CN112813375A - Rare earth nickel-based self-fluxing alloy for boiler four-tube high-frequency induction remelting process and application method thereof - Google Patents
Rare earth nickel-based self-fluxing alloy for boiler four-tube high-frequency induction remelting process and application method thereof Download PDFInfo
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- CN112813375A CN112813375A CN202110006647.5A CN202110006647A CN112813375A CN 112813375 A CN112813375 A CN 112813375A CN 202110006647 A CN202110006647 A CN 202110006647A CN 112813375 A CN112813375 A CN 112813375A
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims abstract description 142
- 239000000956 alloy Substances 0.000 title claims abstract description 76
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 74
- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 74
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 73
- 229910052759 nickel Inorganic materials 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 44
- 230000006698 induction Effects 0.000 title claims abstract description 32
- 230000008569 process Effects 0.000 title claims abstract description 24
- 238000000576 coating method Methods 0.000 claims abstract description 72
- 239000011248 coating agent Substances 0.000 claims abstract description 71
- 238000005452 bending Methods 0.000 claims abstract description 28
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 21
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 239000000843 powder Substances 0.000 claims description 14
- 238000005488 sandblasting Methods 0.000 claims description 12
- 238000003466 welding Methods 0.000 claims description 11
- 238000010285 flame spraying Methods 0.000 claims description 10
- 238000005507 spraying Methods 0.000 claims description 10
- 238000005498 polishing Methods 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 238000011156 evaluation Methods 0.000 claims description 6
- 239000002893 slag Substances 0.000 claims description 6
- QFXZANXYUCUTQH-UHFFFAOYSA-N ethynol Chemical group OC#C QFXZANXYUCUTQH-UHFFFAOYSA-N 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 4
- 239000011247 coating layer Substances 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 230000002035 prolonged effect Effects 0.000 abstract description 2
- 238000012360 testing method Methods 0.000 description 16
- 230000007797 corrosion Effects 0.000 description 11
- 238000005260 corrosion Methods 0.000 description 11
- 239000010410 layer Substances 0.000 description 10
- 239000013078 crystal Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000005336 cracking Methods 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 230000003628 erosive effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000004071 soot Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
- C23C4/06—Metallic material
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
- C23C4/129—Flame spraying
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
- C23C4/14—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying for coating elongate material
- C23C4/16—Wires; Tubes
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/18—After-treatment
Abstract
The invention discloses a rare earth nickel-based self-fluxing alloy used in a high-frequency induction remelting process for four pipes of a boiler, which is sprayed on the surface of a pipe fitting to be bent to prevent cracks during bending, and consists of 7-10 wt% of rare earth yttrium and 90-93 wt% of nickel-based self-fluxing alloy; according to the invention, the toughness of the coating is improved by adding a proper amount of rare earth yttrium into the nickel-based self-fluxing alloy material, so that the problem that the coating on the heating surface of the pipe fitting is easy to crack during bending is solved, and the service life of the pipe fitting is prolonged.
Description
Technical Field
The invention belongs to the technical field of alloy coatings, and particularly relates to a rare earth nickel-based self-fluxing alloy in a four-tube high-frequency induction remelting process of a boiler and an application method thereof.
Background
Industrial boilers are important thermal power equipment and are widely used in various chemical systems. The industrial four-tube boiler (boiler water wall, superheater, reheater and economizer) covers all heated surfaces of the boiler, and is subject to severe three-phase flow abrasion and erosion such as boiler load change, complex high-temperature flue gas environment, molten contamination and slagging infiltration, ash particles, steam soot blowing and the like, so that the pollution and corrosion of the metal surface of the inner wall, especially the heated surface are easily caused, and the service life of the boiler is influenced; taking a boiler water-cooled wall of a garbage power station as an example, under a severe working environment, the service average life is only 1-3 years, and a plurality of water-cooled wall heating surfaces begin to corrode, thin and even explode tubes after being used for more than half a year. In recent years, although various coating protection technologies are developed successively, the service life is improved, but the service life is still unsatisfactory, and the phenomenon that the wall thickness is reduced until the pipe is burst due to high-temperature corrosion occurs.
In 2017, Jiangsu Kehuan company firstly adopts a composite method of flame spraying nickel-based self-fluxing alloy and high-frequency induction remelting to prepare a coating on the surface of a heating surface of four tubes of a boiler domestically, and the coating has a good application effect in a high-temperature (>600 ℃) corrosion environment of the boiler for years. The nickel-based self-fluxing alloy coating has excellent high-temperature corrosion resistance, the performance and service life of the coating are not lower than those of the common surfacing welding applied in China, the preparation cost is far lower than that of the surfacing welding, and the development direction of the high-temperature corrosion-resistant coating on the surface of the four-tube heating surface of the boiler is represented.
However, when the four tubes of the boiler are installed in the boiler as the inner wall, due to the structural characteristics of the interior of the boiler and the limitation of local space, the four tubes need to be bent at multiple positions in the boiler to form various angles (more than right angles), but due to the structural limitation of the high-frequency induction remelting coil, the remelting difficulty after bending the tubes is large; remelting is carried out by adopting a flame spraying method after bending the pipe, but manual operation is basically adopted, and the remelting quality stability is poor; therefore, at present, most of the methods are to bend the surface of the straight pipe after preparing a coating by high-frequency induction, and the bending is realized by applying external force on the pipe bender. Cracks are highly likely to occur at the corners because the coating is more deformed during bending.
Aiming at the problems, the conventional more disposal method is to fill up the cracks by overlaying welding bars, but the local repair and the surrounding coating are jointed in a non-smooth transition manner, namely, the two materials are spliced, micro cracks are easily formed on two sides of the welding line after the welding line is in service for a period of time to form hidden damage, and the micro cracks rapidly expand into macro cracks under the comprehensive actions of thermal shock, soot erosion, high-temperature corrosion and the like, so that leakage is caused. And other methods such as properly adjusting the element proportion in the original nickel-based self-fluxing alloy can also simply improve the plasticity of the coating, but the cost is that the strength of the coating is also correspondingly reduced, namely, on one hand, the integral dust erosion and abrasion resistance of the water wall coating is reduced, and on the other hand, the fatigue strength of the coating is reduced, so that fatigue cracks are easily generated.
Disclosure of Invention
In order to solve the technical problems, the invention adopts the original flame spraying and the high-frequency induction remelting, and puts a proper amount of rare earth yttrium into the nickel-based self-fluxing alloy powder material to prepare the rare earth nickel-based self-fluxing alloy. Preparing a rare earth nickel-based self-fluxing alloy precoat on a substrate by flame spraying, preparing a rare earth nickel-based self-fluxing alloy remelting coating by a high-frequency induction cladding technology, and finally bending on a bending machine. By adding a proper amount of rare earth yttrium into the nickel-based self-fluxing alloy material, the toughness of the coating is improved under the condition of not reducing the strength of the coating, so that the problem that the coating on the heating surface of the pipe fitting is easy to crack during bending is solved, and the service life of the pipe fitting is prolonged.
The technical scheme provided by the invention is as follows:
the rare earth nickel-based self-fluxing alloy used in the high-frequency induction remelting process of the four pipes of the boiler is sprayed on the surface of the heating surface of a pipe fitting to be bent in the four pipes of the boiler to prevent cracks during bending, and consists of 7-10 wt% of rare earth yttrium and 90-93 wt% of nickel-based self-fluxing alloy.
Preferably, the pipe is a pipe to be bent in a water wall, a superheater, a reheater or an economizer.
The invention also discloses an application method of the rare earth nickel-based self-fluxing alloy in the four-tube high-frequency induction remelting process of the boiler, which comprises the following steps:
(1) preparing a rare earth nickel-based self-fluxing alloy which is a mixture of rare earth yttrium and a nickel-based self-fluxing alloy;
(2) carrying out sand blasting treatment on the heated surface of the pipe fitting to be bent;
(3) spraying rare earth nickel-based self-fluxing alloy on the surface of the pipe subjected to sand blasting, wherein the rare earth nickel-based self-fluxing alloy forms a coating after being solidified on the surface of the pipe;
(4) heating the coating to be molten through a high-frequency induction coil, and removing the coating from the coil after the coating is reflected by a mirror surface;
(5) naturally and slowly cooling to room temperature after spraying is finished, and polishing the welding slag at the sharp corner on the surface of the coating layer to be smooth;
(6) and (4) discharging the pipe fitting onto a bending machine, and bending, quality detection, evaluation and warehousing the position sprayed with the rare earth nickel-based self-fluxing alloy.
Preferably, in the step (3), the spraying process is conventional flame spraying.
More preferably, in the step (3), the conventional flame spraying is oxyacetylene flame spraying.
Preferably, in the step (3), the thickness of the obtained coating is 0.5-0.8 mm.
Preferably, in the step (3), the particle size of the rare earth nickel-based self-fluxing alloy powder is-150 +300 meshes.
Preferably, in the step (5), grinding is performed by using a hand grinding wheel.
Compared with the prior art, the invention has the following technical advantages:
(1) when the high-frequency induction remelting operation is carried out, almost all substances in a molten pool are remelted, the active rare earth yttrium element is easy to react with other elements to generate a stable compound, the nucleation rate is increased, and the active rare earth yttrium element is adsorbed on a crystal interface and can block the growth of crystal grains, so that the dendritic crystal structure is refined. The grain refining can simultaneously improve the strength and the plasticity of the coating, thereby effectively improving the toughness of the coating material and ensuring that cracks are not easy to appear during bending. The alloy not only can improve the toughness of the coating, but also can improve the organization structure of the self-fluxing alloy, because the rare earth yttrium has larger atomic radius, has stronger solid solution strengthening effect, and because the surface activity of the rare earth yttrium is larger, the rare earth yttrium is easy to deviate in crystal boundaries, plays a role in strengthening the crystal boundaries, thereby improving the integral high-temperature corrosion resistance of the water wall coating.
(2) The rare earth nickel-based self-fluxing alloy is applied to four tubes of a boiler, and the rare earth element yttrium in the coating is in Fe under the high-temperature condition2O3Preferential oxidation of Y in the internal oxide layer2O3And the nickel-base alloy exists at the front edge of the oxidation layer to block the oxidation process from continuing, so that the high-temperature oxidation resistance of the nickel-base alloy is further improved. The addition amount of the rare earth yttrium is only about 7-10% of the mass of the nickel-based self-fluxing alloy, the cost is slightly increased, but the process is basically unchanged, the method is simple and easy to implement, and the effect is obvious.
Detailed Description
The technical scheme of the invention is further explained by taking a 20G water wall tube bank test piece in a four-tube boiler as an example.
Example 1
The invention discloses a rare earth nickel-based self-fluxing alloy used in a boiler four-tube high-frequency induction remelting process, which is sprayed on the surface of a 20G water-cooled wall tube bank test piece to prevent cracks during bending and consists of 7 wt% of rare earth yttrium and 93 wt% of nickel-based self-fluxing alloy.
The invention also discloses an application method of the rare earth nickel-based self-fluxing alloy in the four-tube high-frequency induction remelting process of the boiler, which comprises the following steps:
(1) preparing a rare earth nickel-based self-fluxing alloy which is a mixture of rare earth yttrium and a nickel-based self-fluxing alloy;
(2) carrying out sand blasting treatment on the heating surface of the 20G water wall tube bank test piece;
(3) spraying a rare earth nickel-based self-fluxing alloy with the powder granularity of 150 meshes on the surface of a 20G water wall tube row test piece subjected to sand blasting by using oxyacetylene flame, wherein the moving speed of a spray gun uniformly moves according to the powder feeding amount, the thickness of a coating is 0.5mm, and the rare earth nickel-based self-fluxing alloy forms a coating after being solidified on the surface of a pipe fitting;
(4) heating the coating to be molten through a high-frequency induction coil, and removing the coating from the coil after the coating is reflected by a mirror surface;
(5) in order to avoid deformation and cracking of the sprayed layer, the sprayed layer needs to be naturally and slowly cooled. After the temperature is reduced to room temperature, polishing sharp-angled welding slag and other parts on the surface of the coating smoothly by using a hand grinding wheel;
(6) and (4) discharging the pipe fitting onto a bending machine, and bending, quality detection, evaluation and warehousing the position sprayed with the rare earth nickel-based self-fluxing alloy.
Example 2
The invention discloses a rare earth nickel-based self-fluxing alloy used in a boiler four-tube high-frequency induction remelting process, which is sprayed on the surface of a 20G water-cooled wall tube bank test piece to prevent cracks during bending and consists of 8 wt% of rare earth yttrium and 92 wt% of nickel-based self-fluxing alloy.
The invention also discloses an application method of the rare earth nickel-based self-fluxing alloy in the four-tube high-frequency induction remelting process of the boiler, which comprises the following steps:
(1) preparing a rare earth nickel-based self-fluxing alloy which is a mixture of rare earth yttrium and a nickel-based self-fluxing alloy;
(2) carrying out sand blasting treatment on the heating surface of the 20G water wall tube bank test piece;
(3) spraying a rare earth nickel-based self-fluxing alloy with the powder granularity of 200 meshes on the surface of a 20G water-cooled wall tube row test piece subjected to sand blasting by using supersonic flame, wherein the moving speed of a spray gun uniformly moves according to the powder feeding amount, the thickness of a coating is 0.7mm, and the rare earth nickel-based self-fluxing alloy forms a coating after being solidified on the surface of a pipe fitting;
(4) heating the coating to be molten through a high-frequency induction coil, and removing the coating from the coil after the coating is reflected by a mirror surface;
(5) in order to avoid deformation and cracking of the sprayed layer, the sprayed layer needs to be naturally and slowly cooled. After the temperature is reduced to room temperature, polishing sharp-angled welding slag and other parts on the surface of the coating smoothly by using a hand grinding wheel;
(6) and (4) discharging the pipe fitting onto a bending machine, and bending, quality detection, evaluation and warehousing the position sprayed with the rare earth nickel-based self-fluxing alloy.
Example 3
The invention discloses a rare earth nickel-based self-fluxing alloy used in a boiler four-tube high-frequency induction remelting process, which is sprayed on the surface of a 20G water-cooled wall tube bank test piece to prevent cracks during bending and consists of 10 wt% of rare earth yttrium and 90 wt% of nickel-based self-fluxing alloy.
The invention also discloses an application method of the rare earth nickel-based self-fluxing alloy in the four-tube high-frequency induction remelting process of the boiler, which comprises the following steps:
(1) preparing a rare earth nickel-based self-fluxing alloy which is a mixture of rare earth yttrium and a nickel-based self-fluxing alloy;
(2) carrying out sand blasting treatment on the heating surface of the 20G water wall tube bank test piece;
(3) spraying a rare earth nickel-based self-fluxing alloy with the powder granularity of 300 meshes on the surface of a 20G water wall tube row test piece subjected to sand blasting by using oxyacetylene flame, wherein the moving speed of a spray gun uniformly moves according to the powder feeding amount, the thickness of a coating is 0.8mm, and the rare earth nickel-based self-fluxing alloy forms a coating after being solidified on the surface of a pipe fitting;
(4) heating the coating to be molten through a high-frequency induction coil, and removing the coating from the coil after the coating is reflected by a mirror surface;
(5) in order to avoid deformation and cracking of the sprayed layer, the sprayed layer needs to be naturally and slowly cooled. After the temperature is reduced to room temperature, polishing sharp-angled welding slag and other parts on the surface of the coating smoothly by using a hand grinding wheel;
(6) and (4) discharging the pipe fitting onto a bending machine, and bending, quality detection, evaluation and warehousing the position sprayed with the rare earth nickel-based self-fluxing alloy.
Comparative example 1
The application method of the nickel-based self-fluxing alloy comprises the following steps:
(1) weighing nickel-based self-fluxing alloy according to requirements;
(2) carrying out sand blasting treatment on the heating surface of the 20G water wall tube bank test piece;
(3) spraying nickel-based self-fluxing alloy with the powder granularity of 300 meshes on the surface of a 20G water-cooled wall tube row test piece subjected to sand blasting by using oxyacetylene flame, wherein the moving speed of a spray gun uniformly moves according to the powder feeding amount, the thickness of a coating is 0.8mm, and the nickel-based self-fluxing alloy forms a coating after being solidified on the surface of a pipe fitting;
(4) heating the coating to be molten through a high-frequency induction coil, and removing the coating from the coil after the coating is reflected by a mirror surface;
(5) in order to avoid deformation and cracking of the sprayed layer, the sprayed layer needs to be naturally and slowly cooled. After the temperature is reduced to room temperature, polishing sharp-angled welding slag and other parts on the surface of the coating smoothly by using a hand grinding wheel;
(6) and (4) discharging the water wall tube onto a bending machine, and performing quality detection, evaluation and warehousing after bending.
Measurement of Performance
The 20G water wall tube row test pieces prepared in the examples 1-3 and the comparative example 1 are subjected to measurement on the tensile strength, the fracture toughness, the high temperature resistance and the corrosion resistance of the coating, and the measurement results are shown in Table 1;
wherein, the tensile strength of the coating is determined according to GB/T228; the determination of the fracture toughness is based on GB/T21143-2014, the high temperature resistance is determined according to the surface appearance observation of the test piece at high temperature in a muffle furnace, and the corrosion resistance is determined according to the thinning amount of the test piece after the test piece resists chlorine corrosion in a tube furnace.
TABLE 1
The tensile strength is a comprehensive index showing that the mechanical properties of the coating are improved after the rare earth is added, and as can be seen from table 1, the comprehensive mechanical properties of the coating are improved compared with the coating of the nickel-based self-fluxing alloy without the rare earth, the tensile strength is increased with the increase of the thickness of the coating, but the tensile strength is stopped increasing after a certain limit, which indicates that the coating is influenced by other factors such as the granularity of the powder, and the thinner the granularity of the powder and the thicker the thickness of the coating are, but the comprehensive game result of all the influencing factors is better. Secondly, as can be seen from table 1, the fracture toughness is significantly increased after the rare earth is added, and the fracture toughness is improved along with the increase of the coating thickness and the refinement of the powder particle size, thereby proving that the addition of the rare earth can improve the toughness of the coating by refining the crystal grains, so that the aim of preventing the water wall tube from cracking during bending can be achieved. In addition, as can be seen from table 1, the coating added with rare earth has certain enhancement effect in the aspects of high temperature resistance and corrosion resistance, but the effect is not outstanding, which shows that the main advantages of the coating are focused on improving the toughness and comprehensive mechanical properties of the coating.
Claims (8)
1. The rare earth nickel-based self-fluxing alloy for the high-frequency induction remelting process of the four pipes of the boiler is sprayed on the surface of the heating surface of a pipe fitting to be bent in the four pipes of the boiler, and cracks are prevented from being generated during bending, and the rare earth nickel-based self-fluxing alloy is characterized in that: consists of 7 to 10 weight percent of rare earth yttrium and 90 to 93 weight percent of nickel-based self-fluxing alloy.
2. The rare earth nickel-based self-fluxing alloy for the boiler four-tube high-frequency induction remelting process according to claim 1, wherein the rare earth nickel-based self-fluxing alloy comprises the following components in percentage by weight: the pipe fitting is a pipe fitting which needs to be bent in a water wall, a superheater, a reheater or an economizer.
3. The application method of the rare earth nickel-based self-fluxing alloy used in the four-tube high-frequency induction remelting process of the boiler is characterized by comprising the following steps of:
(1) preparing a rare earth nickel-based self-fluxing alloy which is a mixture of rare earth yttrium and a nickel-based self-fluxing alloy;
(2) carrying out sand blasting treatment on the heated surface of the pipe fitting to be bent;
(3) spraying rare earth nickel-based self-fluxing alloy on the surface of the pipe subjected to sand blasting, wherein the rare earth nickel-based self-fluxing alloy forms a coating after being solidified on the surface of the pipe;
(4) heating the coating to be molten through a high-frequency induction coil, and removing the coating from the coil after the coating is reflected by a mirror surface;
(5) naturally and slowly cooling to room temperature after spraying is finished, and polishing the welding slag at the sharp corner on the surface of the coating layer to be smooth;
(6) and (4) discharging the pipe fitting onto a bending machine, and bending, quality detection, evaluation and warehousing the position sprayed with the rare earth nickel-based self-fluxing alloy.
4. The application method of the rare earth nickel-based self-fluxing alloy used in the four-tube high-frequency induction remelting process of the boiler according to claim 3 is characterized in that: in the step (3), the spraying process adopts conventional flame spraying.
5. The application method of the rare earth nickel-based self-fluxing alloy used in the four-tube high-frequency induction remelting process of the boiler according to claim 4 is characterized in that: in the step (3), the conventional flame spraying is oxyacetylene flame spraying.
6. The application method of the rare earth nickel-based self-fluxing alloy used in the four-tube high-frequency induction remelting process of the boiler according to claim 3 is characterized in that: in the step (3), the thickness of the obtained coating is 0.5-0.8 mm.
7. The application method of the rare earth nickel-based self-fluxing alloy used in the four-tube high-frequency induction remelting process of the boiler according to claim 3 is characterized in that: in the step (3), the particle size of the rare earth nickel-based self-fluxing alloy powder is-150 +300 meshes.
8. The application method of the rare earth nickel-based self-fluxing alloy used in the four-tube high-frequency induction remelting process of the boiler according to claim 3 is characterized in that: and (5) polishing by using a hand grinding wheel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110006647.5A CN112813375A (en) | 2021-01-05 | 2021-01-05 | Rare earth nickel-based self-fluxing alloy for boiler four-tube high-frequency induction remelting process and application method thereof |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103540928A (en) * | 2013-09-30 | 2014-01-29 | 广州有色金属研究院 | Manufacturing method of air pipe surface coating |
| CN111979542A (en) * | 2020-08-06 | 2020-11-24 | 江苏科环新材料有限公司 | High-frequency remelting coating preparation device for boiler pipe of garbage power station under composite motion condition |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103540928A (en) * | 2013-09-30 | 2014-01-29 | 广州有色金属研究院 | Manufacturing method of air pipe surface coating |
| CN111979542A (en) * | 2020-08-06 | 2020-11-24 | 江苏科环新材料有限公司 | High-frequency remelting coating preparation device for boiler pipe of garbage power station under composite motion condition |
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| 孙永兴等: "稀土元素对喷焊层组织及耐磨性的影响", 《石油工程建设》 * |
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Application publication date: 20210518 |