JPH0211292A - Welding material for weld-repairing of co base precision casting parts - Google Patents

Abstract

PURPOSE:To use casting parts after repairing without scrapping by weld- repairing casting defect in the Co base precision casting parts by using a weld material limiting component composition. CONSTITUTION:The weld-material for weld-repairing the casing defect in the Co base precision casting parts composing of 22-30wt.% Cr, 8-15% Ni, 5-10% W, 2-5% Ta, 0.50-0.70% C, <=1% Ti, <=0.5% Al, <=1% Zr, <=0.015% B and the balance Co with impurities, is composed of 18-27wt.% Cr, 18-27% Ni, 10-18% W, 0.02-0.20% C, 0.02-0.20% La, 0.20-0.50% Si and the balance Co with impurities. By this method, the Co base precision casting parts can be used by weld- repairing without scraping.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a welding material that is applied to welding repair of Co-based precision cast parts such as gas turbines and jet engines.

[Conventional technology]

C is used in turbine vanes of gas turbines and jet engines.
Precision castings made of o-based heat-resistant casting alloys are used, but since these types of blades have complex shapes, casting defects are likely to occur and yields are low.

Traditionally, parts made of high-carbon (0.50% or more) Co-based heat-resistant cast alloys with large defects that require repair welding are used by briding off for small defects. It is being discarded because it cannot be repaired and welded with high quality.

[Problem to be solved by the invention]

The present invention was proposed in view of these circumstances, and
High-carbon Co-based heat-resistant castings with poor weldability can be repaired by welding, and the welded joints exhibit excellent material properties, allowing welding repairs to be performed without discarding Co-based precision casting parts with large casting defects. The purpose of the present invention is to provide a welding material for welding and repairing Co-based precision cast parts that can be used for welding and repairing Co-based precision cast parts.

[Means to solve the problem]

For this purpose, the present invention provides Cr; 22 to 30% by weight;
Ni: 8-15%, W: 5-10%, Ta: 2-5%,
C: 0.50-0.70%, T1: 1% or less, At;
0.5% or less, Zr; 1% or less, B; 0.0
15% or less, the remainder consisting of Co and unavoidable impurities
Cr: 18-27%, Ni: 18-27%, W in weight % for welding repair of casting defects in o-based precision casting parts.
; 10-18%, C; 0.02-0.20%, La;
0.02-0.20%, si; 0.20-0.50
%, the remainder being Co and unavoidable impurities.

[For production]

In the welding material of the present invention, by increasing the C content within a range that does not impair weldability, the amount of carbide precipitation increases and the strength increases, and by adding W, the high temperature strength is improved by solid solution strengthening. Corrosion resistance and oxidation resistance are obtained by adding Cr, and oxidation resistance is improved by adding La, and N
The addition of L stabilizes the austenite (FCC) matrix, and the addition of St improves weldability, resulting in high strength and high ductility for high-carbon (0.50% or more) Co-based heat-resistant cast parts with poor weldability. Repair welding can be performed.

〔Example〕

Examples of the welding material for welding repair of Co-based precision cast parts of the present invention will be explained with reference to the drawings. The figure is an explanatory diagram of the chemical composition range of the welding material of the present invention for welding repair of the Co-based heat-resistant precision casting alloy shown in Figure 1, and Figure 3 is an explanatory diagram of the chemical composition of the base material in specific experimental example V. FIG. 4 is an explanatory diagram of the chemical composition of the welding material in the same as above, and FIG. 5 is an explanatory diagram of the mechanical properties of the welded joint material in the same as above.

First, the composition of the high-carbon Co-based heat-resistant precision casting alloy, which is the object of the present invention, will be explained with reference to FIG. 1, along with the reason for limiting the composition range.

Cr: This is a necessary element from the viewpoint of oxidation resistance and high temperature corrosion resistance. It is also a carbide-forming element, and is an element necessary to form carbides and obtain strength. The amount of Cr that satisfies these two points is 22 to 30% by weight.

Ni: An element that stabilizes the austenite l-(FCC) of the substrate and also improves processability. From these points, the amount of Ni was set to 8 to 15% by weight.

Ti: A carbide-forming element that precipitates carbides and increases strength. In addition, a part of it forms an intermetallic compound with Co or NI, which helps improve high-temperature strength. These points t)'l'
i was set to 1% by weight or less.

W: A solid solution strengthening element, which is absolutely necessary in order to have the strength of a Co-based heat-resistant alloy. Some carbides are also formed, contributing to improved strength.

Based on these points, the content was reduced to 5 to 10% by weight.

Ta: is a solid solution strengthening element as well as a carbide forming element, and contributes to improving the strength of the Co-based heat-resistant alloy. Based on these points, the content was set at 2 to 5% by weight.

C: A carbide-forming element that forms carbides and contributes to strength. The amount of C was 0.50 to 0.70% by weight.

, u: Forms a dense oxide film and contributes to oxidation resistance. A
The amount of t was 0.5% by weight or less.

Zr, B; - strengthens the grain boundary dendrite boundary and contributes to improving high temperature strength. The amount of Zr is 1% by weight or less, and the amount of B is 0.
．． 0.015% by weight or less.

The rest is Co, but industrially unavoidable impurity elements such as Fe, Si, Mn, S, P,
It is desirable that Ag and the like be as low as possible. In addition to the above, small amounts of Y and La may be added to further improve oxidation resistance.

Next, the composition of the welding material for welding and repairing the above-mentioned high-carbon Co-based heat-resistant precision casting alloy is within the range shown in FIG. 2, and the reason for limiting the composition range will be explained below.

Since the base material was a Co-based heat-resistant alloy, the welding material was also a Co-based heat-resistant alloy. Therefore, the role of each element is essentially the same as that described for the base material.

Cr: This is a necessary element from the viewpoint of oxidation resistance and high temperature corrosion resistance. It is also a carbide-forming element, and is an element necessary to form carbides and obtain strength. In particular, V iron used in gas turbine stationary blades is required to have oxidation resistance and corrosion resistance from the viewpoint of fuel diversity, and is required to have at least 18% by weight or more. On the other hand, if the amount is too large, the ductility of the weld metal will decrease and the structure will lack stability due to long-term use at high temperatures, so the weight is set at 27% or less.

Nl: is a stabilizing element for the austenite (CF'CC) of the substrate, and rC is required to be 18% by weight or more in order to increase the amount of solid solution of the solid solution strengthening element W.

On the other hand, if the amount is too high, the heat fatigue resistance and sulfidation resistance, which are characteristics of Co-based heat-resistant alloys, will deteriorate, so the amount is set at 27% or less.

W: A solid solution strengthening element, which is absolutely necessary in order to have the strength of a Co-based heat-resistant alloy. It also forms some carbides and contributes to improving strength. This welding material has a lower C content than the base metal from the viewpoint of weldability, and in order to compensate for this decrease in strength, W is required to be at least 10% by weight.

However, if it is too large, it will cause a decrease in ductility, so 18% by weight
The following was made.

C: A carbide-forming element that forms carbides and contributes to strength. In order to ensure strength, 0.02% by weight or more is required. However, if it is too much, weldability will deteriorate, so 0.
The content was 20% by weight or less.

La: The oxide of La is dense and forms a scale with high oxidation resistance. Therefore, addition of a small amount is effective in improving oxidation resistance, but for this purpose, 0.02% by weight or more is required. However, since La is an expensive element, 0.2
It was set to 0 or less.

SI: Effective as a deoxidizing agent, 0.20% by weight or more is required to improve the cleanliness of weld metal. But al
) If it is too large, it will be harmful, so it is set to 0.50% by weight or less.

The remainder is Co, but it is desirable that industrially unavoidable impurity elements such as Fe, Mn, S, P, Ag, etc. be as low as possible.

Specific experimental examples shown in FIGS. 3 to 5 will be described below.

A round bar (114 x 85
tmm), welding current 40 to 70 by processing 60 V-shaped openings and using 4m class welding material shown in Figure 4.
A welded joint material was made using an ampere and a glabellar temperature of 50 to 60°C.

From this welded joint material, tensile test pieces and creep rupture test pieces with a parallel portion diameter d=6.0 were processed. and 8
Tensile test at 50°C, temperature 870°C, stress 11.3
A creep rupture test was conducted on a 4/jl wing. The test results are shown in FIG.

In the tensile test results shown in Figure 5, good strength and ductility were obtained for the welding material 1.2 of the present invention, which was within the chemical composition range shown in Figure 2, whereas reference welding material 3, which was outside the chemical composition range, was found to have good strength and ductility. , 4 did not provide good tensile properties. That is, in material 3, since the content of Cr, W, and C was high, the strength was high for the above-mentioned reason, but the ductility was low. On the other hand, in material 4, these values were low, so although it had excellent ductility, it had low strength.

In addition, in the creep rupture test results, similar to the tensile test results, the welding material 1 of the present invention within the chemical composition range shown in FIG.
Good strength and ductility were obtained for 2 and 2;
Reference welding materials 3 and 4 outside the chemical composition range did not have good leap rupture properties.

In addition, a round bar (chain 14x85
tmm), a bead-on test was conducted under the conditions described above using the four types of welding materials shown in FIG. 4 in the longitudinal direction.

After welding, liquid penetrant testing was performed after macrostructural testing. As a result, defect indications were observed in welding material 3, whereas no defect indications were observed in welding materials 1.2.4.
Weldability was judged to be good.

As described above, according to the present invention, by using a Co-based welding material having a chemical composition range shown in Fig. 2, a high-carbon Co-based heat-resistant cast product with poor weldability as shown in Fig. 1 can be repaired by welding. The welded joints exhibited excellent material strength properties. Hence the gas turbine.

Co-based precision castings of jet engine turbine stationary blades having casting defects, which were conventionally discarded, can be repaired by welding using the above-mentioned welding material.

[Effect of the invention J In short, according to the present invention, %Cr in weight%: 22 to 30
%, Ni; 8-15%, Was-10%, Ta;
2-5%, C; 0.50-0.70%, Ti;
1% or less, A7: 0.5% or less, Zr: 1% or less, B: 0,015% or less, the remainder being Co and unavoidable impurities. For welding and repairing casting defects in Co-based precision casting parts, In weight%, Cr; 18-27%, Ni;
18-27%, W; 10-18%, C; 0.02-0.
20%, La; 0.02-0.20%, Sl; 0.
By containing 20 to 0.50% and the remainder being Co and unavoidable impurities, it is possible to weld and repair high carbon Co-based heat-resistant castings with poor weldability, and the welded joints exhibit excellent material properties. The present invention is industrially extremely useful because it provides a welding material for welding repair of Co-based precision casting parts that can be used for welding repair without discarding Co-based precision casting parts that have large casting defects. It is.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the chemical composition range of the high carbon Co-based heat-resistant precision casting alloy that is the subject of the present invention, and Figure 2 is the welding material of the present invention for welding and repairing the Co-based heat-resistant precision casting alloy shown in Figure 1. Figure 3 is an explanatory diagram of the chemical composition of the base metal in a specific experimental example, Figure 4 is an explanatory diagram of the chemical composition of the welding material in the same example, and Figure 5 is a welded joint in the same example. FIG. 3 is an explanatory diagram of the mechanical properties of the material. Figure 1f Figure 2 Agent Masa Tsukamoto, Patent Attorney Figure 3 Figure 4

Claims (1)

[Claims] In weight%, Cr: 22-30%, Ni: 8-15%, W
; 5-10%, Ta; 2-5%, C; 0.50-0.7
0%, Ti: 1% or less, Al: 0.5% or less, Zr: 1
% or less, B: 0.015% or less, the balance is Co and unavoidable impurities.For welding repair of casting defects in Co-based precision casting parts, Cr: 18-27%, Ni
; 18-27%, W; 10-18%, C: 0.02-0
．． 20%, La; 0.02-0.20%, Si: 0.2
A welding material for welding and repairing Co-based precision cast parts, characterized in that the content is 0 to 0.50%, and the remainder is Co and unavoidable impurities.