, production of chromic acid from sulfuric acid or oleum and sodium dichromate,
Use in cooling water systems and systems for air pollution control,
Storage and evaporation of alkalis, e.g. production of sodium hydroxide beads,
Use of hot alkalis in chemical processes and as electrode materials in electrolytic processes, also for pickling baths in the steel and metal industry.
Die Erfindung soll anhand der nachfolgenden Beispiele näher erläutert werden.The invention is illustrated by the following examples.
Die Durchführung der Korrosionsversuche wurde nach folgenden, für den Fachmann bekannten Angaben durchgeführt:
- a) Ermittlung von Abtragsraten/Korrosionsgeschwindigkeiten:
Zur Untersuchung des Korrosionsverhaltens der Werkstoffe in diversen Säuren, Mischsäuren und Alkalien wurden folgende DIN-Normen berücksichtigt:
DIN 50905, T1: Korrosion der Metalle;
Korrosionsuntersuchungen: Grundsätze, Ausgabe Januar 1987
DIN 50905, T2: Korrosion der Metalle;
Korrosionsuntersuchungen: Korrosiongrößen bei gleichmäßiger Flächenkorrosion, Ausgabe Janauar 1987,
DIN 50905, T3: Korrosion der Metalle;
Korrosionuntersuchungen: Korrosionsgrößen bei ungleichmäßiger und örtlicher Korrosion ohne mechanische Belastung, Ausgabe Januar 1987
DIN 50905, T4: Korrosion der Metalle;
Korrosionsuntersuchungen: Durchführung von chemischen Korrosionsversuchen ohne mechanische Belastungen in Flüßigkeiten im Laboratorium, Ausgabe Januar 1987
ISO/DIS 8407: Metals and alloys - Procedure for removal of corrosion products from test specimens, submitted 1985-11-28 by ISO/TC 156 - b) Ermittlung der Loch- und Spaltkorrosionsbeständigkeit:
Zur Ermittlung der kritischen Lochfraßtemperatur (CPT) bzw. Spaltkorrosionstemperatur (CCT) wurden Vorschriften in Anlehnung an amerikanische Prüfvorschriften angewandt:- 1. Treseder, R.S.; MTI Manual No. 3, Guideline information on newer Wrought iron- and nickel base corrosion resistent alloys, The Materials Technology Institute of the Chemical Process Industry, Columbus 1980 Appendix B-Methode MTI-2
- 2. ASTM G48: Test for pitting and crevice corrosion resistance of stainless steels and related alloy by the use of ferric chloride solution.
- c) Zum Vergleich der Lockkorrosionsbeständigkeit (Ranking) verschiedener nichtrostender Stähle mittels elektrochemischer Methoden wird seit geraumer Zeit die Technik des zyklischen potentiodynamischen Potentialvorschubs eingesetzt (Wilde, B.E.; Corrosion 28 (1972), 283-291; Kuron, D., Gräfen, H.; Z. Werkstofftechn. 8 182-191 (1977)).
Hierbei werden folgende Korrosionspotentiale ermittelt:- freies Korrosionspotential (UK)
[Open circuit potential (Ecorr)] - dynamisches Lochkorrosionspotential (ULD)
[Pitting potential (Ep)] - Lochpassivierungspotential (ULP)
[pit repassivation potential (Epp)]
ASTM G3-74 (Reaproved 1981)
ASTM G5-87
Als Unterscheidungskriterium wird nach den vorgenannten Methoden die sogenannte "kritische Lochfraßtemperatur" (CPT) [Lau, P., Bernhardsson, S.; Electrochemical Techniques for the Study of Pitting and Crevice Corrosion Resistance of Stainless Steels, Corrosion 85, Paper No. 64, Boston (1985); Qvarfort, R.; Critical Temperature measurements of stainless Steels with an improved Elektrochemical Method, Corrosion Sci., No. 8, 987-993, (1989)] ermittelt, bei der ULP < UK ist, d.h. nicht repassivierbarer Lochfraß auftritt. Die Potentialvorschubgeschwindigkeit dE/dT beträgt 180 mV·h⁻¹. - freies Korrosionspotential (UK)
- a) Determination of removal rates / corrosion rates:
The following DIN standards were taken into account to investigate the corrosion behavior of the materials in various acids, mixed acids and alkalis:
DIN 50905, T1 : corrosion of metals;
Corrosion tests: principles, January 1987 edition
DIN 50905, T2 : corrosion of metals;
Corrosion investigations: Corrosion sizes with uniform surface corrosion, edition Janauar 1987,
DIN 50905, T3 : corrosion of metals;
Corrosion tests: Corrosion sizes in the event of uneven and local corrosion without mechanical stress, January 1987 edition
DIN 50905, T4 : corrosion of metals;
Corrosion tests: Conducting chemical corrosion tests without mechanical stress in liquids in the laboratory, January 1987 edition
ISO / DIS 8407: Metals and alloys - Procedure for removal of corrosion products from test specimens, submitted 1985-11-28 by ISO / TC 156 - b) Determination of pitting and crevice corrosion resistance:
To determine the critical pitting temperature (CPT) or crevice corrosion temperature (CCT), regulations based on American test regulations were applied:- 1. Treseder, RS; MTI Manual No. 3, Guideline information on newer Wrought iron- and nickel base corrosion resistant alloys, The Materials Technology Institute of the Chemical Process Industry, Columbus 1980 Appendix B-Method MTI-2
- 2. ASTM G48: Test for pitting and crevice corrosion resistance of stainless steels and related alloy by the use of ferric chloride solution.
- c) The technique of cyclic potentiodynamic potential feed has been used for some time to compare the corrosion resistance (ranking) of various stainless steels using electrochemical methods (Wilde, BE; Corrosion 28 (1972), 283-291; Kuron, D., Gräfen, H. ; Z. Werkstofftechn. 8 182-191 (1977)).
The following corrosion potentials are determined:- free corrosion potential (U K )
[Open circuit potential (E corr )] - dynamic pitting corrosion potential (U LD )
[Pitting potential (E p )] - Hole passivation potential (U LP )
[pit repassivation potential (E pp )]
ASTM G3-74 (Reaproved 1981)
ASTM G5-87
The so-called "critical pitting temperature" (CPT) [Lau, P., Bernhardsson, S .; Electrochemical Techniques for the Study of Pitting and Crevice Corrosion Resistance of Stainless Steels, Corrosion 85, Paper No. 64, Boston (1985); Qvarfort, R .; Critical Temperature measurements of stainless Steels with an improved Elektrochemical Method, Corrosion Sci., No. 8, 987-993, (1989)], in which U LP <U K , ie non-repassivable pitting occurs. The potential feed rate dE / dT is 180 mV · h⁻¹. - free corrosion potential (U K )
In einem Vakuuminduktionsofen wurden die Stähle der Tabelle 1 im 100 kg Maßstab aus an sich bekannten Rohstoffen erschmolzen und zu Blöcken vergossen. Die Blöcke wurden zu 5 (12) mm dicken Blechen umgeformt. Die abschließende Lösungsglühung erfolgte bei mindestens 1120°C mit anschließender Abschreckung. Es lag jeweils ein vollaustenitisches, ausscheidungsfreies, homogenes Gefüge vor.In a vacuum induction furnace, the steels in Table 1 were melted on a 100 kg scale from raw materials known per se and cast into blocks. The blocks were formed into 5 (12) mm thick sheets. The final solution annealing was carried out at at least 1120 ° C. with subsequent quenching. There was a fully austenitic, excretion-free, homogeneous structure.
Mechanische Eigenschaften der Stähle gemaß Tabelle 1 und typische Vergleichswerkstoffe:
Ergebnis der mechanischen Prüfung:
Result of the mechanical test:
Die mechanischen Eigenschaften der Legierungen deuten auf eine gute Kaltumformbarkeit.The mechanical properties of the alloys indicate good cold formability.
Laborkorrosionsversuche in ruhender Schwefelsäure (99,1 Gew.-% H₂SO₄) bei verschiedenen Temperaturen und nach 7 Tagen Prüfzeit (Blechdicke 4,5 mm):
Abtrag in [mm/a]
Removal in [mm / a]
Korrosionsversuche in ruhender Schwefelsäure (98 Gew.-% H₂SO₄ und 98,5 Gew.-% H₂SO₄) bei verschiedenen Temperaturen und nach 7 Tagen Prüfzeit (Blechdicke 4,5 mm):
Abtrag in [mm/a]
Removal in [mm / a]
Laborkorrosionsversuche in Natronlauge bei verschiedenen Temperaturen und Konzentrationen nach 14 Tagen Prüfzeit:
Abtrag in [mm/a]
Removal in [mm / a]
Vergleichswerkstoffe in 70 % NaOH bei 170°C
Die Werkstoffe 17, 15, 16 sind typische Werkstoffe für diese AnwendungThe materials 17, 15, 16 are typical materials for this application
Versuche im Autoklaven mit einem Ethanol-Wassergemisch mit 7,5 Gew.-% Phosphorsäure bei 280°C und 7 Tagen Prüfzeit:
Der erfindungsgemäße Werkstoff Nr. 2' weist eine Abtragsrate von 0,2 mm/a auf.Autoclave tests with an ethanol-water mixture with 7.5% by weight phosphoric acid at 280 ° C and 7 days test time:
Material no. 2 'according to the invention has a removal rate of 0.2 mm / a.
Vergleichswerkstoffe unter gleichen Bedingungen:
Korrosionsverhalten in siedender azeotroper Salpetersäure im Huey-Test-Destillationsverfahren:
Bestimmung der Lochfraß- und Spaltkorrosionstemperaturen im FeCl₃-Test bei 10 Gew.-% FeCl₃·6H₂O:
Korrosionsverhalten in Mischungen aus Schwefelsäuren unterschiedlicher Konzentration bei verschiedenen Salpetersäuregehalten bei 100°C; nach 7 Tagen Prüfzeit:
Abtrag in [mm/a]
Removal in [mm / a]
Korrosionsversuche in Schwefelsäure-Flußsäurelösungen:
- Lösung 1:
- 92,4 % H₂SO₄ / 7,6 % H₂0 / Spuren HF ; T=150°C
- Lösung 2:
- 91,2 % H₂SO₄ / 7,4% H₂0 / 1,4 % HF; T=140°C
- Lösung 3:
- 90-94 % H₂SO₄ / 4-7 % H₂0 / 2-3 % HF; T=140°C
- Solution 1:
- 92.4% H₂SO₄ / 7.6% H₂0 / trace HF; T = 150 ° C
- Solution 2:
- 91.2% H₂SO₄ / 7.4% H₂0 / 1.4% HF; T = 140 ° C
- Solution 3:
- 90-94% H₂SO₄ / 4-7% H₂0 / 2-3% HF; T = 140 ° C
Abtrag [mm/a] in wäßrigen Phosphorsäure-Lösungen
- Lösung 1:
- 75 % gew.-%ige H₃PO₄; 80°C, 14 Tage
- Lösung 2:
- 75 % gew.-%ige H₃PO₄, 0,63 Gew.-% F⁻, 0,3 Gew.-% Fe³⁺, 14 mmol/l Cl⁻; 80°C, 14 Tage
- Solution 1:
- 75% by weight H₃PO₄; 80 ° C, 14 days
- Solution 2:
- 75% by weight H₃PO₄, 0.63% by weight F⁻, 0.3% by weight Fe³⁺, 14 mmol / l Cl⁻; 80 ° C, 14 days
Korrosionsverhalten in Salpetersäure/Flußsäuregemischen; Massenverlustraten in [g/m²h]; T = 90°C
Lösung 2: 2 mol/l HNO₃ + 0,5 mol/l HF
Lösung 3: 2 mol/l HNO₃ + 2 mol/l HF
Lösung 4: 0,25 mol/l HF + 6 mol/l HNO₃
Lösung 5: 0,25 mol/l HF + 9 mol/l HNO₃
Lösung 6: 0,25 mol/l HF + 12 mol/l HNO₃
Lösung 7: 0,25 mol/l HF + 15 mol/l HNO₃.
Solution 2: 2 mol / l HNO₃ + 0.5 mol / l HF
Solution 3: 2 mol / l HNO₃ + 2 mol / l HF
Solution 4: 0.25 mol / l HF + 6 mol / l HNO₃
Solution 5: 0.25 mol / l HF + 9 mol / l HNO₃
Solution 6: 0.25 mol / l HF + 12 mol / l HNO₃
Solution 7: 0.25 mol / l HF + 15 mol / l HNO₃.
Bestimmung des Lochfraßverhaltens durch potentiodynamische Stromdichtepotentialkurven als Funktion des Lochkorrosionspotentials [ULP]; Anforderung: ULP < UR (freies Korrosionspotential)
Lochfraßkorrosionstemperaturen in 1,0 n NaCl-Lösung, Potentialvorschubgeschwindigkeit
Pitting corrosion temperatures in 1.0 N NaCl solution, potential feed rate
Korrosionsversuche unter Betriebsbedingungen in Schwefelsäure (96-98,5 Gew.-%) bei T = 135 - 140°C
Abb. 1 und 2: Zeit-Temperatur-Sensibilisierungs-Diagramm der Legierung 2'; Flächenbezogene Massenverlustrate
Fig. 1 and 2: Time-temperature sensitization diagram of alloy 2 '; Area-related mass loss rate
Claims (24)
32-37 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max. 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,025 Gew.-% Phosphor
max. 0,01 Gew.-% Schwefel
max. 2 Gew.-% Molybdän
max. 1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,3-0,7 Gew.-% Stickstoff enthalten.Austenitic, corrosion-resistant chromium, nickel, iron alloys with the following composition:
32-37 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
Max. 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.025 wt% phosphorus
Max. 0.01 wt% sulfur
Max. 2% by weight molybdenum
Max. 1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.3-0.7% by weight of nitrogen.
32-37 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max. 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,025 Gew.-% Phosphor
max. 0,01 Gew.-% Schwefel
0,5-2 Gew.-% Molybdän
0,3-1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,3-0,7 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
32-37 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
Max. 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.025 wt% phosphorus
Max. 0.01 wt% sulfur
0.5-2% by weight molybdenum
0.3-1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.3-0.7% by weight of nitrogen.
32-35 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max. 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,025 Gew.-% Phosphor
max. 2 Gew.-% Molybdän
max. 1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,4-0,6 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
32-35 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
Max. 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.025 wt% phosphorus
Max. 2% by weight molybdenum
Max. 1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.4-0.6% by weight of nitrogen.
35-37 Gew.-% Chrom
28-36 Gew.-% Nickel
max. 2 Gew.-% Mangan
max. 0,5 Gew.-% Silizium
max. 0,1 Gew.-% Aluminium
max. 0,03 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,025 Gew.-% Phosphor
max. 2 Gew.% Molybdän
max. 1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,4-0,7 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1, having the following composition:
35-37 wt% chromium
28-36 wt% nickel
Max. 2% by weight of manganese
Max. 0.5% by weight silicon
Max. 0.1% by weight aluminum
Max. 0.03 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.025 wt% phosphorus
Max. 2% by weight molybdenum
Max. 1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.4-0.7% by weight of nitrogen.
32,5 - 33,5 Gew.-% Chrom
30,0 - 32,0 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
0,5-2 Gew.-% Molybdän
0,3-1 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,35-0,5 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
32.5-33.5 wt% chromium
30.0-32.0 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
max. 0.01 wt.% sulfur
Max. 0.02 wt% phosphorus
0.5-2% by weight molybdenum
0.3-1% by weight copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.35-0.5% by weight of nitrogen.
32,5 - 33,5 Gew.-% Chrom
30,0 - 32,0 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,35-0,5 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
32.5-33.5 wt% chromium
30.0-32.0 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.35-0.5% by weight of nitrogen.
34,0 - 35,0 Gew.-% Chrom
30 - 32 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,4-0,6 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
34.0-35.0 wt% chromium
30-32 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.4-0.6% by weight of nitrogen.
35,0 - 36,0 Gew.-% Chrom
30 - 32 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunnreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,4-0,6 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
35.0 - 36.0 wt% chromium
30-32 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.4-0.6% by weight of nitrogen.
36,0 - 37,0 Gew.-% Chrom
30 - 32 Gew.-% Nickel
0,5 - 1,0 Gew.-% Mangan
0,01 - 0,5 Gew.-% Silizium
0,02 - 0,1 Gew.-% Aluminium
max. 0,02 Gew.-% Kohlenstoff
max. 0,01 Gew.-% Schwefel
max. 0,02 Gew.-% Phosphor
max. 0,5 Gew.-% Molybdän
max. 0,3 Gew.-% Kupfer
sowie übliche herstellungsbedingte Beimengungen und Verunreinigungen und den Rest als Eisen, dadurch gekennzeichnet, daß die Legierungen zusätzlich 0,4-0,7 Gew.-% Stickstoff enthalten.Austenitic alloys according to claim 1 with the following composition:
36.0-37.0 wt% chromium
30-32 wt% nickel
0.5-1.0% by weight of manganese
0.01-0.5% by weight silicon
0.02-0.1% by weight aluminum
Max. 0.02 wt% carbon
Max. 0.01 wt% sulfur
Max. 0.02 wt% phosphorus
Max. 0.5 wt% molybdenum
Max. 0.3 wt% copper
as well as usual manufacturing-related admixtures and impurities and the rest as iron, characterized in that the alloys additionally contain 0.4-0.7% by weight of nitrogen.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE4342188 | 1993-12-10 | ||
DE4342188A DE4342188C2 (en) | 1993-12-10 | 1993-12-10 | Austenitic alloys and their uses |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0657556A1 true EP0657556A1 (en) | 1995-06-14 |
EP0657556B1 EP0657556B1 (en) | 1999-02-10 |
Family
ID=6504695
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP94118682A Expired - Lifetime EP0657556B1 (en) | 1993-12-10 | 1994-11-28 | Austenitic alloys and their applications |
Country Status (14)
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US (1) | US5695716A (en) |
EP (1) | EP0657556B1 (en) |
JP (1) | JP3355510B2 (en) |
KR (1) | KR950018592A (en) |
AT (1) | ATE176690T1 (en) |
AU (1) | AU694456B2 (en) |
CA (1) | CA2137522C (en) |
DE (2) | DE4342188C2 (en) |
DK (1) | DK0657556T3 (en) |
ES (1) | ES2128495T3 (en) |
FI (1) | FI107168B (en) |
PL (1) | PL179404B1 (en) |
TW (1) | TW363084B (en) |
ZA (1) | ZA949832B (en) |
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DE19748205A1 (en) * | 1997-10-31 | 1999-05-06 | Abb Research Ltd | Process for producing a workpiece from a chrome alloy and its use |
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WO2008002150A1 (en) * | 2006-06-28 | 2008-01-03 | Hydrogen Technologies As | Use of an austenitic stainless steel and an electrolyser made of such steel |
EP2228578A1 (en) * | 2009-03-13 | 2010-09-15 | NV Bekaert SA | High nitrogen stainless steel wire for flexible pipe |
US8430075B2 (en) | 2008-12-16 | 2013-04-30 | L.E. Jones Company | Superaustenitic stainless steel and method of making and use thereof |
CN109338345A (en) * | 2018-11-30 | 2019-02-15 | 中国科学院金属研究所 | A kind of environment-friendly type surface passivation treatment method of medical high-nitrogen nickel-free stainless steel |
CN110295276A (en) * | 2018-03-21 | 2019-10-01 | 吉林常春高氮合金研发中心有限公司 | The method for improving high nitrogen steel ships propeller corrosion resistance |
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CN110295276A (en) * | 2018-03-21 | 2019-10-01 | 吉林常春高氮合金研发中心有限公司 | The method for improving high nitrogen steel ships propeller corrosion resistance |
CN109338345A (en) * | 2018-11-30 | 2019-02-15 | 中国科学院金属研究所 | A kind of environment-friendly type surface passivation treatment method of medical high-nitrogen nickel-free stainless steel |
Also Published As
Publication number | Publication date |
---|---|
CA2137522C (en) | 2004-04-27 |
FI945771A (en) | 1995-06-11 |
DE59407804D1 (en) | 1999-03-25 |
CA2137522A1 (en) | 1995-06-11 |
ES2128495T3 (en) | 1999-05-16 |
TW363084B (en) | 1999-07-01 |
PL306180A1 (en) | 1995-06-12 |
ATE176690T1 (en) | 1999-02-15 |
EP0657556B1 (en) | 1999-02-10 |
PL179404B1 (en) | 2000-08-31 |
US5695716A (en) | 1997-12-09 |
JP3355510B2 (en) | 2002-12-09 |
FI107168B (en) | 2001-06-15 |
DK0657556T3 (en) | 1999-09-20 |
FI945771A0 (en) | 1994-12-08 |
JPH07197181A (en) | 1995-08-01 |
KR950018592A (en) | 1995-07-22 |
DE4342188C2 (en) | 1998-06-04 |
AU694456B2 (en) | 1998-07-23 |
ZA949832B (en) | 1995-08-22 |
DE4342188A1 (en) | 1995-06-14 |
AU8030794A (en) | 1995-06-15 |
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