JPS63186845A - Ni group heat-resisting alloy having excellent thermal shock resistance - Google Patents

Abstract

PURPOSE:To obtain an Ni group heat-resisting alloy having excellent high temp. strength and thermal shock resistance, by specifying the compsns. consisting of C, Cr, Ti, Al, Fe, W, Mo, Nb, Ta, Hf and Ni. CONSTITUTION:The Ni group heat-resisting alloy contains, by weight, 0.05-0.25% C, 10-25% Cr, 1-3% Ti, 0.5-2.5% Al, 1-15% Fe, one or two kinds of 0.05-1.5% W and Mo, one or more kinds among 0.01-2% Nb, Ta and Hf, and furthermore contains at need, 0.3-3% Co and/or one or two kinds of 0.001-0.2% B and Zr and the balance consisting of Ni with inevitable impurities. Said alloy has excellent thermal shock resistance and has excellent high temp. strength in an as-cast state and heat treatment state. The significantly excellent capacity of the alloy can be therefore shown for long period of time at the time of using the alloy e.g. as the structural member of a secondary combustion chamber of a diesel engine, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a Ni-based heat-resistant alloy that has excellent thermal shock resistance and high-temperature strength.

[Conventional technology]

Traditionally, for example, in the manufacture of structural members for the sub-combustion chamber of a diesel engine, thermal shock resistance, high temperature strength, and heat resistance are required, so it is expressed in heavy electric percentage (the lower % indicates heavy electric percent). Ni-20%Cr
It has a typical composition of -2,4%Ti-1,2%Affl-0,22%C, and is treated with solution (for example, in a vacuum, after being kept at a temperature of 1080°C for 8 hours, followed by air cooling) and By performing an aging treatment (for example, maintaining the temperature in a vacuum at a temperature near 00°C for 16 hours, and then cooling it in air), an intermetallic compound mainly composed of Ni-Al-Ti can be formed on the austenite matrix.
That is, a Ni-based heat-resistant alloy with a structure in which Ni3 (CM, Ti) is finely precipitated, Co-18%Cr-15%W-10%Ni-0.4%
A Co-based heat-resistant alloy having a typical composition of C is used.

[Problem that the invention seeks to solve]

However, in recent years, there has been a severe demand for higher performance for various engines, and as a result, the usage conditions for the sub-combustion chamber of a diesel engine, for example, have become even more severe. Conventional Ni-based heat-resistant alloys and CO-based heat-resistant alloys have satisfactory high-temperature strength and heat resistance, but their thermal shock resistance is particularly insufficient.
There are problems with reliability.

[To solve problems]

Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a material with particularly excellent thermal shock resistance, high-temperature strength, and heat resistance, and as a result, C: 0.05-0. 25%, Cr:10-25%
.

Ti: 1 to 3%, U: O, S to 2.5%.

Fe: 1-15%.

One or two of W and Mo: 0.05 to 1.
5%.

One or two of Nb, Ta, and 'Hf
More than seeds: 0.01-2%! and, if necessary, Co: 0.3 to 3%, and one or two of B and Zr: 0.001 to 0.
．． Ni-based alloys containing either or both of 2% and 2%, with the remainder consisting of Ni and unavoidable impurities, have particularly excellent properties in the as-cast state and in the heat-treated state of solution treatment and aging treatment. It also has excellent high-temperature strength and heat resistance equivalent to the conventional Ni-based heat-resistant alloy and the conventional Co-based heat-resistant alloy described above. They found that when used as a structural member of a combustion chamber, it exhibits excellent performance over a long period of time.

This invention was made based on the above knowledge, and the reason why the component composition was limited as described above will be explained below.

(a) C The C component contains Cr + Tt lWIMo l and Nb
, Ta.

It combines with Hf etc. to form carbides and has the effect of improving the strength at room temperature and high temperature at grain boundaries and within the grains, but if the content is less than 0.05%, it will not have the desired effect. However, the content is 0.25%.
Since the toughness of the alloy decreases when the content exceeds 0.05% to 0.25%.

(b) Cr The Cr component has the effect of forming a solid solution in the austenite matrix and significantly improving the high-temperature oxidation resistance (heat resistance) of the alloy, but if its content is less than 10%, the desired high-temperature oxidation resistance cannot be achieved. However, if the content exceeds 25%, the high-temperature strength and toughness will rapidly decrease. Therefore, the content was set at 10 to 25%.

(cl Ti Ti component C2 is NN15 (, Ti
) to form an intermetallic compound c (hereinafter referred to as γ' phase),
It has the effect of precipitation strengthening the alloy and thereby improving its strength at room temperature and high temperature. However, if the content is less than 1%, the desired effect cannot be obtained, while if the content exceeds 3%, it becomes brittle. Since the η phase (,: gi 3 Ti phase) precipitates in a multi-electrode manner and the toughness of the alloy decreases, its content was determined to be 1 to 3%.

(d) As mentioned above, the AJ ME component has the effect of forming the γ' phase and improving the room temperature and high temperature strength of the alloy as well as the high temperature oxidation resistance. If the content is less than 5%, the desired effect cannot be obtained; on the other hand, if the content is less than 2
．． If it exceeds 5%, the castability and weldability will deteriorate, and the toughness will also decrease, so the content should be reduced to 0.
．． It was set at 5 to 2.5%.

fe) Fe The FeE content has the effect of solidly dissolving in the austenite matrix and further improving the heat-resistant cylinder "Is" properties of the alloy, but if the content is less than 1%, the desired thermal shock resistance cannot be obtained. On the other hand, if the content exceeds 15%, the high-temperature strength of the alloy will decrease significantly, so the content is set at 1 to 15%.

if) W and M.

These components not only form a solid solution in the austenite matrix, but also form carbides as mentioned above and have the effect of improving the room temperature and high temperature strength of the alloy.
If the content is less than 1.5%, the desired effect cannot be obtained, while if the content exceeds 1.5%, the high temperature oxidation resistance and toughness will deteriorate significantly.
．． It was set at 05 to 1.5%.

(g) Nb, Ta, and Hf As mentioned above, these components have the effect of forming MC type carbides to strengthen grain boundaries and grain regions, thereby improving the strength at room temperature and high temperature. If the content is less than 0.01%, the desired effect cannot be obtained, while if the content exceeds 2%, the toughness will decrease. Established.

fh)　C.

The Co component is dissolved in the austenite matrix and has the effect of further improving high temperature strength and high temperature oxidation resistance, so it is included as necessary, but the content is 0.3%.
If the content is less than 3%, the desired effect of improving the above action cannot be obtained, and on the other hand, even if the content exceeds 3%, no further improvement effect can be obtained. It was set at 3%.

fi) B and Zr These components have the effect of toughening grain boundaries and further improving thermal shock resistance, so they are included as necessary, but if the content of 1 is less than 0.001%, The desired effect of improving the above action cannot be obtained, and on the other hand, the content is 0.
．． If it exceeds 2%, the alloy tends to become brittle, so the content was set at 0.001 to 0.2%.

In addition, in the Ni-based heat-resistant alloy of the present invention, even if Si and Mn'ljx are contained as unavoidable impurities, as long as their content is 2% or less, they will not have any adverse effect on the alloy properties. 2% of each ingredient
It is useful to use it as a deoxidizing agent within the following range.

〔Example〕

Next, the Ni-based heat-resistant alloy of the present invention will be specifically explained using examples.

Using an ordinary vacuum melting furnace, prepare molten alloys having the component compositions shown in the first stage, and cast these molten alloys using the a-stwax precision casting method as shown in Figure 1 fa.
A diesel carrot sub-combustion having a shape shown in a plan view at t and a cross-sectional view taken along the line A-A in Fig. The cap member, which is a structural member of the chamber, and the parallel part outer diameter = 7-φ x parallel part length = 50 mm x chuck part outer diameter: 25 mmφ x total length: 9
It is cast into a tensile test piece material with a dimension of 0.0 mm, and a part of these mouthpiece members and the test piece material (see notes in Table 2) is heated in a vacuum at a temperature of 1000 to 1150°C. After holding at the temperature for 4 to 10 hours, solution treatment with air cooling,
After holding the temperature in the range of 650 to 750°C in vacuum for 16 hours, heat treatment consisting of air cooling aging treatment is performed to obtain the Ni-based heat-resistant alloy materials 1 to 25 of the present invention, the conventional Ni-based heat-resistant alloy materials, and Conventional Co-based if1 thermal alloy materials were manufactured respectively.

Next, using the various heat-resistant alloy materials obtained as a result, first, as shown in the schematic diagram in FIG. 3
The above-mentioned cap member S is set at 5, and the flame from the burner 4 heats the upper surface of the cap member S. The heating temperature is observed with a pyroscope 6.
When the temperature reaches 800°C, rotate the arm 2 in the direction of the arrow, immerse the heated cap member S in the water 8 in the water tank 7, and insert it into the nozzle hole of the cap member S. Thermal shock resistance was evaluated by repeating the test until cracking occurred, and high-temperature strength was evaluated using a tensile test piece of a predetermined size cut from the above-mentioned tensile test piece material in air at a temperature of 8.
A tensile test was conducted at 00°C, and evaluation was made by measuring tensile strength and 0.2% proof stress. These results are shown in Table 2.

〔Effect of the invention〕

From the results shown in Tables 1 and 2, the Ni-based heat-resistant alloys 1 to 25 of the present invention are equivalent to or better than the conventional M-based heat-resistant alloy and the conventional Co-based heat-resistant alloy in both the as-cast state and the heat-treated state. It is clear that it has superior high-temperature strength as above, and even superior thermal shock resistance.

As mentioned above, the Ni-based heat-resistant alloy of the present invention has particularly excellent thermal shock resistance and high-temperature strength. It has industrially useful properties such as exhibiting excellent performance over a long period of time when used as a structural member of an auxiliary combustion chamber.

[Brief explanation of the drawing]

Figure 1 (al and (bl) are a plan view showing the mouth member of the auxiliary combustion chamber of a diesel engine and a sectional view taken along the line A-A in Figure 1, and Figure 2 is a schematic explanatory diagram of a thermal shock resistance test. 1...Horizontal rotation axis, 2...Arm, 3...Holder. 4...Burner, 5...Flame gas. 6...Pyroscope, 7...Water 41. 8.
··water. S: Base member.

Claims (4)

[Claims] (1) C: 0.05-0.25%, Cr: 10-25%
, Ti: 1-3%, Al: 0.5-2.5%, Fe: 1
~15%, one or two of W and Mo: 0.05~1.
5%, one or more of Nb, Ta, and Hf:
A Ni-based heat-resistant alloy having excellent thermal shock resistance, characterized in that it contains 0.01 to 2% of the following, with the remainder consisting of Ni and unavoidable impurities (weight percent). (2) C: 0.05-0.25%, Cr: 10-25%
, Ti: 1-3%, Al: 0.5-2.5%, Fe: 1
~15%, one or two of W and Mo: 0.05~1.
5%, one or more of Nb, Ta, and Hf:
Thermal shock resistance characterized by having a composition (the above weight %) containing 0.01 to 2%, further containing Co: 0.3 to 3%, and the remainder consisting of Ni and unavoidable impurities. An excellent Ni-based heat-resistant alloy. (3) C: 0.05-0.25%, Cr: 10-25%
, Ti: 1-3%, Al: 0.5-2.5%, Fe: 1
~15%, one or two of W and Mo: 0.05~1.
5%, one or more of Nb, Ta, and Hf:
0.01 to 2%, and further one or two of B and Zr: 0.001 to 0
．． 1. A Ni-based heat-resistant alloy with excellent thermal shock resistance, characterized by having a composition (weight %) of 2% and the rest consisting of Ni and unavoidable impurities. (4) C: 0.05-0.25%, Cr: 10-25%
, Ti: 1-3%, Al: 0.5-2.5%, Fe: 1
~15%, one or two of W and Mo: 0.05~1.
5%, one or more of Nb, Ta, and Hf:
0.01 to 2%, furthermore, Co: 0.3 to 3%, and one or two of B and Zr: 0.001 to 0.
．． 1. A Ni-based heat-resistant alloy with excellent thermal shock resistance, characterized by having a composition (weight %) of 2% and the rest consisting of Ni and unavoidable impurities.