JP2003136279A - Cr-Ni-Nb-Fe BASED ALLOY FOR BUILD-UP WELDING - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Cr-Ni-Nb-Fe based alloy having excellent thermal stability in which cracking is hard to occur in heating, and which has excellent thermal impact resistance, has a reduced change in hardness, and has no reduction in wear resistance. SOLUTION: The Cr-Ni-Nb-Fe based alloy for build-up welding has a composition containing, by weight, 10 to 50% Cr, 10 to 40% Co, 5 to 25% Fe and 5 to 15% Nb, a balance Ni and inevitable impurities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Cr-Ni-Nb-Fe based alloy for build-up, which has excellent heat resistance and is built up on a part of a base material.

[0002]

2. Description of the Related Art Parts and members (base materials) are composed of metals and alloys having properties suitable for the environment in which they are used. The base material used in a high temperature environment is made of a material having excellent heat resistance, and the base material used in an environment where it is repeatedly in contact with a mating member is made of a material having excellent wear resistance.

For example, an exhaust valve used in an automobile engine is heated to a high temperature, is easily pressed by a valve seat and is easily worn, and is easily corroded and oxidized by lead and sulfur in gasoline. In consideration of this, the exhaust valve is often formed of a material having excellent heat resistance, wear resistance, corrosion resistance, etc. (for example, austenitic heat resistant steel). However, it is difficult to satisfy all these requirements with a single heat-resistant steel. Further, the entire exhaust valve is not exposed to the above atmosphere, but only a part thereof. From these circumstances,
The other part of the exhaust valve is often overlaid with another alloy having more excellent heat resistance and the like.

In order to improve heat resistance and the like of parts and members such as exhaust valves, various overlaying alloys have been adopted so far, and one of them is a Cr-Ni-Nb-Fe based alloy. This alloy basically consists of Cr, Ni, Nb and F
A large amount of e is compounded in this order, and it is characterized by satisfying heat resistance and abrasion resistance to some extent.

[0005]

However, the above-mentioned Cr-N
When the i-Nb-Fe based alloy was built up on the valve surface of the exhaust valve, cracks might occur in the built-up portion during the period of use. When cracks occur, the build-up portion may be partially cut off depending on the size and number of cracks. Also,
As the valve surface was repeatedly contacted with the valve seat, the valve surface was worn and the sealing performance was sometimes impaired. If the sealing performance is impaired, the original function of the exhaust valve will deteriorate.

The present invention has been made in view of the above circumstances, and is a Cr-Ni-Nb-Fe based alloy excellent in heat resistance,
More specifically, it provides a Cr-Ni-Nb-Fe-based alloy that is less prone to cracking in the build-up alloy, has excellent thermal shock resistance, and has little change in hardness (less deterioration in wear resistance) and excellent thermal stability. The purpose is to do.

[0007]

The inventor of the present application has examined the cause of cracking and wear of the above-mentioned built-up portion. As a result, cracking is mainly due to the difference between the expansion and contraction amount of the molten alloy for overlay welding and that of the base metal during wear, and wear is mainly due to the change in alloy material due to the heat applied during overlaying and during use (particularly The formation of austenite phase). So Cr
A method for suppressing cracking and wear was studied while taking advantage of the characteristics of the -Ni-Nb-Fe-based alloy. And Cr-
The present invention has been completed on the idea that adding Co or Mo to a Ni-Nb-Fe based alloy is effective in improving thermal shock resistance and thermal stability.

In the specification of the present application, the amount of expansion and the amount of contraction of the overlay alloy when high heat is applied at the time of overlaying the overlay alloy on the base material and during use of the base material after overlaying. Is said to be “excellent in thermal shock resistance” when there is no great difference from that of the base metal and cracks do not occur in the overlay alloy. Specifically, the thermal shock resistance is improved when the linear expansion coefficient of the cladding alloy is not much different from that of the base material.

Further, even when heating and cooling are repeated when the base material is used in a high temperature environment after overlaying, the material of the overlaying alloy does not change much and hardness does not decrease and is small. Sometimes it is said that "it has excellent thermal stability." Specifically, it means that the increase in the wear amount of the cladding alloy due to the decrease in hardness is small (the wear resistance is large).

That is, the first invention of the present application is to use Cr-N for overlay welding.
The i-Nb-Fe based alloy, in wt%, is Cr: 10 to 50.
%, Fe: 5 to 25%, Nb: 5 to 15%, Co: 10
.About.40%, balance Ni, and unavoidable impurities. In the first invention, Co contributes to the improvement of thermal shock resistance and thermal stability.

The second invention is a Cr-Ni-N for overlay welding.
b-Fe-based alloy, by weight%, Cr: 10 to 30%, F
e: 5 to 25%, Nb: 2 to 10%, Mo: 5 to 20
%, The balance Ni, and unavoidable impurities. In the second invention, Mo contributes to the improvement of thermal shock resistance and thermal stability.

Further, the third invention is Cr-Ni- for overlay welding.
The Nb-Fe based alloy is, by weight%, Cr: 10 to 30%,
Co: 10-40%, Fe: 5-25%, Nb: 2-1
0%, Mo: 5 to 20%, the balance Ni, and unavoidable impurities.

In the third invention, Co and Mo contribute to the improvement of thermal shock resistance and thermal stability.

Incidentally, for example, US Pat. No. 3,18,0012 (first conventional example) has a Co content of 50 to 70% by weight.
A heat resistant alloy consisting of Mo: 25-48% and Si: 2-10% is disclosed. However, the first conventional example is Cr-N.
It is not related to i-Nb-Fe based alloys. In addition, C
Regarding the relationship between o and Mo and heat resistance, the features of the present invention are not disclosed.

Further, Japanese Patent Laid-Open No. 10-156500 (second conventional example) discloses that C: 0.03 to 0.3 in terms of weight%.
%, Si: 0.03 to 1.5%, Mn: 0.1 to 3.0
%, Ni: 0.5 to 10.0%, Cr: 10.0 to 2
A deposited metal layer composed of 0.0%, N: 0.05 to 0.5%, the balance Fe, and unavoidable impurities is disclosed. Then, it is disclosed that Mo: 3.0% or less and / or Co: 3.0% or less can be added to the deposited metal layer in weight%. However, the second conventional example also does not relate to a Cr-Ni-Nb-Fe based alloy. In addition, regarding the relationship between Mo and Co and heat resistance, the features of the present invention are not disclosed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION <Base Material> The base material is a member or part used in a machine or an apparatus. The present invention is intended for members and parts that are used in a high temperature environment and are repeatedly contacted with a mating member. A specific example is an exhaust valve used in an exhaust valve device of an automobile engine.

The material of the base material is not particularly limited and can be made of, for example, carbon steel or martensitic heat resistant steel SCH3. The melting point of aluminum is 660 ° C. and the number of linear expansion particles is 0.237 × 10 ⁻⁴ / K.

The shape of the base material is not particularly limited and may be rod-shaped or plate-shaped. The build-up portion of the build-up alloy on the base material may be the entire length or a part of the rod-shaped base material in the axial direction.
Further, it may be the entire circumference or a part of the circumference in the disk-like circumferential direction.

The thickness of the build-up portion on the base material of the build-up alloy is not particularly limited and can be in the range of 0.3 to 3 mm. Further, the weight of the overlaying metal alloy when the weight of the base material is 100 can be in the range of 5 to 15%. <Cr-Ni-Nb-Fe-based alloy for overlay welding> Overlaying is a kind of surface hardening method for the base material, and is an alloy for overlay overlay (sometimes referred to as "overlay") having excellent specific properties. ) Is welded or sprayed onto the surface of the base material. When overlaying the overlay alloy on the base material, the base material is positioned and a plasma arc or laser beam is emitted from the heat source, and the amount and speed at which the powder of the overlay alloy is melted by the plasma arc, etc. Send out with. Hereinafter, the role of each component of the overlaying alloy and the reason for limiting the range will be described.

In the first aspect of the invention, Cr forms an intermetallic compound of Nb to improve the hardness of the overlaying alloy and reduce the amount of wear. However, if the content of Cr is less than 10% by weight, this effect cannot be obtained, and if it is more than 50% by weight, cracking tends to occur and the thermal shock resistance is deteriorated. Therefore, the compounding amount of Cr is set to 10 to 50% by weight.

Ni forms an intermetallic compound with Nb to improve the hardness of the overlay alloy. It also contributes to the improvement of toughness.

Nb forms an intermetallic compound with Ni, Cr and Fe. This improves the hardness of the alloy for casting and reduces the amount of wear. To obtain this effect (characteristic),
At least 5% by weight or more of Nb is required. On the other hand, N
If the blending amount of b is more than 15% by weight, the toughness of the build-up alloy is likely to decrease. (Becomes fragile) So Nb
The compounding amount was 5 to 15% by weight.

Fe forms an intermetallic compound with Nb to increase the hardness of the overlaying alloy and reduce the amount of wear. To obtain this effect, at least 5% by weight of Fe is required. On the other hand, if the content of Fe is more than 25% by weight, the change in hardness before and after heating becomes large, and the thermal stability decreases. Therefore, the blending amount of Fe is set to 5 to 25% by weight.

By adding Co to the Cr-Ni-Nb-Fe based alloy, the hardness change of the overlay alloy is reduced, the thermal stability is improved, the expansion amount and the contraction amount are increased, and the dust is further reduced. The property is also improved. 1 to obtain these effects
Co of 0% by weight or more is required. On the other hand, if the content of Co exceeds 40% by weight, gas defects will occur during overlaying. Therefore, the blending amount of Co is set to 10 to 40% by weight. Of these, Co: 15 to 30 is particularly effective. Incidentally, C
o has a melting point of 1490 ° C. and a linear expansion diameter of 0.126 × 10
^-4 / K.

In the second invention, Cr-Ni-Nb-F
By adding Mo to the e-based alloy, the change in hardness of the overlaying alloy is reduced, the thermal stability is improved, the expansion amount and the contraction amount are increased, and the toughness is also improved. In order to obtain this effect, 5% by weight or more of Mo is necessary. on the other hand,
If the content of Mo is more than 20% by weight, the toughness of the build-up alloy decreases. Therefore, the blending amount of Mo is 5 to 20.
It was set to% by weight. Of these, the most effective is Mo: 8-
It is 15.

In the second invention containing Mo instead of Co, the compounding amounts of Cr and Nb are smaller than those in the first invention. Mo has a melting point of 2620 ° C. and a linear expansion diameter of 0.051 × 10 ⁻⁴ / K.

In the third invention, Cr-Ni-Nb-F
By adding Co and Mo to the e-based alloy, the hardness of the overlay alloy is less changed than when only Co or Mo is added, the thermal stability is improved, and the expansion amount and shrinkage are increased. The amount increases and the toughness also improves. In order to obtain these effects, 10% by weight or more of Co and 5
Mo weight% or more is required. However, if the content of Co exceeds 40% by weight or the content of Mo exceeds 20% by weight, the above problems occur. Therefore, the compounding amount of Co is 10
˜40 wt%, and the blending amount of Mo was 5˜20 wt%.

In the third invention containing Co and Mo, C
The compounding amounts of r and Nb are smaller than those in the first invention. <Other additives> The alloy for overlay is also Si: 0.5-
4% can be included. Si also lowers the viscosity of the melt of the overlay alloy and improves the welding workability, but if too much silicide is produced, the toughness is reduced. Therefore, the blending amount of Si is set to 0.5 to 4% by weight.

The build-up alloy further comprises C: 0.01-0.
5% may be included. C reduces the viscosity of the molten metal and improves the welding workability, but if the amount of C is too large, it forms carbides and reduces toughness. Therefore, the blending amount of C is set to 0.01 to 0.5% by weight.

[0030]

EXAMPLES The present invention will be described in detail below based on examples.

Alloys for build-up which were mixed with the components shown in Table 1, Table 2, Table 3 and Table 4 were melted and gas-atomized with an inert gas to produce a powder for build-up alloy. This overlaying alloy powder was classified into a range of 44 to 180 μm. <Examples> Samples 1 to 9 having the components shown in Table 1, samples 10 to 20 having the components shown in Table 2, and samples 21 to 35 having the components shown in Table 3 are examples of the present invention.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

<Comparative Example> Samples 36 to 52 having the components shown in Table 4 are comparative examples. This is an alloy for build-up, which has the same components as the build-up alloy of the examples, but the compounding amount of any one component is out of the range of the compounding amount of the examples. Specifically, the samples 36 and 38 have a large Nb content, and the samples 37 and 39 have a low Nb content. Sample 4
0 has a large amount of Co, and sample 41 has a small amount of Co. Sample 42 contains a large amount of C and sample 43 does not contain C.

Sample 44 contains a large amount of Si, and sample 45
Has a small amount of Si. Samples 46 and 47 had a large amount of Cr, and sample 48 had a small amount of Cr. Sample 5
0 is a small amount of Fe. Sample 51 has a large amount of Mo, and sample 52 has a small amount of Mo.

[0037]

[Table 4]

<Conventional Example> Sample 5 shown in Table 5 is a conventionally used triballoy alloy, and sample 54 is a conventionally used Cr-Ni-Nb alloy.

[0039]

[Table 5]

Exhaust valves of the exhaust valve device for automobiles shown in FIG. 1 were prepared by using the alloy powders for overlay welding of Samples 1 to 35 of the above-mentioned Examples, Samples 36 to 52 of Comparative Examples, and Samples 53 to 54 of Conventional Examples. 11 is welded to the valve face surface 12 of the welded surface 11
Was formed. More specifically, the exhaust valve device includes a housing portion 21 having an intake port 20 and a housing portion 2
Housing part 22 remote from 1, and valve 11 at the tip
With a plate 14 at the rear end and housing parts 21 and 2
Exhaust valve 1 disposed so as to be axially movable between
1 and the exhaust valve 11 by contacting the plate 14 and rotating.
A cam 23 that drives the forward direction (downward in FIG. 1),
It includes a spring 24 disposed between the housing portions 21 and 22 for biasing the exhaust valve 11 in the backward direction, and a valve seat 26 made of a Fe-based sintered material.

The exhaust valve 11 is made of SUH35 which is a kind of austenitic steel, and has a valve face 12
In addition, an alloy powder for overlay welding having the components of Samples 1 to 35 of the example by the plasma arc under the conditions of an output of 90 A and a processing speed of 5 mm / s, an alloy powder for overlay welding having the components of Samples 36 to 52 of the comparative example, Further, the alloy powders for overlay welding of Samples 53 to 54 of the conventional example were overlayed. Then, the welding workability, the presence or absence of cracks, the change in hardness and the wear amount of the overlay portion (welded portion) 13 were evaluated. The evaluation method is as follows. (Welding workability) The workability in this overlay (welding) process was visually checked for cracks in the overlay portion 13, the occurrence of gas defects, and the bead shape, and the results were evaluated on a four-level scale. did. The larger the numerical value, the smoother the build-up portion 13 is without blowholes or deficiencies, and the weld build-up portion 13 is sufficiently welded, indicating that the workability is good. (Presence or absence of cracks) The exhaust valve 11 having the build-up portion 13 formed on the valve face 12 was heated to 800 ° C. and then cooled to room temperature in the furnace. When the heating and furnace cooling were repeated 100 cycles, the presence or absence of cracks in the overlay portion 13 was visually confirmed. (Change in Hardness) The hardness is measured at the time when the overlay portion 13 is formed. Next, the exhaust valve 10 is heated at a temperature of 800 ° C. for 100 hours, and the hardness of the overlay portion 10 after heating is measured. Thus, the change in hardness of the overlay portion 13 before and after heating was examined. The hardness was evaluated by Vickers hardness. (Abrasion amount) A wear test was performed by the test apparatus of FIG. 2 using the exhaust valve 11 having the valve surface 12 with the built-up portion 13. More specifically, a propane gas burner was used as a heating source, and the sliding portion between the exhaust valve 11 and the valve seat 26 was set to a propane gas combustion atmosphere. The temperature of the valve seat 26 was controlled at 300 ° C., and a load of 18 kgf was applied between the valve face 12 and the valve seat surface 26 by the spring 24. Exhaust valve 1 at a rate of 2000 times / minute
1 was repeatedly contacted with the valve seat 26, and this contact was continued for 8 hours. Then, the wear depth of the valve face 12 was measured. (Toughness) Toughness was evaluated by the above overlay welding, the presence or absence of cracks in the repeated heating test, and the elongation in the tensile test. <Examples> The results of evaluations in Examples are shown in Table 6 corresponding to Table 1, Table 7 corresponding to Table 2 and Table 8 corresponding to Table 3.

[0042]

[Table 6]

[0043]

[Table 7]

[0044]

[Table 8]

As is clear from these, the welding workability was evaluated to be 4 or 3 in all the samples 1 to 35 of this example, and it is understood that the overlaying work of the alloy for overlaying is easy.

It can be seen that all samples 1 to 35 have no cracks and have excellent thermal shock resistance.

Regarding the change in hardness, there is a sample having a large hardness (indicated by +) and a sample having a small hardness (indicated by −). In any case, it can be seen that the amount of change in hardness is within a certain range (± 20), and the hardness does not change so much.

Here, it is evaluated that the hardness is not changed, which is the best thermal stability, the hardness is the second best, and the hardness is the second best. In that respect, Co-added samples 3 and 5 and Mo-added samples 10 and 1
Samples 22 and 25 to which 1 and Co and Mo are added all have zero change in hardness, which is desirable.

Further, it can be seen that the wear amounts of all the samples 1 to 35 are within a certain range (9 μm or less), and the wear resistance is excellent. More specifically, Co-added Samples 2 and 6, Mo-added Samples 15 and 17, Co and Mo
The samples 24 and 26 to which is added each have a wear amount of 3 μm, which is desirable. Although the evaluation of the change in hardness and the evaluation of the amount of wear do not exactly match, it is sufficient that the amount of wear is 9 μm or less, and there is no practical benefit in discussing their magnitude. Comparative Example On the other hand, in Samples 36 to 52 of Comparative Example, the welding workability of the overlay portion, the presence or absence of cracks, the change in hardness, and the wear amount were evaluated. The evaluation results are shown in Table 9 corresponding to Table 4.

[0050]

[Table 9]

As is clear from Table 9, Samples 36 and 38 containing too much Nb have poor welding workability and thermal shock resistance. In addition, samples 37 and 3 containing too little Nb
No. 9 is inferior in wear resistance. Sample 40 containing too much Co
Has poor welding workability, and Sample 41 having too little Co has poor thermal stability.

Sample 42 containing too much C was inferior in welding workability and thermal shock resistance, and Sample 43 not containing C was inferior in welding workability. Sample 44 containing too much Si was inferior in welding workability and thermal shock resistance, and Sample 4 containing too little Si.
No. 5 is inferior in welding workability.

Samples 46 and 47 containing too much Cr
Has poor thermal shock resistance, and Sample 48 containing a small amount of Cr has poor wear resistance. The sample 50 containing a small amount of Fe has poor wear resistance.

The sample 51 containing too much Mo had poor welding workability and thermal shock resistance, and the sample 52 containing too little Mo.
Has poor thermal stability. <Conventional Example> As shown in Table 10, Sample 53 of the conventional example
The overlay portion 13 of (Trivalloy alloy) has a small change in hardness and a small amount of wear, but has poor welding workability and cracks occur. Further, the sample 54 (Cr-Ni-Nb alloy) is inferior in welding workability, cracks are generated, and hardness is changed. In addition, the wear amount of the initially built-up alloy was 6 μm at 800 ° C.
When heated for 100 hours, it increased to 20 μm.

[0055]

[Table 10]

Next, in order to investigate the relationship between the crack of the overlay portion 13 and the coefficient of linear expansion and elongation, samples 1, 10 and 21 of the example and a sample of the conventional example were formed on a plate member (not shown) made of SUH35. Each of 53 and 54 was built up with a thickness of 10 mm, and a test piece was sampled from the built-up portion. Then, the change in the linear expansion coefficient of the overlay portion before and after heating was examined by measuring the change in the total length of the test piece with temperature. Also, 8
The elongation when the tensile test piece broke at 00 ° C was measured by an autograph.

Table 11 shows the measurement results. As is clear from Table 11, in the sample 1 containing Co, the sample 10 containing Mo, and the sample 21 containing Co and Mo,
Compared with the samples 53 and 54 of the conventional example, the coefficient of linear expansion is large and the elongation in tension is large. As a result, the expansion amount and the contraction amount of the built-up portion 13 during heating are increased, and the exhaust valve 1
It is considered that there was no great difference between the expansion amount and the contraction amount of No. 1 and the occurrence of cracking was prevented as described above.

Further, the relationship between the change in the material of the overlay portion 13, the change in hardness, and the wear amount was investigated. That is, as shown in FIG. 2, on the valve face surface 12 of the exhaust valve 11 made of SUH35, the alloy powders for overlay welding of the samples 1, 10 and 21 of the embodiment were processed by plasma under the conditions of an output of 90 A and a processing speed of 5 mm / s. Flourished And these exhaust valves 11
Used in a 3000cc gasoline engine, 18
A 0-hour durability test was performed. Sample 5 of the conventional example for comparison
Similarly, for 3 and sample 54, the test was conducted by overlaying. Then, the metallographic structure of the overlay portion 13 before and after the durability test was observed with a microscope, and the valve protrusion amount was measured.

Regarding the relationship between the change in the structure of the overlay portion 13 and the change in the hardness, FIGS. 3 (a) and 4 (a) show the metal structures of Samples 21 and 54 before the durability test, and FIG. 4) and FIG. 4B show the metal structures of Samples 21 and 54 after the durability test.

As is clear from FIGS. 3 (a) and 3 (b), the metal structure of the sample 21 hardly changed. On the other hand, as is apparent from FIGS. 4 (a) and 4 (b),
In the sample 54, the metal structure was changed, and as a result of analysis by X-ray diffraction, generation of an austenite phase was confirmed. The change in hardness of the sample 21 is +15, and the change in hardness of the sample 54 is -150, which means that the austenite phase (F
The presence or absence of eNi solid solution)) is assumed to be relevant.
That is, it is considered that the austenite phase was generated in the sample 54, but in the sample 21, precipitation of the FeNi solid solution due to heating was reduced.

Further, the valve protrusion amount was measured in order to examine the relationship between the change in hardness of the overlay portion 13 and the wear amount and the opponent attacking property. Here, the valve protrusion amount is the total of the amount of wear of the valve face 12 (wear resistance) and the amount of wear of the valve seat 26 (opposite attack). Here, the amount of wear of the valve seat 26 is also investigated. Although it is desired that the hardness of the overlay portion 13 be increased in order to reduce the amount of wear of the valve face 12, the bubble seat 26 is too hard if the hardness is too high. This is because it is easy to wear.

The results of the measurement are shown in Table 11. As is clear from Table 11, Samples 1, 10 and 21 of the example have a smaller valve protrusion amount and are superior in wear resistance as compared with Sample 54 of the conventional example. This is considered to be related to the presence or absence of changes in the metallographic structure of Samples 21 and 54 described above. On the other hand, the sample 53 has good wear resistance,
A crack occurred in the. It is considered that this is because the coefficient of linear expansion is small and the elongation is small.

[0063]

[Table 11]

[0064]

As described above, according to the present invention, Cr-Ni-based alloys for overlay welding are less prone to cracking, have excellent thermal shock resistance, and have a small change in hardness and excellent thermal stability.
The effect of obtaining the Nb-Fe based alloy is exhibited.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment (exhaust valve device) of the present invention.

FIG. 2 shows wear tests in examples, comparative examples and conventional examples.

FIG. 3 (a) is a photograph showing a metallographic structure of Sample 21 before a durability test, and FIG. 3 (b) is a photograph showing a metallographic structure after the durability test.

FIG. 4 (a) is a photograph showing a metallographic structure of Sample 54 before a durability test, and FIG. 4 (b) is a photograph showing a metallographic structure after the durability test.

[Explanation of symbols]

11: Exhaust valve 12: Valve face surface 13: Overlay part 26: Valve seat

Claims (7)

[Claims] 1. By weight%, Cr: 10 to 50%, Co:
10-40%, Fe: 5-25%, Nb: 5-15%,
A balance Cr-Ni-Nb-Fe-based alloy for build-up, comprising balance Ni and inevitable impurities. 2. By weight, Cr: 10 to 30%, Fe:
A Cr-Ni-Nb-Fe-based alloy for build-up, comprising 5 to 25%, Nb: 2 to 10%, Mo: 5 to 20%, the balance Ni, and unavoidable impurities. 3. By weight%, Cr: 10-30%, Co:
10-40%, Fe: 5-25%, Nb: 2-10%,
Mo: 5-20%, balance Ni, and unavoidable impurities, Cr-Ni-Nb-Fe base alloy for build-up characterized by the above-mentioned. 4. The Cr-Ni-Nb-Fe-based alloy for build-up according to claim 1, wherein Co is 15 to 30%. 5. The Cr-Ni-Nb-Fe-based alloy for build-up according to claim 2, wherein Mo is 8 to 15%. 6. Co: 20 to 35%, Mo: 10 to 18
% Of Cr-Ni-Nb-Fe for build-up according to claim 3.
Base alloy. 7. The Cr-Ni-Nb for build-up according to claim 1, further comprising C: 0.01 to 0.5% and Si: 0.5 to 4%. -Fe-based alloy.