JPH0353028B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of thickly overlaying a blade body with a self-fusing metal having high hardness and excellent wear resistance. Induced draft fans are generally used in coal-fired power plants and the like. As shown in the plan view of FIG. 1A and the side view of FIG. 1B, the rotor blades of this induced draft fan are subject to severe wear M due to the fly ash, and it is particularly important to take measures against the wear of the leading edge 1l. In FIGS. 1A and 1B, 1 is a rotor blade, 1t is a trailing edge, 2 is a blade root, arrow a is a fluid flow direction, and arrow b is a rotation direction. Conventionally, measures against wear have been taken as shown in FIGS. 2A to 2E. Fig. 2A shows a method of directly welding 21 stellite, stainless steel, etc. to the rotor blade 1 by arc welding, gas welding, etc., Fig. 2B shows a method of directly welding 22 metal carbide with stainless steel etc. as a binder by plasma welding, etc. Fig. 2C shows a method of attaching a hard metal piece (nose piece) 23 with screws 24 or brazing it, Fig. 2D shows a method of attaching a hard metal piece (nose piece) 25 with welding 26, and Fig. 2E
This is a method of coating 27 by spraying and melting a self-fusing metal. However, the measures shown in FIGS. 2A to 2E have the following drawbacks. Figure 2 A: Highly hard materials such as stellite and stainless steel cannot be welded and have insufficient wear resistance. Figure 2B: Welding metal carbides is technically difficult and requires equipment and construction costs. Fig. 2 C, D... There are restrictions in terms of dimensions and hardness, and these are insufficient. Fig. 2 E... Maximum coating thickness is 1~
It is thin at 1.5mm and does not have sufficient lifespan for leading edges. The present invention is a method of overlaying a blade body with a metal having high hardness and excellent wear resistance as thickly as possible,
Moreover, it provides an economical method. That is, the present invention (1) blasts the tip of the blade body and adds W and W to the first layer for the purpose of preventing oxidation.
After spraying a very thin self-fusing metal that does not contain WC, while melting the self-fusing metal with a melting torch, a self-fusing metal containing W or WC is supplied in powder form, then melted with a melting torch, and then,
A thick wall hardfacing method for a wing, characterized by repeatedly supplying the self-fusing metal containing W or WC in powder form and melting with a melting torch, (2) blasting the tip of the wing body, After spraying a very thin layer of self-fusing metal that does not contain W or WC on the first layer for the purpose of preventing oxidation, a self-fusing metal containing W or WC is applied without melting the self-fusing metal in the first layer. applied by thermal spraying, then melted with a melting torch, and then
the same kind of self-fusing metal as the first layer and the W or
A thick hardfacing method for a wing, characterized by repeating thermal spraying of a mixture with a self-fusing metal containing WC and melting with a melting torch, and (3) blasting the tip of the wing body to prevent oxidation. The purpose is to add W and
After spraying a very thin self-fusing metal that does not contain WC, then spraying a self-fusing metal containing W or WC and the same type of self-fusing metal as the first layer, melting with a melting torch, Next, after performing three layers of thermal spraying: a self-fusing metal of the same type as the first layer, a self-fusing metal containing W or WC, and a self-fusing metal of the same type as the first layer. , perform melting with the melting torch again, and then,
The present invention relates to a method of hardfacing a thick wall onto a wing, which is characterized by repeating thermal spraying of the three layers and melting with a melting torch. The method of the present invention can be applied not only to the rotor blades of the above-mentioned induced draft fan, but also to all blades that require hardfacing treatment. In the method of the present invention, the base material of the blade body is
Nickel, Inconel, Monel, Nichrome, Nickel or cobalt-rich superalloys, austenitic stainless steels, low carbon steels (0.30% or less), medium carbon steels, low alloy steels, high carbon steels (0.60% or more), sulfur-free Machined steel (AISI 1100 and 1200 series), highly hardened tool steel, air hardened steel, martensitic chrome steel, etc. can be used. Further, as the self-fusing metal, a nickel- or cobalt-based alloy containing boron and silicon, which is generally called a self-fusing metal alloy, can be used. The alloy is generally thermally sprayed and then remelted in an atmosphere of about 1000 to 1100°C to form a poreless film that is welded to the material. This alloy has high hardness and excellent wear resistance, and an example of its hardness is shown in Table 1.

[Table] *Product name manufactured by Nippon Coating Industry Co., Ltd. It is preferable that the combinations of the base material described above and the self-fusing metals shown in Table 1 be as shown in Table 2.

[Table] Further, the self-soluble metals may be used alone or in combination of two or more. The inventor of the present invention first discovered that when a Ni-Cr-B-Si alloy, which is a self-fusing metal, is mixed with WC and then thermally sprayed and melted, WC with a large specific gravity segregates. We proposed a method of coating by alternately thermal spraying and melting at least one layer of alloy and WC (see Japanese Patent Application Laid-Open No. 14960/1983), but subsequent research revealed that although it was molten, it had little fluidity. The temperature is low and the time is short, and since it melts repeatedly, the melted layer is only the shallow part of the surface layer, and the thickness that can be segregated is limited. It has been found that even if some segregation occurs, there is no problem with erosion resistance. Hereinafter, for convenience, the method of the present invention will be explained in detail using an example in which it is applied to a rotor blade. FIG. 3A is a diagram showing an embodiment of the method of the present invention, and FIG. 3B is a schematic cross-sectional view. In FIGS. 3A and 3B, after blasting the leading edge of the blade body 31 made of carbon steel, low alloy steel, etc., a self-fusing metal 32 selected from Table 2 above is immediately melted with a melting torch 33 to prevent oxidation. Spray it very thinly. This is to prevent the blade body 31 from being oxidized during the next preheating process, and is made of a Ni-Cr-B-Si system having good melting properties, fluidity, adhesion properties, and cracking resistance. An alloy is preferable, and the first layer is formed by thermal spraying because thermal spraying can be performed at a temperature of the base material (here, the blade body 31) near room temperature. Next, preheat to approximately 800°C with the preheating burner 34,
Melting torch 35 with powder supply device (35 ₁ is a powder box, 35 ₂ is a powder amount adjustment lever, 3
5 ₃ is a fuel gas supply pipe), the self-fusing metal 32 coating of the first layer is melted at about 1050 to 1100°C, and at the same time, a self-fusing metal (for example, Ni- A mixture of a Cr-B-Si alloy and a WC-based alloy is supplied and melted while being adjusted using the powder amount adjustment lever ₃₅₂ .
The reason why the self-fusing metal powder is supplied at the same time as melting the first layer is that if the base is melted before the powder is supplied, the powder will easily adhere to the base and flow out with the heating flame flow. This is because it can prevent Thereafter, by repeating supply and melting of self-fusing metal with a melting torch 35 while continuing preheating, build-up 36 is performed in many layers to create a desired thickness and shape. In this case, the supply and melting of the self-fusing metal are actually carried out almost simultaneously, to facilitate the adhesion of the self-fusing metal to the substrate and to prevent it from flowing out with the heated flame stream, as described above. In the above method, once the heat capacity of the melting torch 35 and the heat capacity of the base metal are determined (if they are constant), increasing the amount of self-fusing metal supplied will slow down the melting rate, and decreasing it will increase the melting rate. The amount of filling per hit is determined, and the number of repetitions is also determined by the thickness of the filling. However, since there is a correlation between the self-fusing metal supply amount and the melting rate, it is possible to arbitrarily select these at the same time, and thereby a good built-up layer can be formed. After completing the above operations, slow cooling is performed to prevent cracking and deformation, and finally the outer surface is finished with a grinder to obtain a rotor blade as shown in the cross-sectional view of FIG. 3C. FIG. 4A is a diagram showing another embodiment of the method of the present invention, FIG. 4B is a schematic cross-sectional diagram, and FIG. 4C is FIG. 4B.
FIG. In FIG. 4, the same reference numerals as in FIG. 3 indicate the same parts as in FIG. 3. In FIGS. 4A, B, and C, after the leading edge of the blade body 31 is blasted, the same self-fusing metal 3 as in the case of FIG. 3 is immediately applied to prevent oxidation.
2 as the first layer and sprayed very thinly using a thermal spraying torch 33. Next, the self-fusing metal 32 is heated to about 800°C using a preheating burner 34 without melting.
a self-fusing metal different from the first layer,
For example, self-fusing metal 32b containing a component with high hardness of WC or W (Meteco 31C, 32C, 34 in Table 1)
F, 35C, 36C, PWN, Delorostelai SF
-20, etc.) using a thermal spraying torch 33b, immediately (without melting this self-fusing metal 32b), a self-fusing metal 32a of the same type as the first layer is thermally sprayed using a thermal spraying torch 33, and this In this state, melting treatment is performed using a melting torch 41 at about 1050 to 1100°C. After the melting process, while preheating is continued, the self-fusing metal 32a is thermally sprayed by the thermal spraying torch 33, the self-fusing metal 32b is thermally sprayed by the thermal spraying torch 33b, and the self-fusing metal 32a is thermally sprayed by the thermal spraying torch 33 in exactly the same order. Then, a melting process is performed using a melting torch 41. Here, after the first melting treatment described above, the self-fusing metal 32 is
The reason why a is thermally sprayed is that the adhesion during thermal spraying becomes good. By repeating the thermal spraying and melting processes in the above order, the overlay 36' is applied in many layers to create a desired thickness and shape. Although the case where two types of self-fusing metals are used without mixing them has been explained here, the case where one type of self-fusing metal is used or a mixture of two or more types of self-fusing metals is also used. A desired thickness and shape can be created by repeating thermal spraying and melting. However, in the latter two cases, it goes without saying that only one thermal spraying torch and only one thermal spraying layer are required. After completing the above operations, slow cooling is performed to prevent cracking and deformation as in the case shown in Figure 3, and finally the outer surface is finished with a grinder to obtain the rotor blade as shown in Figure 4D. be able to. Next, examples will be given. Example METCO 32C was applied to two types of wing bodies made from JIS SC46 and JIS S25C in the manner shown in Figure 3.
(50wt%) + METCO 15E (50wt%) was added. For comparison, Stellite #6 was gas welded in the manner shown in Figure 2A, and Stellite #6 was welded in the manner shown in Figure 2B.
NbC (50wt%) was plasma sprayed with SUS (50wt%) as a binder. The result is JIS SC46, JIS
In both cases of S25C, the results were as shown in Table 1.

【table】

[Table] As explained above, the method of the present invention has good workability, is extremely economical, can be built up to any thickness and shape, and has excellent properties such as fluidity, adhesion, and crack resistance. Not only can a homogeneous layer be formed by arbitrarily blending two or more types of self-fusing metals, each of which has unique properties, such as a self-fusing metal with excellent self-fusing metals and a self-fusing metal with excellent wear resistance, but it is also possible to form a homogeneous layer as shown in Figure 4. According to the embodiment, effects such as being able to create a particularly hard layer by enveloping a self-fusing metal with excellent wear resistance with a self-fusing metal with excellent fluidity, adhesion, and crack resistance can be achieved. can.

[Brief explanation of drawings]

Figures 1A and B are schematic diagrams showing the state of wear occurring on the rotor blades of a conventional induced draft fan, Figures 2A to E are schematic diagrams showing examples of the above-mentioned conventional wear countermeasures, and Figures 3A to C
are diagrams for explaining one embodiment of the method of the present invention,
FIGS. 4A to 4D are diagrams for explaining other embodiments of the method of the present invention.

Claims (1)

[Claims] 1. After blasting the tip of the blade body and spraying a very thin layer of a self-fusing metal that does not contain W or WC in the first layer for the purpose of preventing oxidation, the self-fusing metal is melted with a torch. While performing melting, a self-fusing metal containing W or WC is supplied in powder form, then melted with a melting torch, and then the self-fusing metal containing W or WC is supplied in powder form and melting with a melting torch is performed. A method of hardening thick wall overlays on wings, which is characterized by repeating the process. 2 After blasting the tip of the blade body and spraying a very thin layer of self-fusing metal that does not contain W or WC in the first layer for the purpose of preventing oxidation, the first layer of self-fusing metal is not melted. A self-fusing metal containing W or WC is supplied by thermal spraying, then melted with a melting torch, and then a mixture of the same type of self-fusing metal as the first layer and the self-fusing metal containing W or WC is sprayed. A method of hardfacing a thick wall onto a wing, which is characterized by repeating melting with a melting torch. 3. Blast the tip of the blade body, spray a very thin layer of a self-fusing metal that does not contain W or WC as a first layer for the purpose of preventing oxidation, and then spray a self-fusing metal that contains W or WC and the first layer. After thermal spraying a self-fusing metal of the same type as the first layer, melting is performed using a melting torch, and then thermal spraying of a self-fusing metal of the same type as the first layer and a self-fusing metal containing W or WC are performed. After three layers are thermally sprayed with the same type of self-fusing metal as the first layer, melting is performed again using the thermal spraying torch, and then the thermal spraying of these three layers and the melting using the melting torch are repeated. Thick wall hardfacing method for wings.