KR101575096B1 - Ni base superalloys and manufacturing method of ni base superalloys - Google Patents

Abstract

The present invention relates to a Ni-base superalloy and a method of manufacturing the same, and is characterized by comprising 0.08 to 0.20% by weight of C, 12 to 14% by weight of Cr, 3.8 to 5.2% by weight of Mo, 1.8 to 2.8% by weight of Nb, By weight of Ti, 0.5 to 1.0% by weight of Ti, 0.005 to 0.015% by weight of B, 0.05 to 0.15% by weight of Zr, 0.01 to 1.0% by weight of Ca or Y or a combination of these elements, Comprising the steps of: dissolving Ni in a dissolution method selected from the group consisting of an Ni-based superalloy composed of impurities and high-frequency induction heating, arc melting, plasma heating, and electron beam melting; and uniformly dispersing the Ni added superalloy And a method for producing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a Ni-base superalloy,

The present invention relates to a Ni-base superalloy and a method of manufacturing the same.

The Ni-base superalloy is a material used at a high temperature of 800 ° C or higher, and exhibits no significant difference in tensile strength, yield strength and elongation at high temperature, high creep characteristics at high temperatures, and high oxidation resistance at high temperatures have. In recent years, materials that can be used in high temperature environments of 1500 ° C or higher have also been developed, and various materials have been applied depending on the use temperature and usage. 800 ° C grade materials are the most widely used superalloys, and have been widely applied to parts of automotive turbocharger systems. The car turbocharger is effective in improving the torque of the automobile and reducing the amount of exhaust. Recently, the automobile turbocharger has been used as a passenger car for the downsizing of the engine, which is the most consuming place of the superalloy. In addition, as the application of turbochargers to the passenger car sector has expanded, it has become necessary to improve the service life temperature of the gasoline engine from 800 to 900 ° C for the diesel engine and 900 to 1,000 ° C for the gasoline engine. Accordingly, it is necessary to change materials such as Inconel 713C and GR235, which have been generally applied to the range of 800 to 900 ° C, to high-grade materials such as Mar246 and MarM 247, and the cost is increasing.

Table 1 below shows the compositions of Inconel 713C, Inconel 713LC, Mar246, MarM 247 and GR235.

C Cr Ni Co Mo W Nb Ta Ti Al B Zr Hf Fe Tm (占 폚) In713C 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 1260 to 1288 In713LC
0.06 12 Honey - 4.3 - 2 - 0.7 5.8 0.007 0.06 1288 ~ 1321 MarM
246 0.15 9 Honey 10 2.5 10 - 1.5 1.5 5.5 0.015 0.05 1315 ~ 1343 MarM
247 0.16 8.2 Honey 10 0.6 10 - 3 One 5.5 0.015 - 1.5 1305 ~ 1365 GMR235 0.15 15.5 Honey - 5.3 - - - - 3 0.06 - - 10

As shown in Table 1, the MarM 246 and MarM 247 additionally contain high-melting point metal elements such as Ta, W and Hf in the existing material to improve high-temperature strength, high-temperature creep and oxidation resistance. However, since the above-described elements are expensive, there is a problem that the manufacturing cost is increased.

Korean Patent Laid-Open No. 2001-0108041 discloses a die casting product comprising a nickel or cobalt-based superalloy having a fine average grain size and a gas turbine engine element compared to wire-free microstructures and cast molding products.

Korean Unexamined Patent Publication No. 2001-0007520 discloses a ferritic stainless steel comprising, by mass%, at least 0.1% C, at most 2% Si, at most 2% Mn, at most 0.005% S, at least 10-25% Cr, By mass, Mo: 0.01 to 15% by mass, W: 0.01 to 15% by mass, and N: not more than 0.08%, B: not more than 0.03%, Zr: not more than 0.2% And 0.01 to 9% as a total of 2.5 to 15% by weight based on the total weight of the Ni-based heat-resistant alloy.

An object of the present invention is to provide a Ni-base superalloy which can be applied at a temperature of 900 ° C or higher, which is a service temperature of a gasoline engine, by improving high-temperature strength and improving oxidation resistance and creep rupture strength.

In order to achieve the above object, the present invention provides a Ni-based superalloy comprising a trace amount of Y and Ca added to a conventional Inconel 713C component. Specifically, the present invention relates to a ferritic stainless steel comprising C: 0.08 to 0.20 wt%, Cr: 12 to 14 wt%, Mo: 3.8 to 5.2 wt%, Nb: 1.8 to 2.8 wt%, Al: 5.5 to 6.5 wt% Based superalloy composed of 1.0 to 1.0% by weight of B, 0.005 to 0.015% by weight of Z, 0.05 to 0.15% by weight of Zr, 0.01 to 1.0% by weight of Ca or Y or a combination of these elements and the balance of Ni and unavoidable impurities. to provide.

Preferably, the Ca may be added as CaO, and the Y may be added as Y ₂ O ₃ .

The present invention also provides a turbocharger component made of a Ni-base superalloy having the above composition.

The present invention also relates to a ferritic stainless steel comprising 0.08 to 0.20 wt% of C, 12 to 14 wt% of Cr, 3.8 to 5.2 wt% of Mo, 1.8 to 2.8 wt% of Nb, 5.5 to 6.5 wt% of Al, 0.5 to 1.0 Based superalloy consisting of 0.005 to 0.015% by weight of B, 0.05 to 0.15% by weight of Zr, 0.05 to 0.15% by weight of Zr, 0.01 to 1.0% by weight of Ca, Y or a combination of these elements and the balance Ni and inevitable impurities. A method for producing a Ni-based superalloy, comprising the steps of: dissolving Ni in any one of dissolution methods of high-frequency induction heating, arc melting, plasma heating and electron beam melting; and uniformly dispersing each additional element .

The present invention can provide a Ni-base superalloy having an excellent high-temperature characteristic, that is, an excellent ductility, a creep characteristic and an oxidation resistance, and being economical at a high temperature of 900 to 1000 ° C required for parts for gasoline engines of automobiles, turbocharger parts and the like.

Further, the present invention can provide a Ni-base superalloy which can be applied not only to automobiles but also to agricultural machinery, sports leisure vehicles, ships, yachts and aircraft parts, and which is economical and has excellent mechanical properties.

Unless defined otherwise, all technical terms used in the present invention have the following definitions and are consistent with the meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Also, preferred methods or samples are described in this specification, but similar or equivalent ones are also included in the scope of the present invention.

Throughout this specification, the words " comprising " and " comprising ", unless the context clearly requires otherwise, include the steps or components, or groups of steps or elements, And that they are not excluded.

For many parts, such as turbine wheels, wastegate valves, and spindles in the turbocharger system, heat resistant materials of the order of 900 ° C to 1,000 ° C should be applied. In the automotive industry, the most economical material must be applied and the amount of the material to be used is considerably increased. Therefore, an alloy composition considering the same properties and economy is required.

Conventional materials with a temperature of 1000 占 폚 have added expensive Ta, W, Hf, and the like, so that they are not economically suitable as materials used in automobile parts that require mass production. The present invention relates to a process for producing a high-temperature-resistant high-temperature material having a high temperature characteristic and a low cost by adding Ca, Y, or a mixture thereof to a material having a temperature of 800 캜 consisting of conventional C, Cr, Mo, Nb, Al, Ti, B, Zr, The present invention provides a Ni-base superalloy exhibiting oxidation resistance characteristics at a high temperature of about 1,000 ° C, and can produce an automotive turbocharger using the same in an economical manner.

Specifically, the present invention relates to a ferritic stainless steel comprising 0.08 to 0.20 wt% of C, 12 to 14 wt% of Cr, 3.8 to 5.2 wt% of Mo, 1.8 to 2.8 wt% of Nb, 5.5 to 6.5 wt% of Al, 0.5 to 1.0 By weight, B: 0.005 to 0.015% by weight, Zr: 0.05 to 0.15% by weight, Ca, Y or a combination thereof: 0.01 to 1.0% by weight, the balance being Ni and inevitable impurities. Superalloy.

Hereinafter, the chemical composition and action effects of the alloy of the present invention will be described.

C:

C is an advantageous element for improving the tensile strength and creep rupture strength required as heat resistant steel by forming carbides such as MC, M7C3, M23C6 and M6C in combination with elements such as Nb, Ta, Mo, Cr and the like. However, if it exceeds 0.20% by weight, not only the ductility and toughness of the alloy deteriorate but also the Al-containing Ni-based alloy can inhibit the formation of the alumina film. Therefore, the content of C is preferably 0.08 to 0.20% by weight.

 Cr:

Cr acts as a solid solution strengthening element and is an element having oxidation resistance, and acts to uniformly produce an alumina coating at the initial stage of its formation. It also contributes to the improvement of the creep rupture strength by forming carbide. On the other hand, if Cr is contained in excess, the homogeneous formation of the alumina film is inhibited, and the mechanical properties such as toughness and workability can be inhibited. Therefore, the content of Cr is preferably 12 to 14% by weight.

Mo:

Mo serves as solid solution strengthening element, forms carbide to maintain high temperature strength, and strengthens austenite phase to increase creep rupture strength. An excessive amount may lead to precipitation of an intermetallic compound which is a factor of lowering the toughness, and the creep resistance may be lowered. Therefore, the content of Mo is preferably 3.8 to 5.2% by weight.

Nb:

Nb acts as a solid solution strengthening element, forms carbides to maintain high temperature strength, and contributes to improvement of creep rupture strength as carbonitride in addition to solidification in austenite phase or γ 'phase. Therefore, the content of Nb is preferably 1.8 to 2.8% by weight.

Ti:

Ti promotes precipitation of the γ 'phase of Ni ₃ (Al, Ti), thereby improving the creep rupture strength and contributing to strengthening of grain boundaries. However, if it is contained in an amount exceeding 1.0% by weight, the γ 'phase is excessively precipitated, and the hot workability and weldability are remarkably deteriorated. Therefore, the content of Ti is preferably 0.5 to 1.0% by weight.

Al:

Al is an element contributing to formation of carbide by enhancing creep rupture strength by promoting precipitation of? 'Phase of Ni3 (Al, Ti). Therefore, the content of Al is preferably 5.5 to 6.5% by weight.

B, Zr:

These elements are elements which contribute to grain refinement of the alloy mainly, and contribute to improvement of hot workability, weldability and creep characteristics. However, if it is contained in excess, creep rupture strength is lowered. Therefore, it is preferable that the content of B is 0.005 to 0.015% by weight, and the content of Zr is 0.05 to 0.15% by weight.

Y, Ca:

These elements are elements which impart the characteristics of the present invention and fix S in a temperature range of 900 to 1000 캜 with sulfides to improve hot workability and improve high temperature strength and oxidation resistance. Y increases the softness and tensile strength by finely dividing the particle size and the layer spacing, and increases the creep resistance, high temperature properties and oxidation resistance. When Y is added in an excess amount, inclusions such as oxides are increased, and workability and weldability are impaired. Ca improves the hot workability by increasing the grain boundary strength. When Ca is added in an excess amount, the cleanliness is lowered, and hot workability and ductility are impaired. Y and Ca may be added alone in an amount of 0.01 to 1.0% by weight. Preferably, Y and Ca may be added in an amount of 0.01 to 1.0 wt% in order to improve the problems of excessive addition of Y and Ca and improve hot workability, creep resistance and high temperature characteristics.

The present invention also relates to a ferritic stainless steel comprising 0.08 to 0.20 wt% of C, 12 to 14 wt% of Cr, 3.8 to 5.2 wt% of Mo, 1.8 to 2.8 wt% of Nb, 5.5 to 6.5 wt% of Al, 0.5 to 1.0 By weight, B: 0.005 to 0.015% by weight, Zr: 0.05 to 0.15% by weight, Ca, Y or a combination thereof: 0.01 to 1.0% by weight, the balance being Ni and inevitable impurities. A turbocharger component comprising a superalloy. The turbocharger may be used in an automobile, a ship, an aircraft, an agricultural machine, or the like. The turbocharger component may be a turbine wheel, a turbine rotor or a wastegate valve.

The present invention also relates to a ferritic stainless steel comprising 0.08 to 0.20 wt% of C, 12 to 14 wt% of Cr, 3.8 to 5.2 wt% of Mo, 1.8 to 2.8 wt% of Nb, 5.5 to 6.5 wt% of Al, 0.5 to 1.0 Based superalloy composed of 0.005 to 0.015% by weight of B, 0.05 to 0.15% by weight of Zr, 0.01 to 1.0% by weight of Ca, Y or a combination thereof and the balance of Ni and inevitable impurities There is provided a method of manufacturing a Ni-based superalloy including a step of dissolving Ni in any one of dissolution methods of high-frequency induction heating, arc melting, plasma heating and electron beam melting, and uniformly dispersing while adding each additional element .

Example

Hereinafter, the present invention will be described in detail with reference to examples.

Examples 1 to 5 are Ni-based superalloys to which Y is added, Examples 6 to 9 are Ni-based superalloys to which Ca is added, and Examples 10 and 11 are Ni-based superalloys to which both Y and Ca are added. The comparative example is a conventional Ni-base superalloy to which Y and Ca are not added.

The compositions of Comparative Examples and Examples 1 to 11 are shown in Table 2.

weight% C Cr Ni Co Mo W Nb Ta Ti Al B Zr Y Ca Comparative Example 1 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 - - Example 1 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 0.05 - Example 2 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 0.1 - Example 3 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 0.3 - Example 4 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 0.5 - Example 5 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 1.0 - Example 6 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 - 0.1 Example 7 0.1 13.5 honey - 4.5 - 2 - 0.8 6 0.01 0.06 - 0.3 Example 8 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 - 0.5 Example 9 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 - 1.0 Example 10 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 0.25 0.25 Example 11 0.1 13.5 Honey - 4.5 - 2 - 0.8 6 0.01 0.06 0.5 0.5

Table 3 shows the mechanical properties at high temperature when the elements were mixed and alloys according to Examples 1 to 11 and Comparative Examples.

Sample type Tensile Strength (MPa)
at 650 ° C Yield strength (MPa)
at 650 ° C Elongation (%) at 650 ° C Comparative Example 1 Inconel 713C Standard Specification 840 700 6 Example 1 Inconel 713C + 0.05 Y 937 846 7.6 Example 2 Inconel 713C + 0.1 Y 960 866 11 Example 3 Inconel 713C + 0.3 Y 981 887 12 Example 4 Inconel 713C + 0.5 Y 985 870 6.8 Example 5 Inconel 713C + 1.0 Y 988 860 6.2 Example 6 Inconel 713C + 0.1 Ca 971 876 11.4 Example 7 Inconel 713C + 0.3 Ca 973 877 10.8 Example 8 Inconel 713C + 0.5 Ca 976 865 7.5 Example 9 Inconel 713C + 1.0 Ca 980 852 6.7 Example 10 Inconel713C + 0.25Y + 0.25Ca 982 871 7.3 Example 11 Inconel 713C + 0.5Y + 0.5Ca 990 875 6.2

As shown in Table 3, in comparison with the tensile strength, yield strength and elongation of Comparative Example 1, the tensile strengths of Examples 1 to 11 were 937 to 990 MPa, the yield strength was 846 to 887 MPa, and the elongation was 6.2 to 12 It can be seen that it is improved.

As for the tensile strength, Example 11 in which both of Y and Ca were added showed the most improvement to 990 MPa. With respect to the yield strength, Example 3 with Y added was the most improved to 887 MPa. With respect to the elongation percentage, Example 6 in which Ca was added was the most improved to 11.4. As a result, it can be seen that both Y and Ca can improve the tensile strength and the yield strength while maintaining a proper elongation.

Sample type Creep rupture temperature (캜) / stress (MPa) Elongation at break (%) Breaking life (Hr) Comparative Example 1 Inconel 713C Standard Specification 980 ± 2/152 6 30 Example 2 Inconel 713C + 0.1 Y 980 ± 2/152 21.4 74 Example 4 Inconel 713C + 0.5 Y 980 ± 2/152 13.7 42.2 Example 6 Inconel 713C + 0.1 Ca 980 ± 2/152 14.3 62.4 Example 8 Inconel 713C + 0.5 Ca 980 ± 2/152 15 37.2

As shown in Table 4, in Example 2 and Example 6 in which 0.1% of Y and 0.1% of Ca were added under creep rupture temperature and stress, respectively, as in Comparative Example 1, 21.4% and 14.3% Respectively, showing excellent breaking life of 74 hours and 62.4 hours, respectively. It can also be seen that Examples 4 and 8 in which 0.5% of Y and 0.5% of Ca were respectively added are superior in elongation at break and fracture life, as compared with Comparative Example 1 (standard composition of Inconel 713C).

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (4)

C: 0.08 to 0.20 wt%, Cr: 12 to 14 wt%, Mo: 3.8 to 5.2 wt%, Nb: 1.8 to 2.8 wt%, Al: 5.5 to 6.5 wt% 0.005 to 0.015 wt%, Zr: 0.05 to 0.15 wt%, Ca, Y, or a combination of these elements: 0.01 to 1.0 wt%, the balance being Ni and inevitable impurities. The method according to claim 1,
Wherein the Ca is CaO and the Y is added as Y ₂ O ₃ . A turbocharger component comprising a Ni-base superalloy according to claim 1. C: 0.08 to 0.20 wt%, Cr: 12 to 14 wt%, Mo: 3.8 to 5.2 wt%, Nb: 1.8 to 2.8 wt%, Al: 5.5 to 6.5 wt% A method for producing a Ni-based superalloy comprising 0.005 to 0.015% by weight, Zr: 0.05 to 0.15% by weight, Ca, Y, or a combination of these elements in an amount of 0.01 to 1.0% by weight, the balance being Ni and inevitable impurities, Comprising the steps of: dissolving Ni in any one of dissolution method of induction heating, arc melting, plasma heating, and electron beam melting; and uniformly dispersing Ni while adding each additional element.