JPH0892676A - Nickel-based superheat resistant alloy - Google Patents

Abstract

PURPOSE: To obtain an Ni-based superheat resistant alloy easy to melt, less liable to crack at the time of forging and excellent in various physical properties. CONSTITUTION: This alloy consists of <=0.1% C+N, <=1.0% Si, <=0.1% Mn, 2-10% Cr, 4-15% Mo, 20-40% W, 0.01-0.010%, in total, of Mg and/or B, <=0.01% S, <=0.01% P and the balance essentially Ni. This alloy has high strength at high temp. and is excellent in hot workability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel-base superheat-resistant alloy, which provides a superheat-resistant material which is easy to melt and has various physical properties and which has a wide range of applications.

[0002]

2. Description of the Related Art It is known that a large amount of W should be added to Ni in order to increase the heat resistance strength of a nickel-based super heat resistant material. Since the heat resistance strength of the matrix increases as the W content increases, addition of up to about 50% W content has been attempted.

However, when the amount of W exceeds 40%, it becomes difficult for W to form a solid solution in Ni uniformly, and W tends to settle due to the difference in specific gravity. For example, W45% (Ni
55%) and vacuum induction melting-casting (melting temperature is about 1750 ° C.), the W content in the obtained ingot is biased to about 40% at the top and about 50% at the bottom. . Moreover, W-rich (70
Occasionally, there will be ~ 80% of the material left and not flowing into the mold.

Even if such a difficulty is overcome and a W45% alloy is melted and cast, its working is not easy.
Forging the ingot (heating temperature is 1300 ° C.) is necessary to bring the material closer to the product shape and to improve the machinability by refining the microstructure, but cracks are likely to occur even with careful pressing. It is considered that this is because the elongation of the material decreases in a composition having a high W content.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a nickel-base super heat-resistant alloy which is easy to melt while maintaining high strength at high temperature and which is less likely to crack during forging. To provide.

[0006]

The nickel-base superalloy according to the present invention is C + N: 0.1% or less, Si: 1.0% or less, Mn: 1.0% or less, Cr: 2-10%, Mo: 4
~ 15% or less, W: 20 to 40%, and one or two kinds of Mg and B (in the case of two kinds in total amount): 0.0
01-0.010%, S: 0.01% or less,
P: 0.01% or less, having an alloy composition with the balance being Ni.

In the present invention, when an alloy having particularly high strength at high temperature is desired, in the above composition, the amounts of Cr and Mo are made small and the amount of W is made large, that is, C +.
N: 0.1% or less, Si: 1.0% or less, Mn: 1.0%
Below, Cr: 2 to 5%, Mo: 4 to 10% or less, W: 3
0 to 40%, and one or two kinds of Mg and B (in the case of two kinds, the total amount): 0.001 to 0.010%
It is advisable to employ an alloy composition containing S, 0.01% or less, P: 0.01% or less, and the balance being Ni.

[0008]

When W is added to Ni, the amount of W must be suppressed to some extent in order to facilitate dissolution and reduce segregation. When the amount of W is suppressed, the high temperature strength naturally lowers, so it is decided to supplement it with Mo, and further an appropriate amount of Cr is added in order to reinforce the high temperature strength and improve the oxidation resistance. This is the basic composition of the alloy. The functions of each alloy component including the above-mentioned main components and the reasons for limiting the composition range are as follows.

C + N: 0.1% or less Since both C and N enhance the high temperature strength by solid solution strengthening, the presence of a small amount is useful. Since a large amount impairs hot workability, the total amount of C and N is limited to 0.1%.

Si: 1.0% or less Si is necessary as a deoxidizing agent, but since it lowers the melting point and reduces the ductility at high temperatures, it is added up to 1.0%.

Mn: 1.0% or less Mn is added for deoxidation, but it also has the function of fixing S. It also helps improve ductility at high temperatures, but if present in excess of 1%, the high temperature strength will decrease.

Cr: 2 to 10% Cr forms an intermetallic compound with Mo or W, and forms a carbide with C, which suppresses the growth of crystal grains and makes the structure fine.
It also has the effect of improving the oxidation resistance as described above. These effects are obtained by adding 2% or more, but if it exceeds 10%, hot workability is impaired.

Mo: 4 to 15% As mentioned above, Mo assists W to enhance high temperature strength.
Further, the melting point is lowered to enable the use of a steel ingot mold, and the specific gravity is smaller than W, so that there is an advantage of reducing the product weight. In order to obtain such effects, it is necessary to add Mo in an amount of at least 4%. On the other hand, when the amount is large, a large amount of a compound with C or Cr is generated and the machinability at room temperature is deteriorated. Therefore, the upper limit is 15%.

W: 20-40% As described at the beginning, W forms a solid solution in Ni to enhance the high temperature strength, but if the addition amount exceeds 40%, segregation becomes large and a homogeneous ingot can be obtained. It will be difficult. If the W content is reduced, the opposite is true. In the experience of the inventor, segregation of ± 5% above and below the ingot at W: 45% was reduced to ± 2 to 3% at 40%. , 35%
Then it will be close to zero. To obtain the high temperature strength required for this type of alloy, W must be at least 20%.

One or two kinds of Mg and B (total amount in the case of two kinds): 0.001 to 0.01% Both Mg and B have an action of improving hot workability. This effect is 0.001
%, And is saturated relatively quickly even if the amount added is increased, so 0.01% is made the upper limit.

S: 0.01% or less, P: 0.01% or less Since both S and P impair hot workability, the content should be suppressed as much as possible. 0.01% is the acceptable limit.

[0017]

Example An alloy having the composition shown in Table 1 was melted in a vacuum induction furnace and cast into an ingot having a diameter of 70 mm and a length of 150 mm.
A tensile test piece (dimension of parallel portion: diameter 8 mm × length 40 mm) was produced from this ingot by machining, and a high temperature tensile test was performed. The test conditions are 1100 ° C. for 15 minutes and a pulling rate of 3 mm / min. The results are shown in Table 2 together with the evaluation of the machinability (turning property) when the test piece was manufactured.

Table 1 ( No. 1, Example) No. C + N Si Mn W Mo Mo Cr Mg + B P S 1 0.052 0.05 0.08 21.2 14.2 8.6 0.00051 0.003 0.002 2 0.025 0.12 0.24 22.5 13.6 7.5 0.0035 0.002 0.002 3 0.043 0.25 0.18 25.3 12.4 8.1 0.0054 0.003 0.002 4 0.018 0.33 0.53 27.2 11.7 8.8 0.0042 0.026 0.20 0.35 28.5 10.3 5.2 0.0032 0.002 0.001 6 0.065 0.54 0.15 29.4 10.4 6.3 0.0062 0.002 0.001 7 0.038 0.45 0.31 30.3 9.5 5.6 0.0018 0.002 0.001 8 0.035 0.22 0.43 32.3 9.2 5.8 0.0052 0.003 0.002 9 0.012 0.95 0.48 33.8 8.2 4.7 0.0062 0.004 0.001 10 0.012 0.18 0.28 34.4 8.5 5.4. 0.0048 0.002 0.001 11 0.024 0.80 0.95 35.3 8.7 4.0 0.0090 0.001 0.002 12 0.037 0.93 0.18 36.2 8.1 4.8 0.0062 0.002 0.001 13 0.088 0.74 0.84 39.4 5.4 3.2 0.0073 0.002 0.002 14 0.015 0.03 0.88 38.4 6.5 2.3 0.0038 0.002 0.001 Table 1 (Part 2, Comparative Example) No. C + N Si Mn W Mo Mo Cr Mg + B P S 1 0.093 0.35 0.36 16.1 13.7 5.3 0.0041 0.003 0.002 2 0.082 0.50 0.41 18.8 12.4 8.6 0.0028 0.003 0.001 3 0.021 0.20 0.32 44.3 4.3 4.5 0.0072 0.004 0.001 0.004 0.034 0.04 0.35 49.4 4.61 4.8 0.0046 0.004 0.033 0.02 0.42 31.2 3.2 7.1 0.0052 0.003 0.002 6 0.026 0.18 0.56 29.6 17.1 8.3 0.0038 0.004 0.008 7 0.142 0.55 0.03 33.4 9.0 5.2 0.0066 0.002 0.007 8 0.008 1.3 0.75 34.3 8.3 4.4 0.0042 0.003 0.006 9 0.011 0.35 1.5 27.5 11.2 5.4 0.0035 0.004 0.006 10 0.032 0.46 0.34 26.3 11.4 5.9.0.0048 0.016 0.005 11 0.056 0.38 0.26 30.8 10.6 4.3 0.0065 0.002 0.014 12 0.043 0.18 0.32 31.9 9.4 13.2 0.0076 0.003 0.005 13 0.034 0.35 0.49 29.1 10.8 4.4 0.0005 0.002 0.004 14 0.021 0.48 0.77 28.1 11.4 4.5 0.0120 0.003 0.004 % By weight, balance Ni.

Table 2 (No. 1, Example) No. Tensile Strength Elongation Draw Machinability MPa% 1 158 68 73 73 Good 2 162 172 76 76 Good 3 159 71 75 Good 4 165 68 65 Good 5 165 62 68 Good 6 171 58 62 Good 7 168 58 58 65 Good 8 168 63 72 Good 9 169 59 65 65 Good 10 161 64 68 Good 11 164 40 43 Good 12 167 71 69 69 Good 13 171 39 42 Good 14 158 72 43 (Good) Comparative Example) No. Tensile Strength Elongation Drawing Machinability MPa %% 1 133 41 50 Good 2 134 42 51 Good 3 15 2 23 23 18 Good 4 154 21 16 Good 5 125 41 50 Good 6 159 35 35 42 Poor * 7 148 12 15 Good 8 152 13 16 Good 9 148 9 11 Good 10 161 7 10 Good 11 165 8 0 Good 12 165 8 10 Good 13 167 6 8 Good 14 168 7 9 good * was difficult very shaving.

[0020]

EFFECTS OF THE INVENTION The nickel-base alloy of the present invention does not have an excessive W content, and therefore can be cast into an ingot which is easily melted and has less segregation. It has high high-temperature strength, excellent hot workability, less risk of cracking during forging, and good machinability.

Therefore, this alloy is useful as a structural material of a heating furnace or a heat treatment furnace used at a high temperature, and has a long life when used for a hot plastic working tool such as a mandrel or a die of an extrusion pipe forming apparatus. Give a tool.

Claims (2)

[Claims] 1. C + N: 0.1% or less, Si: 1.0%
Hereinafter, Mn: 1.0% or less, Cr: 2 to 10%, Mo:
4 to 15%, W: 20 to 40%, and one or two kinds of Mg and B (in the case of two kinds, in a total amount): 0.0
01 to 0.010%, S: 0.01% or less, P:
Nickel-based superalloys with 0.01% or less and the balance being substantially Ni. 2. C + N: 0.1% or less, Si: 1.0%
Below, Mn: 1.0% or less, Cr: 2 to 5%, Mo: 4
-10%, W: 30-40%, and Mg and B
1 type or 2 types (in the case of 2 types, the total amount): 0.00
1 to 0.010%, S: 0.01% or less, P:
Nickel-based superalloys with 0.01% or less and the balance being substantially Ni.