JPH0243813B2 - GASUTAABINYOKOKYODOCOKITAINETSUGOKIN - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention exhibits high strength and outstanding oxidation resistance in high-temperature oxidizing atmospheres of 1000°C or higher, and also has 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: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one of W and Mo. Or 2 types: 2-12
%, Hf: 0.5 to 5%, and if necessary, Mn: 0.05 to 1%, one or two of Ta and Nb: 0.5 to
3% and one or two of B and Zr: 0.005~
A Co-based alloy containing one or more of the group consisting of 0.1% and the remainder consisting of Co and unavoidable impurities can be heated at 1000°C in a high-temperature oxidizing atmosphere.
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, etc. to form carbides, which strengthens the inside and grain boundaries of grains, improves high-temperature strength, and further improves weldability and castability. However, if the content is less than 0.05%, the desired effect cannot be obtained, while if the content exceeds 0.7%, the toughness will deteriorate.
It was set at 0.05-0.7%. (b) Si In addition to having a deoxidizing effect, the Si component also has the effect of improving the fluidity of the molten metal and further improving the high-temperature oxidation resistance, but if its content is less than 0.1%, the desired effect will not be achieved. On the other hand, if the content exceeds 2%, the toughness and weldability deteriorate, so the content was set at 0.1 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 35%, the desired excellent high-temperature oxidation resistance cannot be achieved;
If the content exceeds 35% to 40%, the high temperature strength and toughness will be significantly reduced.
%. (d) Ni Ni 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 this amount, the hot corrosion resistance tends to deteriorate, so the content was set at 5% to less than 18%. (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 M ₂₃ C ₆ type low melting point carbides and improving high temperature strength, as well as forming a solid solution in the austenite matrix and strengthening it. However, if its content is less than 2%, On the other hand, if the content exceeds 12%, not only will high-temperature oxidation resistance deteriorate rapidly, but also intermetallic compounds such as σ phase, which cause deterioration of toughness, will be produced. The content was determined to be between 2 and 12%. (f) 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, as well as significantly improving hot corrosion resistance. However, if its content is less than 0.5%, the desired effect may not be achieved. No effect was obtained, and on the other hand, even if the content exceeded 5%, no further improving effect could be obtained due to the above-mentioned effects.Considering economic efficiency, the content was determined to be 0.5 to 5%. (g) Mn In addition to having a strong deoxidizing effect, the Mn component has the effect of solid-dissolving into the austenite matrix, stabilizing it, and improving toughness, so it is necessary when these properties are required. However, if the content is less than 0.05%, the desired effect cannot be obtained, while if the content exceeds 1%, the high temperature oxidation resistance tends to deteriorate. Therefore, its content was determined to be 0.05 to 1%. (h) Ta and Nb 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, and further improving hot-temperature resistance. - Since it also has the effect of improving corrosion resistance, it is included as necessary when these properties are particularly required, but if its content is less than 0.5%, the desired effect of improving the above effect cannot be obtained, On the other hand, even if the content exceeds 3%, no further improvement effect will be obtained, so the content was set at 0.5 to 3%. (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%. 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 35 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 90 mm. Next, a creep lap tear test piece was cut from this test piece material for the purpose of evaluating high temperature strength, and using this test piece, the test piece was heated in the atmosphere at a heating temperature of 1100°C and an additional load of 3.5 kg/ ^mm2 . Creep tear tests were conducted under these conditions 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 kept in the air at a temperature of 1000°C for 24 hours. After that, one cycle of descaling was performed, and after 10 cycles, a high temperature oxidation resistance test piece was conducted to measure the oxidation loss. Furthermore, a test piece with dimensions of diameter: 10 mmφ x height: 10 mm was similarly cut out, and this test piece was placed in molten Na ₂ SO ₄ heated to a temperature of 900°C for 200 min.
Immersion test under time immersion conditions

【table】

【table】

【table】

【table】

〔Effect of the invention〕

From the results shown in Table 2, the Co-based heat-resistant alloys 1 to 35 of the present invention all have excellent high-temperature strength and high-temperature oxidation resistance, as well as excellent hot corrosion resistance. Co
As seen in Base 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, the high temperature strength and high temperature oxidation resistance will deteriorate. It is clear that at least one of the properties of hardness 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: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2～12
%, Hf: 0.5-5%, with the remainder consisting of Co and unavoidable impurities (weight %). High-strength Co-based heat-resistant material for gas turbines with excellent hot corrosion resistance. alloy. 2 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5 to 5%, and further contains Mn: 0.05 to 1%, with the remainder consisting of Co and unavoidable impurities (weight %).・High-strength Co-based heat-resistant alloy for gas turbines with excellent corrosion resistance. 3 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5 to 5%, and further contains one or two of Ta and Nb: 0.5 to 5%.
1. A high-strength Co-based heat-resistant alloy for gas turbines having excellent hot corrosion resistance, characterized by having a composition (by weight %) of 3% and the remainder consisting of Co and unavoidable impurities. 4 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5 to 5%, and further contains one or two of B and Zr: 0.005
A high-strength Co-based heat-resistant alloy for gas turbines with excellent hot corrosion resistance, characterized by having a composition (weight %) of ~0.1% and the remainder consisting of Co and unavoidable impurities. 5 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5 to 5%, and further contains Mn: 0.05 to 1%, and one or two of Ta and Nb: 0.5 to 1%.
1. A high-strength Co-based heat-resistant alloy for gas turbines having excellent hot corrosion resistance, characterized by having a composition (by weight %) of 3% and the remainder consisting of Co and unavoidable impurities. 6 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5-5%, and further contains Mn: 0.05-1%, and one or two of B and Zr: 0.005-1%.
1. A high-strength Co-based heat-resistant alloy for gas turbines with excellent hot corrosion resistance, characterized by containing 0.1% and the remainder consisting of Co and unavoidable impurities (weight percent). 7 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5 to 5%, and further contains one or two of Ta and Nb: 0.5 to 5%.
3%, 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. 8 C: 0.05 to 0.7%, Si: 0.1 to 2%, Cr: more than 35% to 40%, Ni: 5 to less than 18%, one or two of W and Mo: 2 to 12
%, Hf: 0.5~5%, and further contains Mn: 0.05~1%, and one or two of Ta and Nb: 0.5~
3% and 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.