CN114131242B - Alloy material for valve seat sealing surface overlaying layer and welding process thereof - Google Patents
Alloy material for valve seat sealing surface overlaying layer and welding process thereof Download PDFInfo
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- CN114131242B CN114131242B CN202111599490.8A CN202111599490A CN114131242B CN 114131242 B CN114131242 B CN 114131242B CN 202111599490 A CN202111599490 A CN 202111599490A CN 114131242 B CN114131242 B CN 114131242B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
- B23K35/3033—Ni as the principal constituent
- B23K35/304—Ni as the principal constituent with Cr as the next major constituent
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K10/00—Welding or cutting by means of a plasma
- B23K10/02—Plasma welding
- B23K10/027—Welding for purposes other than joining, e.g. build-up welding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/34—Laser welding for purposes other than joining
- B23K26/342—Build-up welding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/60—Preliminary treatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K37/00—Auxiliary devices or processes, not specially adapted to a procedure covered by only one of the preceding main groups
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/04—Welding for other purposes than joining, e.g. built-up welding
- B23K9/042—Built-up welding on planar surfaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/16—Arc welding or cutting making use of shielding gas
- B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/235—Preliminary treatment
Abstract
The invention discloses an alloy material for a valve seat sealing surface overlaying layer, which comprises a nickel-based alloy and a cobalt-based alloy, wherein the mass ratio of the nickel-based alloy to the cobalt-based alloy is 1:1-5. The alloy of the invention takes the nickel-based alloy as the buffer layer, and the nickel-based alloy is firstly deposited on the base body of the sealing surface of the valve seat, and then the cobalt-based alloy is deposited, so that the advantages/characteristics of the two materials can be well combined, the comprehensive performances of abrasion resistance, impact resistance, corrosion resistance, high temperature resistance, scratch resistance, oxidation resistance, crack resistance and the like of the sealing surface are simultaneously met, and the sealing surface of the valve seat is fixed with the alloy soup.
Description
Technical Field
The invention relates to the technical field of alloy materials, in particular to an alloy material for a valve seat sealing surface overlaying layer and a welding process thereof.
Background
The valve seat has a considerable specific gravity in mechanical products, especially in the industries of nuclear power, thermal power, petrochemical industry, metallurgy and the like, plays a key role, and has a great dosage. With the progress of scientific technology, valves for valve seat industries at home and abroad in recent years are developed in the directions of high parameters such as large size, high temperature and high pressure resistance, strong corrosion resistance, strong friction, high reliability and long service life.
The conditions of use of the high parameter valve seat are quite severe, and the required safety and reliability are very high. It is counted that the most common fault types of typical valve seats in the industries of nuclear power, thermal power and the like are internal and external leakage and sealing surface damage. The quality of the sealing surface of the valve seat, including the comprehensive properties of wear resistance, impact resistance, corrosion resistance, high temperature resistance, scratch resistance, oxidation resistance and the like, directly influences the reliability and the service life of the valve seat.
F92 steel is used as excellent high-temperature heat-resistant steel and widely applied to supercritical and ultra-supercritical power station boilers, and because F92 is imported from abroad, and a valve seat is used as a key control piece of an ultra-supercritical unit, the welding mode and welding parameters of the valve seat are required to have higher requirements. However, F92 is unsuitable as a sealing surface, and has poor wear resistance and cavitation resistance, and is not resistant to scouring and deep rubbing. The FB2 rotor steel is novel 9% Cr martensitic heat-resistant steel developed in European COST project, the composition is 0.13% C-9.32% Cr-1.5% Mo-1% Co-0.0085% B, and the corresponding cast steel is CB2, so that the steel has higher B element content. The microscopic structure and mechanical property test research on 500kg of FB2 steel shows that after the FB2 is aged at 625 ℃/100000, the creep rupture strength reaches 100MPa, and the CB2 is 85MPa.
Although F92 and FB2 have the above excellent performances, the requirements of the sealing surface of the valve seat can not be met, and the sealing surface of the valve seat of the steam turbine is always in a steam atmosphere when in service and is directly subjected to the effects of impact, heat transfer, cavitation and the like of working steam. In the prior art, tungsten-chromium-cobalt-based alloy powder or welding wire of Stellite 6 (Stellite 6 #) is commonly used for a valve seat sealing surface surfacing layer material, is used as a turbine blade, a forging piece and a casting piece on a nozzle blade of a gas turbine engine or is used as a hardfacing material Guan Jianfa component, and is used for energy sources and key parts of a sea water desalination plant. Although the Stellite alloy serving as a high-temperature wear-resistant layer is overlaid on a steel substrate for use through multiple passes, has the advantages of low friction and wear resistance, excellent heat corrosion resistance, excellent heat fatigue resistance, excellent scratch resistance and the like, particularly in a hot state, the Stellite alloy has the advantages of high hardness, high wear resistance, high strength, cracking and falling of the Stellite overlay under service working conditions are one of the key defect problems generated in power generation equipment, and similar conditions often occur, so that a valve seat sealing surface becomes a vulnerable part, periodic repair or replacement is needed, and the service life of a product is seriously influenced. In addition, cobalt-based alloys exhibit a significant drawback for valve seats operating in a nuclear environment: co-59 in the cobalt-based alloy worn and corroded fragments is excited to form Co-60 isotopes after being irradiated by neutrons, and Co-60 is a strong radioactive source with extremely long half-life, so that the maintenance time is increased and the maintenance personnel are threatened during shutdown maintenance, and the difficulty and the cost of nuclear fuel shielding are greatly increased. In addition, the cobalt-based alloy in China is high in price, and cobalt resources in China are lack, so that the use of the cobalt-based alloy is limited.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an alloy material for a valve seat sealing surface overlaying layer, so as to solve the problems that the tungsten-chromium-cobalt-based alloy commonly used for the valve seat sealing surface overlaying layer in the prior art is frequently cracked, fallen and other failures in the service process.
In order to solve the technical problems, the invention adopts the following technical scheme:
an alloy material for a valve seat sealing surface overlaying layer comprises a nickel-based alloy and a cobalt-based alloy, wherein the mass ratio of the nickel-based alloy to the cobalt-based alloy is 1:1-5;
the nickel-based alloy comprises the following components in percentage by mass: 20-23% of chromium; molybdenum is 8-10%; niobium is 3.15-4.15%; iron <5%; aluminum <0.4%; titanium <0.4%; carbon <0.1%; manganese <0.5%; silicon <0.5%; cobalt <1%; phosphorus <0.015%; sulfur <0.015%; the balance being nickel;
the cobalt-based alloy comprises the following components in percentage by mass: 28-32% of chromium; molybdenum <1.5%; iron <3%; carbon is 0.9-1.4%; manganese <2%; silicon <1.5%; nickel <3%; phosphorus <0.015%; sulfur <0.015%; tungsten is 3.5-5.5%; the balance being cobalt.
The invention also provides a welding process for the surfacing layer of the sealing surface of the valve seat, which adopts the alloy as the surfacing layer and performs welding by the following method:
polishing and cleaning the valve seat sealing surface substrate, then overlaying a nickel-based alloy serving as a buffer layer, and overlaying a cobalt-based alloy to obtain the valve seat sealing surface with an overlaying layer.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, after research on the base material of the sealing surface of the valve seat, when the nickel-based alloy is used as a buffer layer, the nickel-based alloy is firstly deposited on the base of the sealing surface of the valve seat, and then the cobalt-based alloy is deposited, so that the advantages/characteristics of the two materials can be well combined, the comprehensive performances of abrasion resistance, impact resistance, corrosion resistance, high temperature resistance, scratch resistance, oxidation resistance, crack resistance and the like of the deposited layer of the sealing surface can be simultaneously met, the problems of easy cracking, falling off and other failures in the service process are reduced, and the metal soup is solidified on the sealing surface of the valve seat.
2. The invention adopts tungsten argon arc welding (GTAW or TIG), welding rod arc welding (SMAW), plasma arc thermal spray welding (PAW), laser beam cladding overlaying (LBW) and Submerged Arc Welding (SAW) to carry out overlaying, which can achieve the technical effects of the invention, but after a plurality of welding methods are researched, the sealing surface of the valve seat after the overlaying of the PAW process has more excellent wear resistance, and the sealing surface of the valve seat after the overlaying of the TIG and LBW processes also has better performance than the sealing surface of the existing valve seat.
Drawings
FIG. 1 is an optical microscopic view of the nickel-based alloy material (lower) and cobalt-based alloy material (upper) of example 2 valve seat sealing surface build-up.
Fig. 2 is an optical microscopic view of the base material (lower part) of the valve seat sealing surface and the nickel-based alloy material (upper part) of the build-up welding of example 2.
In the figure: cobalt-based material 1, nickel-based material 2, and base material 3.
Detailed Description
The invention will be further described with reference to the drawings and examples.
1. Alloy material for surfacing layer of sealing surface of valve seat
The alloy material comprises nickel base alloy and cobalt base alloy, wherein the mass ratio of the nickel base alloy to the cobalt base alloy is 1:1-5;
the nickel-based alloy comprises the following components in percentage by mass: 20-23% of chromium; molybdenum is 8-10%; niobium is 3.15-4.15%; iron <5%; aluminum <0.4%; titanium <0.4%; carbon <0.1%; manganese <0.5%; silicon <0.5%; cobalt <1%; phosphorus <0.015%; sulfur <0.015%; the balance being nickel;
the cobalt-based alloy comprises the following components in percentage by mass: 28-32% of chromium; molybdenum <1.5%; iron <3%; carbon is 0.9-1.4%; manganese <2%; silicon <1.5%; nickel <3%; phosphorus <0.015%; sulfur <0.015%; tungsten is 3.5-5.5%; the balance being cobalt. Wherein the nickel alloy is located below the cobalt-based alloy as a buffer layer.
The present invention, when studying the base material of the valve seat sealing surface, found that if the tungsten-chromium-cobalt-based alloy material is deposited on the base material of the valve seat sealing surface alone, the material is a tungsten-chromium-cobalt-based alloy having about 1% carbon, although the use requirements can be met in terms of performance requirements such as high temperature resistance, impact resistance, corrosion resistance, wear resistance, etc., this higher carbon content results in a microstructure consisting of a network of carbide particles in a softer matrix, depending on the welding method and dilution ratio. Because of the carbide network, the wear resistance is better, but the build-up layer is easy to crack, so the problem of poor crack resistance exists in the independent build-up cobalt-based alloy. Meanwhile, if the nickel-based alloy material is singly deposited on the base material of the sealing surface of the valve seat, although the nickel-based alloy material can meet the use requirements on performance requirements such as high temperature resistance, corrosion resistance, abrasion resistance and crack resistance, the nickel-based alloy material is Ni-Cr-based solid solution strengthening type deformation superalloy, is solid solution strengthening type nickel-based deformation superalloy taking molybdenum and niobium as main strengthening elements, and has aging hardening phenomenon after long-term use at 550-700 ℃, so that the nickel-based alloy material has better abrasion resistance, has good plasticity, ductility and fatigue resistance at 980 ℃ or below, is easy to generate larger deformation under the action of a certain load and is not impact resistant, and the problem of poor impact resistance still exists in singly deposited nickel-based alloy.
Therefore, after the two alloy materials are deeply researched, if the nickel-based alloy is used as a buffer layer, the nickel-based alloy is firstly deposited on the base body of the valve seat sealing surface, and then the cobalt-based alloy is deposited, so that the obtained sealing surface deposited layer has better comprehensive performance, the advantages/characteristics of the two materials can be well combined, the sealing surface deposited layer can simultaneously meet the comprehensive performances of abrasion resistance, impact resistance, corrosion resistance, high temperature resistance, scratch resistance, oxidation resistance, crack resistance and the like, the problems of easy cracking, falling off and other failures in the service process are reduced, and the valve seat sealing surface is fixed with the metal soup.
TABLE 1 Table of the composition of Nickel-based alloy materials selected for the invention
| Composition of the components | Range | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 |
| Chromium Cr | 20-23％ | 20.89％ | 23.0％ | 20.89％ | 21.5％ | 22.0％ |
| Molybdenum Mo | 8-10％ | 8.49％ | 10.0％ | 8.49％ | 9.0％ | 9.0％ |
| Niobium Nb | 3.15-4.15％ | 3.15％ | 3.15％ | 3.69％ | 3.6％ | 3.56％ |
| Fe of iron | <5％ | 4.67％ | 4.5％ | 2.5％ | 2.5％ | 2.74％ |
| Aluminum Al | <0.4％ | 0.17％ | 0.1％ | 0.17％ | 0.2％ | 0.2％ |
| Titanium Ti | <0.4％ | 0.18％ | 0.34％ | 0.10％ | 0.2％ | 0.1％ |
| Carbon C | <0.1％ | 0.03％ | 0.05％ | 0.058％ | 0.05％ | 0.058％ |
| Mn of Mn | <0.5％ | 0.08％ | 0.45％ | 0.08％ | 0.08％ | 0.01％ |
| Silicon Si | <0.5％ | 0.12％ | 0.45％ | 0.12％ | 0.48％ | 0.04％ |
| Cobalt Co | <1％ | 0.03％ | 0.03％ | 0.1％ | 0.13％ | 0.5％ |
| P of phosphorus | <0.015％ | 0.005％ | 0.015％ | 0.005％ | 0.005％ | 0.005％ |
| Sulfur S | <0.015％ | 0.0004％ | 0.015％ | 0.00044％ | 0.0004％ | 0.0004％ |
| Nickel Ni | Allowance of | Allowance of | Allowance of | Allowance of | Allowance of | Allowance of |
TABLE 2 composition table of cobalt-based alloy material selected in the present invention
| Composition of the components | Range | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 |
| Chromium Cr | 28-32％ | 29.0％ | 29.5％ | 28.0％ | 31.0％ | 30.5％ |
| Molybdenum Mo | <1.5％ | 1.0％ | 0.67％ | 1.4％ | 0.67％ | 1.2％ |
| Fe of iron | <3％ | 2.0％ | 2.0％ | 2.0％ | 2.5％ | 1.8％ |
| Carbon C | 0.9-1.4％ | 1.15％ | 1.2％ | 1.0％ | 1.3％ | 1.2％ |
| Mn of Mn | <2％ | 0.5％ | 1.08％ | 0.5％ | 1.2％ | 1.2％ |
| Silicon Si | <1.5％ | 1.1％ | 1.0％ | 1.1％ | 0.5％ | 0.5％ |
| Nickel Ni | <3％ | 2.3％ | 3％ | 2.5％ | 1.8％ | 1.5％ |
| P of phosphorus | <0.015％ | 0.005％ | 0.005％ | 0.005％ | 0.005％ | 0.005％ |
| Sulfur S | <0.015％ | 0.005％ | 0.005％ | 0.005％ | 0.005％ | 0.005％ |
| Tungsten W | 3.5-5.5％ | 4.0％ | 4.5％ | 4.0％ | 5.0％ | 3.5％ |
| Cobalt Co | Allowance of | Allowance of | Allowance of | Allowance of | Allowance of | Allowance of |
TABLE 3 Nickel-based alloy and cobalt-based alloy build-up welding formulation in the present invention
| Examples | Build-up welding material | Build-up welding ratio |
| 1 | Nickel-base alloy: cobalt-based alloy | 1:1 |
| 2 | Nickel-base alloy: cobalt-based alloy | 1:2 |
| 3 | Nickel-base alloy: cobalt-based alloy | 1:3 |
| 4 | Nickel-base alloy: cobalt-based alloy | 1:4 |
| 5 | Nickel-base alloy: cobalt-based alloy | 1:5 |
For the surfacing ratio, the surfacing ratio of 1:2 is taken as an example, namely, during surfacing, firstly surfacing 1 layer of nickel-base alloy, then surfacing 2 layers of nickel-base alloy, and when the nickel-base alloy is distributed on the pass, firstly surfacing 1/2/3/4 … … pass nickel-base alloy, and then surfacing 2/4/6/8 … … pass cobalt-base alloy. In actual operation, the number of the passes is selected and determined according to the model specification of the sealing surface of the valve seat, the number of the passes is relatively small (generally 1-4 passes) if the valve seat is a sealing surface of a small valve seat, and the number of the passes is relatively large (generally more than 10 passes) if the valve seat is a sealing surface of a large valve seat. The model specification of the valve seat sealing surface is related to the type of the turbine (namely the steam temperature of the turbine, wherein the steam temperature refers to the rated temperature of new steam at the inlet of a main steam valve of the turbine), and the higher the power grade parameter of the turbine is, the larger the model specification of the sealing surface of the valve seat is, but small sealing surface parts are also existed in the turbine with high power grade. Therefore, the number of passes is comprehensively determined according to the actual working environment of the steam turbine and the structure thereof.
2. Welding process for surfacing layer of sealing surface of valve seat
Polishing and cleaning the base body of the sealing surface of the valve seat, then overlaying a nickel-based alloy on the base body as a buffer layer, and overlaying a cobalt-based alloy to obtain the valve seat with the sealing surface of the overlaying layer.
Examples 1 to 5 were prepared by using the nickel-based alloy material compositions shown in Table 1 and the cobalt-based alloy material compositions shown in Table 2, respectively, and the nickel-based alloy and cobalt-based alloy weld-up were performed on the simulated ring member of the valve seat sealing surface of a steam turbine having a diameter of Φ20X3cm by using inert gas tungsten argon arc welding (GTAW, also called TIG), plasma arc thermal spray welding (PAW) and laser beam deposition weld-up (LBW), respectively, as shown in Table 3.
The present invention will be described in further detail with reference to examples 1 to 5.
1. Argon tungsten-arc welding
Welding wires are used for the nickel-based alloy and the cobalt-based alloy for build-up welding.
(1) Firstly polishing and cleaning a valve seat sealing surface substrate material;
(2) The method comprises the steps of forming a V-shaped groove on a base material of a sealing surface ring of a valve seat, overlaying a nickel-based alloy, wherein the polarity of a power supply is in direct current reverse connection, the welding current is 200-300A, the welding voltage is 9-15V, the welding speed is 70-95 mm/min, the interlayer temperature is 100 ℃, and the overlaying of the nickel-based alloy is completed according to the overlaying proportion, the layer number and the pass;
(3) The cobalt-base alloy is deposited by direct current positive connection, the welding current is 200-300A, the welding voltage is 9-15V, the welding speed is 70-95 mm/min, the preheating temperature before welding is more than 200 ℃, the post-heating temperature is controlled at 430-480 ℃, the interlayer temperature is controlled at 300-350 ℃, and the cobalt-base alloy is deposited according to the ratio of deposited, the layer number and the pass.
Table 4 shows the welding process parameters of examples 1-5 for the nickel-based alloy and cobalt-based alloy deposited by argon tungsten-arc welding
2. Plasma arc thermal spray welding
The nickel-based alloy and the cobalt-based alloy for build-up welding use alloy powder.
(1) Polishing and cleaning the base material of the sealing surface of the valve seat, and then cutting a V-shaped groove on the base material of the ring of the sealing surface of the valve seat.
(2) Surfacing nickel-base alloy: the polarity of the power supply is in direct current reverse connection, and one or more layers of nickel-based alloys are deposited on the surface of the sealing surface matrix according to the deposited welding proportion to serve as a buffer layer; in the step (2), when the first nickel-base alloy layer is deposited, the welding current is 162-200A, the welding voltage is 27-33V, the welding speed is 80-110 mm/min, the powder feeding speed is 20-33 g/min, the ion arc gas is argon, the flow rate is 180-200L/min, the shielding gas is argon, the flow rate is 540-600L/min, the powder feeding gas is argon, and the flow rate is 380-420L/min; when the second layer and above (if multiple layers are selected) are deposited, the welding current is 162-198A, the welding voltage is 27-33V, the welding speed is 80-110 mm/min, the powder feeding speed is 20-33 g/min, the ion arc gas is argon, the flow rate is 180-200L/min, the shielding gas is argon, the flow rate is 540-600L/min, the powder feeding gas is argon, the flow rate is 380-420L/min, the pre-welding preheating temperature is 90-110 ℃, and the interlayer temperature is 140-160 ℃.
(3) Build-up welding of cobalt-based alloy; the polarity of the power supply is connected directly, and one or more layers of cobalt-base alloy are deposited on the buffer layer according to the deposition proportion. In the step (3), when the first layer is built up by build-up welding cobalt-based alloy, the welding current is 162-200A, the welding voltage is 27-33V, the welding speed is 70-101 mm/min, the powder feeding speed is 33-40 g/min, the ion arc gas is argon, the flow is 170-190L/min, the shielding gas is argon, the flow is 540-660L/min, the powder feeding gas is argon, and the flow is 380-420L/min; when the second layer of the cobalt-based alloy is deposited and welded, the welding current is 162-198A, the welding voltage is 27-33V, the welding speed is 70-101 mm/min, the powder feeding speed is 33-40 g/min, the ion arc gas is argon, the flow rate is 170-190L/min, the shielding gas is argon, the flow rate is 540-660L/min, the powder feeding gas is argon, and the flow rate is 380-420L/min; the preheating temperature before welding is higher than 200 ℃, the post-heating temperature is controlled between 430 and 480 ℃, and the interlayer temperature is controlled between 300 and 350 ℃.
Table 5 shows the welding process parameters for the plasma arc thermal spray welding of the nickel-based alloys and the cobalt-based alloys of examples 1-5
3. Laser beam cladding build-up welding
The nickel-based alloy and the cobalt-based alloy for build-up welding use alloy powder.
(1) Polishing and cleaning the base material of the sealing surface of the valve seat, and then cutting a V-shaped groove on the base material of the ring of the sealing surface of the valve seat.
(2) Surfacing nickel-base alloy: the laser scanning speed is 8mm/s, the laser power is 1300W, the powder feeding speed is 10g/min, the coaxial air flow is 16L/min, the interlayer temperature is controlled at 90-110 ℃, and one or more layers of nickel-based alloy is/are deposited on the surface of the sealing surface substrate according to the deposition ratio to serve as a buffer layer.
(3) Build-up welding of cobalt-based alloy; the laser scanning speed is 8mm/s, the laser power is 1500W, the powder feeding speed is 10g/min, the coaxial air flow is 16L/min, the preheating temperature before welding is more than 200 ℃, the post-heating temperature is controlled at about 430-480 ℃, the interlayer temperature is controlled at 300-350 ℃, and one or more layers of cobalt-base alloy are deposited on the buffer layer according to the deposited welding proportion.
Table 6 shows the welding process parameters of examples 1 to 5 for the laser beam deposited weld build-up of nickel-based alloys and cobalt-based alloys
In specific implementation, the valve seat with the surfacing layer sealing surface is subjected to heat treatment, and the heat treatment temperature is 340-670 ℃. The build-up welding also includes shielded metal arc welding and submerged arc welding. The heat treatment temperature after surfacing needs to be determined according to the application and working environment of the sealing surface of the valve seat, and taking a steam turbine as an example, the working steam temperatures of different types of steam turbines are different, and the new steam temperature (DEG C) regulated by nine types of steam turbines is as follows: 1. low pressure non-reheat steam turbine: 340 ℃. 2. Secondary intermediate pressure non-reheat steam turbine: 390 ℃; 3. medium pressure non-reheat steam turbine: 435 ℃, 450 ℃, 470 ℃; 4. a secondary high pressure non-reheat steam turbine: 435 ℃, 450 ℃, 460 ℃, 470 ℃; 5. high pressure non-reheat steam turbine: 535 deg.c; 6. ultrahigh pressure reheat steam turbine: 535 ℃, 537 ℃, 538 ℃, 540 ℃; 7. subcritical reheat pressure turbine: 535 ℃, 537 ℃, 538 ℃, 540 ℃; 8. supercritical reheat pressure turbine: 538 ℃ and 566 ℃; 9. ultra-supercritical pressure turbine: 566 ℃, 580 ℃, 593 ℃, 600 ℃. In addition, the fresh steam temperature of the ultra-supercritical pressure turbine can be agreed by both suppliers and consumers, and the temperature of the fresh steam may exceed 600 ℃, so that the heat treatment temperature ranges from 340 ℃ to 670 ℃.
3. Performance testing
Comparative example 1 is a non-overlay substrate FB2 martensitic steel, and comparative example 2 is a non-overlay substrate F92 martensitic steel.
In order to intuitively illustrate various performance parameters of various embodiments, the wear resistance and the high temperature resistance are quantified by the high temperature wear percentage, the friction coefficient and the wear amount; quantifying the impact resistance, crack resistance and high temperature resistance by the length change percentage, the diameter change percentage and the crack initiation number of the high-temperature impact test; quantifying the crack resistance and the high temperature resistance by using the number of crack initiation strips in a high-low temperature cycle test; quantifying scratch resistance, crack resistance and high temperature resistance by using the number of crack initiation strips in a solid particle erosion test; the heat stability, oxidation resistance and high temperature resistance are quantified by the dilution rate of the high temperature aging test.
Wherein, the liquid crystal display device comprises a liquid crystal display device,
in units of 10 -5 mm 3 /N·m；
TABLE 7
Examples 1 to 5 and comparative examples 1 to 2 were subjected to a high temperature abrasion test, a high temperature impact test, a high and low temperature cycle test, a solid particle erosion test and a high temperature aging test, respectively, at 650 ℃. As can be seen from the results of table 7, the comparative examples have a large abrasion loss at high temperature, the abrasion resistance is far inferior to that of the examples, and the impact test length change percentage and the diameter change percentage are far higher than those of the examples, which means that the comparative examples are extremely easy to deform at high temperature, the examples have good impact resistance, the comparative examples develop a plurality of cracks after the high temperature solid particle erosion test, and the examples are all conditions of crack initiation, which means that the examples have good abrasion resistance, erosion resistance and high temperature resistance, and the dilution rate of main elements in the high temperature aging test is kept in a low range, which means that the examples have good thermal stability, oxidation resistance and high temperature resistance, and can work under normal operation at high temperature. The welded test pieces of example 2 were visually inspected and penetration-inspected, and no macrocracks were observed in the welded test pieces of example 2, as exemplified in example 1 to example 5. As shown in FIGS. 1-2, the nickel-based alloy material (lower part) and the cobalt-based alloy material (upper part) of the sealing surface of the valve seat of example 2 are subjected to build-up welding under an optical microscope and a scanning electron microscope, and all the nickel-based alloy material (lower part) and the cobalt-based alloy material (upper part) have no defects such as microscopic cracks, no pores, loose and unfused defects after observation. Example 2 optical microscopy of a base material (lower) for the valve seat sealing surface and a nickel-based alloy material (upper) for the weld overlay. The observation shows that the glass has no defects of micro cracks, air holes, looseness, unfused and the like.
According to the invention, after research on the base material of the sealing surface of the valve seat, when the nickel-based alloy is used as a buffer layer, the nickel-based alloy is firstly deposited on the base of the sealing surface of the valve seat, and then the cobalt-based alloy is deposited, so that the advantages/characteristics of the two materials can be well combined, the comprehensive performances of abrasion resistance, impact resistance, corrosion resistance, high temperature resistance, scratch resistance, oxidation resistance, crack resistance and the like of the deposited layer of the sealing surface can be simultaneously met, and the sealing surface of the valve seat is made of the solid-state alloy soup. The invention adopts tungsten argon arc welding (GTAW or TIG), welding rod arc welding (SMAW), plasma arc thermal spray welding (PAW), laser beam cladding overlaying (LBW) and Submerged Arc Welding (SAW) to carry out overlaying, which can achieve the technical effects of the invention, but after a plurality of welding methods are researched, the sealing surface of the valve seat after the overlaying of the PAW process has more excellent wear resistance, and the sealing surface of the valve seat after the overlaying of the TIG and LBW processes also has better performance than the sealing surface of the existing valve seat.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the technical solution, and those skilled in the art should understand that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the present invention, and all such modifications and equivalents are included in the scope of the claims.
Claims (2)
1. The welding process for the surfacing layer of the sealing surface of the valve seat is characterized in that nickel-based alloy and cobalt-based alloy are adopted as the surfacing layer, and the mass ratio of the nickel-based alloy to the cobalt-based alloy is 1:1-5;
the nickel-based alloy comprises the following components in percentage by mass: 20-23% of chromium; molybdenum is 8-10%; 3.15-4.15% of niobium; iron <5%; aluminum <0.4%; titanium <0.4%; carbon <0.1%; manganese <0.5%; silicon <0.5%; cobalt <1%; phosphorus <0.015%; sulfur <0.015%; the balance being nickel;
the cobalt-based alloy comprises the following components in percentage by mass: 28-32% of chromium; molybdenum <1.5%; iron <3%; carbon is 0.9-1.4%; manganese <2%; silicon <1.5%; nickel <3%; phosphorus <0.015%; sulfur <0.015%; tungsten is 3.5-5.5%; the balance being cobalt;
the nickel-based alloy is used as a buffer layer and positioned below the cobalt-based alloy and on the surface layer of the base body of the sealing surface of the valve seat;
the welding process comprises the following steps:
firstly polishing and cleaning a valve seat sealing surface substrate, then overlaying a nickel-based alloy serving as a buffer layer on the valve seat sealing surface substrate, and overlaying a cobalt-based alloy to obtain a valve seat sealing surface with an overlaying layer;
the overlaying is a laser beam cladding overlaying, and is carried out by the following steps:
(1) Firstly polishing and cleaning a valve seat sealing surface substrate material;
(2) Surfacing nickel-base alloy: the laser scanning speed is 8mm/s, the laser power is 1300W, the powder feeding speed is 10g/min, the coaxial air flow is 16L/min, the interlayer temperature is controlled to be 90-110 ℃, and one or more layers of nickel-based alloys are deposited on the surface of the sealing surface substrate according to the deposited proportion to serve as a buffer layer;
(3) Build-up welding of cobalt-based alloy; the laser scanning speed is 8mm/s, the laser power is 1500W, the powder feeding speed is 10g/min, the coaxial air flow is 16L/min, the preheating temperature before welding is more than 200 ℃, the post-heating temperature is controlled at 430-480 ℃, the interlayer temperature is controlled at 300-350 ℃, and one or more layers of cobalt-base alloy are deposited on the buffer layer according to the deposited welding proportion.
2. The welding process for a build-up layer of a valve seat sealing surface according to claim 1, wherein the valve seat with the build-up layer sealing surface is heat treated at a temperature of 340-670 ℃.
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