Nickel alloy welding wire for ultra-supercritical boiler and preparation method of nickel alloy welding wire

Abstract

The invention belongs to the field of metal material processing, and particularly relates to a nickel alloy welding wire for an ultra-supercritical boiler and a preparation method thereof.The nickel alloy welding wire for the ultra-supercritical boiler comprises, by weight, 0.01%-0.05% of C, 0.10%-0.30% of Si, 20.0%-23.0% of Cr, 17.0%-19.0% of Fe, 1.0%-2.0% of Co, 0.50%-1.00% of W, 3.0%-6.0% of Mo, 0.005%-0.010% of B, 3.5%-5.5% of the total amount of Al and Ti, 0.005%-0.050% of Zr, 2.0%-2.5% of Nb, smaller than 0.005% of S, smaller than 0.005% of P, 4.0%-7.0% of nano ceramic materials and the balance Ni, the preparation method comprises the following steps: smelting, refining at high and low temperatures, annealing, forging, rolling, carrying out multi-pass drawing-annealing, carrying out solid solution-aging treatment, and finally, carrying out acid pickling, coating and plating. The problem that in the prior art, deposited metal formed after welding of nickel alloy welding wires for ultra-supercritical boilers has unstable grain boundary structures at the temperature of 700 DEG C or above, and consequently the high-temperature mechanical property is poor can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of metal materials, and in particular relates to a nickel alloy welding wire for an ultra-supercritical boiler and a preparation method thereof. Background Art

[0002] With the development of thermal power generation technology, the development of ultra-supercritical coal-fired power generation technology at 700℃ and above is of great significance and practical application value for my country to save energy, reduce pollutants and carbon dioxide emissions. Looking at the development plans of 700℃ A-USC at home and abroad, all countries have regarded the development of superheater and reheater materials, which are the key components with the highest operating temperature, as the main research direction of A-USC power plants. During the long-term operation of the 700℃ A-USC power plant boiler, the inner wall of the superheater and reheater tubes operates in a water vapor environment with a high temperature of 700℃ and a high pressure of 30-40MPa, while the outer wall of the tube is subjected to the radiation of the high temperature furnace fire of about 750-760℃, as well as flue gas and thermal corrosion, and the working environment is very harsh. Under advanced ultra-supercritical conditions, traditional ferrite, austenite heat-resistant steel and nickel-based alloys can no longer meet the requirements. Precipitation-strengthened nickel-based high-temperature alloys with higher endurance, good oxidation resistance, coal ash corrosion resistance and higher organizational stability are required to meet the requirements of superheater and reheater materials of advanced ultra-supercritical power generation units.

[0003] Since the welding joint (weld) is the weak link of the key high-temperature components of the power station, welding filler materials with a higher grade than the parent material are usually selected during welding to ensure welding performance. High-temperature alloy welding filler materials are widely used in the welding of high-temperature components of power stations (including dissimilar welding) due to their excellent high-temperature comprehensive performance. At present, the candidate nickel-based or nickel-iron-based high-temperature alloy welding rods (such as AWSENiCrFe 3, ENiCrFe 2, ENiCrCoMo 1 (mod.), ENiCrMo 3, etc.) for 700℃ ultra-supercritical thermal power units as welding filler materials cannot meet the requirements of 700℃ service conditions.

[0004] The traditional weld structure has no chance of controlled rolling and deformation heat treatment for the deposited metal, so it is impossible to refine the directional columnar (dendritic) crystals; at the same time, due to the fast cooling speed of the weld, the alloy elements are severely segregated, and Nb, V, etc. in the deposited metal are difficult to precipitate as fine carbides and nitrides during the solidification and cooling process. Therefore, the comprehensive mechanical properties of the weld are far inferior to those of the parent material, and there is anisotropy. With the extension of the service time of the welded joint, the mechanical properties (especially toughness) of the weld are significantly attenuated, and the service life is shortened; at the same time, due to the residual stress of welding, stress corrosion (SCC) is prone to occur, becoming the weak link of the entire (welded) component, affecting the safe operation of the power station. Summary of the invention

[0005] The purpose of the present invention is to provide a new type of nickel alloy welding wire for ultra-supercritical boilers and a preparation method thereof to solve the problem that the deposited metal formed after welding with nickel alloy welding wire for ultra-supercritical boilers in the prior art has unstable grain boundary structure at temperatures of 700°C and above, resulting in poor high-temperature mechanical properties; the new type of material can effectively solve the above problem, and the yield strength of the deposited metal at 700°C is above 550MPa. To achieve the above purpose, the technical solution adopted by the present invention to solve its technical problem is: The present invention provides a nickel alloy welding wire for an ultra-supercritical boiler, comprising the following powder raw materials in parts by weight: C: 0.01-0.05%, Si: 0.10-0.30%, Cr: 20.0-23.0%, Fe: 17.0-19.0%, Co: 1.0-2.0%, W: 0.50-1.00%, Mo: 3.0-6.0%, B: 0.005-0.010%, total amount of Al+Ti: 3.5-5.5%, Zr: 0.005-0.050%, Nb: 2.0-2.5%, S: <0.005%, P: <0.005%, nano-ceramic materials: 4.0-7.0%, Ni balance.

[0006] Furthermore, the weight ratio of Al to Ti is 1:(0.8-1.5).

[0007] Furthermore, the weight ratio of Al to Ti is 1:(1.0-1.5).

[0008] Furthermore, the nano-ceramic material is carbide, oxide or boride.

[0009] Further, the carbide is titanium carbide or silicon carbide; The oxide is zirconium oxide or aluminum oxide; and The boride is titanium boride.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S11: The raw materials are weighed according to the mass percentage of the formula, and a uniform and refined mixed powder is obtained after processing; S12: putting the mixed powder and nano-ceramic material in S1 into a smelting furnace for smelting, and after high-temperature refining and low-temperature refining, remelting and refining are performed to cast into alloy ingots; S13: After annealing the alloy ingot, forging and rolling are performed to prepare alloy wire rods; S14: performing multiple drawing-annealing steps on the alloy wire rod after pretreatment; S15: Processing the alloy wire into the required size and performing solution-aging treatment; S16: pickling the alloy wire; coating; and S17: Plating is performed on the surface to obtain a target product.

[0011] Furthermore, the solution-aging treatment in S5 is a multi-step graded treatment.

[0012] Another object of the present invention is to provide a welding method for the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S21: Preparation before welding, i.e. Prepare grooves at the interface of the parent material and remove impurities; S22: Welding, i.e. The ultra-supercritical boiler nickel alloy welding wire is welded on the base material by manual TIG welding or semi-automatic wire-filling tungsten inert gas TIG welding; S23: Post-weld treatment, i.e. After welding and when welding is interrupted, heat treatment is immediately carried out at 200-250℃ for 1-2h, and then the weld joint is heat treated at 1100-1150℃ for 0.5-1.0h, and then air-cooled to form weld deposited metal.

[0013] The present invention has the following beneficial effects: (1) The present invention provides a nickel alloy welding wire for ultra-supercritical boilers, with Ni as the matrix, Cr can improve the high-temperature oxidation resistance and corrosion resistance of the alloy; Co can improve the carbonization resistance, plasticity and hot working performance; Mo can refine the grains and improve the thermal stability of the alloy; W can improve the strength of the alloy. The addition of Cr, Co, Mo and W achieves a solid solution strengthening effect, improving its high-temperature oxidation resistance and thermal strength; at the same time, Cr, Co, Mo and W can generate carbides with C, and hard phases such as chromium carbide are dispersed in the solid solution strengthened matrix, improving high-temperature strength and plasticity; moreover, the improvement of high-temperature oxidation resistance and high-temperature strength can effectively inhibit welding pores caused by oxidation, and can effectively improve welding strength.

[0014] (2) The present invention provides a nickel alloy welding wire for ultra-supercritical boilers, in which a certain proportion of Mo, Fe and B are added. During the high-temperature remelting process, a reaction can occur to form Mo2FeB2 and Mo2NiB2 ternary boride hard phases, which have excellent mechanical properties such as corrosion resistance, hardness and wear resistance; in addition, B also has the function of improving the plasticity of the nickel alloy.

[0015] (3) The present invention provides a nickel alloy welding wire for ultra-supercritical boilers, in which a certain amount of Fe and Nb are added. First, Fe can improve the resistance to high-temperature carburizing environment and control thermal expansion; at the same time, it can reduce the material fundamental; and when combined with Nb, it can improve the plasticity and high-temperature strength of the alloy and reduce stress cracking; second, Nb is a high-temperature strengthening phase forming element, which can effectively improve the high-temperature strength and high-temperature stability of the alloy. The precipitation of its carbide at the grain boundary can make the grain boundary morphology more complex and curved, increase the grain boundary sliding resistance, and thus reduce the tendency of strain cracking; in addition, Nb has a good affinity with O and can generate a stable oxide Nb2O5, which has the effect of delaying corrosion.

[0016] (4) The present invention provides a nickel alloy welding wire for ultra-supercritical boilers, in which a certain amount of composite Al and Ti elements are added. On the one hand, Al and Ti can improve the weldability of the alloy. They have a strong affinity with oxygen and can be used as deoxidizing elements to protect the weld from oxidation, thereby effectively inhibiting the formation of CO and N2 pores, facilitating the formation of the weld, and having a certain strengthening and toughening effect on the alloy, which is beneficial to improving the high-temperature mechanical properties of the alloy.

[0017] (5) The present invention provides a nickel alloy welding wire for ultra-supercritical boilers, in which a certain amount of nano-ceramic material is added. First, it can improve the high-temperature oxidation resistance and wear resistance of the welding material; second, it can terminate the microcracks generated by stress and improve the mechanical properties.

[0018] (6) The present invention provides a method for preparing nickel alloy welding wire for ultra-supercritical boilers, which adopts a multi-step graded solid solution-aging treatment. On the one hand, the interfacial bonding force between the nano-ceramic material and the nickel alloy matrix is ​​improved, thereby improving the performance; on the other hand, the grain size can be refined, thereby further improving the mechanical properties.

[0019] (7) The present invention provides a welding method for nickel alloy welding wire for ultra-supercritical boilers. After welding, high-temperature heat treatment is used to cause crystal transformation in the solidified state of the weld zone, thereby eliminating weld component segregation and welding residual stress to the greatest extent and maintaining consistency with the parent material structure. DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the examples. However, it should be understood that the following examples are only illustrative of the embodiments of the present invention, and are not intended to limit the scope of the present invention.

[0021] The purpose of the present invention is to develop a nickel alloy welding wire for ultra-supercritical boilers to solve the problems existing in the existing nickel alloy welding wire for ultra-supercritical boilers. The idea of ​​implementation is: Ni is the main component, and high-temperature resistant elements such as Cr, Co, Mo, and W are added through formula design to achieve solid solution strengthening, improve oxidation resistance and thermal corrosion resistance; add elements such as B and Fe to improve hardness and plasticity; add Nb to improve the alloy's resistance to stress cracking and high-temperature plasticity; at the same time, precipitation strengthening elements such as Al and Ti are added to improve high-temperature strength, purify grain boundaries, and improve alloy structure stability; finally, nano-ceramic materials are compounded to improve mechanical properties. The above components are subjected to a grain refinement process to improve interphase compatibility and further improve performance; finally, a post-weld heat treatment process is used to promote crystal transformation and eliminate welding stress, so that high-performance weld deposited metal can be obtained. The embodiments of the present invention are as follows: An embodiment of the present invention provides a nickel alloy welding wire for an ultra-supercritical boiler, comprising the following powder raw materials in parts by weight: C: 0.01-0.05%, Si: 0.10-0.30%, Cr: 20.0-23.0%, Fe: 17.0-19.0%, Co: 1.0-2.0%, W: 0.50-1.00%, Mo: 3.0-6.0%, B: 0.005-0.010%, total amount of Al+Ti: 3.5-5.5%, Zr: 0.005-0.050%, Nb: 2.0-2.5%, S: <0.005%, P: <0.005%, nano-ceramic materials: 4.0-7.0%, Ni balance.

[0022] The weight ratio of Al to Ti is 1:(0.8-1.5).

[0023] And further preferably, the weight ratio of the above-mentioned Al to Ti is 1:(1.0-1.5).

[0024] Al and Ti can improve the weldability of the alloy, can be used as deoxidizing elements, are conducive to the formation of welds, and have a certain toughening effect on the alloy. Al is the main element that forms the γ'(Ni3Al) phase. 80% of the Al added to the alloy forms Ni3Al with Ni, which plays a precipitation strengthening role. 90% of Ti enters the γ' phase, and Ti can replace Al in the γ'(Ni3Al) phase to form Ni3(Al, Ti). Under the condition of a certain Al content, the increase in Ti content and the increase in Ti / Al will increase the trend of the γ' phase to the η phase, and the amount of η phase precipitation will also increase. In addition, when Ti / Al is too high, the γ' phase is also easy to grow. Therefore, the Ti / Al should be reasonably controlled under the premise of ensuring the amount of γ' phase precipitation, which can greatly improve the structural stability of the alloy. Comprehensive considerations are controlled to the total amount of Al+Ti: 3.5-5.5%; and the weight ratio of Al to Ti is 1: (0.8-1.5), and is further preferably 1: (1.0-1.5).

[0025] The nano ceramic material is carbide, oxide or boride.

[0026] The carbide is titanium carbide or silicon carbide; The above oxide is zirconium oxide or aluminum oxide; and The above boride is titanium boride.

[0027] The above-mentioned nano-ceramic materials can form a dispersion strengthening phase, hinder dislocation movement or refine grains to improve the high-temperature yield strength, toughness, crack resistance and other mechanical properties of nickel alloy materials.

[0028] In addition, other important components and functions in the embodiments of the present invention are as follows: Cr is the main element to ensure the high temperature oxidation resistance of the alloy of the present invention, and is the most important element to stabilize the alloy surface. It forms a dense Cr2O3 protective layer on the surface of the base material that is resistant to oxidation and corrosion, and can prevent high temperature oxidation and hot corrosion. Generally, when the Cr content exceeds 12%, it will have better high temperature oxidation resistance. When it exceeds 33%, the increase in Cr content has little effect on improving the high temperature oxidation resistance, and will precipitate α Cr phase that is not conducive to mechanical properties. Therefore, the present invention controls the Cr content to 20.0-23.0%.

[0029] The addition of Co element achieves solid solution strengthening effect, improves its high temperature oxidation resistance and thermal strength. A slightly excessive amount of Co can generate carbides with C, which are dispersed in the solid solution strengthened matrix, improving high temperature strength and plasticity. Therefore, the present invention controls the Co content to 1.0-2.0%.

[0030] The Mo element can improve the high temperature strength and corrosion resistance of the alloy, especially in the case of compounding with chromium, the pitting corrosion resistance is more excellent; at the same time, Mo can enhance the creep resistance of the alloy through solid solution strengthening and reduce the grain boundary weakening caused by radiation. The addition of Mo can significantly improve the corrosion resistance and high temperature strength of the welding wire. Therefore, the present invention controls the Mo content to 3.0-6.0%.

[0031] Fe is a matrix element of Ni Cr Fe alloy, which can improve the strength of weld by solid solution strengthening. Therefore, the Fe content is controlled within 17.0-19.0% in the present invention. In addition, under the condition of controlling the performance, adding more Fe is beneficial to reducing the cost of welding wire.

[0032] Nb is a strengthening element in high temperature environment, which can increase the solid solution lattice distortion and lattice atomic bond attraction, strengthen the matrix, and has a significant solid solution strengthening effect; at the same time, it is also a strong carbide forming element, which can form MC, M6C or M2C type carbides, which plays a significant second phase strengthening role on the weld metal, improves the high temperature strength and plasticity combination, and improves the high temperature durability of the nickel alloy of the present invention; in addition, it can also reduce the segregation of alloy elements and improve the plasticity of the weld metal. Therefore, the present invention controls the Nb content to 2.0-2.5%.

[0033] The addition of trace amounts of Zr and B elements strengthens the grain boundaries and improves the long-lasting strength of the weld deposited metal, and trace additions will not increase the sensitivity of welding hot cracks.

[0034] The embodiment of the present invention also provides a method for preparing the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S11: The raw materials are weighed according to the mass percentage of the formula, and a uniform and refined mixed powder is obtained after processing.

[0035] The above treatment process and the treatment process described in the following embodiments of the present invention are: adding raw material powders except nano-ceramic materials to ethanol, stirring at 1000r / min magnetic force for 3h, placing it in 50KHz ultrasonic treatment for 2h to obtain an ethanol suspension; filtering, taking insoluble matter, placing it in an 80°C drying oven for drying for 2h, placing the insoluble matter in a ball mill, adding long-chain fatty acids, and placing the ball mill on a high-energy ball mill for ball milling to obtain a uniform and refined mixed powder; wherein the grinding ball material is corundum ball, the ball-to-material mass ratio is 6:1, the ball milling process is 7h, and the ball mill speed is 150 200r / min; The ratio of the above long-chain fatty acid to the total mass of the raw material powder is 2g:100g; The above-mentioned long-chain fatty acid is myristic acid.

[0036] S12: The mixed powder and nano-ceramic material in S11 are placed in a smelting furnace for smelting, and after high-temperature refining and low-temperature refining, remelting and refining are performed, and then cast into alloy ingots.

[0037] The above high temperature refining is smelting at 1750-1850°C for 30-45 minutes; The above-mentioned low temperature refining is smelting at 1650-1700°C for 15-25 minutes; The above remelting is electroslag remelting, and the furnace temperature is 1750-1850°C.

[0038] S13: After annealing, the alloy ingot is forged and rolled to prepare an alloy wire rod.

[0039] The above annealing process is heating to 1000-1050°C and keeping the temperature for 20-35h; The forging process is as follows: at 950°C, the billet is forged into alloy billet I with a forging ratio of 3-4; after tempering at 950-1000°C for 1-2 hours, the billet is forged into alloy billet II at 1050°C with a forging ratio of 6-7; and then the billet is forged into alloy billet III at the same temperature with a forging ratio of 3-4; The above rolling process is to keep the temperature at 1000-1050°C for 0.5-1.5h and hot-roll the alloy wire rod at 950-1100°C into Φ4.05.0mm.

[0040] S14: After pre-treatment, the alloy wire rod is subjected to multiple drawing-annealing steps.

[0041] The above-mentioned pretreatment is to heat the alloy wire rod to 950°C and keep it at that temperature for 1.5 hours, oil cool it for softening treatment, alkali boil it, then high-pressure water wash it, then pickle it after water washing, and then ultrasonic wash it; In the above-mentioned drawing, a lubricant is added before drawing, and the alloy wire is obtained by multiple drawing processes; The above annealing is vacuum annealing after 6-10 drawing passes, and the annealing temperature is 640-800°C.

[0042] S15: Processing into alloy wire of required size and performing solution-aging treatment.

[0043] The solid solution-aging treatment in S5 is a multi-step graded treatment; specifically, in a nitrogen environment, heating to 950-1050°C, keeping warm for 2-3h, continuing to heat to 1050-1100°C, keeping warm for 2-3h, continuing to heat to 1100-1150°C, keeping warm for 1-2h, continuing to heat to 1150-1170°C, keeping warm for 1-2h, and rapidly quenching in water to obtain a solid solution alloy; the above-mentioned aging is heating to 800-850°C, keeping warm for 3-8h, air cooling, and then heating to 750-770°C, keeping warm for 10-15h, and air cooling.

[0044] S16: pickling the alloy wire; coating; and The pickling described above and in the following embodiments of the present invention are all to pickle the alloy wire after the solution heat treatment, first pickle it with a mixed pickling solution containing 100 g / L nitric acid and 20 g / L hydrofluoric acid, control the temperature to be ≤50°C, and the pickling time to be 10 min; finally, clean the residual acid on the surface; The above coating and the coating described in the following embodiments of the present invention are all obtained by coating a layer of water-soluble coating agent on the surface of the alloy wire after pickling, and the coated alloy wire is naturally air-dried.

[0045] S17: Plating is performed on the surface to obtain a target product.

[0046] The above surface coating process and the surface coating process described in the following embodiments of the present invention are all as follows: Pretreatment: The surface of the high-temperature nickel-based alloy welding wire was cleaned, sanded with sandpaper, and then polished, and then cleaned in a mixed solution of sodium hydroxide (20 g / L), trisodium phosphate (30 g / L), and sodium silicate (30 g / L) at 50°C for 10 min. Finally, electrolytic polishing was performed in a mixed acid of 80% acetic acid and 20% perchloric acid, with an electrolytic voltage of 27 V and a power supply of 7 s to obtain welding wire I; Nickel plating: prepare a Watt-type electrolyte, the plating solution includes nickel sulfate hexahydrate, nickel chloride hexahydrate, and boric acid, electroplate a nickel layer on the surface of welding wire I to obtain welding wire II, and the electroplating process parameters are a current density of 3A / dm 2 , electroplating time 10min, electroplating temperature 45℃, stirring speed 300r / min; TiC plating: prepare TiC electroplating solution, which includes TiC 30g / L, NiSO4 400g / L, NiCl2 45g / L, H3BO 350g / L by mass volume ratio, and the balance is water; the particle size of TiC is 3-10μm, and a TiC coating is electroplated on the nickel layer of welding wire II to obtain welding wire III. The electroplating process parameters are current density 3A / dm 2 , electroplating time 0.5h, electroplating temperature 45℃, stirring speed 300r / min; Nickel plating: prepare a Watt-type electrolyte, which includes 400g / L NiSO4, 45g / L NiCl2, 50g / L H3BO3, and the balance is water. Electroplating a nickel layer on the TiC coating of welding wire III to obtain a nuclear power high-temperature nickel-based alloy composite welding wire. The electroplating process parameters are a current density of 3A / dm 2 , electroplating time 10min, electroplating temperature 45℃, stirring speed 300r / min.

[0047] The embodiment of the present invention further provides a welding method for the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S21: Preparation before welding, i.e. Prepare grooves at the interface of the parent material, clean the grooves and both sides of the inner and outer walls, and remove water, oil and impurities; The above-mentioned parent materials and the parent materials in the following embodiments of the present invention are all GH2984 nickel-iron based alloy.

[0048] S22: Welding, i.e. The ultra-supercritical boiler nickel alloy welding wire is welded on the base material by manual TIG welding or semi-automatic wire-filling tungsten inert gas TIG welding; Welding current intensity: 105-170A; welding arc voltage: 11-15V; welding speed: 100-140mm / min; current type / polarity: DC / SP; interlayer temperature not higher than 100℃; shielding gas: Ar, gas flow rate 12-16L / min.

[0049] S23: Post-weld treatment, i.e. After welding and when welding is interrupted, heat treatment is immediately carried out at 200-250℃ for 1-2h, and then the weld joint is heat treated at 1100-1150℃ for 0.5-1.0h, and then air-cooled to form weld deposited metal.

[0050] In order to further understand the present invention, the nickel alloy welding wire for ultra-supercritical boiler provided by the present invention is described in detail below in conjunction with specific embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0051] Example 1 This embodiment provides a nickel alloy welding wire for an ultra-supercritical boiler, comprising the following powder raw materials in parts by weight: C: 0.03%, Si: 0.20%, Cr: 21.5%, Fe: 18.0%, Co: 1.5%, W: 0.70%, Mo: 4.5%, B: 0.008%, total amount of Al+Ti: 4.5%, Zr: 0.030%, Nb: 2.35%, S: 0.002%, P: 0.002%, nano-ceramic material: 5.5%, Ni balance.

[0052] The weight ratio of Al to Ti is 1:1.2.

[0053] The above-mentioned nano ceramic material is carbide.

[0054] The above carbide is titanium carbide.

[0055] This embodiment also provides a method for preparing the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S1: The raw materials are weighed according to the mass percentage of the formula and processed to obtain a uniform and refined mixed powder.

[0056] S2: The mixed powder and nano-ceramic material in S1 are placed in a smelting furnace for smelting, and after high-temperature refining and low-temperature refining, they are remelted and cast into alloy ingots.

[0057] The above high temperature refining is smelting at 1800°C for 35 minutes; The above low temperature refining is smelting at 1680°C for 20 minutes; The above remelting is electroslag remelting, and the furnace temperature is 1780°C.

[0058] S3: After annealing the alloy ingot, forging and rolling are performed to prepare alloy wire rods.

[0059] The above annealing process is heating to 1020°C and keeping it at this temperature for 25h; The forging process is as follows: at 950°C, the billet is forged into alloy billet I with a forging ratio of 3.5; after tempering at 970°C for 1.4h, the billet is forged into alloy billet II at 1050°C with a forging ratio of 6.5; and then the billet is forged into alloy billet III at the same temperature with a forging ratio of 3.5; The above rolling process is to keep the temperature at 1020°C for 1 hour and hot-roll the alloy wire rod at 1000°C into Φ4.5mm.

[0060] S4: After pre-treatment, the alloy wire rod is subjected to multiple drawing-annealing steps.

[0061] The above-mentioned pretreatment is to heat the alloy wire rod to 950°C and keep it at that temperature for 1.5 hours, oil cool it for softening treatment, alkali boil it, then high-pressure water wash it, then pickle it after water washing, and then ultrasonic wash it; In the above-mentioned drawing, a lubricant is added before drawing, and the alloy wire is obtained by multiple drawing processes; The above annealing is vacuum annealing after 8 drawing passes, and the annealing temperature is 720°C.

[0062] S5: Processing the alloy wire into the required size and performing solution-aging treatment.

[0063] The solution-aging treatment in S5 is a multi-step graded treatment; specifically, in a nitrogen environment, heating to 1000°C, keeping warm for 2.3 hours, continuing to heat to 1080°C, keeping warm for 2.5 hours, continuing to heat to 1120°C, keeping warm for 1.5 hours, continuing to heat to 1155°C, keeping warm for 1.5 hours, and rapid water quenching to obtain a solid solution alloy; the above-mentioned aging is heating to 820°C, keeping warm for 5 hours, air cooling, and then heating to 760°C, keeping warm for 12 hours, and air cooling.

[0064] S6: pickling the alloy wire; coating; and S7: Plating is performed on the surface to obtain a target product.

[0065] This embodiment further provides a welding method for the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S21: Preparation before welding, i.e. Prepare a groove at the interface of the parent material, and clean the groove and both sides of the inner and outer walls to remove water, oil and impurities.

[0066] S22: Welding, i.e. The ultra-supercritical boiler nickel alloy welding wire is welded to the base material by manual TIG welding; Welding current intensity: 140A; welding arc voltage: 13V; welding speed: 120mm / min; current type / polarity: DC / positive connection SP; interlayer temperature not higher than 100℃; shielding gas: Ar, gas flow rate 13L / min.

[0067] S23: Post-weld treatment, i.e. After welding and when welding is interrupted, heat treatment is immediately performed at 220°C for 1.5 hours, and then the weld joint is heat treated at 1100°C for 1.0 hour and air-cooled to form weld deposited metal.

[0068] Example 2 This embodiment provides a nickel alloy welding wire for an ultra-supercritical boiler, comprising the following powder raw materials in parts by weight: C: 0.01%, Si: 0.30%, Cr: 20.0%, Fe: 17.0%, Co: 2.0%, W: 0.50%, Mo: 6.0%, B: 0.01%, total amount of Al+Ti: 5.5%, Zr: 0.005%, Nb: 2.0%, S: 0.002%, P: 0.002%, nano-ceramic material: 7.0%, Ni balance.

[0069] The weight ratio of Al to Ti is 1:1.2.

[0070] The above-mentioned nano ceramic material is carbide.

[0071] The above carbide is titanium carbide.

[0072] This embodiment also provides a method for preparing the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S1: The raw materials are weighed according to the mass percentage of the formula and processed to obtain a uniform and refined mixed powder.

[0073] S2: The mixed powder and nano-ceramic material in S1 are placed in a smelting furnace for smelting, and after high-temperature refining and low-temperature refining, they are remelted and cast into alloy ingots.

[0074] The above high temperature refining is smelting at 1750°C for 45 minutes; The above low temperature refining is smelting at 1650°C for 25 minutes; The above remelting is electroslag remelting, and the furnace temperature is 1750°C.

[0075] S3: After annealing the alloy ingot, forging and rolling are performed to prepare alloy wire rods.

[0076] The above annealing process is heating to 1000°C and keeping the temperature for 35h; The forging process is as follows: at 950°C, the billet is forged into alloy billet I with a forging ratio of 3; after tempering at 950°C for 2 hours, the billet is forged into alloy billet II at 1050°C with a forging ratio of 7; and then the billet is forged into alloy billet III at the same temperature with a forging ratio of 4; The above rolling process is to keep the temperature at 1000°C for 1.5 hours and hot-roll the alloy wire rod at 950°C into Φ4.0mm.

[0077] S4: After pre-treatment, the alloy wire rod is subjected to multiple drawing-annealing steps.

[0078] The above-mentioned pretreatment is to heat the alloy wire rod to 950°C and keep it at that temperature for 1.5 hours, oil cool it for softening treatment, alkali boil it, then high-pressure water wash it, then pickle it after water washing, and then ultrasonic wash it; In the above-mentioned drawing, a lubricant is added before drawing, and the alloy wire is obtained by multiple drawing processes; The above annealing is vacuum annealing after 10 drawing passes, and the annealing temperature is 640°C.

[0079] S5: Processing the alloy wire into the required size and performing solution-aging treatment.

[0080] The solution-aging treatment in S5 is a multi-step graded treatment; specifically, in a nitrogen environment, heating to 1050°C, keeping warm for 2 hours, continuing to heat to 1100°C, keeping warm for 2 hours, continuing to heat to 1150°C, keeping warm for 1 hour, continuing to heat to 1170°C, keeping warm for 1 hour, and rapid water quenching to obtain a solid solution alloy; the above-mentioned aging is heating to 850°C, keeping warm for 3 hours, air cooling, then heating to 770°C, keeping warm for 10 hours, and air cooling.

[0081] S6: pickling the alloy wire; coating; and S7: Plating is performed on the surface to obtain a target product.

[0082] This embodiment further provides a welding method for the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S21: Preparation before welding, i.e. Prepare a groove at the interface of the parent material, and clean the groove and both sides of the inner and outer walls to remove water, oil and impurities.

[0083] S22: Welding, i.e. The ultra-supercritical boiler nickel alloy welding wire is welded to the base material by manual TIG welding; Welding current intensity: 170A; welding arc voltage: 15V; welding speed: 140mm / min; current type / polarity: DC / SP; interlayer temperature not higher than 100℃; shielding gas: Ar, gas flow rate 16L / min.

[0084] S23: Post-weld treatment, i.e. After welding and when welding is interrupted, heat treatment is immediately performed at 250°C for 1.0h, and then the weld joint is heat treated at 1150°C for 0.5h and air-cooled to form weld deposited metal.

[0085] Example 3 This embodiment provides a nickel alloy welding wire for an ultra-supercritical boiler, comprising the following powder raw materials in parts by weight: C: 0.05%, Si: 0.10%, Cr: 23.0%, Fe: 19.0%, Co: 1.0%, W: 1.0%, Mo: 3.0%, B: 0.005%, total amount of Al+Ti: 3.5%, Zr: 0.05%, Nb: 2.5%, S: 0.002%, P: 0.002%, nano-ceramic material: 4.0%, Ni balance.

[0086] The weight ratio of Al to Ti is 1:1.2.

[0087] The above-mentioned nano ceramic material is carbide.

[0088] The above carbide is titanium carbide.

[0089] This embodiment also provides a method for preparing the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S1: The raw materials are weighed according to the mass percentage of the formula and processed to obtain a uniform and refined mixed powder.

[0090] S2: The mixed powder and nano-ceramic material in S1 are placed in a smelting furnace for smelting, and after high-temperature refining and low-temperature refining, they are remelted and cast into alloy ingots.

[0091] The above high temperature refining is smelting at 1850°C for 30 minutes; The above low temperature refining is smelting at 1700°C for 15 minutes; The above remelting is electroslag remelting, and the furnace temperature is 1850°C.

[0092] S3: After annealing the alloy ingot, forging and rolling are performed to prepare alloy wire rods.

[0093] The above annealing process is heating to 1050°C and keeping it warm for 20 hours; The forging process is as follows: at 950°C, the billet is forged into alloy billet I with a forging ratio of 4; after tempering at 1000°C for 1 hour, it is forged into alloy billet II at 1050°C with a forging ratio of 6; and then forged into alloy billet III at the same temperature with a forging ratio of 3; The above rolling process is to keep the temperature at 1050°C for 0.5h and hot-roll the alloy wire rod at 1100°C into Φ5.0mm.

[0094] S4: After pre-treatment, the alloy wire rod is subjected to multiple drawing-annealing steps.

[0095] The above-mentioned pretreatment is to heat the alloy wire rod to 950°C and keep it at that temperature for 1.5 hours, oil cool it for softening treatment, alkali boil it, then high-pressure water wash it, then pickle it after water washing, and then ultrasonic wash it; In the above-mentioned drawing, a lubricant is added before drawing, and the alloy wire is obtained by multiple drawing processes; The above annealing is vacuum annealing after 6 drawing passes, and the annealing temperature is 800°C.

[0096] S5: Processing the alloy wire into the required size and performing solution-aging treatment.

[0097] The solution-aging treatment in S5 is a multi-step graded treatment; specifically, in a nitrogen environment, heating to 950°C, keeping warm for 3 hours, continuing to heat to 1050°C, keeping warm for 3 hours, continuing to heat to 1100°C, keeping warm for 2 hours, continuing to heat to 1150°C, keeping warm for 2 hours, and rapid water quenching to obtain a solid solution alloy; the above-mentioned aging is heating to 800°C, keeping warm for 8 hours, air cooling, then heating to 750°C, keeping warm for 15 hours, and air cooling.

[0098] S6: pickling the alloy wire; coating; and S7: Plating is performed on the surface to obtain a target product.

[0099] This embodiment further provides a welding method for the above-mentioned nickel alloy welding wire for ultra-supercritical boiler, comprising the following steps: S21: Preparation before welding, i.e. Prepare a groove at the interface of the parent material, and clean the groove and both sides of the inner and outer walls to remove water, oil and impurities.

[0100] S22: Welding, i.e. The nickel alloy welding wire for ultra-supercritical boiler is welded on the base material by using semi-automatic tungsten inert gas (TIG) welding; Welding current intensity: 105A; welding arc voltage: 11V; welding speed: 100mm / min; current type / polarity: DC / SP; interlayer temperature not higher than 100℃; shielding gas: Ar, gas flow rate 12L / min.

[0101] S23: Post-weld treatment, i.e. After welding and when welding is interrupted, heat treatment is immediately performed at 200°C for 2.0h, and then the weld joint is heat treated at 1100°C for 1.0h and air-cooled to form weld deposited metal.

[0102] Example 4 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably, the weight ratio of Al to Ti is 1:1.0.

[0103] Example 5 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably, the weight ratio of Al to Ti is 1:1.5.

[0104] Example 6 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably, the weight ratio of Al to Ti is 1:0.8.

[0105] Example 7 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably the nano-ceramic material is an oxide.

[0106] The above oxide is zirconium oxide.

[0107] Example 8 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably the nano-ceramic material is an oxide.

[0108] The above oxide is aluminum oxide.

[0109] Example 9 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably the nano-ceramic material is carbide.

[0110] The above carbide is silicon carbide.

[0111] Example 10 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, Preferably the nano-ceramic material is a boride.

[0112] The above boride is titanium boride.

[0113] The following comparative examples are compared with Example 1: Comparative Example 1 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, The weight ratio of Al to Ti is 1:0.5.

[0114] Comparative Example 2 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, The weight ratio of Al to Ti is 1:2.0.

[0115] Comparative Example 3 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, The weight fraction of Nb is 0; that is, no Nb is added.

[0116] Comparative Example 4 The rest is the same as in Example 1, except that: In a nickel alloy welding wire formula for ultra-supercritical boilers, The weight fraction of the nano-ceramic material is 0; that is, no nano-ceramic material is added.

[0117] Comparative Example 5 The rest is the same as in Example 1, except that: In a method for preparing a nickel alloy welding wire for an ultra-supercritical boiler, The S15 process was not performed, that is, no solution-aging treatment was performed.

[0118] Comparative Example 6 The rest is the same as in Example 1, except that: In a method for preparing a nickel alloy welding wire for an ultra-supercritical boiler, in S15, The solid solution is heated to 1000°C in a nitrogen environment, kept warm for 2.3 hours, continued to heat to 1155°C, kept warm for 1.5 hours, and quickly water quenched to obtain a solid solution alloy; the aging is heated to 760°C, kept warm for 12 hours, and air cooled.

[0119] Comparative Example 7 The rest is the same as in Example 1, except that: A welding method for a nickel alloy welding wire for an ultra-supercritical boiler, wherein S23: The post-weld heat treatment parameters are heat treatment at 750°C for 8.0 hours, followed by air cooling to form weld deposited metal.

[0120] The physical properties of the nickel alloy welding wire for ultra-supercritical boiler prepared in the embodiment of the present invention and the comparative example were measured respectively, and the results are shown in Table 1.

[0121] Table 1 Physical test performance of each embodiment It can be observed from Examples 1-10 that the nickel alloy welding wire for ultra-supercritical boilers of the present invention has excellent mechanical properties, corrosion resistance, hardness, and also has excellent surface properties.

[0122] It can be observed from Example 1 and Comparative Examples 1-4 that the nickel alloy welding wire for ultra-supercritical boilers of the present invention contains appropriate amounts of Al and Ti, and the appropriate ratio has a certain strengthening and toughening effect on the alloy; Nb has the ability to reduce the tendency of strain cracking, and can improve the high temperature strength, creep resistance, corrosion resistance and other properties of the alloy; the nano-ceramic material has good mechanical strength, etc.; It can be observed from Example 1 and Comparative Examples 5-6 that the solution-aging process and the multi-step solution-aging process are beneficial to grain refinement and enhance the interphase compatibility of materials such as ceramic materials, thereby further improving the performance; that is, the appropriate preparation process has a positive effect on the performance of the nickel-based alloy welding material; It can be observed from Example 1 and Comparative Example 7 that a suitable post-weld heat treatment process is beneficial to the transformation of solidified columnar crystals and dendrites in the weld zone into equiaxed crystals, and eliminates weld component segregation and welding residual stress to the greatest extent; and can positively improve mechanical properties; In summary, the nickel alloy welding wire for ultra-supercritical boilers of the present invention has excellent mechanical properties, corrosion resistance, etc., and can meet the use requirements of 700°C ultra-supercritical boilers.

[0123] The test method is as follows: (1) Crack resistance: Observe whether there are visible cracks on the welding strip, and if the specimen is intact after bending or the length of a single crack is ≤1.5mm, it is recorded as "OK". On the contrary, if there are visible cracks and the length of a single crack after bending is greater than 1.5mm, it is recorded as "NG".

[0124] (2) Hardness. Measured using a microhardness tester (HXS 1000A) with a load of 30 kgf and a loading time of 15 seconds. Each sample was tested at 5 points and the arithmetic mean was taken to obtain the hardness value (HV30).

[0125] (3) Mechanical properties test: According to GB / T2651-2008 “Tensile test method for welded joints”, the room temperature mechanical properties and high temperature mechanical properties tests of welded joints were carried out at room temperature and 700°C respectively.

[0126] (4) Corrosion rate: The corrosion resistance test was carried out using ASTM G28 A method, and the test time was 120 hours.

[0127] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A nickel alloy welding wire for ultra-supercritical boiler, characterized in that: The powder raw materials include the following parts by weight: C: 0.01-0.05%, Si: 0.10-0.30%, Cr: 20.0-23.0%, Fe: 17.0-19.0%, Co: 1.0-2.0%, W: 0.50-1.00%, Mo: 3.0-6.0%, B: 0.005-0.010%, total amount of Al+Ti: 3.5-5.5%, Zr: 0.005-0.050%, Nb: 2.0-2.5%, S: <0.005%, P: <0.005%, nano-ceramic materials: 4.0-7.0%, Ni balance.

2. The nickel alloy welding wire for ultra-supercritical boiler according to claim 1, characterized in that: The weight ratio of Al to Ti is 1:(0.8-1.5).

3. A nickel alloy welding wire for ultra-supercritical boiler according to claim 1 or 2, characterized in that: The weight ratio of Al to Ti is 1:(1.0-1.5).

4. The nickel alloy welding wire for ultra-supercritical boiler according to claim 1, characterized in that: The nano ceramic material is carbide, oxide or boride.

5. The nickel alloy welding wire for ultra-supercritical boiler according to claim 4, characterized in that: The carbide is titanium carbide or silicon carbide; The oxide is zirconium oxide or aluminum oxide; and The boride is titanium boride.

6. A method for preparing a nickel alloy welding wire for an ultra-supercritical boiler as claimed in claim 1, characterized in that: The following steps are involved: S11: The raw materials are weighed according to the mass percentage of the formula, and a uniform and refined mixed powder is obtained after processing; S12: putting the mixed powder and nano-ceramic material in S1 into a smelting furnace for smelting, and after high-temperature refining and low-temperature refining, remelting and refining are performed to cast into alloy ingots; S13: After annealing the alloy ingot, forging and rolling are performed to prepare alloy wire rods; S14: performing multiple drawing-annealing steps on the alloy wire rod after pretreatment; S15: Processing the alloy wire into the required size and performing solution-aging treatment; S16: pickling the alloy wire; coating; and S17: Plating is performed on the surface to obtain a target product.

7. The method for preparing a nickel alloy welding wire for an ultra-supercritical boiler according to claim 6, characterized in that: The solution-aging treatment in S5 is a multi-step graded treatment.

8. A welding method for a nickel alloy welding wire for an ultra-supercritical boiler as claimed in claim 1, characterized in that: The following steps are involved: S21: Preparation before welding, i.e. Prepare grooves at the interface of the parent material and remove impurities; S22: Welding, i.e. The ultra-supercritical boiler nickel alloy welding wire is welded on the base material by manual TIG welding or semi-automatic wire-filling tungsten inert gas TIG welding; S23: Post-weld treatment, i.e. After welding and when welding is interrupted, heat treatment is immediately carried out at 200-250℃ for 1-2h, and then the weld joint is heat treated at 1100-1150℃ for 0.5-1.0h, and then air-cooled to form weld deposited metal.

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