US20080138232A1 - Duplex Stainless Steel - Google Patents

Duplex Stainless Steel Download PDF

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US20080138232A1
US20080138232A1 US11/666,903 US66690305A US2008138232A1 US 20080138232 A1 US20080138232 A1 US 20080138232A1 US 66690305 A US66690305 A US 66690305A US 2008138232 A1 US2008138232 A1 US 2008138232A1
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alloy
weight
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Pasi Kangas
Karin Jakobsson
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Sandvik Intellectual Property AB
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
    • B23K35/3053—Fe as the principal constituent
    • 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
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • 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
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

Definitions

  • the present invention concerns to a duplex stainless steel alloy having a high Cr-, Mo- and N- content and a ferrite content of 30-70%.
  • Duplex stainless steels are characterised by an austenite-ferrite structure where both phases have different chemical compositions. They are attractive as structural materials where both high mechanical strength and excellent resistance to corrosion are required. Duplex stainless steels are often used as alternatives to austenitic stainless steels and nickel-based alloys due to their lower cost, which is a consequence of the lower nickel content in duplex stainless steels.
  • Duplex stainless steels are extensively used in the onshore and offshore sectors of the oil and gas industry due to their corrosive resistance to the various corrosive media, such as CO 2 , H 2 S and chlorides, found in such onshore/offshore environments.
  • Umbilical pipes, or “umbilicals”, that interconnect units on the land or sea surface with units at the bottom of the sea to transport substances therebetween, such as to crude oil and gas from a source to an oil rig, are often made of duplex stainless steel pipes that are welded together.
  • Downhole tubes which are grooved tubes that are generally installed within a drill-hole, and integrated production tubes (IPUs), which are composite tubes comprising umbilicals and downhole tubes, are also often made of duplex steel.
  • a downhole tube has to be resistant both to corrosion in the sea water that surrounds it and to corrosion in the substances that it transports.
  • Downhole tubes are supplied in threaded finish and joined to the necessary lengths by means of couplings. Since oil and gas wells are situated at a considerable depth below sea level the length of a downhole tube can be quite considerable.
  • the demands on the material that is used for downhole tubes can be summarised as follows:
  • U.S. Pat. No. 6,749,697 discloses a duplex stainless steel alloy with austenite-ferrite structure having a high Cr-, Mo- and N- content.
  • This alloy fulfils the above-mentioned requirements since when in hot extruded and annealed finish the alloy shows high strength, good corrosion resistance in several acids and bases and has especially good pitting resistance in chloride environments, as well as good weldability.
  • the PRE number of this alloy is over 40.
  • the alloy contains in weight-% max 0.05% C, 0-2.0% Si 0-3.0% Mn, 25-35% Cr, 4-10% Ni, 2-6% Mo, 0.3-0.6% N, balance Fe and normally occurring impurities whereby the content of ferrite is 30-70%.
  • WO 03/020994 describes an alloy characterised by Mn 0-3%, Cr 24-30%, Ni 4.9-10%, Mo 3-5, Cu 0-2%, W 0-3%, N 0.28-0.5% and Co 0-3.5%.
  • This alloy has a high Cr-, Mo and N content, which increases the alloy's pitting resistance but on the other hand increases the risk of poor structural stability.
  • By alloying with Co the alloy is considered to be more structurally stable so at least 0.5% Co, preferably at least 1.5%, max 3.5% Co can be added to increase the corrosion resistance and this is also reported to increase structural stability.
  • This alloy has a PRE/PREW number over 40.
  • U.S. Pat. No. 6,312,532 discloses a duplex stainless steel alloy containing Mn 0.3-4%, Cr 27-35%, Ni 3-10%, Mo 0-3%, N 0.3-0.55%, Cu 0.5-3% and W 2-5%.
  • the alloy exhibits a relatively high resistance to corrosion in chloride environments due to alloying with W. Alloying with Cu in combination with high W or Mo contents is stated to decrease the precipitation of intermetallic phases on slow cooling. This property is of great importance when manufacturing stainless steel products of large dimensions where the rate of cooling is relatively slow, which in general increases the risk of intermetallic phases precipitating in the temperature range of about 700-1000° C.
  • This alloy has a PREW number over 40.
  • the patent states that at least 2% W should be added for optimal effect and combinations of Mo+0.5 W should not exceed 3.52.
  • the Cu content should exceed 1.5% to maximise the structural stability. If large amounts of Cu are used the Mo content should be low to ensure good protection against inter-crystalline corrosion.
  • duplex stainless steels A disadvantage with duplex stainless steels is that their high alloy content makes them susceptible to the formation of intermetallic phases, such as the sigma and chi phases, from extended exposure to high temperatures.
  • the sigma phase is a hard, brittle and highly corrodible intermetallic compound that is rich in Cr and Mo.
  • the chi phase is an intermetallic compound with a manganese sulphide structure.
  • the object of the present invention is to provide a duplex stainless steel that shows high strength, good corrosion resistance, good workability and which is weldable.
  • a duplex stainless steel alloy having the composition disclosed herein namely an alloy that contains (in weight %): Cr 25-35%, Ni 4-10%, Mo 1-6%, N 0.3-0.6%, Mn greater than 0 to 3%, Si max 1.0% and C max 0.06%, Cu and/or W and/or Co 0.1-10%, W 0.1-5%, balance Fe and normally occurring impurities wherein the ferrite content is 30-70%, and which alloy has a yield point in tension being minimum 760 MPa.
  • Such an alloy having high contents of Cr, Mo and N and containing W or W and Cu and/or Co has surprisingly good mechanical and corrosion properties, particularly as regards pitting in a chloride environment.
  • the high contents of Cr, Mo and N give the alloy a very high strength and simultaneously a good workability, especially for hot extrusion into articles such as seamless tubes.
  • the addition of W or W and Cu and/or Co enhances the alloy's corrosion resistance in acid environments, improves its structural stability and its weldability and confers greater resistance to some types of corrosion attack by seawater.
  • the inventive alloy has a high resistance to stress corrosion cracking caused by hydrogen sulphide.
  • the alloy has good hot workability, is easier to roll and is well suited for applications that require welding, such as the manufacture of butt-welded seamless tubes and seam-welded tubes for various coiled tubing applications. Consequently, the alloy is especially suited for hydraulic tubes, such as umbilicals, downhole tubes and IPUs.
  • the most remarkable characteristic of the alloy according to the invention is the extraordinary combination of a high yield point in tension and a high impact toughness.
  • the present inventors has found the following relationship between yield point in tension and composition for a duplex stainless steel alloy:
  • Tungsten which is similar to molybdenum in function and effect in terms of corrosion chemistry, is used to partly replace the molybdenum in the alloy since tungsten is not as active as molybdenum in promoting the precipitation of intermetallic phases such as the sigma phase. Partly substituting molybdenum with tungsten also increases the alloy's low temperature impact toughness. The utilization of both molybdenum and tungsten improves duplex stainless steel alloy's corrosion resistance. Furthermore since molybdenum is much more expensive than tungsten the substitution of molybdenum with tungsten provides a more cost-effective alloy.
  • W or W and Cu and/or Co is also essential for suppressing the precipitation of intermetallic phases.
  • the alloy's pitting corrosion properties and its resistance to intergranular corrosion are furthermore enhanced by a simultaneous addition of W and Cu, where W at least partly substitutes Mo.
  • high contents of W in combination with high contents of Cr and Mo increase the risk of intergranular precipitations so the content of W should therefore be limited to max 5 weight %.
  • the alloy contains 0.40-0.55% N. It has been found that this high content of nitrogen results in a particularly favourable combination of a high yield point in tension and a high impact toughness.
  • the alloy is manufactured using a conventional metallurgical method, such as melting in an arc furnace.
  • the inventive alloy may therefore be readily melted and cast using conventional techniques and equipment.
  • the alloy is manufactured by a powder metallurgy method.
  • the alloy comprises a maximum of 1 weight % alloying additions that are added for process metallurgical or hot workability reasons.
  • the present invention also concerns an article in the form of a tube, wire, strip, rod, sheet or bar or any other article having high strength and/or good corrosion resistance, which comprises an alloy according to any of the embodiments disclosed above.
  • Such an article may be a seamless tube, a welding wire, a seam-welded tube, a flange, a coupling, a rotor blade, a fan, a cargo tank, weld material or high strength highly resistant wiring.
  • Said article is either made of the inventive alloy or it comprises a coating of the inventive alloy.
  • the article comprises the inventive alloy metallurgically or mechanically bonded (or clad) to a base material such as carbon steel.
  • alloy and the article according to any of embodiments described above are intended for use particularly but not exclusively as a construction material or a mechanical or structural component, such as an umbilical, a downhole tube or an integrated production unit (IPU), in sea-water environments, in chloride environments, in corrosive environments, in chemical plants, in the paper industry or as welding wire.
  • a construction material or a mechanical or structural component such as an umbilical, a downhole tube or an integrated production unit (IPU), in sea-water environments, in chloride environments, in corrosive environments, in chemical plants, in the paper industry or as welding wire.
  • FIG. 1 is a diagram in the form of a plot of the impact toughness versus the yield point in tension for test charges of alloys according to embodiments of the invention.
  • FIG. 2 is a diagram showing the relation for test charges of alloys according to embodiments of the invention at measured values of yield point in tension and a prediction according to a formula drawn up by the present inventors.
  • Chromium (Cr) is a very active element that improves the resistance to a plurality of corrosion types. Moreover chromium increases the strength of the alloy. High chromium content additionally implies a very good solubility of N in the material. Consequently it is desirable to keep the Cr-content as high as possible in order to improve the strength and resistance to corrosion. For very good strength properties and resistance to corrosion the content of chromium should be at least 25 weight %, preferably at least 28 weight %. However the content should not exceed 33%. However high contents of Cr increase the risk of forming intermetallic precipitations. For this reason the chromium content preferably not exceed 35 weight %.
  • Nickel (Ni) is used as an austenite-stabilising element and is added to the alloy at a suitable level in order to attain the desirable content of austenite and ferrite, respectively.
  • the content of nickel should be at least 4 weight %, preferably at least 5 weight % and should not exceed 10 weight %, preferably not exceed 9 weight %.
  • Molybdenum (Mo) is an active element which improves the resistance to corrosion in chloride environments as well as in reducing acids.
  • An excessive Mo-content in combination with a high Cr-content means that the risk of forming intermetallic precipitations increases. Since Mo increases the strength of the alloy, the content of Mo should be in the range of at least 1 weight %, preferably at least 3%, it should not exceed 6 weight %, preferably not exceed 5 weight %.
  • N Nitrogen
  • N is a very active element which partly increases the resistance to corrosion and partly increases the structural stability as well as the strength of the material. Furthermore, a high N-content improves the reformation of austenite after welding, which ensures good properties for welded joints. In order to attain a good effect at least 0.3 weight % N should be added. High contents of N increase the risk of precipitation of chromium nitrides, especially when the content of chromium is also high. Furthermore, a high N-content implies that the risk of porosity increases because the solubility of N in the steel melt or weld pool will be exceeded. The N-content should therefore be limited to max 0.60 weight %, it should preferably be at least 0.40 weight %, and should not exceed 0.55 weight % N.
  • Manganese (Mn) is added in order to increase the solubility of N in the material, among other things. There are however other elements that have a higher influence on the solubility. Mn in combination with high contents of sulphur can also give rise to the formation of manganese sulphides, which act as initiation points for pitting corrosion.
  • the content of Mn should therefore be limited to being greater than 0 weight %, preferably at least 0.5 weight %, it should not exceed 3 weight %, preferably not exceed 1.5 weight %.
  • Silicon (Si) is utilized as a deoxidiser during steel production and it also increases the floatability under production and welding. It is known that high silicon contents support the precipitation of an intermetallic phase. It has been surprisingly shown that an increased content of silicon favourably reduces the precipitation of sigma phase. For this reason a certain content of silicon should be optionally permitted. The content of silicon should however be limited to max 1.0 weight %. Silicon would for example be added up to 0.15% or 0.10%.
  • Carbon (C) strengthens stainless steel but promotes the formation of precipitates harmful to corrosion resistance and therefore has to be considered to be a contaminant in this invention. Carbon has a limited solubility in both ferrite and austenite and this implies a risk of precipitation of chromium carbides.
  • the carbon content should therefore be limited to max 0.05 weight %, preferably to max 0.03 weight % and most preferably to max 0.02 weight %.
  • Copper (Cu) is added in order to improve the duplex stainless steel's resistance to certain corrosive environments such as in acid environments, such as sulphuric acid, and it also decreases the alloy's susceptibility to stress corrosion cracking and provides age-hardening effects. It has been found that Cu decreases the precipitation rate of intermetallic phase on slow cooling in materials with relatively high contents of Mo and/or W. The reason for this is possibly that the precipitation of a copper-rich austenite or epsilon phase prevents the precipitation of other intermetallic phases such as the sigma phase.
  • the appearance of small amounts of copper-rich epsilon phase is a positive factor in the inventive alloy.
  • high contents of copper mean that the solubility limit is exceeded so the Cu-content should be limited to max 5 weight %.
  • the Cu-content should be at least 0.1 weight %, preferably at least 0.8 weight %, and should not exceed 5 weight %, preferably not exceed 3.5 weight %.
  • Tungsten improves the resistance to corrosion in chloride environments as well as in reducing acids and the alloy's resistance to pitting and crevice corrosion. It has been found that alloying with W as a replacement for Mo increases the alloy's low temperature impact strength. At the same time alloying with W and Cu, where W replaces the element Mo in the alloy with the aim of improving pitting resistance properties, can take place with the aim of reducing the risk of worsening the inter-crystalline corrosion resistance. However a too high W-content in combination with a high Cr-content increases the risk of precipitation of intermetallic phases, such as the sigma phase. When present, the W-content should therefore be limited to at least 0.1 weight %, it should not exceed 5 weight %, preferably not exceed 3 weight %, and it may be min weight 1%.
  • Co Co
  • Co Co
  • the content of cobalt should be greater than 0%, preferably greater than 0.5% and should not exceed 3.5%, preferably not exceed 2% Co.
  • Ferrite The content of ferrite is important in order to obtain good mechanical properties and corrosion properties as well as good weldability and workability. From a corrosion and welding point of view it is desirable to obtain good properties with a ferrite content between 30-70%. High ferrite contents cause deterioration in low temperature impact toughness and resistance to hydrogen embrittlement.
  • the ferrite content is therefore at least 30%, max 70%, preferably at least 35%, and should not exceed 55%, the remainder being austenite.
  • Alloying additions Elements added for process metallurgical reasons, in order to obtain melt purification from S or O, for example, or added in order to improve the workability of the material. Examples of such elements are Al, B, Ca, Ce and Mg. In order for such elements not to have a harmful effect on the properties of the alloy, the levels of each individual element should be less than 0.1%. The total level of alloying additions should be less than 1%, preferably max 0.1%.
  • Table 2 gives the compositions in the ferrite and the austenite phases respectively.
  • Table 3 contains parameters taken from the calculated phase diagrams; such as the amount of sigma phase at 900° C., the maximum temperature for sigma phase (SIGMA) i.e. the temperature at which the sigma phase starts to precipitate at thermodynamic equilibrium, which means that this parameter is a dimension for the structural stability of the alloy, the maximum temperature for chromium nitrides Cr 2 N and the maximum temperature for the precipitation of chromium-rich austenite phase.
  • SIGMA maximum temperature for sigma phase
  • Cu decreases the maximum temperature for sigma phase in alloys with W (see Table 3, compare alloys 3 and 4 with alloys 7 and 8). For each weight % Cu T maxsigma decreases by 20-30° C.
  • W as a replacement for Mo should give an increased tensile yield limit because W is a bigger atom, which should have a greater effect on solution hardening.
  • Mo By replacing Mo with W in the ratio 1:2 the structural stability will be largely unchanged but a better strength will be achieved.
  • Co decreases the risk of sigma phase precipitation by lowering the maximum temperature for sigma phase precipitation.
  • test charges were produced by casting 170 kg blooms. The blooms were hot-forged to round bars, from which test materials for investigations with respect to corrosion, strength and structural stability were taken.
  • composition of the sixteen test charges successfully hot-forged to round bars with a diameter of 40 mm are given in Table 4.
  • test plates from the rods were subjected to solution heat treatment at 7 temperatures between 900-1200° C. (in steps of 50° C.).
  • the best possible heat treatment temperature with the lowest degree of intermetallic phase was determined by studies in a light optical microscope.
  • the material was then subjected to solution heat treatment at this temperature during 5 minutes before the test material was taken out.
  • the ferrite content was determined by means of point counting in a light optical microscope (LOM). The results are presented in Table 5.
  • test material was rapidly heated to the dissolving temperature, were annealed 3 minutes and cooled with a cooling rate of ⁇ 17.5° C./minute and ⁇ 100° C./minute down to room temperature.
  • the amount of sigma phase in the test charges was then determined by picture analysis of pictures from the BSE-detector in a Scanning Electron Microscope (SEM). The results are presented in Table 6.
  • the mechanical strength of the test charges was determined at room temperature and the impact toughness was determined at room temperature and ⁇ 50° C.
  • the results are presented in Table 7. However, a number of the test bars exhibited cracks.
  • the results are also shown in diagram form in FIG. 1 , which is a plot of the impact toughness versus the yield point in tension.
  • yield point in tension R p0.2 is strongly dependant upon solution hardening elements.
  • the relation between yield point in tension and the composition satisfies with a comparatively good correlation the formula:
  • FIG. 2 shows the relation for the test charges at the measured values of R p0.2 and the prediction according to this formula. It appears from the formula that for a high yield point in tension N has the strongest influence, while Cr, Mo and W have the same influence. Since W is an element which does not influence the structural stability as negatively as Mo, it is favourable to alloy with W while lowering the content of Mo for avoiding problems with the structural stability. However, Mo has a greater influence upon the corrosion properties. For a maintained structural stability it is possible to alloy with W that replaces Mo by a factor 2, which means that the content of W may be increased with 2% if the content of Mo is lowered by 1%, for optimizing the yield point in tension.
  • test charges 5536 in comparison with 5542 and 5548 it is possible to increase the yield point in tension for the materials by lowering the content of Mo and N and at the same time increase the content of W and Cu.
  • a problem for high tensile materials in general is that it is very difficult to obtain a combination of a good impact toughness and a high yield point in tension. It has for the present invention been demonstrated that for charges having a very high yield point in tension, where R p0.2 exceeds 800 MPa, it is possible to obtain an acceptable impact toughness at ⁇ 50° C. for charges where the content of W and Cu is high at the same time as the content of N has been reduced. It was by that possible to obtain a combination of two important properties for construction materials, which so far has been difficult to obtain for duplex steels.
  • the resistance of the test materials to pitting and crevice corrosion were measured according to ASTM G48C and MTI-2.
  • the critical pitting corrosion temperature (CPT) and the critical crevice corrosion temperature (CCT) were determined and are shown in Table 8. However, several of the test bars had cracks.
  • the composition in the ferrite and austenite phase, respectively, has been determined by means of microprobe analysis (EPMA), and the results are shown in Table 9.
  • the PRE number should be as balanced as possible between the austenite and the ferrite phases.
  • the charge 5548 is the best one with respect to the combination of corrosion resistance, yield point in tension and impact toughness. It appears from Table 4 that this charge has a content of Cu of about 2%, W about 4% and Co about 0.1% in weight. Thus, it is favourable to have all these three elements present in the alloy.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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  • Metallurgy (AREA)
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US11/666,903 2004-11-04 2005-11-04 Duplex Stainless Steel Abandoned US20080138232A1 (en)

Applications Claiming Priority (3)

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SE0402698-5 2004-11-04
SE0402698A SE528782C2 (sv) 2004-11-04 2004-11-04 Duplext rostfritt stål med hög sträckgräns, artiklar och användning av stålet
PCT/SE2005/001661 WO2006049572A1 (en) 2004-11-04 2005-11-04 Duplex stainless steel

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EP (1) EP1812614A4 (sv)
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KR (1) KR20070073870A (sv)
CN (1) CN101057002A (sv)
AU (1) AU2005301376B2 (sv)
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EP2228578A1 (en) * 2009-03-13 2010-09-15 NV Bekaert SA High nitrogen stainless steel wire for flexible pipe
US20120187093A1 (en) * 2011-01-20 2012-07-26 Mohamed Youssef Nazmy Filler material for welding
US20130316193A1 (en) * 2011-02-14 2013-11-28 Hiroyuki Nagayama Welded joint of duplex stainless steel
US20160319405A1 (en) * 2013-12-27 2016-11-03 Sandvik Intellectual Property Ab Corrosion resistant duplex steel alloy, objects made thereof, and method of making the alloy
US20180209022A1 (en) * 2015-07-20 2018-07-26 Sandvik Intellectual Property Ab Duplex stainless steel and formed object thereof
US20200332378A1 (en) * 2017-11-15 2020-10-22 Nippon Steel Corporation Duplex stainless steel and method for producing duplex stainless steel
US20210071287A1 (en) * 2017-12-22 2021-03-11 Saipem S.P.A. Duplex stainless steels and uses thereof
JP2021508785A (ja) * 2017-12-22 2021-03-11 タバセクス イノベーション エー．アイ．イー． 耐食性の二相ステンレス鋼
WO2023198721A1 (en) * 2022-04-12 2023-10-19 Alleima Tube Ab A new welding duplex stainless steel material suitable for welding a duplex stainless steel, a welded joint and a welding method thereof
WO2023198720A1 (en) * 2022-04-12 2023-10-19 Alleima Tube Ab New duplex stainless steel

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CN101367161B (zh) * 2007-08-18 2011-07-20 中国船舶重工集团公司第七二五研究所 一种低氢型超级双相不锈钢焊条
SE534779C2 (sv) 2010-03-03 2011-12-20 Sandvik Intellectual Property Metod för att tillverka en trådprodukt av rostfritt stål
EP2677054B1 (en) * 2011-02-14 2020-03-25 Nippon Steel Corporation Duplex stainless steel plate or pipe, and process for production thereof
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CA2586452A1 (en) 2006-05-11
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AU2005301376B2 (en) 2010-04-22
NO20072275L (no) 2007-06-13

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