JPH02230968A - Water turbines and equipment and their manufacturing methods - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a water turbine and a method for manufacturing the same, and in particular, the surfaces of rotating equipment members used in running water containing a large amount of sediment are susceptible to cavitation, sediment abrasion, and the like. The present invention relates to a water turbine having an underwater earth and sand abrasion cladding weld layer suitable for preventing such damage, and a method for manufacturing the same.

[Conventional technology]

Components that come into contact with flowing water, such as water turbine runners, guide vanes, and stevens for hydroelectric power generation equipment, may be damaged by cavity collapse, cavitation due to impact, or erosion, depending on the shape of the component and the relationship with the flow velocity. Damage to a member due to cavitation is a phenomenon in which a cavity generated in high-speed flowing water collides with the surface of the member, and when it collapses, a high impact stress is applied to the member, and that portion is eroded. At that time, the impact pressure is as high as 514 to 1745 atm at a flow rate of 35 to 120 m/see.

For this reason, metal overlay welding materials have been developed that attempt to suppress damage by overlaying stainless steel materials with excellent cavitation and erosion resistance on the surface of the base metal in areas that come into contact with flowing water. The composition of these welding materials is disclosed in JP-A-57-15
Stainless steel materials have been used as disclosed in Japanese Patent Application Laid-open No. 2447, Japanese Patent Application Laid-Open No. 57-156894, and Japanese Patent Application Laid-Open No. 57-199593. Metal materials that can suppress damage caused by cavitation include those with high strength and hardness, or overlay welding materials that are expected to work harden the surface layer of flowing water using impact pressure. On the other hand, since cast iron, which is a component of pumps and the like, does not have sufficient wear resistance, wear-resistant materials have been developed in which ceramic particles are dispersed in wear-resistant rubber, polyurethane, epoxy resin, or the like.

The composition of such materials is disclosed in Japanese Patent Application Laid-Open No. 59-45363.
Publication No. - JP-A-59-45366, JP-A-59-Sho.
Publication No. 9-68349, JP-A-62-7292
Many of these are disclosed in Publications No. 2 to JP-A No. 62-72923, etc.

However, in hydroelectric power generation turbines that use river water containing a large amount of sediment, the constituent members of the turbine are made of hard SiO2, which is a component of sediment.
It is eroded by the cutting action of z and A Q z○3. It is said that harder metals are more resistant to cavitation damage. This is not necessarily the case in environments containing soil and sand. It is generally believed that erosion caused by cutting action, etc. can be prevented if the material is harder than the constituent substances of earth and sand. However, it is generally very difficult to apply a material with high hardness in a predetermined shape to large structural parts. Additionally, water turbines for hydroelectric generators have relatively little experience of being used in locations with high sediment content. There are no materials that have been developed to directly suppress wear caused by underwater sediment. Therefore, parts such as water turbine runners are hardened and tempered to satisfy their strength characteristics.
9m is used, and the surface is JISD3 made of stainless steel.
08, JISD309Mo, HST25, etc., is currently being used.
However, this method was not implemented with consideration given to underwater sediment abrasion resistance, so when targeting water turbines for hydroelectric generators in locations with high sediment content, underwater sediment abrasion resistance is insufficient and wear is significant. ．． Additionally, as a material for coated arc welding, a technique for forming a built-up layer on the surface of a base material using a mixed powder of Co-based super heat-resistant alloy powder and ceramic powder was disclosed in JP-A-62-1.
Although disclosed in the specification of No. 34193, this technique is a technique for imparting heat resistance, compression deformation resistance, etc. to the surface of a high-temperature member, and is not a technique applied to the water turbine that is the object of the present invention.

(Problems to be Solved by the Invention) Overlay welding of water turbine members using conventional metal welding materials has been carried out with the main purpose of preventing corrosion due to cavitation erosion of the water turbine runners, etc., as well as corrosion resistance. Therefore, the underwater soil and sand abrasion resistance is not necessarily high.

This is because cavitation erosion and sediment abrasion have different damage mechanisms. That is, the former is caused by impact pressure when cavities generated in high-speed water collide with the material surface and collapse, while the latter is caused mainly by the cutting action of earth and sand. Also,
In flowing water with a high sediment content, when cavitation and sediment abrasion work together, material damage is accelerated more than either factor alone. Therefore, the conventional slanless steel JISD308, JISD309Mo, H
ST25 etc. had problems when applied to water turbines in locations with high soil content. On the other hand, a polymer-ceramic composite material that is resistant to sediment abrasion has been developed, which is a composite of organic polymer material and ceramics. This is an attempt to alleviate the cutting action of earth and sand by dispersing hard ceramics in polymers. However, when used underwater, it is not necessarily only abrasion of earth and sand, but combined damage with cavitation and erosion is large.In particular, the abrasion resistance of polymer-ceramic composite materials in water is not inferior to that of metal materials. However, it is much inferior to metal materials in terms of cavitation damage. Therefore, there is a problem in terms of reliability when using polymer-ceramic composite materials for water turbine structural members at flow points containing high soil and sand. The first object of the present invention is to obtain a water turbine having a built-up weld layer on the base of the turbine, which is subjected to water impact, that simultaneously suppresses erosion due to cavitation and wear due to earth and sand, and is easy to construct. The second object of the present invention is to provide a method for manufacturing a water turbine having an overlay weld layer that simultaneously suppresses cavitational erosion and wear due to earth and sand and is easy to construct. [Means for Solving the Problems] The present invention provides a water turbine equipped with a guide vane that adjusts the flow of running water and a runner that is rotated by the running water. a member having a weld build-up layer, the weld build-up layer including a matrix of austenitic stainless steel;
It is characterized by a metal structure with carbides dispersed in this matrix. The method for manufacturing a water turbine of the present invention, which achieves the second object of the present invention, provides a build-up weld layer having higher cavitation resistance than the base material on at least a portion of the portion subjected to water impact. The method is characterized in that a mixed powder with carbide-based ceramic powder is melted by a plasma arc and supplied to the part to be welded, and a pool of molten metal is created in the part to be welded to form an overlay weld layer of a desired thickness. ．． The content of carbide is preferably 1 to 50% in terms of area ratio. Particularly in areas that are subject to rapid impact from running water and cavitation, it is best to use a material with high toughness as a build-up weld layer.
~10% is preferred. In addition, in areas where wear due to running water is dominant, 10 to 50% is preferable, and the hardness is Hv
300-700 is preferable. The relationship between the amount of carbide added and the area percentage of crystallized substances contained in the overlay weld layer is 20% when the amount added is 5% by weight, 40% when the amount is 10% by weight, and 15%.
In terms of weight%, it is 60%.

In the water turbine of the present invention, the carbides dispersed in the matrix of the austenitic stainless steel constituting the overlay weld layer provided in the portion subjected to water impact are: (A) the metal remaining in the overlay weld layer; It includes both carbide-based ceramic particles and (B) metal composite carbide which is crystallized after overlay welding without any remaining metal-carbide-based ceramic particles. (A) The remaining solidified structure structure coating layer of the ceramic particles is:
The powder particle size of the metal carbide ceramic (S) having a high melting point is such that the particle size ratio S/M is 2 or less, preferably 1 to 2 with respect to the powder particle size of the austenitic stainless steel (M) of 10 to 200 μm. , metal carbide ceramic (S) is contained in an amount of 20 to 80% by volume, and the overlay weld layer has a solidified structure in which metal carbide ceramic particles remain in the layer. In addition, as the austenitic stainless steel, AI
SI304, 316, etc. can be used. That is, these materials have a weight of . C0.01~0.15%, Si1
% or less, Mn 13% or less, Cr 16~26%, Ni2~
Based on 22%. In addition, Mo 5% or less, Co 12% or less, Cu 5% or less, NO. 3% or less, N
It contains 0.1 to 5% of at least one of b, Ti, W, and V. More preferably c: o.% by weight.
os~0.15%, Si: 0.2~1.0%, M
n: 7-13%, Ni: 2-7%, Co: 6-1O%
, Cr: 17 to 23%. Furthermore, Mo: 1 to 3
%, N: 0.3% or less, the remainder consists of Fe and accompanying inevitable impurities, (Mn% + Co%) /
The composition has a Cr% value of 0.6 to 1.3,
It is preferable to use pseudo-martensitic stainless steel, which has higher work hardenability than AISI 304 or 316.

Further, the metal carbide ceramics include SiC, VC,
At least one species selected from the group of NbC, TiC, WC, and CraCz. On the other hand, (B) the composite powder used to form the overlay weld layer with a solidified structure in which no ceramic particles remain has a powder particle size of the metal carbide ceramic (S) having a high melting point and the austenitic stainless steel 11 (M ) has a powder particle size in the range of 10 to 200 μm, has a particle size ratio S/M of 1 or less, contains 1 to 40% by volume of metal carbide ceramics (S), and the coating layer contains It has a solidified structure in which no metal carbide-based ceramic particles remain and crystallized metal composite carbides are dispersed. In addition, the austenitic stainless steel used in the case of this (B) welding layer with no residual solidification structure of ceramic particles is the same stainless steel as in the case of (A) welding layer with residual solidification structure of ceramic particles. Used. Furthermore, the metal carbide ceramics have a lower density than stainless steel, have a cubic crystal structure, and include SiC, Ti, etc.
At least one species selected from group C. Further, in (A) and (B) the solidified structure build-up weld layer with residual or non-residual ceramic particles, the powder shapes of both the austenitic stainless steel and the metal carbide ceramic are round, square, rounded square, Or a mixture thereof is preferred. The overlay welding layer is preferably formed by plasma arc overlay welding, and has a thickness of 5 am or less. The water turbine of the present invention is applied to a water turbine for hydroelectric power generation that uses water containing high sediment content, and is intended to minimize damage caused by cavitation, damage caused by sediment abrasion, and the occurrence of combined damage thereof.

Furthermore, the water turbine of the present invention will be explained. (A) Ceramic particles (7331! In the existing solidified structure welding layer, Si
Metal carbide ceramic powder such as c, vc, NbC, TiC, WC4 and CrsCz is mixed into stainless steel powder.
By mixing ~80% by volume to form a composite powder and performing plasma overlay welding, a solidified structure in which ceramic particles remain is formed. In this case, the particle size ratio S/M of the ceramic powder (S) and the stainless steel powder (M) is set to 1 to 2. This is because ceramics has a higher melting point than stainless steel, and stainless steel powder melts in the plasma arc, leaving ceramic particles behind.

If the ratio becomes too large, large particles will be adjacent to each other,
This increases the tendency for segregation, and as a result, cracks are more likely to occur due to the stress used in actual machine applications. On the other hand, the reason why the above-mentioned ceramics were selected is to suppress the erosion caused by the cutting action of the earth and sand by dispersing the ceramics which are harder than the earth and sand constituent materials Si02 and kQzo3.

(B) SiC and TiC powders of metal composite carbide ceramics that are present in the non-residual solidified structure coating layer of the ceramic particles and have a lower density than stainless steel are selected and mixed with stainless steel powder to form a composite powder. A build-up weld layer is formed by plasma build-up welding, and as a result, no ceramic particles remain in the build-up weld layer, and a solidified structure in which metal composite carbides are crystallized and dispersed is formed. For this purpose, the particle size of stainless steel powder and ceramic powder is 10 to 200.
μm is preferred. When these particle sizes are increased, unmelted stainless steel powder and ceramic powder particles remain. However, the melting point of stainless steel and ceramic powder is higher for ceramics, so in order to weld these composite powders, it is better to make the particle size of ceramic powder smaller than that of stainless steel powder, so that it will be easier to melt by plasma arc. Therefore, as mentioned above, it is preferable to set the S/M to 1 or less. In addition, in the case of both (A) and (B) welding layers with residual or non-residual solidified structure of ceramic particles, both the stainless steel powder and the ceramic powder have a round shape, a square shape, a rounded rectangular shape,
or a mixture thereof, and can be manufactured by ordinary powder metallurgy techniques. In addition, the larger the amount of overlay welding actually formed on the surface of the equipment component, the better, but considering the ductility and toughness of these welds, it is necessary to form a layer that is hardly mixed with the component (base metal). Therefore, it is sufficient if it is 5 ow or less, and wear resistance performance can be achieved. In addition, when overlaying on parts that are subject to water impact, cover arc,
This can be done by a normal welding method such as TIG or MIG welding. However, as in the present invention, it is relatively difficult to overlay a composite powder of ceramic powder and stainless steel powder using these methods, and therefore plasma arc welding, which allows welding by mixing the powders, It can be implemented effectively. According to the present invention, in the water turbine, at least a portion of the surface of the equipment member that comes into contact with water containing high soil and sand contains 20Cr-4N i -
6 Co-1. 5 Mo-1 0
Mn-0. A composite powder of 2N austenitic stainless steel and metal carbide ceramics, which has a higher melting point and hardness than stainless steel, is used to form an overlay weld layer by plasma arc welding. This overlay weld layer has a structure in which carbides are dispersed in the matrix of austenitic stainless steel, and this structure can minimize damage caused by sand to turbine equipment components that utilize river water containing high sediment content, making it reliable. It is possible to configure a highly flexible system.

In addition, damage due to earth and sand abrasion, damage due to cavitation, and combined damage of both (A) a built-up weld layer with a residual solidified structure of ceramic particles and (B) a built-up weld layer with a solidified structure without a residual solidified structure of ceramic particles. However, the former (A) is particularly suitable for soil and sand abrasion resistance, and the latter (A) is particularly suitable for soil and sand abrasion resistance.
B) is easy to manufacture the overlay weld layer. Furthermore, the erosion-resistant overlay welding layer according to the present invention includes austenitic stainless steel, metal carbide ceramics with a metal coating layer on the surface, and rare earth element composite powder welded overlay on the substrate surface of the equipment member. This overlay weld layer suppresses erosion due to cavitation, earth and sand abrasion, and combined damage thereof, and has good toughness and weldability.

Next, FIG. IA shows a cross-sectional view of the water turbine to which the overlay weld layer, which is the main component of the present invention, is applied, and FIG. IB shows a perspective view of the runner part when viewed in the X direction in FIG. IA. Shown below. The runner body, which is the main feature of this water turbine, has a plurality of blades 3 between the crown 1 and the shroud 2, and is composed of a runner cone 4, a guide vane 5, a steven 6, a runner liner 7, and a sheet liner 8. Flowing water containing earth and sand that has passed through 6 flows from guide vane 5 to blade 3, imparts rotational energy to the runner blade, and falls downward. 9 indicates a band.

Figure 2 shows an example of the welding state of the overlay weld layer provided on the blade 3 of the water turbine of the present invention with the blade, and the microscopic structure of the overlay weld layer in which crystallized carbides are precipitated in the austenitic stainless steel matrix. This is the photo shown. This blade 3 is generally made of Nil3Cr-containing material obtained by ordinary melting and casting.
&II9. However, considering the damage caused by cavitation on the surface that comes into contact with the flowing water,
Conventionally, measures to prevent this have been taken by applying overlay welding to austenitic stainless steel (stainless steel JISD308, D309Mo, etc.). However, it has been found that these materials do not necessarily show good results in terms of soil abrasion. Therefore, we investigated overlay welding metal materials with high hardness, but it is known that they do not necessarily provide satisfactory wear characteristics and have limitations due to the relationship with the base material, such as cracks occurring in the overlay part. It was done. After various studies, we focused on the fact that austenitic overlay welding materials have fewer weld cracks and are easier to work with.
Cavitation resistance is JISD308 and D309M
20Cr-4Ni-6Co- of the present invention which is superior to o
1. 5 M o − 1 0 M n −− 0
．． A layer 10 was formed by plasma overlay welding of a mixed powder of 2N austenitic stainless steel powder and metal carbide ceramic powder. It has been revealed that this layer 10 has a metal structure comprising an austenitic stainless steel matrix and carbides dispersed in this matrix, and has excellent cavitation resistance and earth and sand abrasion resistance. The thickness of the overlay weld layer is 5 m or less, and although it may be multi-layered, a single layer can be sufficiently effective, and is preferably 1 to 3 m. It should be noted that the powder used in the present invention can be obtained by a production method commonly used in powder metallurgy technology. Furthermore, the aforementioned austenitic stainless steel powder is used as the base material of the mixed powder used in plasma overlay welding, and this powder has good weldability and cavitation resistance, and the base material of the present invention by being optimal.

Next, the reasons for limiting each ingredient will be described.

(Austenitic stainless steel powder) Compositions indicate weight percent. C is a strong austenite-forming element and contributes to stabilizing austenite and strengthening the base. When the amount of C is small, the amount of δ ferrite precipitation increases, and the ductility, toughness, and cavitation resistance decrease. However, increasing the amount of C increases the susceptibility to weld cracking during welding.
is preferably in the range of 0.05 to 0.15%. Si is added to deoxidize the welded parts, and is 0.2%.
If it is less than 1.0%, this deoxidizing effect will be insufficient, and if it exceeds 1.0%, low melting point compounds will be created at the solidified grain boundaries, increasing hot cracking susceptibility, so it is preferable that Si is in the range of 0.2 to 1.0%. It is. Mn is usually added in an amount of 13% or less to further improve work hardening properties for deoxidizing and desulfurizing steel materials, but it contributes to increasing the amount of N solid solution and is an austenite forming element. The amount added according to the present invention, together with Ni and Co, stabilizes the austenite composition and further softens the austenite matrix, but increases work hardenability, thereby significantly improving earth and sand wear resistance. As a result, when the amount of Mn added increases, cutting resistance increases and soil wear resistance is imparted. Therefore, in order to obtain this work hardenability, the amount of Mn added is preferably 7% or more. On the other hand, excessive addition of Mn impairs metal flowability and increases welding fume during welding, reducing welding workability, so the upper limit of the Mn content is set at 13%. Therefore, the Mn content is 0.5 to 13%, but a range of 7 to 13% is suitable for achieving work hardening properties. Ni is an austenite-forming element, and together with Mn and Co, it stabilizes austenite and needs to be added in an amount of 2% or more to improve ductility and toughness. However, when the amount added exceeds 6%, stabilization of austenite progresses. In order to have high earth and sand abrasion resistance and cavitation resistance accompanied by work hardening properties, the Ni content is preferably in the range of 2 to 7%. The upper limit of Ni is preferably 22%. Co, together with Mn and Ni, moderately stabilizes austenite and particularly improves earth and sand abrasion resistance, cavitation resistance, and erosion resistance, so it is preferably contained in an amount of 12% or less. If the amount is less than 6%, these effects will not be sufficient, and if it exceeds 10%, the base will be strengthened and the ductility and ductility will be reduced.

In particular, a range of 6 to 10% Co is suitable for soil abrasion resistance.

Cr is effective in improving corrosion resistance in water and is necessary for strengthening bases, but if it is less than 17%, soil and sand abrasion resistance cannot be fully demonstrated. On the other hand, if it exceeds 23%, the amount of δ ferrite produced increases, resulting in a decrease in ductility and toughness, so Crl
A range of 6 to 26% is suitable. More preferably 17~
It is 23%.

Mo not only strengthens the base but also improves corrosion resistance, and is effective in improving soil abrasion resistance, cavitation, and erosion resistance. However, if it exceeds 5%, the amount of δ ferrite produced increases and the toughness decreases. In particular, Mo is preferably in a range of 1 to 3%. N works together with C to stabilize austenite, and is an essential element for austenite formation, especially in low C steels. It is also effective in improving soil abrasion resistance, etc.
If added in excess, it forms nitrides and impairs toughness.
It is preferable to keep N at 0.3% or less. More preferably, it is 0.05 to 0.2%.

Cu solidly dissolves in the austenite base, strengthens the base, and improves soil abrasion resistance and cavitation resistance. but,
If the amount added is increased too much, cracks due to welding will increase, so the range is preferably 0.1 to 5%.

Nb, Ti, W, and V are grain refining and carbide forming elements, and if this type of carbide ceramics is not used, they will react with decomposed and melted C to form carbides and improve ductility and toughness. ．． However, if added too much, weldability will deteriorate, so a range of 0.1 to 5% is preferable.

The remainder consists of Fe and accompanying impurities, including P, S, and therefore As, Sb, etc., but these elements impair ductility and toughness and reduce weldability, so it is desirable to have as little as possible. (Metal coating on metal carbide ceramic powder) Metal coating on metal carbide ceramic powder suppresses the scattering of ceramics during welding, especially when combining ceramics with a smaller specific gravity with stainless steel powder. It is also a means for uniformly dispersing and melting the overlay weld layer.

This metal-coated carbide ceramic has a specific gravity close to that of stainless steel powder, making it easier to supply the powder.
It is effective in welding workability.

The surface of carbide ceramics is coated with metals such as Ni, Cr, Cu, Fe, Co, and alloys thereof by chemical plating, electroplating, and other physical and chemical methods. In this case, a single metal coating with a high melting point is preferable.
However, Ni-P compounds can be easily applied to ceramic powder by chemical plating. In addition, in relation to stainless steel and rare earth elements described later, the amount of metal coating is determined by the ratio of the thickness of the metal coating layer to the radius of the carbide ceramic grain size that does not impair powder mixing and welding workability.
The following are preferred.

(Rare Earth Element) The mixing of the rare earth element powder of the present invention causes the formation of a compound with a particularly low melting point on the surface of the metal carbide ceramic particles.
It is effective in the case of a coating layer containing such as. This is based on the fact that these rare earth elements combine with P and the like to form a high melting point compound.

The rare earth elements are preferably lanthanide elements listed in numbers 57 to 71 of the periodic table and alloys thereof.

However, commonly used powders of La, Ce, and their compounds are preferable. In particular, single elements of La and Ce are easily oxidized, and when handled in the atmosphere, they form an oxide layer and impair weldability. These compounds such as L
aNie etc. are optimal. If the mixing amount is less than 0.1%, the effect will not be exhibited, and if it is more than 5%, it will have the effect of reducing weldability, so 0.1 to 5% is preferable. The amount to be mixed in the mixed powder of stainless steel powder and ceramic powder is preferably 1 to 5 VoQ%. On the other hand, these build-up layers can effectively exhibit erosion resistance by imparting compressive residual stress to their surfaces by shot peening or the like. Furthermore, if the surface is treated by peening or the like, metal powder etc. from the treatment will remain on the surface of the built-up layer due to entrainment, etc., so by removing the surface layer, damage resistance can be more effectively exhibited.

In this case, if the surface layer is removed using emery paper or the like with a large pressing force, compressive residual stress will remain on the cut surface, which is effective in imparting damage resistance, and the surface roughness will increase.
It should be 0 μm or less.

The erosion-resistant coating layer of the present invention is particularly suitable for water turbines, where river water contains 1% or less of sediment in a steady state; It is useful for

Equipment used in solid-liquid multiphase fluid media includes at least water turbine runners, liners and nozzles, steam turbine blades,
It is effective for ship propellers, sand pump impellers and liners, slurry transport pumps and piping, and the surfaces of materials that handle these media. (Metal carbide ceramics) Regarding metal carbide ceramics, (A) a coating layer having a solidified structure in which ceramic particles remain, and (B)
In both cases (A) and (B), the ceramic has a high melting point and high hardness, compared to the overlay weld layer that has a solidified structure in which no ceramic particles remain and crystallized carbide, which is a metal composite carbide, is dispersed. Any metal carbide ceramic can be used. However, in the case of (A) or (B), it is more preferable to use the following metal carbide ceramics.

(A) Solidified microstructure in which ceramic particles remain
, WC, CrsCz, NbC, and VC, and by forming an overlay welding layer with a mixed powder with stainless steel and leaving ceramic particles in the layer, effective underwater soil abrasion resistance is achieved. It is a sign of improvement. The residual amount of these particles depends on the welding conditions, but if they are less than 20% by volume of stainless steel, they will not penetrate into the layer and have no effect. However, when it exceeds 80% by volume, the area in which the ceramic particles come into contact with each other increases, and this area becomes more frequently chipped by earth and sand, making it more likely that cracks will occur based on this area. Therefore, the amount of ceramics is preferably 20 to 80% by volume based on the amount of stainless steel powder. Among ceramics, SiC is preferred. (B) SiC, which is a solidified structure carbide-based ceramic in which no ceramic particles remain and crystallized metal composite carbides are dispersed. By mixing TiC powder with stainless steel powder and creating an overlay weld layer from this mixed powder, a metal structure in which carbides crystallize in an austenitic stainless steel matrix is obtained, which reduces cavitation, earth and sand wear, and their composites. This is to suppress damage. These damage resistance effects cannot be achieved unless 1% by volume is mixed with stainless steel. However, if more than 40% by volume is added, this stainless steel becomes susceptible to cracking, so the mixing amount is preferably 1 to 4% by volume based on the amount of stainless steel powder. In addition, in the present invention. S
iC and TiC were chosen because their crystal structures are cubic, similar to stainless steel. Furthermore, in consideration of relieving the stress caused by centrifugal force in the rotating part, the material is limited to a material having a lower density than stainless steel. In this case, the effect is that construction is easy. Base material: C0.2% or less, Si2% or less, Mn2%
Below, forged steel containing 8 to 14% Cr and 6% or less Ni,
Cast steel is preferred. Furthermore, this composition contains Mo 2% or less,
Wl% or less, Ti, Nb, ■1% or less, Zr, Hf0.
It can contain at least 5% of at least one species. [Example] Example 1 Table 1 shows the stainless steel powder (particle size 125μ) shown in the table.
m) metal carbide ceramic powder (particle size 210 μm)
) are mixed at various volume ratios. This mixture was welded using a powder plasma overlay welding device with an arc current of 22
0 to 250A, arc voltage 32 to 35V, torch weaving width 94cm, 15 to 16 cycles/wi
n, Ar gas supply amount (Q/+sin) for plasma 3
, carrier 5, shield 15, and a 3m layer was built up under the welding conditions. The resulting overlay weld layer had a solidified structure in which metal carbide ceramics remained in the overlay weld layer. Figure 12 is a schematic cross-sectional view of a commercially available plasma overlay welding device. Plasma gas (Ar) 23 at the start of operation
A pilot arc is generated by introducing gas and flowing it between the W electrode (-) 21 and the base metal (+) 22, and then a shield gas (Ar) 24 is caused to flow between the electrode 21 and the workpiece 22. A voltage was applied to generate a plasma arc. Then, a mixture 25 of powder (stainless steel powder + ceramic powder) and carrier gas (Ar) is supplied from the powder feeding device to the plasma arc 26, and the powder is transferred to the base material 22 by plasma heat. It was melted on the surface and welded to the base metal to create a build-up weld layer.

For comparison, a conventional overlay weld layer was constructed as follows. Table 2 shows the chemical composition of welding rods used in conventional covered arc welding.

The welding conditions are: diameter 4aiφ, 1! Current 150A, voltage 23V
, a 3m layer was built up under the condition of heat input of 16KJ/aI1. In addition, in the construction of the overlay weld layer of the present invention and the overlay weld layer of the comparative material, both welds are made of Nil3Cru steel containing Nil3Cru steel (components are the same as Nα12 in Table 2) in the base material and are 25tX100mmX.
A plate with dimensions of 150 nn was provided. After welding, an underwater earth and sand abrasion test piece of 5 t x 20 mm x 50 na was taken, and the test surface was finished with #1200 emery paper and used for the test.

Comparison of cavitation resistance in experiments was conducted using a magnetostrictive vibration cavitation tester at a frequency of 6.5 KHz.
, volume loss (cd) calculated by dividing the weight loss after a 2-hour test in tap water by the density under conditions of an amplitude of 120 μm and a test temperature of 25°C.
It was evaluated by

On the other hand, the soil and sand abrasion properties of the liquor were tested and evaluated using a water jet test device containing soil and sand under the following conditions. Jet velocity 4Qm/s, collision angle 45deg. The soil was AQzOs with an average particle size of 8 μm, the content was 30 g/Q, and the test time was 4 hours. The amount of wear after the test is the volume loss divided by the density (
．． ffl). Note that this device uses a method that can inject water containing sediment into the water, and can generate cavitation. Therefore, the cavitation coefficient K = 0.12 and K
=0.6. This condition can cause combined damage of cavitation and soil abrasion. V”/2
g However, V: Average jet velocity (m/s) g: Acceleration rate of gravity (m/s'') Pa: Atmospheric pressure (mAg) Pv: Vapor pressure (mAg) Pg: Fluid pressure (mAg) That is, K= 0.6 is the condition where damage is caused only by earth and sand abrasion, and K=0.12 is a condition where earth and sand abrasion and cavitation are combined.Figure 3 shows the condition where the cavitation coefficient is K0.6 and 0.12. Curve A shows the relationship between SiC content and the amount of wear due to earth and sand, and curve A is K=
0.6, and curve B represents the case where K=0.12. The amount of wear tended to decrease as the amount of SiC added increased. Furthermore, since the amount of wear tends to increase when the amount of SiC reaches 80% by volume, the upper limit was set.

Figure 4 shows the results of testing the overlay weld layer of the present invention shown in Table 1 and the overlay weld layer of the comparative material shown in Table 2 under the condition of a cavitation coefficient of 0.6. Sample Nα in the table is plotted on the horizontal axis, and the amount of wear due to earth and sand is shown. The overlay weld layers Nα2 to 11 of the present invention have a significantly smaller amount of wear than the comparative materials &1.12 to 16. Therefore, it is clear that the overlay weld layer of the present invention can be sufficiently effective as a component of a water turbine that uses water containing high soil and sand.

In addition, the mixed powder containing 40% of the volume of SiC of the present invention was used on equipment members made of 5Nil3Cr cast steel such as the guide vanes 5 and sheet liners 8 of a water turbine as shown in the schematic diagrams of FIGS. A build-up welding layer 10 was provided by build-up welding, and this was annealed at 550 to 650°C, and then machined to a predetermined thickness (1 to 3 m) to form a coating layer 10. Welded overlay layers were also formed on the turbine runner and cover liner in the same way.

By forming this overlay weld layer, it was possible to prevent wear due to earth and sand, erosion due to cavitation, and combined damage thereof.

Example 2 Table 3 shows the stainless steel powder (particle size 149
μm) to metal carbide ceramic powder (particle size 149μm)
) are mixed at various volume ratios. This mixture was welded using a powder plasma overlay welding device with an arc current of 22
0 to 250A, arc voltage 32 to 35V, torch weaving width 94I, 15 to 16 cycles/
win, Ar 3am under welding conditions with gas feed rate (Q/win) of plasma 3, carrier 5, and shield 15
Overlay was applied and the overlay weld layer was easily formed. Note that N i 1 3 Cr (components are the same as Nal2 in Table 2) cast steel (25t x 100w + x 150m) was used as the base material. An overlay weld layer with no remaining metal carbide ceramics and a solidified structure consisting of an austenitic steel matrix and crystallized carbides dispersed therein was obtained.
Figure 2 shows the microscopic structure of this overlay. The resulting overlay weld layer of the present invention was subjected to a wear test by causing combined damage of cavitation and sand abrasion with a cavitation coefficient K=0.12 in the same manner as in the examples, and the results are shown in FIG. Curve C shows SiC, and curve D shows TiC addition amount and cavitation weight loss. In addition, the hardness of both SiC and TiC improves as the amount of addition increases, especially for SiC40.
A Vickers hardness of approximately 700 in volume % was obtained. Note that if more than this is added, the hardness will be improved, but cracking will easily occur, so the present invention has set the limit at 40% by volume.

Similar to hardness, cavitation loss decreases as the amount added increases. When compared with the base material (point 1), it can be seen that its cavitation resistance is greatly improved. FIG. 8 shows the weight loss due to cavitation between the overlay weld layer of the present invention shown in Table 3 and the overlay weld layer of the comparative material shown in Table 2. Sample Nα in Figure 8 is the same as sample number 2 in Table 3.
The sample rod in the table is represented by the overlay weld layer Nα17-2 of the present invention.
6 is compared to the comparative materials Nα1, 12 to 16, and the overlay weld layer made of the stainless steel-ceramic composite powder of the present invention is better than the comparative materials such as Nil3Cr-containing cast steel, SUS304, and conventional overlay welding materials. It is clear that it is very good.

In addition, Fig. 9 shows SiC (curve E) and TiC (curve F).
It shows the amount of addition and the amount of wear due to earth and sand.

Moreover, FIG. 10 shows the amount of wear due to earth and sand of the overlay weld layer of the present invention (samples Ncl7 to 26 in Table 3) and the overlay weld layer of the comparative material (samples Nα1 and 12 to 16 in Table 2). From Figures 9 and 10, it can be seen that the wear amount of the overlay weld layer of the present invention decreases as the amount of SiC and TiC added increases, as well as the cavitation resistance, and compared to the comparative material and the base material (point 1).
It is clear that the overlay weld layer of the present invention has excellent composite damage resistance compared to the above. Example 3 A water pot shown in Figures IA and IB was manufactured. Chapter I
The surface of the water turbine runner shown in Figure B that comes into contact with water (action surface P
) side (Fig. 11B), both inlet ends (A, B) of the blade 3
) Centered on each of the blade inlet lengths (LL) (approximately 1
65mm) with a radius of 1/2 to 1/5)
10) An overlay welding layer 1o was provided. Regarding the reverse side of the working surface (reaction surface (R)) of the water turbine runner shown in FIG. 172~1/
The overlay welding layer 11 is provided in a fan-shaped area with a radius of 5, and the width (W) is 50 to 150 m from the outer exit end (E) of the blade 3 (shown in Figures IA and 11A), and the blade outlet length is 50 to 150 m. The overlay weld layer 12 was provided in a length (Q) range of 1/2 to 2/3 of the length L2. These overlay welding layers were created using the same welding conditions as in Example 2 and using the mixed powder of Na20 shown in Table 3, and then this layer 550
It was made by sintering and purifying at ℃ to 650℃ and then machining it to a thickness of 1 to 3 IIn. The fan-shaped part (10) centered at the inlet end (A, B) on the action side of the blade 3 is a part where wear is large due to running water containing earth and sand; Both the fan-shaped portion (11) extending from the outer exit end (E) and the portion corresponding to the overlay weld layer (12) are susceptible to damage due to cavitation. That's the ugly part.

The guide vanes and sheet liners were the same as those shown in Example 1. Next, these parts were assembled to create a water wheel. When this turbine was actually operated in running water containing sediment, it showed both excellent wear resistance and cavitation resistance.

Example 4 Table 4 shows the stainless steel powders shown in the table (average particle size 1
49μm). Ni-P surface coated metal carbide ceramic powder (average particle size before and after surface coating treatment: 105 μm → 18
5 μm) and rare earth element compound LaNi5 (average particle size 140 μm) are mixed in various volume ratios. This mixture was welded using a powder plasma arc overlay welding device at an arc current of 220 to 25 OA and a 7-volt voltage of 32 to 3.
5v, torch weaving width 94mm, number of times 15-16c
ycle/win, Ar gas supply amount (ff/win
) was overlaid on three fields under welding conditions of plasma 3, carrier 5, and shield 15 to form an overlay weld layer. Note that the surface coating treatment on the surfaces of the metal carbide ceramic particles was performed in an electroless nickel plating solution in a neutral bath.

The base material used for this weld overlay construction was Nil3Cr-containing cast a.
l! (25tX100mX150am).

For comparison, NilaCr&!, which is used as a water turbine runner material, is also shown below. Steel, AISI 304, a stainless steel build-up welded by conventional covered arc welding, and a powder plasma build-up layer of stainless steel and ceramics without a surface metal coating layer were provided. Tables 5 and 6 show their chemical and formulation compositions. The coating mark welding conditions were a rod diameter of 4 mmφ, a current of 150 A, a voltage of 23 V, and a heat input of 16 KJ/am, taking into account dilution with the base metal.
Although the welding was performed by 8 m, the powder plasma welding conditions were the same as those described above. In addition, the impact test piece (JIS Z2242 is 15 nm
It was collected in bulk.

The construction of the welded overlay layer of the present invention and the welded overlay layer of the comparative material is the same as described above.

It was confirmed that the amount of wear due to earth and sand in this example shows almost the same value as shown in FIG. 3 above when the SiC content is 10 to 80 VoQ%.

Table 7 shows the evaluation results of the inventive overlay weld layer and the comparative overlay weld layer in powder plasma overlay welding.

Compared to the comparative layer, the layer according to the present invention has a similar hardness, but has improved welding crackability, ductility, and toughness.

On the other hand, as is known from the results for Na2-10, when surface metal-coated (Ni-P) SiC is used, the SiC1
Cracking occurred even with 0VoΩ% formulation. There was no cracking in the SiC10VoR% formulation (Nα20) with no surface metal coating, but in &5 to 10, the rare earth element formulation was La
Cracking is improved when Ni5 is added at 0.3% or more. This is approximately 0.1% when converted to La.

Figures 13 and 14 show the weight loss due to cavitation damage and the weight loss due to earth and sand abrasion under the condition of K=0.6 between the overlay weld layer of the present invention shown in Table 4 and the overlay weld layer of the comparative material shown in Table 5. shows. Inventive overlay welding layer Nα4, 7, 8
．． Although the erosion resistance of No. 10 is the same as that of the comparison materials Na21 and 25, the comparison materials Na27-3
It is clear that this material is extremely superior to the Nil3Cr-containing cast steel of No. 1, SLIS304, and conventional coated arc welding materials.

Therefore, it is clear that the welded overlay layer of the present invention can be sufficiently effective as a structural equipment member used in a mixed flow field containing high soil and solid matter, such as a water turbine.

In addition, the above-mentioned mixed powder containing 40% of the surface metal-coated SiC by volume was used on equipment members made of 5Nil3Cr cast steel such as the guide vane 5 and sheet liner 8 of a water turbine as shown in the schematic diagrams of FIGS. 5 and 6. The overlay weld layer 10 was formed by plasma overlay welding. Welded overlay layers were also formed on the turbine runner and cover liner in the same way. By forming this overlay weld layer, it was possible to prevent wear due to earth and sand, wear due to cavitation, and combined damage. [Effects of the Invention] The coating layer of the water turbine of the present invention is intended for water turbines for hydroelectric power generation that utilize river water containing sediment, and is made of a composite powder of austenitic stainless steel and metal carbide ceramics, so that ceramic particles do not remain. Because it forms a built-up layer on the surface of equipment parts that has a solidified structure, or a solidified structure in which no ceramic grains remain and crystallized carbides are dispersed in the matrix, cavitation, earth and sand abrasion, and composite damage can be suppressed. Therefore, it was possible to prevent the equipment from being eroded, reduce the decrease in operating efficiency, and greatly improve the lifespan of the equipment.

[Brief explanation of the drawing]

FIG. 1(A) is a sectional view showing the main part of a water turbine to which the overlay weld layer according to the present invention is applied, and FIG.
) as seen from the X direction, Figure 2 is a microscopic photograph showing the metal structure of the cross section of the overlay weld layer in which crystallized carbides are dispersed in the matrix of austenitic stainless steel among the coating layers of the present invention, and Figure 3 is a diagram showing the relationship between the amount of SiC added and the amount of wear due to earth and sand, Figure 4 is a comparison diagram of the amount of wear due to earth and sand between the inventive overlay weld layer and the comparative material, and Figures 5 and 6 are the relationship between the amount of SiC added and the amount of wear due to earth and sand. Schematic diagram of a water turbine component with a welded weld layer, No. 7
The figure shows the relationship between the amount of SiC and TiC added and the cavitation weight loss. Figure 8 shows the cavitation weight loss of the overlay weld layer of the present invention and the comparative material. Figure 9 shows the relationship between the amount of SiC and TiC added and the weight loss due to sediment Figure 1o is a diagram showing the relationship between the amount of wear and erosion due to earth and sand between the overlay weld layer of the present invention and the comparison material, and Figure 11 (A) and Figure 11 (
B) is a diagram showing the locations where the coating layer is provided on the blade of the water turbine according to the embodiment of the present invention, FIG. 12 is a schematic diagram of the plasma arc welding device used to provide the overlay welding layer, and FIG. 13
The figure is a graph showing the weight loss due to cavitation for each sample, and Figure 14 is a graph showing the weight loss due to sediment for each sample shown in Figure 13. 1... Crown, 2... Shroud, 3... Vane, 4... Runner cone, 5... Guide vane, 6...
... Steben, 7... Runner liner, 8... Sheet liner, 10... Overlay welding layer. Fig. 2 5 /trr+ Fig. SiC content (Vot%) Fig. Fig. Fig. Fig. SiC, TiC (Vot%) Additive ceramics Fig. SiC, TiC (Vol. %)

Claims (1)

[Claims] 1. In a water turbine equipped with a guide vane that adjusts the flow of flowing water and a runner that is rotated by the flowing water, overlay welding that has higher cavitation resistance than the base material on the part that is subjected to impact from the flowing water. 1. A water turbine comprising a member having a layer, the overlay weld layer having a metal structure having a matrix of austenitic stainless steel and carbides dispersed in the matrix. 2. The overlay weld layer is a layer obtained by overlay welding a mixed powder of austenitic stainless steel powder and metal carbide ceramic powder, and the carbide is a single metal carbide and the carbide and matrix metal. 2. The water turbine according to claim 1, comprising a composite eutectic carbide. 3. The water turbine according to claim 1, wherein the carbide is a crystallized composite carbide of a matrix metal, with substantially no single metal carbide present in the matrix. 4. The water turbine according to claim 2, wherein the carbide is a metal carbide ceramic grain. 5. The metal carbide ceramics are SiC, TiC,
The water turbine according to claim 1 or 2, wherein the water turbine is at least one selected from the group of WC, Cr_3C_2, NbC, and VC. 6. The austenitic stainless steel contains C by weight%
:0.05~0.15%, Si:0.2~1.0%, M
n: 13% or less, Ni: 2 to 7%, and Cr: 17 to
Contains 23%, or Mo: 1 to 3%, N: 0.3
% or less and Co: 10% or less, with the remainder consisting of Fe and accompanying inevitable impurities. 7. The water turbine according to claim 6, wherein the austenitic stainless steel contains 0.1 to 5% by weight of at least one of rare earth elements numbered 57 to 71 in the periodic table. 8. The value of (Mn%+Co%)/Cr% is 0.6 to 1
．． 8. The water turbine according to claim 6 or 7, wherein the water turbine has a composition in the range of 3. 9. The water turbine according to any one of claims 1 to 8, wherein the overlay welding layer is formed by plasma arc overlay welding and has a thickness of 5 mm or less. 10. The overlay welding layer covers the entire inlet end portion of the blade of the water turbine runner on the working surface side and the reaction surface side, the outer outlet end portion of the blade on the reaction surface side, the entire surface of the guide vane except for the supporting portion, and The water turbine according to any one of claims 1 to 9, wherein the water turbine is provided on a sliding surface of a sheet liner. 11. In a method for manufacturing a water turbine, in which a built-up welding layer with higher cavitation resistance than the base metal is provided on at least a portion of the part that is subjected to water impact, a mixed powder of austenitic stainless steel powder and metal carbide ceramic powder is heated by a plasma arc. A method for manufacturing a water turbine, comprising: melting the stainless steel powder and supplying it to a welded part, and forming a build-up weld layer of a desired thickness while creating a pool of molten metal in the welded part. . 12. The powder particle size of the metal carbide ceramic (S) is the powder particle size of austenitic stainless steel (M) 1
A solidified structure formed with a particle size ratio S/M of 1 to 2 with respect to 0 to 200 μm, containing 1 to 80% by volume of the metal carbide ceramic (S), and a solidified structure in which the metal carbide ceramic powder remains. 12. The method for manufacturing a water turbine according to claim 11, wherein the metal carbide ceramic powder has a structure including a composite carbide crystallized by decomposition and melting. 13. The metal carbide ceramics are SiC, TiC
13. The method for manufacturing a water turbine according to claim 12, wherein the water turbine is at least one selected from the group consisting of , WC, Cr_3C_2, NbC, and VC. 14. The powder particle size of the metal carbide ceramic (S) and the powder particle size of the austenitic stainless steel (M) are each in the range of 10 to 200 μm, and the particle size ratio S/M
is 1 or less, and the metal carbide ceramic (
S) is contained in an amount of 1 to 40% by volume, and the metal carbide ceramic powder is decomposed and dissolved in the molten metal, so that no metal carbide ceramic particles remain in the metal base, and the composite metal carbide is in the austenitic stainless steel matrix. The method for manufacturing a water turbine according to claim 11, which has a solidified structure in which water is crystallized and dispersed. 15. The method for manufacturing a water turbine according to any one of claims 11 to 14, wherein the overlay welding layer is formed by plasma arc overlay welding, and has a thickness of 5 mm or less, and at least one layer is formed. 16. Claims 11 to 15, characterized in that the metal carbide ceramic powder is coated with a metal coating layer.
A method for manufacturing a water turbine according to any of the above. 17. In a water turbine equipped with guide vanes that adjust the flow of flowing water and runners that are rotated by the flowing water, overlay welding that has higher cavitation resistance than the base material of martensitic stainless steel cast steel is applied to the parts that are subject to impact from the flowing water. The overlay welding layer has a metal structure having a matrix of austenitic stainless steel and carbides dispersed in this matrix, and the austenitic stainless steel has C: 0.05 in weight%. ~0.15%
, Si: 0.2 to 1.0%, Mn: 13% or less, Ni:
Consisting of steel containing 2 to 7% Co:10
% or less, Cr: 17-23%, Mo: 1-3%, N: 0
．． 3% or less of at least one kind, the remainder consisting of Fe and accompanying unavoidable impurities, and the metal carbide ceramic contains at least one kind selected from the group of SiC, TiC, WC, Cr_3C_2, NbC and VC. A method of manufacturing a water wheel. 18. A metal member having a build-up weld layer on the surface of the base material that has higher erosion resistance than the base metal, wherein the build-up weld layer has a metal structure in which carbides of a single metal are dispersed in a matrix of austenitic stainless steel. A metal member with high erosion resistance.