JPH0243812B2 - GASUTAABINYOKOKYODOCOKITAINETSUGOKIN - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] This invention exhibits high strength and outstanding oxidation resistance in high-temperature oxidizing atmospheres of 1000°C or higher, as well as excellent hot resistance and excellent oxidation resistance in high-temperature corrosive atmospheres of approximately 900°C or lower. The present invention relates to a Co-based heat-resistant alloy that exhibits corrosion resistance and is therefore suitable for use as a structural material for gas turbines that require these properties. [Prior Art] Conventionally, various types of Co, which have excellent high-temperature oxidation resistance and hot corrosion resistance, have been used to manufacture structural members such as turbine nozzles and vanes of gas turbines, which are generally exposed to high-temperature corrosive and oxidizing atmospheres. Base heat-resistant alloys are used. On the other hand, in recent years, with the improvement in the performance of gas turbines,
Gas turbine inlet temperatures continue to rise,
Its temperature has reached over 1300℃. [Problem to be solved by the invention] However, when the above-mentioned conventional gas turbine member made of a Co-based heat-resistant alloy is exposed to the above-mentioned high-temperature oxidizing atmosphere of 1300°C or higher, its own temperature becomes air-cooled. Even in these cases, the temperature at the highest temperature rose to over 1000°C, and due to the lack of high-temperature strength, the service life was reached in a relatively short period of time. For this reason, the development of materials that exhibit high strength in high-temperature oxidizing atmospheres is progressing, but improving high-temperature strength tends to result in a decrease in oxidation resistance, and along with this, hot corrosion resistance However, the current situation is that a material having all of the above characteristics has not yet been obtained. [Means for Solving the Problems] Therefore, from the above-mentioned viewpoints, the present inventors set out to develop a material that has high-temperature oxidation resistance and high-temperature strength, and also has hot corrosion resistance. As a result of research, in weight percent, C: 0.01-1%, one or two of Si and Mn: 0.01-1%
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01 to 3%, Hf: 0.05 to 5%, and if necessary, (A) one or more of Ta, Nb, and Ti: 0.01 to 5%, (B) One or two of B and Zr: 0.005
~0.1%, (C) Rare earth element: 0.005~0.1%, Co-based alloy containing one or more of the above (A) to (C), with the remainder consisting of Co and inevitable impurities. is in a high temperature oxidizing atmosphere at 1000℃
At above temperatures, this Co When base heat-resistant alloys are used to manufacture gas turbine components that require these properties, the resulting gas turbine components exhibit exceptional long-term performance, even under the harsh conditions described above. We obtained the knowledge that This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained below. (a) C The C component includes Cr, W,
It combines with Mo, Hf, Ta, Nb, Ti, etc. to form carbides, which strengthens the inside of grains and grain boundaries, improves high-temperature strength, and further improves weldability and castability. However, if the content is less than 0.01%, the desired effect cannot be obtained, while if the content exceeds 1%, the toughness will deteriorate, so the content is 0.01 to 1%. It was determined that (b) Si and Mn These components have a strong deoxidizing effect, so they are essential for deoxidizing molten metal, but if their content is less than 0.01%, the desired deoxidizing effect cannot be achieved. On the other hand, if the content exceeds 2%, the deoxidizing effect not only becomes saturated, but also the alloy properties tend to deteriorate, so the content was set at 0.01 to 2%. (c) Cr The Cr component is an essential austenite component for ensuring excellent high-temperature oxidation resistance.
If the content is less than 15%, the desired high-temperature oxidation resistance cannot be achieved, while if the content exceeds 40%, the high-temperature strength and toughness will be significantly reduced. % to 40%. (d) Ni Ni component has the effect of improving high-temperature strength when coexisting with Cr, but if its content is less than 5%, the desired effect cannot be obtained;
If the content exceeds 5%, the hot corrosion resistance tends to deteriorate, so the content was set at 5% to 15%. (e) W and Mo These components combine with C to form MC type carbide, which is a high melting point carbide, while M ₇ C ₃ type and
It has the effect of suppressing the formation of _{M23C6 type} low melting point carbides, improving high temperature strength, and strengthening the austenite matrix by forming a solid solution therein, but if the content is less than 2%, the above effects will not be achieved. On the other hand, if the content exceeds 12%, not only will high-temperature oxidation resistance rapidly deteriorate, but also intermetallic compounds such as σ phase will be formed, which will cause toughness deterioration. Therefore, the content was set at 2% to 12%. (f) Al Al component has the effect of improving high temperature oxidation resistance when coexisting with Hf, but its content is 0.01
If the content is less than 3%, the desired effect of improving high temperature oxidation resistance cannot be obtained, while if the content exceeds 3%, the castability will deteriorate and the alloy will tend to become brittle. Content 0.01~3
%. (g) Hf The Hf component is a high melting point carbide without forming MC type or M ₇ C ₃ type eutectic carbide.
Forms MC-type primary carbide, which has the effect of improving high-temperature oxidation resistance and high-temperature strength, and also significantly improving hot corrosion resistance, but if its content is less than 0.05%, the desired effect may not be achieved. No effect was obtained, and on the other hand, even if the content exceeded 5%, further improvement effects could not be obtained due to the above-mentioned effects.Considering economic efficiency, the content was determined to be 0.05 to 5%. (h) Ta, Nb, and Ti When these components coexist with Hf, they form MC-type primary composite carbides, which are high-melting point carbides, further improving high-temperature oxidation resistance and high-temperature strength. Since it also has the effect of improving hot corrosion resistance, it is included as necessary when these properties are particularly required, but if its content is less than 0.01%, the desired effect of improving the above effects cannot be obtained. On the other hand, even if the content exceeds 5%, no further improvement effect will be obtained, so the content was set at 0.01 to 5%. (i) B and Zr These components have the effect of strengthening grain boundaries and further improving the high-temperature strength of the alloy, so they are included as necessary when high-temperature strength is particularly required. If the content is less than 0.005%, the desired high-temperature strength improvement effect cannot be obtained, while if the content exceeds 0.1%, the toughness will decrease, so the content was set at 0.005 to 0.1%. (j) Rare earth elements Rare earth elements, that is, elements with atomic numbers 57 to 71 in the periodic table of elements, have the effect of further improving high-temperature oxidation resistance and hot corrosion resistance, especially when coexisting with Hf. It is included as necessary when particularly excellent high-temperature oxidation resistance and hot corrosion resistance are required, but if the content is less than 0.005%, the desired effect cannot be obtained; on the other hand, 0.1% If the content exceeds 0.005, the castability and workability tend to deteriorate.
It was set at 0.1%. Among the inevitable impurities in the Co-based heat-resistant alloy of the present invention, Fe in particular does not impair the alloy properties even if it is contained up to 3%. It may be actively included. [Example] Next, the Co-based heat-resistant alloy of the present invention will be specifically explained with reference to Examples. Co-based heat-resistant alloys 1 to 51 of the present invention and comparative Co-based heat-resistant alloys 1 to 10, each having the composition shown in Table 1, were melted by an ordinary melting method, and the parallel parts were melted using a lost wax precision casting method. Outer diameter: 7mm
φ x Parallel length: 50mm x Chuck outside diameter: 25mmφ
×Overall length: Cast into a test piece material with dimensions of 90mm. Next, a creep lap tear test piece was cut out from this test piece material for the purpose of evaluating high-temperature strength, and this test piece was used under the following conditions: atmosphere: air, heating temperature: 1000℃, added load: 7Kg/mm ² A creep lap tear test was conducted to measure the rupture life. In addition, a test piece with dimensions of diameter: 10 mmφ x height: 10 mm was cut out from the chuck part of the test piece after the above-mentioned creep rapture test, and this test piece was held in the atmosphere at a temperature of 1200°C for 5 hours. After that, a high temperature oxidation resistance test was conducted to measure the oxidation loss after 10 cycles of descaling. Furthermore, a test piece with dimensions of diameter: 10 mmφ x height: 10 mm was similarly cut out, and using this test piece, 35% Na ₂ SO ₄ +65% was heated to a temperature of 900°C.
An immersion test was conducted under the condition of immersion in a molten salt of Na ₂ CO ₃ for 25 hours, and the hot corrosion resistance was evaluated by measuring the corrosion loss after descaling of the test piece after the test. These measurement results are also shown in Table 2. [Effects of the Invention] From the results shown in Table 2, the Co-based heat-resistant alloys 1 to 51 of the present invention all have excellent high-temperature strength and high-temperature oxidation resistance, as well as excellent hot corrosion resistance. compared to

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] As seen in Co-based heat-resistant alloys 1 to 10, if the content of any of the constituent components (marked with * in Table 1) falls outside the scope of this invention,
It is clear that at least one of high temperature strength, high temperature oxidation resistance, and hot corrosion resistance becomes inferior. As mentioned above, the Co-based heat-resistant alloy of the present invention is
It has excellent high-temperature strength, high-temperature oxidation resistance, and excellent hot corrosion resistance, so it has excellent long-term properties when used as a structural component of high-performance gas turbines that require these properties. It has industrially useful properties such as exhibiting excellent performance.

Claims (1)

[Claims] 1 C: 0.01 to 1%, one or two of Si and Mn: 0.01 to 1%
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01 to 3%, Hf: 0.05 to 5%, and the remainder consists of Co and inevitable impurities (weight %), and has excellent hot corrosion resistance. High-strength Co-based heat-resistant alloy for turbines. 2 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01-3%, Hf: 0.05-5%, and further contains one or more of Ta, Nb, and Ti: 0.01-5%, and the remainder is Co. A high-strength Co-based heat-resistant alloy for gas turbines with excellent hot corrosion resistance, characterized by having a composition (the above weight %) consisting of unavoidable impurities. 3 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01~3%, Hf: 0.05~5%, and further contains one or two of B and Zr: 0.005~
1. A high-strength Co-based heat-resistant alloy for gas turbines with excellent hot corrosion resistance, characterized by having a composition (by weight) of 0.1% and the remainder consisting of Co and unavoidable impurities. 4 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01 to 3%, Hf: 0.05 to 5%, and further contains rare earth elements: 0.005 to 0.1%, with the remainder being Co and inevitable impurities (weight %). A high-strength Co-based heat-resistant alloy for gas turbines with excellent hot and corrosion resistance. 5 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01-3%, Hf: 0.05-5%, and further contains one or more of Ta, Nb, and Ti: 0.01-5%, and B and Zr. Type 1 or Type 2: 0.005~
1. A high-strength Co-based heat-resistant alloy for gas turbines with excellent hot corrosion resistance, characterized by having a composition (by weight) of 0.1% and the remainder consisting of Co and unavoidable impurities. 6 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01 to 3%, Hf: 0.05 to 5%, and further contains one or more of Ta, Nb, and Ti: 0.01 to 5%, and rare earth elements: 0.005 to 0.1. %, with the remainder consisting of Co and unavoidable impurities (weight %). 7 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01~3%, Hf: 0.05~5%, and further contains one or two of B and Zr: 0.005~
0.1%, rare earth elements: 0.005 to 0.1%, and the remainder consists of Co and unavoidable impurities (weight %).High strength for gas turbines with excellent hot corrosion resistance. Co-based heat-resistant alloy. 8 C: 0.01~1%, one or two of Si and Mn: 0.01~
2%, Cr: 15-40%, Ni: 5-15%, one or two of W and Mo: 2-12
%, Al: 0.01-3%, Hf: 0.05-5%, and further contains one or more of Ta, Nb, and Ti: 0.01-5%, and B and Zr. Type 1 or Type 2: 0.005~
0.1%, rare earth elements: 0.005 to 0.1%, and the remainder consists of Co and unavoidable impurities (weight %).High strength for gas turbines with excellent hot corrosion resistance. Co-based heat-resistant alloy.