JP5062709B2 - Cr-based alloy containing Re and Ag - Google Patents

Description

  The invention of this application relates to an improvement of a Cr (chromium) based heat resistant alloy. More specifically, the invention of this application relates to high temperature environments such as jet engine and gas turbine blades, engine intake valves and exhaust valves, rocker arms, motorcycle and automobile engine turbocharger connecting rods, for example, 1100 ° C. or higher. The present invention relates to a Cr-based alloy that is suitable as a structural heat-resistant material to be used below and has excellent compressive strength and oxidation resistance at high temperatures and high tensile ductility (elongation) at room temperature.

  Ni (nickel) -based alloys and Co (cobalt) -based alloys are widely used as structural heat-resistant materials such as jet engines and gas turbine blades or engine intake valves and exhaust valves. However, these alloys are not only expensive, but also have a problem that the actual service temperature is limited to about 1100 ° C. due to restrictions such as a high thermal expansion coefficient and a melting point.

  In general, it is said that the thermal efficiency of a gas turbine can be dramatically improved by increasing the temperature at the inlet of the turbine. Larger devices such as gas turbines that are used in many countries around the world can greatly contribute to the suppression of global warming by improving the thermal efficiency of the devices. Development of structural structural materials is strongly desired.

Against this background, Cr (chromium) has excellent melting resistance (1863 ° C.) and good oxidation resistance, and has excellent conditions as a heat-resistant alloy that has a lower density than Ni and high thermal conductivity. . For this reason, Cr-based alloys are attracting attention as an alternative to Ni-based alloys and Co-based alloys. Up to now, attention has been paid to this feature of Cr (chromium) -based alloys, and further, heat resistance, workability, strength, etc. Ideas and improvements for improvement have been proposed (for example, Patent Documents 1 to 4 and Non-Patent Documents 1 to 5).
JP 2002-266046 A JP 2000-336449 A JP 2001-342534 A JP 2003-155536 A AHSully: Metallurgy of the rarer metals-1, Chromium, 1st ed., 63-104; 1954, London, Butterworths Scientific Pub. MJUdy: “Chromium”, 1956, NY Reinhold. CSWukusick: “The rhenium ductilizing effect” Refractory Metals and Alloys IV-Research and Development, NY Gordon and Breach Science Pub. 1967, p.231-245. WDKlopp: “A review of chromium, molybdenum and tungsten alloys”, J. Less-Common Metals 42 (1975) 261-278. CNReid and A. Gilbert: Dislocation structure in chromium, Chromium-rhenium and Chromium-iron alloys, J. Less-common Metals, 10 (1966) 77-90.

However, conventional Cr-based heat-resistant alloys have not yet been fully solved for problems such as difficult workability at room temperature, brittleness, and high ductile brittle transition temperature (DBTT). Has not been put to practical use. Therefore, if these problems of the Cr-base heat-resistant alloy can be overcome, the Cr-base heat-resistant alloy can replace the Ni-base heat-resistant alloy having a high service temperature.

  Therefore, the invention of this application has been made in view of the circumstances as described above, and solves the conventional problems. For example, as an alloy for heat-resistant structures such as jet engine and gas turbine blades, 1100 An object of the present invention is to provide a Cr-based heat-resistant alloy that has high-temperature strength and oxidation resistance that can be used even in a high-temperature environment at or above ° C., and is excellent in room temperature ductility (elongation).

In order to solve the above problems, the invention of this application is as follows. First, it is used in a high temperature use environment containing 0.05 mass% to 0.1 mass% of Ag and the balance being Cr and inevitable impurities. A Cr-based heat-resistant alloy having a tensile ductility at room temperature of 3% or more is provided.

In the invention of this application, secondly, in the above Cr-base heat-resistant alloy, Re is further 0.3 to 18. Provided is a Cr-based heat resistant alloy having a good tensile ductility and contained in the range of 0% by mass.

Thirdly, the invention of this application provides a Cr-based heat-resistant alloy having good tensile ductility, wherein Ir is contained in the range of 0.5 to 2.0 mass% in the above Cr-based heat-resistant alloy.

The invention of this application is, fourthly , in a high temperature use environment containing 0.3 to 18.0% by mass of Re , 0.5 to 2.0% by mass of Ir , and the balance of Cr and inevitable impurities. Provided is a Cr-based heat-resistant alloy that is used and has a tensile ductility at room temperature of 3% or more .

Fifth , the invention of this application is characterized in that it is composed of a Cr-based alloy having a good tensile ductility, a jet engine or gas turbine blade, an engine intake valve or exhaust valve, a rocker arm, Or provide a heat resistant article of either a turbocharger connecting rod of a motorcycle or an automobile engine.

According to the invention of the first Cr-base superalloy, compressive strength and oxidation resistance at high temperatures is excellent, yet the tensile ductility (elongation) is high Cr-base superalloy at room temperature is achieved.

According to the second Cr-base superalloy, it is possible to yield strength and ultimate strength is high Cr-base superalloy.

According to the invention of the third Cr-base heat-resistant alloy, the same effects as those of the second aspect can be obtained, and a Cr-base heat-resistant alloy having high yield strength and ultimate strength can be obtained.

According to the fourth Cr-base heat-resistant alloy, even if a small amount of Re is contained, a heat-resistant article of Cr-base heat-resistant alloy having excellent tensile ductility, yield strength, and ultimate strength can be obtained by containing Ir. .

According to the fifth heat-resistant article of the invention, it can be used for various applications that require heat resistance and workability.

  The invention of this application has the characteristics as described above, and is compressed even in a high temperature environment of 1100 ° C. or higher by containing a small amount of Ag (silver) or Ag (silver) and Re (rhenium) in Cr (chromium). The present invention provides a Cr-based alloy having excellent strength, oxidation resistance, etc., and excellent tensile ductility (elongation) at room temperature.

  The present applicant has so far made Cr as a main component, and by adding Re (rhenium) and W (tungsten) in the range of 1 to 40 atomic% (1.75 to 70 mass%), high temperature strength and A Cr-based heat-resistant alloy with excellent compressive ductility has been developed and a patent application has already been filed (Patent Document 1). The invention of this application is obtained by adding Re or W to Cr in the invention of the previous application. It is a further improvement of the Cr-based heat-resistant alloy having excellent high-temperature strength and compressive ductility.

  In other words, the invention of this application shows that the tensile ductility (elongation) is reduced by using it together with Ag (silver) even if the Re content is limited to a small amount (0.3 to 18% by mass) relative to Cr. As a matter of fact, it is a significant improvement. Furthermore, the invention of this application not only uses Re and Ag together but also significantly improves the tensile ductility (elongation) by including only a small amount of Ag (0.05% to 0.1% by mass). ing. In the invention of this application, the Cr-base heat-resistant alloy as described above is configured as Cr—Ag and Cr—Re—Ag as the composition thereof, and these may contain inevitable impurities.

  In the invention of this application, in the case of Cr metal composed only of Cr and inevitable impurities, room temperature tensile ductility is not recognized as 0% at all, whereas the contents of Re and Ag are 0.3 to 0.3 respectively. It has been found that by limiting to 18% by mass and 0.05 to 0.1% by mass, remarkable room temperature tensile ductility, for example, room temperature tensile ductility of 3% or more is exhibited.

  In the Cr-Ag binary alloy, the room temperature tensile ductility reaches 8% by containing 0.05% by mass of Ag. If the Ag content is less than 0.05% by mass, the effect is not so great. If the Ag content exceeds 0.1% by mass, the strength of the metal decreases, which is not preferable.

  As described above, the invention of this application realizes a Cr-based alloy having excellent compressive strength and oxidation resistance at high temperatures and excellent tensile ductility (elongation) at room temperature by containing a small amount of Re and Ag in Cr. However, the yield strength and ultimate strength are improved by adding Ir (iridium) element in the range of 0.5 to 2.0 mass% in the Cr-based alloy containing a small amount of Re and Ag. Can be made.

  Moreover, the effect similar to Ir does not exceed 5.0 mass% of 1 or more types of transition elements, such as Ta, Mo, W, Fe, Ru, Co, Rh, Ni, Pt, and Ti, instead of Ir. It is also realized by adding in a range.

For example, when Ta was used as one of the transition elements and an alloy having a composition of Cr-0.3Re-0.5Ta (mass%) was manufactured and measured for physical properties, the yield strength at room temperature was 196 MPa, It has been confirmed that the material has a strength of 227 MPa and an elongation of 2.1%.

  The Cr-based alloy of the present invention may contain inevitable impurities such as Al, O, N, H, S, C, Fe, Si, Cu, and Pd. Needs to be within the range described in Table 1.

  Therefore, an example will be shown below and further detailed description will be given. In this example, an alloy manufactured by arc melting was used, but the same result was obtained with an alloy manufactured by casting or powder metallurgy, and the invention is not limited by the following examples.

<Example 1>
According to the composition table of Table 1, a Cr-based alloy comprising Cr—Re, Cr—Ag, Cr—Re—Ag, Cr—Ir—Re, and Cr—Ir—Re—Ag components is produced by arc melting, A test piece was cut out from this by electric discharge machining, and a tensile ductility (elongation) at room temperature and a compression test (yield strength) from room temperature to 1300 ° C. were performed.

Note that Cr—Re in Table 1 is a measurement of changes in Re content and tensile ductility when only Re is used relative to Cr. As shown in FIG. The highest numerical value is shown in the range of 0.3 to 18.0% by mass.

Table 2 shows the mechanical properties of the Cr-based alloys obtained with the components in Table 1. As is clear from the mechanical properties shown in Table 2, when only Cr is used, the tensile ductility (elongation) at room temperature is 0%, whereas the Cr-based heat-resistant alloy containing Re and Ag contains The tensile ductility (elongation) at room temperature is 3 to 9.4%, which is remarkably improved. Generally, if the tensile ductility at room temperature is around 5%, it is said that the Cr-based heat-resistant alloy of the invention of this application is practical as a heat-resistant structural material. These are expected to be used as heat-resistant structural materials used at high temperatures, such as intake and exhaust valves, rocker arms and engine turbocharger connecting rods.

Although Cr-base heat-resistant alloy containing Ir at when comparing Cr-base superalloy containing no Cr-base superalloy and Ir which contains Ir from the results in Table 2 is reduced tensile ductility (elongation) at room temperature It can be confirmed that both the compressive strength (yield strength) and the ultimate strength are improved.

  In addition, the Cr-based heat-resistant alloy obtained by the invention of this application has been obtained in which the oxidation resistance in the exposure test for 200 hours in the atmosphere at 1100 and 1300 ° C. is remarkably improved as compared with that of Cr alone. Thus, it has been confirmed that the room temperature ductility (compression ductility) in the temperature range from room temperature to 1300 ° C. can be about twice as high as that of Cr alone.

<Example 2>
In the same manner as in Example 1, when the compressive strength of Cr-based heat-resistant alloy and Cr alone produced by adding Re and Ag to this alloy as shown in Table 1 was evaluated, as shown in FIG. The Cr-based heat-resistant alloy containing Re and Ag in addition shows a compressive strength (0.2% yield strength) almost twice that of Cr alone at temperatures from room temperature to 1300 ° C. Further, when the oxidation resistance is evaluated, “weight change in unit area” in FIG. 3 indicates that the content of Re is in the range of 5 to 18% by mass while maintaining the content of Ag at 0.1% by mass with respect to Cr. The change in weight was examined when the Cr—Re—Ag alloy and Cr alone changed in the above were exposed at a temperature of 1100 ° C. in the atmosphere for up to 200 hours. As is clear from FIG. 3, the Cr—Re—Ag heat - resistant alloy shows less oxidation change and higher oxidation resistance (heat resistance) than Cr alone.

In addition, “weight change in unit area” in FIG. 4 indicates that Re is 5 mass% with respect to Cr and Ag is 0.2%. This is a change in weight when a Cr-based heat-resistant alloy and Cr alone contained at 1 mass% are exposed at a temperature of 1300 ° C. in the atmosphere for up to 200 hours.

  As is clear from FIG. 4, the Cr—Re—Ag alloy has little change in weight, whereas the weight of the Cr alone is drastically reduced, and the Cr—Re—Ag alloy exhibits high oxidation resistance (heat resistance). Yes.

  The Cr-based alloy obtained by the invention of this application is excellent in compressive strength and oxidation resistance at high temperatures suitable as a structural heat-resistant material for use in high-temperature environments, and has a tensile ductility (elongation) of 5% at room temperature. Therefore, the possibility of practical application as heat-resistant articles such as jet engine and gas turbine blades, engine intake and exhaust valves, rocker arms, and turbocharger connecting rods of motorcycle and automobile engines is expected.

This shows the relationship between the tensile ductility at room temperature of the Cr-Re alloy and the content of Re. This shows the temperature dependence of 0.2% compressive yield strength of Cr and Cr-5Re-0.1Ag alloy (mass%) from room temperature to 1300 ° C. 3 shows the change in weight per unit area when Cr and Cr-5 to 18Re-0.1Ag alloy were exposed to the atmosphere at 1100 ° C. for up to 200 hours (h). It shows the change in weight per unit area when Cr and Cr-5Re-0.1Ag (mass%) are exposed to the atmosphere at 1300 ° C. for up to 200 hours (h).

Claims (5)

A Cr-based heat-resistant alloy containing 0.05 mass% to 0.1 mass% of Ag , the balance being Cr and inevitable impurities, which is used in a high temperature use environment, and has a tensile ductility of 3% or more at room temperature A Cr-based heat-resistant alloy with good tensile ductility.   The Cr-base heat-resistant alloy according to claim 1, further comprising Re in a range of 0.3 to 18.0 mass%, and having a good tensile ductility.   The Cr-base heat-resistant alloy according to claim 1 or 2, wherein Ir is contained in a range of 0.5 to 2.0% by mass, and the tensile ductility is good. A Cr-based heat-resistant alloy used in a high-temperature environment including Re of 0.3 to 18.0% by mass , Ir of 0.5 to 2.0% by mass and the balance of Cr and inevitable impurities, A Cr-based heat-resistant alloy having good tensile ductility, characterized by having a tensile ductility at room temperature of 3% or more . Wing of a jet engine or gas turbine, characterized in that the tensile ductility is claimed in any one of 4 is formed from a good Cr-base superalloy, suction valve or an exhaust valve of an engine, the rocker A heat-resistant article, either an arm or a turbocharger connecting rod of a motorcycle or automobile engine.

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