CN113122847A - Composite manufacturing method for prolonging service life of hard surface seal of valve - Google Patents

Composite manufacturing method for prolonging service life of hard surface seal of valve Download PDF

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CN113122847A
CN113122847A CN202110478262.9A CN202110478262A CN113122847A CN 113122847 A CN113122847 A CN 113122847A CN 202110478262 A CN202110478262 A CN 202110478262A CN 113122847 A CN113122847 A CN 113122847A
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cobalt
valve
service life
surfacing
composite manufacturing
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罗雄光
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Dongguan Huaxin Laser Technology Co ltd
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Dongguan Huaxin Laser Technology Co ltd
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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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/021—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material including at least one metal alloy layer
    • 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
    • C22C19/07—Alloys based on nickel or cobalt based on cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F3/00—Changing the physical structure of non-ferrous metals or alloys by special physical methods, e.g. treatment with neutrons
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
    • 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
    • C23C24/00—Coating starting from inorganic powder
    • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
    • C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
    • C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
    • C23C24/106—Coating with metal alloys or metal elements only

Abstract

The invention relates to a composite manufacturing method for prolonging the service life of a hard surface seal of a valve, which comprises the following steps: the first step is as follows: adopting plasma surfacing equipment (PTA), selecting cobalt-based alloy powder, and forming a metallurgically bonded cobalt-based surfacing layer with the thickness of 1.0-3.0mm on the sealing surface of the valve; the second step is that: carrying out heat treatment on the sample in the first step, wherein the heat treatment temperature is 520-580 ℃, and preserving heat for 3-8 h; the third step: machining the sample subjected to heat treatment to a machining allowance of a final size of plus (0.05-0.10) mm; the fourth step: performing laser shock strengthening treatment on the surface of the cobalt-based alloy surfacing layer; the fifth step: machining, grinding and polishing to an assembly size; and a sixth step: a Cr-Al coating which has both high-temperature oxidation resistance and wear resistance is physically vapor deposited; the process greatly reduces the cracking risk of the valve sealing surface in the using process, improves the wear resistance and high-temperature oxidation resistance, improves the safety and reliability of a unit and prolongs the service life.

Description

Composite manufacturing method for prolonging service life of hard surface seal of valve
Technical Field
The invention relates to the field of valve manufacturing, in particular to a composite manufacturing and maintaining method of plasma surfacing, laser shock peening and PVD coating for prolonging the service life of a hard surface seal of a valve.
Background
The valve is widely applied to various fields of industrial production, pipeline transportation, nuclear power, transportation and the like. The failure mode of the valve of the steam turbine set is mainly caused by cracking, abrasion, high-temperature oxidation and the like of a sealing surface due to the specific high-temperature and high-pressure working environment of the steam turbine set.
The sealing form of the valve is generally plane or conical surface sealing, and in order to improve the service life and the working stability of the valve, wear-resistant and high-temperature-resistant Stellite (cobalt-based) and nickel-based alloy are usually welded on a sealing surface of the valve in a surfacing mode; the alloy takes eutectic carbide as a strengthening phase, and the alloy has higher hardness, so that the service life and the working stability of the valve can be obviously improved; however, the process has disadvantages, on one hand, the quality of the surfacing layer is reduced due to welding defects such as looseness, air holes, incomplete fusion and the like; on the other hand, because the alloy has high hardness and large cracking, the combined action of thermal stress, mechanical stress and welding residual stress exists in the use process, and a surfacing layer is easy to crack in the use process, so that the valve is prematurely failed, the safe operation of a unit can be influenced in serious cases, and major accidents are caused.
Disclosure of Invention
The invention aims to provide a composite manufacturing method for prolonging the service life of a hard-surface seal of a valve, which greatly reduces the risk of cracking of the seal surface of the valve and improves the wear resistance and high-temperature oxidation resistance.
In order to achieve the above purpose, the invention adopts the technical scheme that: a composite manufacturing method for prolonging service life of a hard surface seal of a valve is characterized by comprising the following steps:
the first step is as follows: adopting plasma surfacing equipment (PTA), selecting cobalt-based alloy powder, and forming a metallurgically bonded cobalt-based surfacing layer with the thickness of 1.0-3.0mm on the sealing surface of the valve; the whole workpiece is preheated to 200 ℃ and 300 ℃ before welding, and the temperature is kept for 3-8 h;
the second step is that: performing stress relief tempering heat treatment on the sample in the first step, wherein the heat treatment temperature is 520-580 ℃, and preserving heat for 3-8 h;
the third step: machining the sample subjected to heat treatment to a machining allowance of a final size + (0.05-0.10 mm);
the fourth step: performing laser shock strengthening treatment on the surface of the cobalt-based alloy surfacing layer:
the fifth step: machining, grinding and polishing to an assembly size;
and a sixth step: and a Cr-Al composite coating which has both high-temperature oxidation resistance and wear resistance is physically vapor deposited.
Preferably, the cobalt-based alloy powder used in the first step consists of, by mass, 0.9% -1.4% of carbon, 28.0% -30.0% of chromium, 0-3.0% of iron, 0-0.5% of manganese, 0-1.0% of molybdenum, 0-3.0% of nickel, 0.70% -1.55% of silicon, 3.5% -5.5% of tungsten, and the balance cobalt.
Preferably, the technical parameters of the plasma surfacing process are as follows: 1-2 layers, the diameter of a nozzle is 4.0mm, the current is 135-185A, the flow of ion gas argon is 2.5L/min, the flow of protective gas argon is 16L/min, the welding speed is 200 mm/min, the lap joint rate is 50%, the powder feeding amount is 8-10g/min, and the flow of powder feeding gas argon is 6L/min.
Preferably, in the fourth step, the specific parameters of the laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 8-10J, the spot diameter is 2.5mm, the frequency is 10 Hz, flowing water is used as a restraint layer, and black paint is used as a light absorption coating.
Preferably, in the sixth step, the thickness of the Cr-Al coating is 2 to 12 μm.
The process parameters of the laser shock can be adjusted accordingly.
The specific preparation process of the coating (Cr-Al) with high temperature oxidation resistance and wear resistance comprises the following steps: the method adopts a multi-arc ion plating technology, argon with the purity of 99.99 percent is selected as working gas, a CrAl alloy target (the atomic percentage of Cr/Al is 1: 1) is adopted as a target material, the surface of a workpiece is polished step by using sand paper (No. 360, 600, 800, 1000, 1200 and 1500), the workpiece is polished, the workpiece is cleaned for 10 to 60 minutes in an ultrasonic way by absolute ethyl alcohol, and the workpiece is dried and then is charged. Vacuum chamber of furnace chamber is pumped to 8.0 x 10-3Setting the bias voltage of the workpiece support to be negative 500V below Pa, introducing Ar gas, and cleaning the surface of the workpiece for 10-30min and 30-60min by using the Ar gas and CrAl targets respectively. Before the CrAl working layer is deposited, the bias voltage is adjusted to negative (70-120) V, and the current is 100A, depositing a CrAl transition layer for 30-90min, wherein the deposition thickness is 0.5 mu m, and when preparing the coating, the temperature of a workpiece substrate is 400-500 ℃, the bias voltage is negative (30-50) V, the current is 100A, the gas pressure is 1.5-4Pa, and the deposition time of a CrAl target is 2-12 h.
The material of the constraint layer is irradiated by short pulse high-energy laser to induce high-temperature and high-pressure (GPa) plasma to generate high-pressure shock waves, the high-pressure shock waves act on the surface of the metal and propagate inwards, a dense and stable dislocation structure is formed on the surface layer of the material, meanwhile, the surface layer of the material is subjected to strain hardening, large compressive stress is remained, and the fatigue resistance, stress corrosion resistance and other properties of the material are obviously improved.
According to the scientific principle of materials, cobalt-based alloy with low carbon content and good plasticity is selected, and after surfacing and laser shock strengthening treatment, the hardness is greatly improved, the wear resistance is remarkably enhanced, and good plasticity and toughness are kept.
The residual surface compressive stress counteracts the thermal stress and the mechanical stress in the use process of the valve, delays and avoids the initiation of potential microcracks, and greatly reduces the risk of cracking of the sealing surface of the valve.
On the sealing surface of the valve, a Cr-Al coating which has both high-temperature oxidation resistance and wear resistance is physically vapor deposited, so that the wear resistance and the high-temperature oxidation resistance are improved.
The valve sealing surface manufactured by the process has better shock resistance and better high-temperature oxidation resistance under the same hardness value (wear resistance index), avoids the problem of cracking of the sealing surface with great harmfulness, and after the treatment of the laser shock strengthening process, the surfacing layer metal surface layer forms a dense and stable dislocation structure, simultaneously, the material surface layer generates strain hardening, and remains great compressive stress, so that the performances of fatigue resistance, stress corrosion resistance and the like of the material are obviously improved, the residual compressive stress with the surface depth of about 0.7mm is formed, the thermal stress and the mechanical stress in the use process of the valve are counteracted, the initiation of potential microcracks is delayed and avoided, the risk of cracking of the valve sealing surface is greatly reduced, the reliability of the valve is improved, and the service life is prolonged.
Drawings
Fig. 1 is a hardness gradient comparison chart of samples prepared by a conventional surfacing process, case 1 and case 2.
Fig. 2 is a statistical chart of cold-hot impact test cracks of samples prepared by a conventional surfacing process, case 1 and case 2.
Fig. 3 is a comparison chart of the cold and hot impact test samples of the samples prepared by the conventional surfacing process, case 1 and case 2.
FIG. 4 is a diagram of a high temperature wear resistance test apparatus.
Fig. 5 is a schematic of samples after wear testing of samples prepared by conventional build-up welding process, case 1 and case 2.
Fig. 6 is a weight loss statistical graph after wear tests of samples prepared by the conventional surfacing process, case 1 and case 2.
Fig. 7 is a cross-sectional metallographic examination of samples prepared in case 1 and case 2.
FIG. 8 is a scanning electron microscope image of a PVD composite coating during the fabrication of the composite process.
Fig. 9 is a general flowchart of the composite process.
Detailed Description
The present invention is described in detail below for the purpose of better understanding technical solutions of the present invention by those skilled in the art, and the description of the present invention is only exemplary and explanatory and should not be construed as limiting the scope of the present invention in any way.
The valve core and valve seat are made of American ASTM standard, high-temperature wrought alloy P91.
Example 1
(1) Machining a valve seat or a valve core to be surfacing-welded according to drawing information, putting the valve seat or the valve core into a resistance furnace for preheating treatment before welding, wherein the preheating temperature is 270 ℃, and the heat preservation time is 4 hours, and the size thickness of the valve seat and the valve core is taken as the standard, and the surface temperature and the internal temperature of the valve seat and the valve core are uniform;
(2) adopting a plasma surfacing process, selecting cobalt-based alloy powder Stellite6, and forming a metallurgically bonded 2.5 mm-thick cobalt-based Stellite6 surfacing layer on the surface of the P91 material;
the technical parameters of the plasma surfacing process are as follows: 2 layers, and the diameter of a nozzle is 4.0 mm. The current is 168A, the flow of ion gas and argon is 2.5L/min, the flow of protective gas and argon is 16L/min, the welding speed is 200 mm/min, the lap joint rate is 50%, the powder feeding amount is 9g/min, and the flow of powder feeding gas and argon is 6L/min; the cobalt-based alloy comprises, by mass, 1.2% of carbon, 28.5% of chromium, 1.0% of iron, 0.5% of manganese, 1.0% of molybdenum, 2.0% of nickel, 0.36% of silicon, 4.5% of tungsten and the balance of cobalt; after surfacing, immediately placing the steel plate into a resistance furnace for stress relief tempering treatment, keeping the temperature at 560 ℃ for 6h, and discharging the steel plate from the furnace for air cooling after the temperature is reached; the original thickness of the two layers after overlaying is about 3.3mm, the residual effective thickness is 2.5mm after machining is about 0.8mm, and the machining allowance of the final size of the sealing surface plus 0.10mm is ensured;
(3) carrying out laser shock strengthening treatment on the surface of the cobalt-based surfacing layer, wherein the specific parameters of the laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 10J, the spot diameter is 2.5mm, and the frequency is 10 Hz; selecting flowing water as a restraint layer and black paint as a light absorption coating; grinding, precisely grinding and polishing to an assembly size;
(4) and a Cr-Al coating with the thickness of 3 mu m and the performances of high-temperature oxidation resistance and wear resistance is physically deposited on the sealing surface in a vapor phase manner.
Example 2
(1) Machining a valve seat or a valve core to be surfacing-welded according to drawing information, putting the valve seat or the valve core into a resistance furnace for preheating treatment before welding, wherein the preheating temperature is 300 ℃, and the heat preservation time is 3 hours, and the size thickness of the valve seat and the valve core is taken as the standard, and the surface temperature and the internal temperature of the valve seat and the valve core are uniform;
(2) adopting a plasma surfacing process, selecting cobalt-based alloy powder Stellite6, and forming a metallurgically bonded 1.2 mm-thick cobalt-based Stellite6 surfacing layer on the surface of the P91 material;
the technical parameters of the plasma surfacing process are as follows: 1 layer, the diameter of a nozzle is 4.0mm, the current is 160A, the welding speed is 200 mm/min, the lap joint rate is 50 percent, and the powder feeding amount is 10 g/min; the cobalt-based alloy comprises, by mass, 1.2% of carbon, 28.5% of chromium, 1.0% of iron, 0.5% of manganese, 1.0% of molybdenum, 2.0% of nickel, 0.36% of silicon, 4.5% of tungsten and the balance of cobalt; after surfacing, immediately placing the steel plate into a resistance furnace for stress relief tempering treatment, keeping the temperature at 520 ℃ for 3h, and discharging the steel plate from the furnace for air cooling after the temperature is reached; the original thickness after overlaying is about 1.8mm, the residual effective thickness is 1.2mm after machining is about 0.6mm, and the machining allowance of the final size of the sealing surface plus 0.05 mm is ensured;
(3) carrying out laser shock strengthening treatment on the surface of the cobalt-based surfacing layer, wherein the specific parameters of the laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 8J, the spot diameter is 2.5mm, and the frequency is 10 Hz; selecting flowing water as a restraint layer and black paint as a light absorption coating; machining, precisely grinding and polishing to an assembly size;
(4) and a Cr-Al coating with the thickness of 5 mu m and the performances of high-temperature oxidation resistance and wear resistance is physically deposited on the sealing surface in a vapor phase manner.
Example 3
(1) Machining a valve seat or a valve core to be surfacing-welded according to drawing information, putting the valve seat or the valve core into a resistance furnace for preheating treatment before welding, wherein the preheating temperature is 250 ℃, and the heat preservation time is 5 hours, and the size thickness of the valve seat and the valve core is taken as the standard, and the surface temperature and the internal temperature of the valve seat and the valve core are uniform;
(2) adopting a plasma surfacing process, selecting cobalt-based alloy powder Stellite6, and forming a metallurgically bonded 1.0 mm-thick cobalt-based Stellite6 surfacing layer on the surface of the P91 material;
the technical parameters of the plasma surfacing process are as follows: 1 layer, the diameter of a nozzle is 4.0mm, the current is 135A, the welding speed is 200 mm/min, the lap joint rate is 50 percent, and the powder feeding amount is 9 g/min; the cobalt-based alloy comprises, by mass, 1.2% of carbon, 28.5% of chromium, 1.0% of iron, 0.5% of manganese, 1.0% of molybdenum, 2.0% of nickel, 0.36% of silicon, 4.5% of tungsten and the balance of cobalt; after surfacing, immediately placing the steel plate into a resistance furnace for stress relief tempering treatment, keeping the temperature at 560 ℃ for 5h, and discharging the steel plate from the furnace for air cooling after the temperature is reached; the original thickness after overlaying is about 1.6mm, the residual effective thickness is 1.0mm after machining is about 0.6mm, and the machining allowance of the final size of the sealing surface plus 0.08 mm is ensured;
(3) carrying out laser shock strengthening treatment on the surface of the cobalt-based surfacing layer, wherein the specific parameters of the laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 10J, the spot diameter is 2.5mm, and the frequency is 10 Hz; selecting flowing water as a restraint layer and black paint as a light absorption coating; grinding, precisely grinding and polishing to an assembly size;
(4) and a Cr-Al coating with the thickness of 8 mu m and the performances of high-temperature oxidation resistance and wear resistance is physically deposited on the sealing surface in a vapor phase manner.
Example 4
(1) Machining a valve seat or a valve core to be surfacing-welded according to drawing information, putting the valve seat or the valve core into a resistance furnace for preheating treatment before welding, wherein the preheating temperature is 260 ℃, and the heat preservation time is 3.5 hours, and the size thickness of the valve seat and the valve core is taken as the standard, and the surface temperature and the internal temperature of the valve seat and the valve core are uniform;
(2) adopting a plasma surfacing process, selecting cobalt-based alloy powder Stellite6, and forming a metallurgically bonded 2.0 mm-thick cobalt-based Stellite6 surfacing layer on the surface of the P91 material;
the technical parameters of the plasma surfacing process are 2 layers, the diameter of a nozzle is 4.0mm, the current is 135A, the welding speed is 200 mm/min, the lap joint rate is 50 percent, and the powder feeding amount is 8 g/min; the cobalt-based alloy comprises, by mass, 1.2% of carbon, 28.5% of chromium, 1.0% of iron, 0.5% of manganese, 1.0% of molybdenum, 2.0% of nickel, 0.36% of silicon, 4.5% of tungsten and the balance of cobalt; after surfacing, immediately placing the steel plate into a resistance furnace for stress relief tempering treatment, keeping the temperature at 580 ℃ for 3 hours, and discharging the steel plate from the furnace for air cooling after reaching a point; the original thickness of the two layers after overlaying is about 2.8mm, the residual effective thickness is 2.0mm after machining is about 0.8mm, and the machining allowance of the final size of the sealing surface plus 0.10mm is ensured;
(3) carrying out laser shock strengthening treatment on the surface of the cobalt-based surfacing layer, wherein the specific parameters of the laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 8J, the spot diameter is 2.5mm, and the frequency is 10 Hz; selecting flowing water as a restraint layer and black paint as a light absorption coating; grinding, precisely grinding and polishing to an assembly size;
(4) and a Cr-Al coating with the thickness of 2 mu m and the performances of high-temperature oxidation resistance and wear resistance is physically deposited on the sealing surface in a vapor phase.
Example 5
(1) Machining a valve seat or a valve core to be surfacing-welded according to drawing information, putting the valve seat or the valve core into a resistance furnace for preheating treatment before welding, wherein the preheating temperature is 280 ℃, and the heat preservation time is 4.5 hours, and the surface layers and the internal temperatures of the valve seat and the valve core are uniform and consistent according to the size thickness of the valve seat and the valve core;
(2) adopting a plasma surfacing process, selecting cobalt-based alloy powder Stellite6, and forming a metallurgically bonded 3.0 mm-thick cobalt-based Stellite6 surfacing layer on the surface of the P91 material;
the technical parameters of the plasma surfacing process are as follows: 2 layers, the diameter of a nozzle is 4.0mm, the current is 185A, the welding speed is 180 mm/min, the lap joint rate is 50 percent, and the powder feeding amount is 10 g/min; the cobalt-based alloy comprises, by mass, 1.2% of carbon, 28.5% of chromium, 1.0% of iron, 0.5% of manganese, 1.0% of molybdenum, 2.0% of nickel, 0.36% of silicon, 4.5% of tungsten and the balance of cobalt; after surfacing, immediately placing the steel plate into a resistance furnace for stress relief tempering treatment, keeping the temperature at 580 ℃ for 8 hours, and discharging the steel plate from the furnace for air cooling after reaching a point; the original thickness of the two layers after overlaying is about 3.8mm, the residual effective thickness is 3.0mm after machining is about 0.8mm, and the machining allowance of the final size of the sealing surface plus 0.10mm is ensured;
(3) carrying out laser shock strengthening treatment on the surface of the cobalt-based surfacing layer, wherein the specific parameters of the laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 10J, the spot diameter is 2.5mm, and the frequency is 10 Hz; selecting flowing water as a restraint layer and black paint as a light absorption coating; grinding, precisely grinding and polishing to an assembly size;
(4) and a Cr-Al coating with 12 mu m and both high-temperature oxidation resistance and wear resistance is physically deposited on the sealing surface in a vapor phase manner.
The valves obtained in the embodiments 1 and 2 are compared with the valves obtained only by plasma surfacing in hardness gradient, 3 parallel samples are tested in a single test, an average value is taken to obtain a graph 1, the graph can obviously show that the hardness of the sealing surface is obviously improved after the process treatment of the application, taking the Stellite6 alloy as an example, the normal hardness is 370-410HV0.3After laser shock strengthening in the composite process, the hardness is remarkably improved to 500-550HV0.3(figure 1), after the Cr-Al coating is physically vapor deposited by the composite process, the surface hardness can reach 2850HV0.005(ii) a And the residual stress of the valve obtained by surfacing welding is about 260MPa, and is converted into the compressive stress of minus 460MPa after the laser shock strengthening treatment of the process, and the depth of the effective compressive stress is about 0.7 mm.
Respectively manufacturing two groups of 3 cylindrical samples according to the processes of the embodiment 1 and the embodiment 2, simultaneously manufacturing a group of 3 cylindrical samples which are only subjected to a single process of plasma surfacing, then putting the three groups of 9 samples in total into a 600 ℃ resistance furnace for heat preservation for 15min, taking out and putting into flowing tap water for rapid cooling; in such a cycle, the average number of cracks on the surface of the sample is counted to obtain a bar chart shown in fig. 2 and a crack appearance shown in fig. 3, and the graphs in fig. 2-3 can obviously show that the sample treated by the process has more excellent cold and hot impact resistance, so that the cracking risk of the valve sealing surface in the using process is reduced.
Three sets of 2 samples (FIG. 5) of 25mm diameter were made according to ASTM G98-17 standard (FIG. 4) and tested for high temperature wear resistance: the average weight loss of the plasma surfacing St6 is 3 times of that of the composite process (figure 6), and the high-temperature wear resistance of the sample treated by the process is greatly improved.
Finally, it should be noted that the above embodiments are only used for the technical solution of the present invention and are not limited; although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (7)

1. A composite manufacturing method for prolonging service life of a hard surface seal of a valve is characterized by comprising the following steps:
the first step is as follows: adopting plasma surfacing equipment (PTA), selecting cobalt-based alloy powder, and forming a metallurgically bonded cobalt-based surfacing layer with the thickness of 1.0-3.0mm on the sealing surface of the valve;
the second step is that: performing stress relief tempering heat treatment on the workpiece in the first step, wherein the heat treatment temperature is 520-580 ℃, and preserving heat for 3-8 h;
the third step: machining the sample subjected to heat treatment to a machining allowance of a final size + (0.05-0.10 mm);
the fourth step: performing laser shock strengthening treatment on the surface of the cobalt-based alloy surfacing layer:
the fifth step: machining, grinding and polishing to an assembly size;
and a sixth step: and a Cr-Al coating which has both high-temperature oxidation resistance and wear resistance is physically vapor deposited.
2. The composite manufacturing method for prolonging the service life of the hard surface seal of the valve according to claim 1, wherein the valve seat or the valve core is integrally preheated to 200-300 ℃ before plasma surfacing, and the temperature is kept for 3-8 h.
3. The composite manufacturing method for prolonging the service life of the hard surface seal of the valve according to claim 1, wherein the cobalt-based alloy powder adopted in the first step consists of, by mass, 0.9% -1.4% of carbon, 28.0% -30.0% of chromium, 0-3.0% of iron, 0-0.5% of manganese, 0-1.0% of molybdenum, 0-3.0% of nickel, 0.70% -1.55% of silicon, 3.5% -5.5% of tungsten, and the balance of cobalt.
4. The composite manufacturing method for prolonging the service life of the hard surface seal of the valve according to claim 3, wherein the cobalt-based alloy powder adopted in the first step consists of, by mass fraction, 1.2% of carbon, 28.5% of chromium, 1.0% of iron, 0.5% of manganese, 1.0% of molybdenum, 2.0% of nickel, 0.36% of silicon, 4.5% of tungsten, and the balance cobalt.
5. The composite manufacturing method for prolonging the service life of the hard surface seal of the valve according to claim 1, wherein the technical parameters of the plasma surfacing process are as follows: 1-2 layers, the diameter of a nozzle is 4.0mm, the current is 135-185A, the flow of ion gas argon is 2.5L/min, the flow of protective gas argon is 16L/min, the welding speed is 200 mm/min, the lap joint rate is 50%, the powder feeding amount is 8-10g/min, and the flow of powder feeding gas argon is 6L/min.
6. The composite manufacturing method for prolonging the service life of the hard-surface seal of the valve according to claim 1, wherein in the fourth step, specific parameters of laser shock are as follows: the laser wavelength is 1.06 mu m, the pulse time is 22 ns, the power is 8-10J, the spot diameter is 2.5mm, the frequency is 10 Hz, flowing water is used as a restraint layer, and black paint is used as a light absorption coating.
7. The composite manufacturing method for improving the service life of the hard-surface seal of the valve according to claim 1, wherein in the sixth step, the thickness of the Cr-Al coating is 2-12 μm.
CN202110478262.9A 2021-04-30 2021-04-30 Composite manufacturing method for prolonging service life of hard surface seal of valve Pending CN113122847A (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103409758A (en) * 2013-07-12 2013-11-27 江苏大学 Method for prolonging life of pump shells and blades by carrying out laser strengthening micro-cracks

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
CN103409758A (en) * 2013-07-12 2013-11-27 江苏大学 Method for prolonging life of pump shells and blades by carrying out laser strengthening micro-cracks

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吴亚文等: "锆合金表面CrAl基耐高温涂层及氧化行为研究", 《表面技术》 *
李明等: "阀门密封面粉末等离子堆焊钴基合金技术研究", 《阀门》 *
郭洋等: "超超临界汽轮机阀门部件的两层等离子喷焊司太立合金工艺研究", 《东方汽轮机》 *

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