WO2018182250A1 - Self-healing ultra-heat-resistant nickel alloy - Google Patents

Abstract

The present invention relates to a self-healing ultra-heat-resistant nickel alloy containing 10-15 wt% of cobalt (Co), 15-30 wt% of chromium (Cr), 5-15 weight% of molybdenum (Mo), 0.05-0.2 wt% of carbon (C), and < 200 ppm of boron (B), and the balance nickel (Ni) and other inevitably contained impurities.

Description

Self-Healing Super Heat-resistant Nickel Alloy

The present invention relates to a nickel alloy. Specifically, the present invention relates to a self-healing super heat resistant nickel alloy due to boron precipitation and segregation at high temperature.

Recently, as environmental problems such as air pollution have emerged, in order to minimize the emission of greenhouse gases, including carbon dioxide, many methods have been proposed to increase the efficiency of engines and generators. Due to the nature of engines and generators operating at high temperatures, increasing the maximum usable temperature, in particular, has emerged as an important issue.

Monocrystalline nickel-based alloys have been used for existing parts used at ultra-high temperatures of 700 ° C. or higher, such as aircraft engines or gas turbines. However, the existing nickel-based alloys still need to increase the available temperature and increase the limit creep strength due to the problem of improving fuel efficiency and extending the life of the product.

In response to these social demands, studies have been conducted to self-heale actual cracks in stainless steel. Japanese Laid-Open Patent Publication No. 2005-179755 discloses Fe- (0.04-0.1) C-(<1.0) Si-(<2.0) Mn-(<0.003) S- (9-13) Ni- (17-20) Cr- (0.3 ~ 1.0) (Nb, Ta)-(0.3 ~ 0.6) Cu- (0.002 ~ 0.02) Ce- (0.005 ~ 0.01) B (Mass%) After the heat treatment of the stainless steel, water-cooled to inhibit precipitation Creep experiments were conducted. During the creep test, a void surface is formed inside the specimen, in which boron (B), a solid solution element in the base material, diffuses into the void surface. In this way, a method of suppressing the growth of creep voids by segregating boron on the surface of the creep voids, expressing self-healing function against breakage caused by creep void growth, and improving the creep limit strength has been proposed.

However, the prior art is based on stainless steel, there is a problem that shows a creep limit strength much lower than the social demand for the available temperature. In other words, when used at a high temperature of 700 ℃ or more, the self-healing ability is reduced, the life is short, the frequent cycle of parts replacement is a source of efficiency and cost increases. This is a problem with stainless steels having low usable temperatures of about 400-500 ° C.

Accordingly, there is a need for a new alloy design having a high effective optimum temperature to an optimum available temperature and having a high self-healing effect and having a high creep limit strength, but a solution for this has not been proposed.

Self-healing super heat-resistant nickel alloy according to the present invention has the following challenges.

First, it is intended to increase the self-healing temperature, that is, the available temperature, through nano-scale precise control of supersaturated regions in the existing solid solution.

Second, we want to cure early defects, prevent further defect propagation and improve creep resistance.

Third, to improve the oxidation resistance of the alloy material at the use temperature.

The problem of the present invention is not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention is cobalt (Co): 10-15% by weight, chromium (Cr): 15-30% by weight, molybdenum (Mo): 5-15% by weight, carbon (C): 0.05-0.2% by weight, boron (B ): A self-healing super heat-resistant nickel alloy containing <200 ppm of components and composed of the balance of nickel (Ni) and other inevitable impurities.

In the present invention, it is possible that the nickel alloy further contains 0.001 to 1.0% by weight of titanium (Ti).

In the present invention, it is possible that the nickel alloy further contains 0.001-3.0 wt% of at least one total selected from the group consisting of iron (Fe), silicon (Si) and aluminum (Al).

In the present invention, the optimum self-healing temperature of the nickel alloy is preferably 700-800 ° C.

The present invention is a nickel alloy having a self-healing function, when a void is formed in the nickel alloy, boride (Boride) is precipitated at the void interface, the boride is boron (B), molybdenum (Mo) , Chromium (Cr), nickel (Ni) and cobalt (Co).

Nickel alloy according to the present invention is cobalt (Co): 10-15% by weight, chromium (Cr): 15-30% by weight, molybdenum (Mo): 5-15% by weight, carbon (C): 0.05-0.2% by weight , Boron (B): a base composition containing a component of <200 ppm and containing a balance of nickel (Ni) and other unavoidable impurities; Or one selected from the group consisting of iron (Fe), silicon (Si), and aluminum (Al) in the first composition further containing titanium (Ti): 0.001-1.0 wt% in the basic composition. It is preferable that the above is a composition which further contains at least one composition of the 2nd composition which contained 0.001-3.0 weight% further.

Method for producing a self-healing super heat-resistant nickel alloy according to the present invention is cobalt (Co): 10-15% by weight, chromium (Cr): 15-30% by weight, molybdenum (Mo): 5-15% by weight, carbon (C ): 0.05-0.2 wt%, boron (B): nickel alloy hot rolled steel sheet containing a base composition containing <200 ppm of components and containing a balance of nickel (Ni) and other unavoidable impurities, or titanium ( Ti): 0.001-3.0% by weight of at least one selected from the group consisting of iron (Fe), silicon (Si) and aluminum (Al) in the first composition further containing 0.001-1.0% by weight of components Providing a hot rolled steel sheet or hot forged steel sheet of nickel alloy further containing at least one of the further second compositions; Step S4 of reheating the steel sheet of nickel alloy to a predetermined temperature; S5 step of maintaining isothermal and heat treatment at a predetermined temperature; And it may include the step S6 for cooling the steel sheet isothermally maintained.

The reheating temperature of the step S4 according to the present invention is preferably higher than the temperature at which the boride pre-precipitated in the nickel alloy is dissolved.

In the step S5 according to the present invention, the preset temperature at which isothermal is maintained is preferably 1150-1250 ° C.

In the step S5 according to the present invention, the preset temperature at which isothermal is maintained is preferably 1250-1300 ° C.

Step S6 according to the present invention is preferably cooled by water cooling.

The microstructure of step S6 according to the present invention is preferably austenite single phase.

The steel sheet providing step according to the present invention is a step S1 to melt and melt the nickel alloy having the composition; S2 step of hot rolling or hot forging the solution-molded nickel alloy; And S3 cooling the hot rolled or hot forged steel sheet.

The self-healing super heat resistant nickel alloy according to the present invention has the following effects.

First, there is an effect of increasing the available temperature, that is, the available temperature for self-healing through nano-scale precise control of the supersaturated region in the existing metal solid solution.

Second, the addition of B or Si has the effect of healing the initial defects from the local solute precipitation effect of the supersaturation region, preventing further defect propagation and improving creep resistance.

Third, there is an effect excellent oxidation resistance than Nb alloy or Mo alloy of the existing material.

Fourth, by supersaturating the surface of the material with high oxygen / nitrogen affinity to form a dense oxidized / nitride film, and spontaneously forming an oxidized / nitride film with excellent surface bonding ability and prevention of foreign material penetration at high temperature. There is an effect of improving the oxidation resistance of the material.

The effects of the present invention are not limited to those mentioned above, and other effects that are not mentioned will be clearly understood by those skilled in the art from the following description.

1 shows a method for producing a self-healing super heat resistant nickel alloy in the present invention.

2 is a diagram illustrating a manufacturing and heat treatment process of a hot rolled sheet of a nickel alloy according to the present invention.

Figure 3 is a graph showing the results of thermodynamic calculation of the fraction of the microstructure with temperature using the TCFE9 program of the nickel alloy according to the present invention.

Figure 4 is a graph showing the results of thermodynamic calculation of the constituent fraction of the boron (B) precipitates with temperature using the TCFE9 program of the nickel alloy according to the present invention.

Figure 5 shows the initial microstructure of the hot rolled plate of the nickel alloy according to the present invention, Figure 4a is an optical microscope picture and Figure 4b is a scanning microscope picture.

Figure 6 shows the microstructure after fracture test of the hot rolled sheet of nickel alloy according to the present invention, Figure 6a is an optical microscope picture, Figure 6b is a scanning microscope picture.

7 and 8 are photographs showing the distribution of each element after the tensile test fracture of the hot rolled sheet of nickel alloy according to the present invention.

9 shows the microstructure after heat treatment of the hot rolled sheet of nickel alloy according to the present invention after heat treatment at 800 ° C. for 14 hours.

10 and 11 are photographs showing the distribution of each element after heat treatment of the hot-rolled sheet of nickel alloy according to the present invention after heat treatment at 800 ° C. for 14 hours.

12 is an optical micrograph showing the microstructure after 33% deformation of the hot rolled sheet of nickel alloy according to the present invention.

FIG. 13 is a graph showing tensile test results of two specimens in which a tensile test of 33% of a hot rolled sheet of nickel alloy according to the present invention was deformed.

14 is a graph showing the results of the tensile test before and after the heat treatment of 800 ℃ 16 hours of the specimen subjected to the 33% tensile test of the hot rolled sheet of nickel alloy according to the present invention.

The present invention is a self-healing super heat-resistant nickel alloy, cobalt (Co): 10-15% by weight, chromium (Cr): 15-30% by weight, molybdenum (Mo): 5-15% by weight, carbon (C): 0.05 -0.2% by weight, boron (B): it is preferably composed of components containing <200 ppm, the balance of nickel (Ni) and other inevitably contained impurities.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art can easily understand, the embodiments described below may be modified in various forms without departing from the concept and scope of the present invention. Where possible, the same or similar parts are represented using the same reference numerals in the drawings.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” include plural forms as well, unless the phrases clearly indicate the opposite.

As used herein, the meaning of "comprising" embodies a particular property, region, integer, step, operation, element, and / or component, and other specific properties, region, integer, step, operation, element, component, and / or It does not exclude the presence or addition of groups.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in advance are additionally interpreted to have a meaning consistent with the related technical literature and the presently disclosed contents, and are not interpreted in an ideal or very formal sense unless defined.

The content of the composition herein is described using weight percent.

The present specification provides a (1) self-healing super heat-resistant nickel alloy design and (2) a method of manufacturing the same to replace the existing alloy to improve the precipitation-based creep characteristics. EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

(1) Self-healing super heat resistant nickel alloy design

Nickel alloy according to the present invention is cobalt (Co): 10-15% by weight, chromium (Cr): 15-30% by weight, molybdenum (Mo): 5-15% by weight, carbon (C): 0.05-0.2% by weight , Boron (B): <200 ppm by weight of the component, it is characterized by being composed of the balance of nickel (Ni) and other inevitable impurities (hereinafter referred to as 'base composition').

The nickel alloy according to the present invention may further contain 0.001-1.0 wt% of titanium (Ti) (hereinafter referred to as 'first composition').

The nickel alloy according to the present invention may further contain 0.001-3.0 wt% of one or more total selected from the group consisting of iron (Fe), silicon (Si) and aluminum (Al) (hereinafter referred to as 'second composition'). ).

The present invention may further contain at least one of a first composition and a second composition in the basic composition.

Hereinafter, each element contained in the nickel alloy which concerns on this invention is demonstrated.

Cobalt (Co): 10-15 wt%

Cobalt (Co) has little effect of solid-solution strengthening at room temperature, but at high temperature, it increases high capacity and slows the precipitation strengthening time, thereby increasing the high temperature strength significantly. Therefore, in order to maintain strength at a high temperature for a long time, 10 wt% or more is required. However, when cobalt (Co) exceeds 15 wt%, it combines with other alloying elements to form an intermetallic compound, thereby reducing the strength. . Therefore, the content of cobalt (Co) in the present invention is preferably 10-15% by weight.

Chromium (Cr): 15-30 wt%

Chromium (Cr) is an element that improves the corrosion resistance and oxidation resistance in super heat resistant alloys, and inhibits the formation of carbides to promote the formation of borides expected in the present invention. If the content of chromium (Cr) is less than 15% by weight, it is difficult to expect corrosion and oxidation resistance effects. If the content of chromium (Cr) exceeds 30% by weight, creep properties are deteriorated, and it causes a decrease in strength because it promotes the deposition of harmful phases such as the TCP (Topologically Close Packed) phase, which adversely affects the mechanical properties when exposed to high temperatures at high temperatures. . Therefore, the content of chromium (Cr) in the present invention is preferably 10-15% by weight.

Molybdenum (Mo): 5-15 wt%

Molybdenum (Mo) is a solid solution strengthening element to improve the high temperature tensile characteristics and creep characteristics of super heat-resistant alloys. In addition, it binds with carbon (C) to form M ₆ C-type carbide at grain boundaries to suppress grain growth. However, if a large amount is added, there is a fear that a TCP phase is generated and the hot workability is lowered. If the molybdenum (Mo) content is less than 5% by weight, it is difficult to expect a solid solution strengthening effect. When molybdenum (Mo) content exceeds 15 weight%, hot workability will fall and a TCP phase will form easily. Therefore, the content of molybdenum (Mo) in the present invention is preferably 10-15% by weight.

Carbon (C): 0.05-0.2 wt%

Carbon (C) is combined with titanium (Ti), tungsten (W), molybdenum (Mo), chromium (Cr) and the like to form carbides in the form of MC, M ₆ C or M ₂₃ C ₆ to contribute to grain refinement. In addition, the grain strength is improved by forming carbides at grain boundaries. If the content of carbon (C) is less than 0.05% by weight, sufficient carbides are not formed. If the content of carbon (C) is more than 0.2% by weight, too much carbide is formed and ductility, workability, and the like decrease. Therefore, the content of carbon (C) in the present invention is preferably 10-15% by weight.

Boron (B): <200 ppm

Boron (B) segregates at grain boundaries to improve grain strength and to suppress grain growth. And it is an essential element for forming boride which is the self-healing effect of this invention. Boride means a compound consisting of a metal element and boron (B). However, when boron (B) is added excessively, melting | fusing point of a material will fall, hot workability will fall, and ductility will fall. Therefore, the content of boron (B) in the present invention is preferably 200 ppm or less.

Titanium (Ti): 0.001-1.0 wt%

Titanium (Ti) is an element that strengthens the γ 'phase by substituting the γ' phase aluminum as the γ 'phase forming element together with aluminum (Al), and improves the high temperature corrosion resistance of the alloy. When the content of titanium (Ti) is less than 0.001% by weight, it is difficult to expect that the strength is improved by substituting aluminum (Al). If it exceeds 0.1% by weight, the manufacturing cost will rise excessively. In addition, Eta (Ni ₃ Ti) phase is formed during the casting of the alloy, thereby lowering the phase stability and mechanical properties. Therefore, the content of titanium (Ti) in the present invention is preferably 0.001-1.0% by weight.

Total of at least one of iron (Fe), silicon (Si) and aluminum (Al): 0.001-3.0 wt%

In the alloy, preferably, at least one selected from the group consisting of iron (Fe), silicon (Si), and aluminum (Al) is contained in an amount of 0.001-3.0 wt%.

Iron (Fe) improves creep ductility, contributes to improvement of creep rupture strength, and contributes to improvement of room temperature workability. When the addition amount of iron (Fe) is small, it is difficult to expect the above effects, and in many cases, the creep rupture strength and hot workability are deteriorated.

Silicon (Si) serves to improve the oxidation resistance of the alloy. When the addition amount is small, the addition amount is insignificant, and therefore, it is difficult to properly exhibit the oxidation resistance improving effect. When the addition amount is large, the oxidation resistance is improved, but there is a problem that the creep characteristics are sharply lowered.

Aluminum (Al) is a member of the γ 'phase, which is a major strengthening phase, and contributes to the improvement of oxidation resistance. When the addition amount is small, it is difficult to properly exhibit the γ 'phase precipitation and the oxidation resistance improving effect, and in many cases, there is a problem that the workability is degraded due to excessive precipitation of the γ' phase. Therefore, the total of at least one selected from the group consisting of iron (Fe), silicon (Si) and aluminum (Al) is preferably included in 0.001-3.0% by weight.

Boride

Boride means a compound containing boron as a boron (B) precipitate. The optimum self-healing temperature of the nickel alloy according to the present invention is preferably 700-800 ° C. At 1250 ° C. or lower, which is the deposition temperature of boride, boride is deposited into a void formed in the nickel alloy. Although the self-healing alloy of the stainless steel base has an available temperature of only 400-500 ° C., the nickel alloy according to the present invention has the advantage that the self-healing function operates smoothly not only at 400-500 ° C., but also at 700-800 ° C. above the temperature. There is this.

The present invention includes a nickel alloy in which boride is precipitated in a void. That is, when a void is formed inside the nickel alloy, boride is deposited at the void interface, thereby filling the void. In the present invention, the element of boride to be precipitated is preferably specified as boron (B), molybdenum (Mo), chromium (Cr), nickel (Ni) and cobalt (Co).

In the present invention, even when the composition components and composition ratios of the nickel alloys are different, borides having the five constituent elements described above are precipitated. However, it is more preferable to have the following composition components and composition ratios.

That is, the nickel alloy in which the boride is precipitated according to the present invention is cobalt (Co): 10-15% by weight, chromium (Cr): 15-30% by weight, molybdenum (Mo): 5-15% by weight, carbon (C) : 0.05-0.2% by weight, boron (B): basic composition containing components of <200 ppm and containing balance nickel (Ni) and other unavoidable impurities; Or one selected from the group consisting of iron (Fe), silicon (Si), and aluminum (Al) in the first composition further containing titanium (Ti): 0.001-1.0 wt% in the basic composition. It is preferable that the above is a composition which further contains at least one composition of the 2nd composition which contained 0.001-3.0 weight% further.

(2) alloy manufacturing method

The alloy production method according to the present invention is a melt-solvation step (S1 step), hot rolling or hot forging step (S2 step), cooling step (S3 step), reheating step (S4 step) and heat treatment step (S5 step) Contains,

① dissolution-solvation step (S1 step)

It is preferable that the solvation temperature of S1 step is 1200 degreeC, and the melting temperature is more than the solvation temperature. Solvation time means the time required until all the alloying elements are uniformly dissolved, and proceeded to 30 minutes in the embodiment.

② Hot rolling or hot forging step (S2 step)

If hot rolling or hot forging temperature exceeds 1200 ° C., hot rolling may result in energy loss. If the hot rolling or hot forging temperature is less than 900 ℃, precipitates may be precipitated during hot rolling or hot forging, where the precipitate may adversely affect self-healing in the subsequent creep experiment. In other words, it can inhibit the self-healing performance to be obtained in the present invention. Therefore, the hot rolling temperature of the step S2 is preferably 900-1200 ° C.

③ Cooling stage (S3 stage)

It is necessary to prevent precipitation of precipitates in the cooling process after hot rolling or hot forging in step S2. To this end, quenching through a water cooling method was first applied as an example. After that, while cooling by general air cooling method, the difference of microstructure after hot rolling according to the cooling rate was examined. As a result, not only the water cooling method but also the air cooling method confirmed that the precipitate hardly precipitated after hot rolling. Here, the fact that the self-healing is implemented by the air cooling method can be seen that the applicability in the actual industry is very high.

In summary, step S3 is preferably at least one of a cooling method of water cooling or air cooling. In the present invention, a water cooling method was selected as an example.

On the other hand, if precipitates are generated, it is preferable to control the precipitates by reheating the temperature of step S4.

④ Reheating step (S4 step)

The most important role in implementing self-healing is boride (B) precipitate. Therefore, it is necessary to solidify the precipitated boride back to the nickel alloy. Therefore, the reheating temperature of the step S4 is preferably set to the temperature at which the precipitated boride is dissolved again and the temperature at which it is not reprecipitated.

The temperature is raised to a predetermined temperature through reheating in step S4, and heat treatment is performed while isothermally maintaining the temperature in step S5.

Therefore, the heat treatment temperature of the step S4 is a temperature in the region where the precipitate of boride, which is a boron precipitate, and a small amount of boride precipitate, are precipitated, but in a region where the size of the crystal grains of the nickel alloy can be minimized. Do.

Figure 3 is a result of thermodynamic calculation of the microstructure for each heat treatment temperature of the boron (B) addition nickel alloy according to the present invention using the TCFE9 program. When the heat treatment is performed based on these results, precipitates are precipitated for each temperature region. In particular, boride, the most important boron (B) precipitate for self-healing, precipitates in an area of 1250 ° C or lower. However, the boron precipitate is an element to be used when self-healing as it is deposited inside a void, which is a defect space generated by stress or the like. If boron, which is such an element, is precipitated in advance in the heat treatment step, when voids are generated due to stress or the like, a problem of lowering self-healing performance may be generated by inhibiting the phenomenon in which boron B is precipitated. Therefore, the heat treatment temperature of the step S4 is preferably the temperature of the region where the precipitate of boride, which is boron precipitate, does not precipitate.

On the other hand, if the temperature is higher than 1300 ℃ there is a problem that the liquidation proceeds in close contact with the melting point of the material itself. Therefore, it is more preferable to raise the temperature to a temperature range of 1150-1300 ° C through reheating in step S4.

⑤ isothermal holding-heat treatment step (S5 step)

In step S5, it means maintaining the isothermal temperature in a state where the temperature is raised to the reheating temperature range in step S4. The isothermal holding time is preferably until the precipitated boride dissolves to the maximum and disappears. In the present specification, 30 minutes were applied in one embodiment.

A large role in the implementation of self-healing is the grain size of boride (B) precipitates, such as boride and nickel alloys. Therefore, it is necessary to solidify the precipitated boride back to the nickel alloy, it is important to minimize the size of the grains.

To this end, the isothermal holding temperature in step S5 according to the present invention may be divided into two sections. All of the precipitated borides remain in trace and do not dissolve, reducing the self-healing effect. However, since the creep strength improvement due to the minimization of the grain size of the nickel alloy may be greater, the self-healing may be realized, and thus the temperature may be set to a temperature that minimizes the grain size. Thus, the first temperature range may be 1150 ° C. or more and 1250 ° C. It is preferable that it is the temperature range of 1150 degreeC-1250 degreeC which is the following temperatures. For reference, the dissolution temperature means the precipitation temperature.

The second temperature section may be set to a temperature at which the precipitated boride is dissolved again and not re-precipitated, and is preferably in a temperature range of 1250 ° C to 1300 ° C that exceeds 1250 ° C and 1300 ° C or less.

In the self-healing nickel alloy according to the present invention, a first temperature section or a second temperature section may be selectively applied.

⑥ Cooling stage (S6 stage)

The isothermally maintained hot rolled plate is quenched to room temperature. If it is not quenched, boron precipitates may remain at room temperature, which may cause a problem that the self-healing effect is not sufficiently secured. Therefore, in the step S6, a quenching system such as water cooling is preferable.

In the present invention, the steps S1 to S6 may be performed in succession, or may be performed separately. For example, one practitioner performs steps S1 to S3 and prepares an intermediate result. At this time, another operator may be provided with an intermediate result to further perform steps S4 to S6 to produce a final result.

Hereinafter, an embodiment of the above-described manufacturing method will be described. Furthermore, with respect to defects generated in the manufactured nickel alloy, it will be described whether the function of self-healing is implemented.

In the present invention, in order to observe the self-healing implementation, an initial defect was generated in the hot rolled sheet due to micropore formation or stress. The alloy plate was heated and maintained to a temperature for evaluating creep resistance. It was maintained at the heating temperature for 10-100000 hours. It is difficult to evaluate a creep phenomenon when the said heat holding time is less than 10 hours.

In the present invention, the most important role in implementing self-healing is boron (B) precipitate. The boron (B) precipitate is composed of elements based on boron (B), molybdenum (Mo) and chromium (Cr).

In this embodiment, the elemental composition of boride (B), which is a boron (B) precipitate, is determined by thermodynamic calculation using the TCFE9 program, and thus boron (B), molybdenum (Mo), chromium (Cr), nickel (Ni), and cobalt (Co). It was confirmed that the (see Figure 4).

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

Example 1

A steel slab (Inconel 617B), which is prepared as shown in Table 1, was heated for 30 minutes at a reheating temperature of 1150 ° C to 1250 ° C and hot rolled. At this time, hot rolling was finished hot rolling at 900 ℃-1100 ℃, and re-heated at 1300 ℃ for 30 minutes to control the boron precipitate was water cooled. These processes and heat treatment conditions are shown in detail in FIGS. 1 and 2. The microstructure of the water cooled hot rolled sheet is shown in FIG. 5.

Steel grade	Ni	B	Al	Co	Cr	Mo	Mn	Fe	Ti	C	Si	S	P
Invenel 617B	Base	0.004	1.09	12.20	22.20	9.53	0.07	1.15	0.38	0.09	0.08	0.002	0.003

Using the hot rolled sheet thus prepared to prepare a tensile specimen to generate a defect was carried out a tensile test until failure. Microstructure after tension is shown in FIG. 6. The distribution of each element of the microstructure is shown in FIGS. 7 and 8. Elemental segregation or precipitation was not observed around the defects after tensioning.

After tensioning the specimens were heated and water cooled at 800 ° C. for 14 hours to achieve self healing. The microstructure after heat treatment is shown in FIG. The distribution of each element of the microstructure is shown in FIGS. 10 and 11. Unlike the microstructure before heat treatment, it was confirmed that boron (B), molybdenum (Mo), and chromium (Cr) segregated around defects. As a result, it was confirmed that the supersaturated invasive solid solution selectively precipitated on the material defect site.

Example 2

In order to confirm the effect of self-healing on the mechanical properties, two tensile specimens were fabricated in the same hot-rolled sheet of Example 1, giving only 33% of deformation before fracture. The microstructure of the tensile specimens with 33% strain is shown in FIG. 12.

To implement self-healing, two specimens were first applied with 33% tensile stress. Two tensile test results are shown in FIG. 13. Thereafter, only one tensile specimen was heated at 800 ° C. for 16 hours and water cooled. Tensile test results of 33% strained tensile specimens before and after heat treatment are shown in FIG. 14. The elongation of the tensilely annealed tensile specimens was restored to that of the non-annealed tensile specimens, indicating self-healing.

The embodiments described in the present specification and the accompanying drawings merely illustrate some of the technical ideas included in the present invention. Therefore, since the embodiments disclosed herein are not intended to limit the technical spirit of the present invention but to explain, it is obvious that the scope of the technical spirit of the present invention is not limited by these embodiments. Modifications and specific embodiments that can be easily inferred by those skilled in the art within the scope of the technical idea included in the specification and drawings of the present invention should be construed as being included in the scope of the present invention.

Claims (16)

1. Cobalt (Co): 10-15 wt%, Chromium (Cr): 15-30 wt%, Molybdenum (Mo): 5-15 wt%, Carbon (C): 0.05-0.2 wt%, Boron (B): < A self-healing super heat-resistant nickel alloy containing 200 ppm of components and composed of residual nickel (Ni) and other inevitable impurities.
2. The method according to claim 1,

   Titanium (Ti): the self-healing super heat-resistant nickel alloy, characterized in that it further contains 0.001-1.0% by weight of the component.
3. The method according to claim 1,

   Self-healing super heat-resistant nickel alloy, characterized in that the nickel alloy further contains 0.001-3.0% by weight of at least one total selected from the group consisting of iron (Fe), silicon (Si) and aluminum (Al).
4. The method according to claim 1,

   Self-healing superheat-resistant nickel alloy, characterized in that the optimum self-healing temperature of the nickel alloy is 700-800 ℃.
5. Nickel alloy with self-healing function,

   When a void is formed inside the nickel alloy, boride is deposited at the void interface.

   The boride is self-healing super heat-resistant nickel alloy, characterized in that consisting of boron (B), molybdenum (Mo), chromium (Cr), nickel (Ni) and cobalt (Co).
6. The method of claim 5, wherein the nickel alloy

   Cobalt (Co): 10-15 wt%, Chromium (Cr): 15-30 wt%, Molybdenum (Mo): 5-15 wt%, Carbon (C): 0.05-0.2 wt%, Boron (B): < A base composition containing 200 ppm of the component and containing the balance of nickel (Ni) and other unavoidable impurities; or

   At least one selected from the group consisting of iron (Fe), silicon (Si), and aluminum (Al) in the first composition further containing titanium (Ti): 0.001-1.0 wt% in the basic composition. A self-healing super heat-resistant nickel alloy, characterized in that the composition further contains at least one of the second compositions containing 0.001-3.0% by weight.
7. Cobalt (Co): 10-15 wt%, Chromium (Cr): 15-30 wt%, Molybdenum (Mo): 5-15 wt%, Carbon (C): 0.05-0.2 wt%, Boron (B): < Nickel alloy hot rolled steel sheet containing a basic composition containing 200 ppm of components and containing the balance of nickel (Ni) and other unavoidable impurities, or

   At least one selected from the group consisting of iron (Fe), silicon (Si), and aluminum (Al) in the first composition further containing titanium (Ti): 0.001-1.0 wt% in the basic composition. Providing a hot rolled steel sheet or a hot forged steel sheet of nickel alloy further containing at least one of the second compositions containing 0.001-3.0% by weight;

   Step S4 of reheating the steel sheet of nickel alloy to a predetermined temperature;

   S5 step of maintaining isothermal and heat treatment at a predetermined temperature; And

   Method of producing a self-healing super heat-resistant nickel alloy comprising the step S6 of cooling the steel sheet isothermally maintained.
8. The method according to claim 7,

   The reheating temperature of the step S4 is a method of producing a self-healing super heat-resistant nickel alloy, characterized in that more than the temperature at which the pre-deposited boride is dissolved in the nickel alloy.
9. The method according to claim 7,

   The pre-set temperature at which the isothermal temperature is maintained in the step S5 is 1150-1250 ℃ manufacturing method of self-healing super heat resistant nickel alloy.
10. The method according to claim 7,

    The method of manufacturing a self-healing super heat-resistant nickel alloy, characterized in that the predetermined temperature is maintained at step S5 is 1250-1300 ℃.
11. The method according to claim 7,

    The step S6 is a method of producing a self-healing super heat-resistant nickel alloy, characterized in that the cooling by water cooling.
12. The method according to claim 7,

    The microstructure of step S6 is a method for producing a self-healing super heat-resistant nickel alloy, characterized in that the austenite single phase.
13. The method according to claim 7,

    The steel sheet providing step

    S1 step of dissolving and then melting the nickel alloy having the composition;

    S2 step of hot rolling or hot forging the solution-molded nickel alloy; And

    Method of producing a self-healing super heat-resistant nickel alloy comprising the step S3 of cooling the hot rolled or hot forged steel sheet.
14. The method according to claim 13,

    The solution temperature of the step S1 is 1200 ℃, the dissolution temperature is a method of producing a self-healing super heat-resistant nickel alloy, characterized in that the solution temperature or more.
15. The method according to claim 13,

    The hot rolling or hot forging temperature of the step S2 is 900-1200 ℃ manufacturing method of self-healing super heat-resistant nickel alloy.
16. The method according to claim 13,

    The step S3 is a method of producing a self-healing super heat-resistant nickel alloy, characterized in that the cooling method of at least one of water or air cooling.

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