Classifications

• • 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
  • B23K35/3033—Ni as the principal constituent
  • B23K35/304—Ni as the principal constituent with Cr as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/053—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 30% but less than 40%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
• • 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
  • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
  • B23K35/0255—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in welding
  • B23K35/0261—Rods, electrodes, wires

Definitions

• the invention relates to a nickel-base alloy for the electro-welding of nickel alloys and steels, in particular non-alloyed or low alloy steels and stainless steels.
• the invention also relates to wires and electrodes for the electro-welding of parts made of nickel alloy and/or steel, in particular in the field of the construction, assembly and repair of components of nuclear reactors.
• alloy 600 a nickel alloy containing approximately 15% of chromium, known as alloy 600, has been used for the production of units or components of pressurised water-cooled nuclear reactors.
• Electro-welding wires or electrodes of nickel alloy of which the composition is adapted to the welding of the alloy 600 or the alloy 690 are used to produce welds on these nickel alloy units or components.
• Table 1 below shows typical compositions of commercially available wires for the welding of the alloy 690 and for the welding of the alloy 600 (alloy 52 or alloy 82).
• Alloy 52 wires or 82 may be used, in particular, for the inert gas electro-welding of the alloy 690 or the alloy 600.
• the alloy 52 welding wires are used, in particular, in the nuclear field, to produce welds in zones of the nuclear reactor components in contact with the primary fluid, which is water at a very high temperature (approximately 310° C.) and under very high pressure (approximately 155 bars), in the case of pressurised water-cooled nuclear reactors.
• the primary fluid which is water at a very high temperature (approximately 310° C.) and under very high pressure (approximately 155 bars), in the case of pressurised water-cooled nuclear reactors.
• Alloy 52 is used for the homogeneous welding of alloy 690 parts and for producing heterogeneous welds.
• These heterogeneous welds may be, for example, welds on an alloy 600 containing 15% of chromium in solid form or deposited on a base metal, wherein the chromium content of the deposited metal may be from 15% to 20%.
• Another application for alloy 52 in heterogeneous welding is the coating of low alloy steels such as the steels 16MND5, 18MND5 or 20MND5 or the welding of low alloy steels to austenitic stainless steels.
• the alloy 52 may also be used to repair zones of nuclear reactor units or components consisting of various metals such as low alloy steels (for example of the type 18MND5), stainless steels of the type 304L (for example in solid form), of the type 308L (in deposited form) or else 316L (in solid or deposited form). These zones may comprise a plurality of these materials on which heterogeneous welds made of alloy 52 are produced.
• low alloy steels for example of the type 18MND5
• stainless steels of the type 304L for example in solid form
• the type 308L in deposited form
• 316L in solid or deposited form
• Tests were carried out on welding wires of different compositions under variable welding conditions, in particular by fusing these wires on various base metals such as: nickel alloys as mentioned above and stainless steels, in the form of solid metals or of layers pre-deposited by welding.
• type 2 hot cracks were observed in certain cases.
• Type 2 cracks were observed, in particular, in the zones of pronounced dilution of the welding alloy (in the metal deposited during the first welding passes or in the region of the parts to be joined) or more generally in the case of the welding of stainless steels.
• the niobium to silicon ratio is high (higher than 30 or even 45).
• these grades contain boron and zirconium as complementary elements.
• the object of the invention is therefore to propose a nickel-base alloy for the electro-welding of nickel alloys and steels, in particular stainless steels, which allow the production of homogeneous or heterogeneous welds on these materials, which are free of hot-cracking and of traces of oxidation.
• the alloy according to the invention contains, by weight, less than 0.05% of carbon, from 0.015% to 0.5% of silicon, from 0.4% to 1.4% of manganese, from 28% to 31.5% of chromium, from 8% to 12% of iron, from 2% to 7% of molybdenum, from 0.1% to 0.8% of titanium, from 0.6% to 2% in total of niobium and tantalum, the ratio of percentages of niobium plus tantalum and of silicon being at least 4, from 0.05% to 0.75% of aluminium, less than 0.04% of nitrogen, from 0.0008% to 0.0120% of zirconium, from 0.0010% to 0.010% of boron, less than 0.01% of sulphur, less than 0.020% of phosphorus, less than 0.30% of copper, less than 0.15% of cobalt and less than 0.10% of tungsten, the remainder of the alloy, with the exception of unavoidable impurities of which the total content is at most
• the invention also relates to a welding wire for the electro-gas welding of nickel-base alloy according to the invention.
• the invention additionally relates to the application of the alloy and of the electro-welding wire to the welding of units or components of nuclear reactors, in particular pressurised water-cooled nuclear reactors, for the realization of joints during the construction of nuclear reactors, the coating of components by metal deposition and for making repairs, wherein these welding operations may be operations for the homogeneous or heterogeneous welding of any nickel alloy or steel component.
• column 1 shows the minimum contents of the various elements of the alloy
• column 2 the maximum contents of these elements
• column 3 the preferred contents.
• Silicon is an element which is always present in the alloy but of which the content is to be limited to a low value, preferably lower than 0.05%. In all cases, this content must be lower than 0.5% to limit hot cracking of the welding metal. However, the silicon must be present in a content of at least 0.015% to obtain good weldability on account of the fact that it influences the wetting and the viscosity of the bath during welding.
• the manganese must be at least 0.4% to achieve satisfactory conditions for the production of the alloy in the presence of sulphur (limited to the value of 0.01% mentioned hereinafter).
• the manganese contributes to the resistance to fissuration in heat, but this effect is rapidly saturated as a function of the manganese content, and a manganese content limited to 1.4% leads to satisfactory results.
• the chromium must be close to the percentage of chromium in the alloy 690, and the composition range of 28% to 31.5%, which is also that of the alloys 52, has been found to be satisfactory in the case of homogeneous and heterogeneous welds employing the alloy 690 or stainless steels. This level of chromium is required for achieving good anti-corrosion behaviour in a primary PWR medium.
• Copper must be strictly limited to less than 0.30% to avoid a deterioration in the properties of the alloy.
• the cobalt must necessarily be limited to a value below 0.15%. In fact, this element, which is activated in the presence of radiation in a nuclear reactor, must be avoided as far as possible in any application to the construction or repair of nuclear reactors.
• Molybdenum is a particularly important element in the production of the alloys according to the invention, and this represents a significant difference relative to previously known alloys (see Table 1) which have only very low molybdenum contents.
• the cracking resistance of the welding alloy is substantially improved if the alloy contains sufficient quantities of titanium (and/or of aluminium).
• the molybdenum content has to be at least 2% in order to obtain, in all cases of use in welding, very high resistance to cracking and, in particular, a total disappearance of type 2 cracks, while limiting the total titanium and aluminium content to a level at which oxidation of the welding metal is avoided.
• a molybdenum content higher than 7% is possible, but not essential, in so far as the influence of the molybdenum on the cracking resistance is saturated at a value of approximately 7%.
• a content higher than 7% increases the price of the alloy and may undesirably modify the properties of the welding metal.
• the molybdenum should preferably be in the region of 4%.
• the aluminium and titanium are used, in particular, as deoxidising and denitriding agents and lead to the formation of oxide films. These elements also reduce the grain size of the welding alloy during solidification.
• the oxides and nitrides formed in the form of fine particles in the liquid metal initiate the germination of the solidification grains and refine the structure.
• the titanium must be present in the alloy in a proportion of between 0.1% and 0.8% and, for example, close to 0.30%.
• the aluminium must be present in the alloy in a proportion of between 0.05% and 0.75% and, for example, in the region of 0.15%.
• the zirconium must be present in the alloy according to the invention in a proportion of between 0.0008% and 0.012% and preferably in a proportion of approximately 0.006%.
• the boron In relation to these proportions of zirconium, the boron must be between 0.001% and 0.010% and, preferably, in the region of 0.004%.
• Niobium affects the resistance to hot cracking. To avoid increasing the risks of hot cracking and undesirably modifying the characteristics of the deposited metal, this element must not be present in an excessively large quantity.
• the proportion of niobium must be at least 0.6% to obtain the desirable effects of resistance to hot cracking and at most 2%.
• the proportion of niobium within this range must be fixed at a value which is such that the ratio of the percentage of niobium to the percentage of silicon is higher than 4 to obtain a satisfactory effect on the resistance to hot cracking.
• the iron is fixed at a content of between 8% and 12% for good resistance to stress corrosion in a PWR medium.
• Nitrogen which is a residual element, is not necessary in the alloy.
• the nitrogen will be limited, in all cases, to a value of less than 0.040%.
• Tungsten is an element which is not desired in the alloy, this residual element being limited to 0.10% in any case to avoid undesirable modification of the properties of the welding metal.
• the alloy may contain small proportions of other residual elements; these elements may be, for example, tin, vanadium, lead, cadmium, magnesium, zinc, antimony, tellurium, calcium or cerium. These elements, which are in a very small quantity in the alloy, are in a total proportion with the other residual elements considered above (carbon, sulphur, phosphorus, copper, cobalt, nitrogen and tungsten) of less than 0.5% by weight.
• compositions of two welding alloys according to the invention are shown in Table 2 under columns 5 and 6 (example 1 and example 2).
• the molybdenum content is at the optimum value (4%).
• the aluminium content is in the region of the lower limit of the range of aluminium and the titanium content has a value close to the typical value of 0.30%.
• the silicon content of the alloy is low (0.025%) and is clearly below the preferred upper limit.
• the niobium content is only 0.80%, the niobium/silicon ratio is high and is approximately the same as in commercial alloys of the improved type shown in Table 1 (32). The value of this ratio is much higher than the lower limit imposed.
• the zirconium and boron contents lie towards the bottom of the claimed range.
• the molybdenum content is higher than the mean content considered as preferred (4%).
• the aluminium content which is substantially higher than in the case of example 1 is fixed above the typical value of 0.15% and the titanium content is lower than the typical value, the entirety of the aluminium and titanium representing a percentage by weight which is substantially identical in the case of example 1 and in the case of example 2.
• the boron content is higher than in the case of example 1 and corresponds to the preferred values.
• the silicon content is substantially higher than in the case of example 1.
• the niobium content is also slightly higher than in the case of example 1. Owing to the presence of a fairly large quantity of silicon, the niobium to silicon ratio is substantially lower in the case of example 1.
• Welding wires in the two grades corresponding to examples 1 and 2 were produced.
• the welding wires were used for diverse homogeneous or heterogeneous welding of nickel alloys containing 30% and 15% of chromium and stainless steels.
• the comparison alloy in column 5 (CF 52) has a silicon content comparable to that of example 1 according to the invention and a slightly higher niobium content, the niobium to silicon ratio being 50% higher than the niobium to silicon ratio of example 1.
• this alloy according to the prior art contains only a very small proportion of molybdenum (0.012%) whereas the alloys according to the invention contain more than 2% and generally 4% or more of molybdenum.
• the alloy CF 52 does not result in a resistance to cracking which is comparable to that of the alloys according to the invention.
• the silicon and niobium contents and the niobium to silicon ratio are similar to those of the alloy of example 1.
• the aluminium and the titanium are limited to values comparable to those of the examples according to the invention.
• the zirconium and boron contents of the comparison alloys are, moreover, similar to those of the alloys of examples 1 and 2 according to the invention respectively.
• a comparison of the examples according to the invention and the examples of alloys according to the prior art therefore shows that a welding alloy having a molybdenum content of approximately 4% or slightly higher, an adequate niobium content to obtain a niobium to silicon ratio substantially higher than 4 and moderate aluminium and titanium contents solves the welding problems of nickel alloys containing approximately 15% and 30% of chromium as well as stainless steels.
• the alloy according to the invention leads to electro-gas welding wires for the perfect homogeneous or heterogeneous welding of nickel alloys and stainless steels for the construction and repair of nuclear reactor components.
• the alloy according to the invention may be used not only in the form of electro-gas welding wires or rods but also in other forms, for example in the form of coated electrodes.
• the alloy is intended, in particular, for applications in the field of the construction and repair of nuclear reactors, its use in other industries may be considered.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Arc Welding In General (AREA)
• Nonmetallic Welding Materials (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Conductive Materials (AREA)

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• 2002
  • 2002-09-26 FR FR0211937A patent/FR2845098B1/fr not_active Expired - Fee Related
• 2003
  • 2003-03-12 US US10/385,837 patent/US20040062677A1/en not_active Abandoned
  • 2003-07-23 AT AT03291821T patent/ATE295904T1/de not_active IP Right Cessation
  • 2003-07-23 EP EP03291821A patent/EP1408130B1/fr not_active Expired - Lifetime
  • 2003-07-23 ES ES03291821T patent/ES2242931T3/es not_active Expired - Lifetime
  • 2003-07-23 DE DE60300676T patent/DE60300676T2/de not_active Expired - Lifetime
  • 2003-07-23 SI SI200330058T patent/SI1408130T1/xx unknown
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