KR102147227B1 - Method for making nickel-based superalloys with excellent machinability and mechanical properity by using centrifugal casting - Google Patents

Abstract

The present invention relates to a method for manufacturing nickel-based super heat-resistant alloys by using centrifugal casting. The method comprises: a first step of preparing an alloy material for manufacturing a nickel-based super heat-resistant alloy containing, based on the total weight, 0.01 to 0.30 wt% of carbon (C), 0.10 to 0.50 wt% of sulfur (S), 0.1 to 1.0 wt% of manganese (Mn), 10.0 to 15.0 wt% of chromium (Cr), 2.0 to 7.0 wt% of molybdenum (Mo), 0.1 to 5.0 wt% of tungsten (W), 0.1 to 2.0 wt% of titanium (Ti), 1.0 to 5.0 wt% of niobium (Nb), 3.0 to 10.0 wt% of aluminum (Al), and the remainder of nickel (Ni) and inevitable impurities; a second step of feeding the alloy material into a crucible and melting the alloy material to form a molten metal; a third step of tapping the molten metal from the crucible and feeding the molten metal into a centrifugal casting mold; a fourth step of performing centrifugal casting by rotating the centrifugal casting mold; and a fifth step of removing oxide or slag after separating the casting formed by centrifugal casting from the centrifugal casting mold. Therefore, the method can manufacture nickel-based super heat-resistant alloys with improved mechanical properties and machinability while performing centrifugal casting in the air.

Description

A method of manufacturing nickel-based superheat-resistant alloys with excellent machinability and mechanical properties using centrifugal casting method {METHOD FOR MAKING NICKEL-BASED SUPERALLOYS WITH EXCELLENT MACHINABILITY AND MECHANICAL PROPERITY BY USING CENTRIFUGAL CASTING}

The present invention relates to a method of manufacturing a nickel-based superheat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method.

The super heat-resistant alloy is an alloy made for the main purpose of withstanding the use at an ultra-high temperature of about 900 ℃ or higher. Superheat-resistant alloys are formed by mixing additional components such as chromium, aluminum, titanium, tungsten, molybdenum, etc., with main components such as nickel, cobalt, and iron for the purpose of improving strength, heat resistance, and corrosion resistance. It contains elements inside and outside branches.

Among them, nickel-based superheat-resistant alloys are remarkably excellent in high temperature corrosion resistance and heat resistance, and their use is increasing. Nickel-based super heat-resistant alloy uses nickel (Ni) as a matrix, and is manufactured by adding about 10 alloying elements such as chromium, cobalt, aluminum, titanium, tungsten, tantalum, molybdenum, carbon, and rhenium. . For example, in Korean Patent Laid-Open No. 10-2011-0113486, a raw material consisting of 16 to 20% chromium, 5 to 9% molybdenum, 0.5 to 3% aluminum, 1% manganese, 2% tin, and the rest is nickel , Disclosed is a nickel-based alloy prepared by melting in a vacuum atmosphere to prepare a molten metal, and injecting the molten metal into a mold for precision casting in a vacuum state.

In general, in manufacturing a nickel-based superheat-resistant alloy, titanium, aluminum, etc., including nickel, constituting the nickel-based superheat-resistant alloy, form an excessive amount of oxide or slag when exposed to the atmosphere during the melting process. There was a problem that the mechanical properties of the alloy were significantly deteriorated. Accordingly, most of the processes for manufacturing the nickel-based superheat-resistant alloy are performed through vacuum casting, as disclosed in Korean Patent Laid-Open No. 10-2011-0113486.

However, in order to perform vacuum casting, as a separate vacuum chamber is required, the process itself becomes complicated, and costs associated with provision of a vacuum chamber and maintenance of a vacuum state are excessively generated, which is not economical.

Accordingly, in the manufacture of nickel-based superheat-resistant alloys, it is required to develop a method of manufacturing nickel-based superheat-resistant alloys with excellent mechanical properties while casting in the air, instead of vacuum casting, which is complicated and inexpensive in the process. Has become.

In addition, the conventional nickel-based superheat-resistant alloy containing the above patent is mainly aimed at improving mechanical properties such as heat resistance, creep resistance, tensile strength, yield strength, and oxidation resistance. There is a problem that is not considered for improving the machinability or free machinability of the.

Therefore, in order to solve the above problems, the applicant of the present invention proposes a method of manufacturing a nickel-based super-heat-resistant alloy, which can improve the mechanical properties and machinability of the nickel-based super-heat-resistant alloy by centrifugal casting in the air. Developed.

Republic of Korea Patent Publication No. 10-2011-0113486

An object of the present invention is to provide a method for producing a nickel-based superheat-resistant alloy having excellent mechanical properties and machinability by performing centrifugal casting in the atmosphere, not in vacuum casting.

The object of the present invention is not limited to the technical problem as described above, and another technical problem may be derived from the following description.

In order to achieve the above object, in the method of producing a nickel-based superheat-resistant alloy by this centrifugal casting method, carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten ( W), titanium (Ti), niobium (Nb), aluminum (Al) and nickel (Ni) and a first step of preparing an alloy raw material for manufacturing a nickel-based superheat-resistant alloy composed of inevitable impurities;

A second step of injecting the alloy raw material into a solubility crucible and melting the alloy raw material to form a molten metal; A third step of injecting the molten metal into a mold for centrifugal casting after tapping the molten metal from the solubility crucible; A fourth step of performing centrifugal casting by rotating the centrifugal casting mold; And a fifth step of removing oxide or slag after separating the casting formed by centrifugal casting from the mold for centrifugal casting, wherein the alloy raw material for manufacturing the nickel-based superheat-resistant alloy in the first step is based on the total weight. Carbon (C): 0.01 to 0.30 wt%, Sulfur (S): 0.10 to 0.50 wt%, Manganese (Mn): 0.1 to 1.0 wt%, Chromium (Cr) 10.0 to 15.0 wt%, Molybdenum (Mo) 2.0 to 7.0 Wt%, tungsten (W) 0.1 to 5.0 wt%, titanium (Ti) 0.1 to 2.0 wt%, niobium (Nb): 1.0 to 5.0 wt%, aluminum (Al): 3.0 to 10.0 wt%, and the balance of nickel ( Provides a method of manufacturing a nickel-based superheat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method containing Ni) and inevitable impurities.

The alloy raw material for manufacturing the nickel-based superheat-resistant alloy may further contain at least one selected from the group consisting of silicon (Si), boron (B), zirconium (Zr), and iron (Fe).

In the second step, the alloy raw material for producing the nickel-based superheat-resistant alloy may be heat-treated at a temperature of 1,600 to 1,700°C.

The third step includes a 3-1 step of tapping the molten metal from the solubility crucible using a ladle; A 3-2 step of inoculating strontium into the molten metal tapped from the solubility crucible; And a third step of injecting the molten metal into the centrifugal casting mold by moving the molten metal inoculated with strontium into a pouring basin.

Before performing the step 3-1, the ladle and the injection basin may be preheated to 250 to 350°C.

In step 3-2, the strontium (Sr): 0.001 to 1.0% by weight may be inoculated based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy.

In the fourth step, the centrifugal casting may be carried out under conditions of rotational speed: 1,950 to 2,250 rpm and gravity multiple: 80 to 160.

The third and fourth steps may be performed in an anti-oxidation atmosphere composed of one or more process gases selected from the group consisting of argon (Ar) gas, hydrogen (H ₂ ) gas, and carbon monoxide (CO) gas.

According to the present invention, it is possible to manufacture a nickel-based superheat-resistant alloy having excellent mechanical properties and machinability through centrifugal casting in the atmosphere rather than vacuum casting. In particular, the nickel-based superheat-resistant alloy manufactured by the method of the present invention has excellent mechanical properties such as tensile strength, yield strength, and elongation at room temperature and high temperature, and may have excellent machinability.

1 is a flowchart of a method of manufacturing a nickel-based superheat-resistant alloy using a centrifugal casting method according to an embodiment of the present invention.
2 is a flowchart of a method of manufacturing a nickel-based superheat-resistant alloy using a centrifugal casting method according to another embodiment of the present invention.
3 is a diagram showing the degree of formation of oxides or slag by temperature of the molten metal in Experimental Example 1.
4 is a view showing a cross section of a nickel-based superheat-resistant alloy according to Example 2 and Comparative Example 28 in Experimental Example 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts not related to the description are omitted in order to clearly describe the present invention.

The terms or words used in the specification and claims of the present invention are not limitedly interpreted in a conventional or dictionary meaning, and the inventor can appropriately define the concept of the term in order to describe his own invention in the best way. Based on the principle, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

In the entire specification of the present invention, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. .

In the entire specification of the present invention, "A and/or B" means A or B, or A and B.

Hereinafter, the present invention has been described in detail, but the present invention is not limited thereto.

The present invention provides a method of manufacturing a nickel-based superheat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method.

In one embodiment of the present invention, in the method of manufacturing a nickel-based superheat-resistant alloy by centrifugal casting, carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W) ), titanium (Ti), niobium (Nb), aluminum (Al) and nickel (Ni) and a first step of preparing an alloy raw material for manufacturing a nickel-based superheat-resistant alloy composed of inevitable impurities; A second step of injecting the alloy raw material into a solubility crucible and melting the alloy raw material to form a molten metal; A third step of injecting the molten metal into a mold for centrifugal casting after tapping the molten metal from the solubility crucible; A fourth step of performing centrifugal casting by rotating the centrifugal casting mold; And a fifth step of removing the oxide or slag after separating the casting formed by the centrifugal casting from the mold for centrifugal casting, and including, in the first step, carbon based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy ( C): 0.01 to 0.30 wt%, sulfur (S): 0.10 to 0.50 wt%, manganese (Mn): 0.1 to 1.0 wt%, chromium (Cr) 10.0 to 15.0 wt%, molybdenum (Mo) 2.0 to 7.0 wt% , Tungsten (W) 0.1 to 5.0% by weight, titanium (Ti) 0.1 to 2.0% by weight, niobium (Nb): 1.0 to 5.0% by weight, aluminum (Al): 3.0 to 10.0% by weight and the balance of nickel (Ni) And inevitable impurities, there is provided a manufacturing method capable of producing a superheat-resistant alloy having excellent mechanical properties and machinability while performing centrifugal casting in the atmosphere without performing vacuum casting.

1 is a flowchart of a method of manufacturing a nickel-based super-heat-resistant alloy using a centrifugal casting method according to the present embodiment. Hereinafter, the method of manufacturing a nickel-based super-heat-resistant alloy according to the present invention is described with reference to FIG. It was divided into and described in detail.

(1) Carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), niobium (Nb), aluminum (Al) and nickel The first step of preparing an alloy raw material for manufacturing a nickel-based superheat-resistant alloy composed of (Ni) and inevitable impurities

1, in the first step of this embodiment, carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), niobium (Nb), aluminum (Al), nickel (Ni) and inevitable impurities for the production of a nickel-based superheat-resistant alloy, based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy, carbon (C): 0.01 to 0.30% by weight , Sulfur (S): 0.10 ~ 0.50% by weight, manganese (Mn): 0.1 ~ 1.0% by weight, chromium (Cr) 10.0 ~ 15.0% by weight, molybdenum (Mo) 2.0 ~ 7.0% by weight, tungsten (W) 0.1 ~ 5.0 Weight%, titanium (Ti) 0.1 to 2.0% by weight, niobium (Nb): 1.0 to 5.0% by weight, aluminum (Al): 3.0 to 10.0% by weight, and alloy raw materials containing the balance of nickel (Ni) and inevitable impurities Prepare.

Hereinafter, the role and content of each component included in the nickel-based superheat-resistant alloy according to the present invention will be described in detail.

Carbon (C)

Carbon (C) combines with the elements contained in the nickel-based superheat-resistant alloy of this embodiment to form a carbide in the form of MC, M ₆ C, M ₇ C ₃ or M ₂₃ C _{6 at the} grain boundaries, thereby minimizing the grain boundaries. It serves to improve the strength.

It may contain 0.01 to 0.30% by weight, preferably 0.10 to 0.25% by weight, more preferably 0.10 to 0.20% by weight of carbon, based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of this embodiment. If the amount of carbon is less than 0.01% by weight based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of the present embodiment, there may be a problem in that mechanical properties are deteriorated because carbides are not sufficiently formed. On the other hand, when carbon is contained in an amount exceeding 0.30% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment, there may be a problem in that mechanical properties and machinability are deteriorated by excessively formed carbide.

Sulfur (S)

Sulfur (S) may improve heat resistance by preferentially bonding with manganese (Mn) contained in the nickel-based superheat-resistant alloy of the present embodiment to form a compound having an Mn-S structure. Preferably, the sensitivity of hot cracking of the nickel-based superheat-resistant alloy can be minimized by the compound of the Mn-S structure. In addition, as the compound of the Mn-S structure serves as a solid lubricant in machining, the machinability, free machinability, or machinability of the nickel-based superheat-resistant alloy according to the present embodiment can be remarkably improved.

The alloy raw material for producing a nickel-based superheat-resistant alloy of this embodiment contains 0.10 to 0.50% by weight of sulfur, preferably 0.20 to 0.40% by weight, more preferably 0.25 to It may contain 0.32% by weight. If the amount of sulfur is less than 0.10% by weight based on the total weight of the alloy raw material for the manufacture of the nickel-based superheat-resistant alloy of this embodiment, the compound of the Mn-S structure is not sufficiently formed, resulting in deterioration in heat resistance, machinability, and workability. There may be. On the other hand, when the amount of sulfur is contained in an amount exceeding 0.50% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, the mechanical strength may be lowered and weldability may be lowered due to the properties of the sulfur itself.

Manganese (Mn)

Manganese (Mn) serves to improve the corrosion resistance and creep properties of the nickel-based superheat-resistant alloy at room temperature or high temperature. In addition, as disclosed above, by reacting with sulfur to form a compound having an Mn-S structure, heat resistance, machinability, and workability of the nickel-based superheat-resistant alloy can be improved.

The alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment may contain manganese in an amount of 0.1 to 1.0% by weight, preferably 0.20 to 0.90% by weight, and more preferably 0.40 to 0.80% by weight, based on the total weight. If manganese is contained in an amount of less than 0.1% by weight based on the total weight of the alloy raw material for the production of the nickel-based superheat-resistant alloy of the present embodiment, there may be a problem that the corrosion resistance, creep characteristics, heat resistance, and machinability at room temperature or high temperature are deteriorated. have. On the other hand, if manganese is included in an amount exceeding 1.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment, there may be a problem that mechanical properties at high temperature are significantly deteriorated due to sensitivity to hot cracking.

In particular, in the present embodiment, by further including manganese in an amount of about 1.3 to 2.5 times the weight of sulfur, the Mn-S structure compound can be sufficiently formed, thereby reducing the amount of sulfur remaining in the nickel-based superheat-resistant alloy. , It is possible to prevent the problem of poor mechanical properties or weldability due to sulfur. Preferably, in the present embodiment, manganese may be further contained in an amount of about 2.2 to 2.3 times the weight of sulfur, thereby achieving more excellent mechanical properties and machinability.

Chrome(Cr)

Chromium (Cr) plays a role in improving the corrosion resistance and oxidation resistance of the nickel-based superheat-resistant alloy. In particular, chromium is oxidized to form a film containing Cr ₂ O ₃ or the like, thereby remarkably improving corrosion resistance and oxidation resistance at room temperature and high temperature. However, as chromium can react with carbon to form carbide or TCP (Topologically Close Packed) phase, it can be used in an appropriate amount.

The alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment may contain 10.0 to 15.0 wt% of chromium, preferably 11.0 to 14.0 wt%, and more preferably 12.0 to 14.0 wt%, based on the total weight. If, in the case of containing less than 10.0% by weight of chromium based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment, there may be a problem of deteriorating corrosion resistance and oxidation resistance. On the other hand, in the case of containing more than 15.0% by weight of chromium based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of this embodiment, there may be a problem of deteriorating creep characteristics and mechanical properties at high temperatures by forming carbides and TCP. have.

Molybdenum (Mo)

Molybdenum (Mo) is a solid solution strengthening element and serves to improve high temperature tensile properties and creep properties of superheat-resistant alloys.

The alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment may contain 2.0 to 7.0% by weight of molybdenum, preferably 2.5 to 5.0% by weight, and more preferably 2.5 to 4.0% by weight based on the total weight. If, in the case of containing less than 2.0% by weight of molybdenum based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of the present embodiment, the solid solution strengthening effect is insignificant, and thus there may be a problem of deteriorating high-temperature tensile properties and creep properties. On the other hand, when molybdenum is contained in an amount exceeding 7.0% by weight based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of this embodiment, there may be a problem in that the free-machining property is deteriorated, the stability of the microstructure is deteriorated, and mechanical properties are deteriorated. .

Tungsten (W)

Tungsten (W) strengthens the gamma (γ) matrix through solid solution strengthening, thereby increasing the high temperature strength and creep strength of the nickel-based superheat-resistant alloy.

The alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment may contain 0.1 to 5.0% by weight, preferably 0.2 to 4.0% by weight, and more preferably 3.0 to 4.0% by weight of tungsten based on the total weight. If tungsten is contained in an amount of less than 0.1% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, the gamma (γ) base is not sufficiently strengthened, and thus the high temperature strength and creep characteristics are not sufficiently improved. There may be. On the other hand, when tungsten is contained in an amount exceeding 5.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, the stability of the microstructure is deteriorated and mechanical properties may be deteriorated.

Titanium (Ti)

Titanium (Ti) is an element forming a gamma prime (γ') phase, and serves to improve the high-temperature properties of a nickel-based superheat-resistant alloy by increasing the energy of the reverse phase boundary (APB) of the gamma prime phase.

The alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment may contain 0.1 to 2.0% by weight, preferably 0.5 to 1.5% by weight, and more preferably 0.8 to 1.2% by weight of titanium based on the total weight. If the amount of titanium is less than 0.1% by weight based on the total weight of the alloy raw material for the production of the nickel-based superheat-resistant alloy of this embodiment, the gamma prime phase is not sufficiently formed, and thus mechanical properties at high temperatures may not be sufficiently improved. have. On the other hand, in the case of including titanium in excess of 2.0% by weight based on the total weight of the alloy raw material for the production of the nickel-based superheat-resistant alloy of the present embodiment, the gamma prime phase may be excessively formed, resulting in a problem of lowering phase stability and mechanical properties. .

Niobium (Nb)

Niobium (Nb) plays a role in improving the mechanical properties of a nickel-based superheat-resistant alloy.

The alloy raw material for producing a nickel-based superheat-resistant alloy of this embodiment may further contain niobium in an amount of 1.0 to 5.0% by weight, preferably 1.5 to 3.0% by weight, more preferably 2.0 to 2.5% by weight, based on the total weight. If niobium is included in an amount of less than 1.0% by weight or more than 5.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, there may be a problem of deteriorating mechanical properties.

Aluminum (Al)

Aluminum (Al) is an element forming a gamma prime phase of a nickel-based superheat-resistant alloy, and serves to improve oxidation resistance and mechanical properties.

The alloy raw material for producing a nickel-based superheat-resistant alloy of this embodiment may further contain aluminum in an amount of 3.0 to 10.0% by weight, preferably 5.0 to 7.0% by weight, and more preferably 6.0 to 6.8% by weight, based on the total weight. If aluminum is contained in an amount of less than 3.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, a gamma prime phase may not be sufficiently formed and thus mechanical properties may be low. On the other hand, when aluminum is included in an amount exceeding 10.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment, there may be a problem in that machinability is deteriorated due to excessive formation of a gamma prime phase.

In addition, the nickel-based superheat-resistant alloy of the present embodiment may further contain at least one selected from the group consisting of silicon (Si), boron (B), zirconium (Zr), and iron (Fe).

Silicon (Si)

Silicon (Si) can improve the corrosion resistance and oxidation resistance of a nickel-based superheat-resistant alloy.

The alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment may further contain silicon in an amount of 0.001 to 7.0% by weight, preferably 0.001 to 4.0% by weight, and more preferably 0.001 to 1.0% by weight, based on the total weight. If, in the case of containing less than 0.001% by weight of silicon based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of the present embodiment, there may be a problem in that the effect of improving corrosion resistance and oxidation resistance is insignificant. On the other hand, in the case of containing more than 7.0% by weight of silicon based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy of the present embodiment, corrosion resistance and oxidation resistance may be improved, while creep characteristics may be deteriorated.

Boron (B)

Boron (B) serves to strengthen the grain boundaries by depositing borides having the form of M ₃ B ₂ and M ₀ B ₃ in the grain boundaries. That is, boron plays a role of improving the mechanical properties of the nickel-based superheat-resistant alloy at room temperature and high temperature by depositing an appropriate amount of boride at the grain boundaries.

The alloy raw material for producing a nickel-based superheat-resistant alloy of this embodiment may further contain boron in an amount of 0.001 to 1.0% by weight, preferably 0.003 to 0.20% by weight, and more preferably 0.003 to 0.015% by weight, based on the total weight. If boron is contained in an amount of less than 0.001% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, the precipitation of boride is insignificant, and thus there may be little improvement in mechanical properties. On the other hand, when the amount of boron exceeds 1.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, there may be a problem in that mechanical properties are deteriorated due to an excessively formed boride.

Zirconium (Zr)

Zirconium (Zr) plays a role in strengthening grain boundaries along with carbon and boron. Particularly, in the nickel-based superheat-resistant alloy of the present embodiment, by combining with manganese and remaining amount of sulfur to form sulfide, it is possible to prevent deterioration of mechanical properties due to sulfur.

The alloy raw material for producing a nickel-based superheat-resistant alloy of this embodiment may further contain zirconium in an amount of 0.01 to 1.0% by weight, preferably 0.05 to 0.2% by weight, more preferably 0.1 to 0.15% by weight, based on the total weight. If the amount of zirconium is less than 0.01% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, the degree of grain boundary strengthening is insignificant and mechanical properties may be deteriorated. On the other hand, when containing more than 1.0% by weight of zirconium based on the total weight of the alloy raw material for the production of the nickel-based superheat-resistant alloy of the present embodiment, there may be a problem of inducing excessive grain boundary segregation and lowering mechanical properties and machinability at high temperatures. .

Iron (Fe)

Iron (Fe) plays a role in improving the mechanical properties of a nickel-based superheat-resistant alloy.

The alloy raw material for producing a nickel-based superheat-resistant alloy of the present embodiment may further contain iron in an amount of 0.001 to 10.0% by weight, preferably 0.01 to 3.0% by weight, and more preferably 0.1 to 2.5% by weight, based on the total weight. If the amount of iron exceeds 10.0% by weight based on the total weight of the alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment, there may be a problem in that mechanical properties are deteriorated.

In addition to the above components, the nickel-based superheat-resistant alloy of the present embodiment may contain the balance of nickel and unavoidable impurities.

As disclosed above, the nickel-based superheat-resistant alloy of this embodiment is carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), and nio. Contains empty (Nb), aluminum (Al), and nickel (Ni), but based on the total weight of the alloy raw material for manufacturing the nickel-based super heat-resistant alloy, carbon (C): 0.01 ~ 0.30% by weight, sulfur (S): 0.10 ~ 0.50 Wt%, manganese (Mn): 0.1 to 1.0 wt%, chromium (Cr) 10.0 to 15.0 wt%, molybdenum (Mo) 2.0 to 7.0 wt%, tungsten (W) 0.1 to 5.0 wt%, titanium (Ti) 0.1 to It may contain 2.0 wt%, niobium (Nb): 1.0 to 5.0 wt%, aluminum (Al): 3.0 to 10.0 wt%, and the balance of nickel (Ni) and inevitable impurities.

Preferably, the nickel-based superheat-resistant alloy of this embodiment is carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), niobium ( It may contain Nb), aluminum (Al), strontium (Sr), and nickel (Ni). In particular, when the nickel-based superheat-resistant alloy of this embodiment is composed of the above components, carbon (C): 0.01 to 0.30% by weight, sulfur (S): 0.10 based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy. ~ 0.50 wt%, manganese (Mn): 0.1 ~ 1.0 wt%, chromium (Cr) 10.0 ~ 15.0 wt%, molybdenum (Mo) 2.0 ~ 7.0 wt%, tungsten (W) 0.1 ~ 5.0 wt%, titanium (Ti) 0.1 to 2.0% by weight, niobium (Nb): 1.0 to 5.0% by weight, aluminum (Al): 3.0 to 10.0% by weight, strontium (Sr): 0.001 to 1.0% by weight, and the remaining amount of nickel (Ni) and inevitable impurities It may contain. In particular, since the nickel-based superheat-resistant alloy of the present embodiment further contains strontium, machinability can be remarkably improved along with mechanical properties.

More preferably, the nickel-based superheat-resistant alloy of this embodiment is carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), niobium It may contain (Nb), aluminum (Al), strontium (Sr), silicon (Si), boron (B), zirconium (Zr), iron (Fe), and nickel (Ni). In particular, when the nickel-based superheat-resistant alloy of this embodiment is composed of the above components, carbon (C): 0.01 to 0.30% by weight, sulfur (S): 0.10 based on the total weight of the alloy raw material for producing the nickel-based superheat-resistant alloy. ~ 0.50 wt%, manganese (Mn): 0.1 ~ 1.0 wt%, chromium (Cr) 10.0 ~ 15.0 wt%, molybdenum (Mo) 2.0 ~ 7.0 wt%, tungsten (W) 0.1 ~ 5.0 wt%, titanium (Ti) 0.1 to 2.0 wt%, Niobium (Nb): 1.0 to 5.0 wt%, Aluminum (Al): 3.0 to 10.0 wt%, Strontium (Sr): 0.001 to 1.0 wt%, Silicon (Si): 0.001 to 7.0 wt% , Boron (B): 0.001 to 1.0% by weight, zirconium (Zr): 0.01 to 1.0% by weight, iron (Fe): 0.001 to 10.0% by weight, and the balance may contain nickel (Ni) and inevitable impurities.

(2) the second step of injecting the alloy raw material into a solubility crucible and melting the alloy raw material to form a molten metal

As shown in FIG. 1, in the second step of the present embodiment, an alloy raw material for manufacturing the nickel-based superheat-resistant alloy prepared according to the first step is introduced into a solubility crucible, and the alloy raw material is dissolved to form a molten metal.

In particular, in the second step of the present embodiment, the alloy raw material for manufacturing the nickel-based superheat-resistant alloy is heated to a temperature of 1,600 to 1,700 °C, preferably 1,610 to 1,690 °C, more preferably 1,630 to 1,660 °C. It can be dissolved.

If the heat treatment is performed at less than 1,600° C. in the second step of the present embodiment, there may be a problem in that an excessive amount of oxide or slag is generated during the melting process of the alloy material. In particular, elements such as aluminum, titanium, and chromium constituting the nickel-based superheat-resistant alloy are entangled to the excess oxide or slag, so when the oxide or slag is removed, the constituent elements of the nickel-based superheat-resistant alloy are also removed. , There may be a problem that the process yield is significantly lowered. On the other hand, in the second step of the present embodiment, when the heating treatment is performed at a temperature exceeding 1,700° C., some elements are peroxidated or evaporated at a high temperature, resulting in component change, and there may be a problem of deteriorating the stability of the molten metal. . That is, in the second step of the present embodiment, when the alloy raw material for producing the nickel-based super-heat-resistant alloy is heated and dissolved in a state that does not satisfy the temperature condition of 1,600 to 1,700°C, the mechanical properties and machinability of the nickel-based super-heat-resistant alloy There may be a problem with this deterioration.

(3) the third step of injecting the molten metal into a mold for centrifugal casting after tapping the molten metal from the solubility crucible

1, in the third step of the present embodiment, the molten metal is tapped from the solubility crucible, and the tapped molten metal is injected into a centrifugal casting mold for centrifugal casting.

The mold for centrifugal casting of the present embodiment may be formed in all known forms applicable to the centrifugal casting method. For example, the centrifugal casting mold may be formed in a cylindrical shape with a hollow inside, but is not limited thereto.

In the third step of this embodiment, as shown in FIG. 2, step 3-1 of tapping the molten metal from the solubility crucible using a ladle, and inoculating strontium into the molten metal tapped from the solubility crucible. Step 3-2 and step 3-3 of injecting the molten metal into the centrifugal casting mold by moving the molten metal inoculated with the strontium to an injection basin (Pouring basin) may be further included.

In step 3-1 of the present embodiment, the molten metal dissolved in the solubility crucible according to the second step may be tapped using a ladle. The ladle means a means for tapping the molten metal from the solubility crucible. The ladle is not particularly limited in shape, material, size, etc. as long as it is a means capable of tapping the molten metal from the solubility crucible.

In step 3-2 of the present embodiment, strontium may be inoculated into the molten metal tapped from the solubility crucible into the ladle according to the step 3-1.

Strontium is contained in a nickel-based superheat-resistant alloy, so that the machinability can be remarkably improved while maintaining excellent mechanical properties.

The alloy raw material for producing a nickel-based superheat-resistant alloy according to the present embodiment may contain 0.001 to 1.0% by weight, preferably 0.003 to 0.70% by weight, and more preferably 0.004 to 0.10% by weight, based on the total weight. If the alloy raw material for manufacturing the nickel-based superheat-resistant alloy of the present embodiment contains less than 0.001% by weight of strontium based on the total weight, there may be a problem in that the effect of improving machinability is insignificant. On the other hand, when the alloy raw material for manufacturing the nickel-based superheat-resistant alloy of the present embodiment contains more than 1.0% by weight of strontium based on the total weight, while the machinability is improved, mechanical properties may be deteriorated.

At this time, inoculation is one of the ladle addition methods that promote nucleation even if there is no alloying effect.In this embodiment, strontium is further mixed with the molten metal formed in the second step to obtain the molten metal in a dissolved state. It may mean to form, but is not limited thereto.

In this embodiment, strontium is not mixed with the alloying raw materials including carbon, sulfur, manganese, chromium, molybdenum, tungsten, titanium, niobium, aluminum and nickel in the first step, but is added alone in a separate step. , It is possible to remarkably improve the mechanical properties and machinability of the nickel-based superheat-resistant alloy manufactured according to the present embodiment.

In more detail, according to the present embodiment, when strontium is added in the third step instead of the first step, grain boundary refinement may be induced and the internal structure may be uniformly formed in an equiaxed crystal shape. Accordingly, the nickel-based superheat-resistant alloy of the present embodiment can achieve uniform mechanical properties over an entire area, and improve overall mechanical properties and machinability.

On the other hand, when strontium is not added alone in a separate step and is mixed with alloying materials other than in the first step, fine grain boundaries are not sufficiently induced, and the internal structure is not uniformly formed in the form of an equiaxed crystal. And, as the columnar crystal shape and the equiaxed crystal shape appear together, there may be a problem in that the mechanical properties and machinability of the nickel-based superheat-resistant alloy are not sufficiently improved. In addition, there may be a problem in that the internal structure is not uniformly formed over the entire area, and thus a significant difference in mechanical properties occurs in each area of the nickel-based superheat-resistant alloy.

In step 3-3 of the present embodiment, the molten metal inoculated with strontium according to step 3-2 is moved to an injection basin, and then the molten metal may be injected into a mold for centrifugal casting.

In the third step of the present embodiment, before performing the 3-1, 3-2, and 3-3 steps, the process of tapping the molten metal from the solubility crucible including the ladle and the injection basin, and the Each member used in the process of injecting the molten metal into the centrifugal casting mold may be preheated to 250 to 350 °C, preferably 270 to 350 °C, more preferably 290 to 350 °C.

Accordingly, in this embodiment, a molten metal having a uniform chemical composition can be injected into the mold for centrifugal casting while minimizing the generation of oxides or slag, so that a nickel-based superheat-resistant alloy having excellent mechanical properties and machinability can be manufactured. .

If the preheating treatment is performed at a temperature of less than 250°C, or if the preheating treatment is not performed, excessive oxides or slag may be generated. There may be difficulties in controlling the amount of molten metal injected into the casting mold. In particular, when the molten metal tapped from the solubility crucible is cooled and solidified during the transfer process and remains attached to a ladle, an injection basin, etc., it may be difficult to move the molten metal, and it may be difficult to predict the tapping amount and injection amount of the molten metal. On the other hand, when the preheating treatment is performed at a temperature exceeding 350° C., the temperature of the ladle, the injection basin, etc. is improved, and excessive cost and time are required to maintain the temperature, thereby reducing economic efficiency.

(4) The fourth step of performing centrifugal casting by rotating the centrifugal casting mold

In the fourth step of the present embodiment, centrifugal casting is performed while rotating the mold for centrifugal casting into which the molten metal is injected in the third step.

Preferably, in the fourth step of the present embodiment, centrifugal casting is performed, but in the atmosphere, unlike conventional vacuum casting, as centrifugal casting is performed so as to satisfy the condition that the gravity multiple is 80 to 160 and the rotational speed is 1,950 to 2,250 rpm. While centrifugal casting is performed, a nickel-based superheat-resistant alloy with excellent mechanical properties and machinability can be manufactured.

In addition, unlike conventional vacuum casting, when centrifugal casting is performed, oxides, slags, impurities, etc. in the molten metal are collected in the center by centrifugal force, so oxides or slags located in the center of the casting obtained after performing the fourth step, By removing impurities and the like, it may be possible to manufacture a nickel-based superheat-resistant alloy of high purity.

In the mold for centrifugal casting used in the fourth step of this embodiment, a figure layer may be formed for the purpose of preventing chilling by molten metal and preventing seizure. The figure layer may be formed using a known figure such as silica or magnesium oxide. In this case, the figure layer may have a thickness of about 0.8 to 1.2 mm, but is not limited thereto.

Centrifugal casting is carried out in the fourth step of this embodiment, but it can be carried out under the condition that the gravity multiple is 80 to 160.

If, in the fourth step of this embodiment, centrifugal casting is performed, but when the gravity multiple is less than 80, the rotational force and the centrifugal force are insufficient, making it difficult to manufacture a nickel-based superheat-resistant alloy in a homogeneous state, as well as the centrifugal casting process. Oxide, slag, impurities, etc. are not sufficiently moved to the center of the material, and thus oxide, slag, impurities, etc. may not be easily removed from the casting. On the other hand, if centrifugal casting is performed in the fourth step of the present embodiment, but when the gravity multiple exceeds 160, there may be a problem that cracks are generated in the casting or nickel-based superheat-resistant alloy due to excessive stress.

In addition, in the fourth step of the present embodiment, centrifugal casting is performed, but the number of revolutions may be 1,950 to 2,250 rpm, preferably 2,000 to 2,200 rpm, more preferably 2,100 to 2,150 rpm.

If, in the fourth step of this embodiment, centrifugal casting is performed, but the rotational speed thereof is less than 1,950 rpm, the nickel-based superheat-resistant alloy does not have a uniform composition, the density of the structure decreases, and the In addition to the difference in cooling rate, there may be a problem in that it is difficult to remove impurities. On the other hand, if centrifugal casting is performed in the fourth step of this embodiment, but if the rotational speed thereof exceeds 2,250 rpm, there may be a problem that the mechanical properties of the nickel-based superheat-resistant alloy are deteriorated due to rapid cooling. , Oxide or slag may be generated, and there may be a problem of cracking in a casting or nickel-based superheat-resistant alloy.

That is, when centrifugal casting is performed in the fourth step of the present embodiment, but the rotational speed of the alloy does not satisfy the conditions of 1,950 to 2,250 rpm, the mechanical properties and machinability of the nickel-based superheat-resistant alloy manufactured according to the present embodiment are significantly reduced. There may be a problem.

In the fourth step of this embodiment, centrifugal casting was performed so that the gravity multiple was 80 to 160 and the rotational speed satisfies 1,950 to 2,250 rpm, but the final temperature of the casting formed by gradually cooling and solidifying the molten metal reached 700 to 800 °C. At this time, centrifugal casting can be stopped and the casting can be taken out.

If the final temperature of the casting is less than 700 °C in the fourth step of the present embodiment, the cooling rate of the casting may be slowed in the process of cooling the taken out casting, so that there may be a problem that some mechanical properties are deteriorated. There may be a problem that the mechanical life of the casting mold is reduced. On the other hand, in the fourth step of the present embodiment, when the final temperature of the casting exceeds 800° C., there may be a problem that separation between the casting and the centrifugal casting mold is not easy.

In this embodiment, the third and fourth steps are carried out in an anti-oxidation atmosphere composed of one or more process gases selected from the group consisting of argon (Ar) gas, hydrogen (H ₂ ) gas, and carbon monoxide (CO) gas. I can. At this time, the anti-oxidation atmosphere means that each component constituting the alloy material is prevented from being oxidized by reacting with oxygen in the atmosphere.

Preferably, the process gas may be argon (Ar) gas, but is not limited thereto.

If the third and fourth steps of this embodiment are not carried out in the reducing atmosphere as described above, excessive oxides or slag are generated in processes such as melting, tapping out of molten metal, injecting molten metal, and taking out castings, The mechanical properties and machinability of the nickel-based superheat-resistant alloy can be significantly deteriorated.

(5) A fifth step of removing oxide or slag after separating the casting formed by the centrifugal casting from the mold for centrifugal casting

In the fifth step of the present embodiment, the casting formed by the centrifugal casting is separated from the mold for centrifugal casting and then rapidly cooled by adding it to cooling water, and oxides or slag formed on the surface thereof are removed.

As disclosed in the third step of this embodiment, when a mold formed in a hollow cylindrical shape is used, oxide or slag is moved toward the inner diameter by rotation during centrifugal casting, so in the fifth step, the formed on the inner diameter side By removing the oxide or slag, the purity of the nickel-based superheat-resistant alloy can be further improved.

Accordingly, since the nickel-based superheat-resistant alloy of the present embodiment is formed with a high purity containing a minimum of oxide or slag, it may have more excellent mechanical properties and machinability.

After performing the fifth step, a shot blast treatment, a boring treatment, or the like may be performed to remove the figure layer and foreign matter adhered to the outer surface of the final casting, but is not limited thereto.

In performing the first step, the second step, the third step, the fourth step and the fifth step, a conventional centrifugal casting method may be applied, except for the above-described matters.

The nickel-based superheat-resistant alloy of this embodiment prepared according to the above, tensile strength (TS) at room temperature conditions: 760 to 850 MPa, yield strength (YS): 660 to 710 MPa, and elongation (EL): 1 to 10 %, and tensile strength (TS): 840 ~ 900 MPa, yield strength (YS): 690 ~ 730 MPa, and elongation (EL): 2 ~ 9% under 650 ℃ condition. That is, the nickel-based superheat-resistant alloy of the present embodiment may realize excellent mechanical properties at both room temperature and high temperature, as well as excellent machinability.

Preferably, the nickel-based superheat-resistant alloy manufactured according to the present embodiment is, at room temperature, tensile strength (TS): 760 to 850 MPa, yield strength (YS): 660 to 710 MPa, and elongation (EL): 6 to It may have 10%, tensile strength (TS): 840 ~ 900 MPa, yield strength (YS): 690 ~ 730 MPa, and elongation (EL): 5 ~ 9% under 650 ℃ conditions. That is, the nickel-based superheat-resistant alloy of the present embodiment can not only realize remarkably mechanical properties at room temperature and high temperature, but also can have remarkably excellent machinability.

Hereinafter, a method of manufacturing a nickel-based superheat-resistant alloy having excellent machinability and mechanical properties by using the centrifugal casting method of the present invention through Examples, Comparative Examples, and Experimental Examples will be described in detail. Since these examples are for illustrative purposes only, the scope of the present invention is not to be construed as being limited by these examples.

[Example]

Examples 1 to 5

(1) First, an alloy raw material for producing a nickel-based superheat-resistant alloy excluding strontium was prepared in the composition shown in Table 1 [unit: wt%].

(2) The alloy material was sequentially added to a solubility crucible and heated to 1,630° C. to dissolve the alloy material, thereby forming a molten metal.

(3) After tapping the molten metal into a ladle, strontium in the amount shown in Table 1 was inoculated thereto, and then the molten metal inoculated with strontium was moved to an injection basin and injected into a mold for centrifugal casting. At this time, prior to tapping the molten metal, members used for tapping and injecting the ladle and the pouring basin were preheated to about 300°C.

(4) Centrifugal casting was performed while rotating the mold for centrifugal casting into which the molten metal was injected under conditions of a gravity drainage of 150 and a rotational speed of 2,032 rpm. At this time, during the process of performing centrifugal casting from the process of tapping the molten metal, argon gas was injected to form an anti-oxidation atmosphere.

(5) Thereafter, by separating the casting from the centrifugal casting mold and removing oxide or slag, a nickel-based superheat-resistant alloy was prepared.

Example 1 Example 2 Example 3 Example 4 Example 5 nickel Contains residual nickel (+ contains inevitable impurities) carbon 0.141 0.141 0.141 0.166 0.166 sulfur 0.33 0.33 0.33 0.31 0.255 manganese 0.43 0.43 0.43 0.71 0.765 chrome 14.2 14.2 14.2 13.28 13.28 molybdenum 4.56 4.56 4.56 2.82 2.82 tungsten 0.21 0.21 0.21 3.27 3.27 titanium 0.54 0.54 0.54 0.91 0.91 strontium - 0.038 1.1 0.058 0.058 silicon 0.16 0.16 0.16 0.25 0.25 aluminum 5.6 5.6 5.6 6.6 6.6 Boron 0.012 0.012 0.012 0.011 0.011 Niobium 2.3 2.3 2.3 2.4 2.4 zirconium 0.13 0.13 0.13 0.10 0.10 iron 2.2 2.2 2.2 1.85 1.85

Example 6

It was prepared in the same manner as in Example 4, except that the centrifugal casting was carried out under the conditions of a gravity drainage of 90 and a rotational speed of 2,145 rpm.

[Comparative Example]

Comparative Examples 1 to 18

It was prepared in the same manner as in Examples, except that it was prepared according to the composition of Table 2 [unit: wt%] to Table 4 [unit: wt%].

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 nickel Contains residual nickel (+ contains inevitable impurities) carbon 0.001 0.35 0.141 0.141 0.141 0.141 sulfur 0.33 0.33 0.01 0.60 0.33 0.33 manganese 0.43 0.43 0.43 0.43 0.01 1.2 chrome 14.2 14.2 14.2 14.2 14.2 14.2 molybdenum 4.56 4.56 4.56 4.56 4.56 4.56 tungsten 0.21 0.21 0.21 0.21 0.21 0.21 titanium 0.54 0.54 0.54 0.54 0.54 0.54 strontium 0.038 0.038 0.038 0.038 0.038 0.038 silicon 0.16 0.16 0.16 0.16 0.16 0.16 aluminum 5.6 5.6 5.6 5.6 5.6 5.6 Boron 0.012 0.012 0.012 0.012 0.012 0.012 Niobium 2.3 2.3 2.3 2.3 2.3 2.3 zirconium 0.13 0.13 0.13 0.13 0.13 0.13 iron 2.2 2.2 2.2 2.2 2.2 2.2

Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 nickel Contains residual nickel (+ contains inevitable impurities) carbon 0.141 0.141 0.141 0.141 0.141 0.141 sulfur 0.33 0.33 0.33 0.33 0.33 0.33 manganese 0.43 0.43 0.43 0.43 0.43 0.43 chrome 5.0 20.0 14.2 14.2 14.2 14.2 molybdenum 4.56 4.56 1.0 10.0 4.56 4.56 tungsten 0.21 0.21 0.21 0.21 0.01 10.0 titanium 0.54 0.54 0.54 0.54 0.54 0.54 strontium 0.038 0.038 0.038 0.038 0.038 0.038 silicon 0.16 0.16 0.16 0.16 0.16 0.16 aluminum 5.6 5.6 5.6 5.6 5.6 5.6 Boron 0.012 0.012 0.012 0.012 0.012 0.012 Niobium 2.3 2.3 2.3 2.3 2.3 2.3 zirconium 0.13 0.13 0.13 0.13 0.13 0.13 iron 2.2 2.2 2.2 2.2 2.2 2.2

Comparative Example 13 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Comparative Example 18 nickel Contains residual nickel (+ contains inevitable impurities) carbon 0.141 0.141 0.141 0.141 0.141 0.141 sulfur 0.33 0.33 0.33 0.33 0.33 0.33 manganese 0.43 0.43 0.43 0.43 0.43 0.43 chrome 14.2 14.2 14.2 14.2 14.2 14.2 molybdenum 4.56 4.56 4.56 4.56 4.56 4.56 tungsten 0.21 0.21 0.21 0.21 0.21 0.21 titanium 0.01 7.0 0.54 0.54 0.54 0.54 strontium 0.038 0.038 0.038 0.038 0.038 0.038 silicon 0.16 0.16 0.16 0.16 0.16 0.16 aluminum 5.6 5.6 5.6 5.6 1.0 15.0 Boron 0.012 0.012 0.012 0.012 0.012 0.012 Niobium 2.3 2.3 0.5 10.0 2.3 2.3 zirconium 0.13 0.13 0.13 0.13 0.13 0.13 iron 2.2 2.2 2.2 2.2 2.2 2.2

Comparative Example 19

Inconel 713C alloy (Special Metal Corp.) was prepared.

Comparative Examples 20 to 22

It was prepared in the same manner as in Example 2, except that the alloy raw material for producing the nickel-based superheat-resistant alloy was heat-treated at the temperature of Table 5 to form a molten metal.

Example 2 Comparative Example 20 Comparative Example 21 Comparative Example 22 Melt temperature (℃) 1,630 1,450 1,550 1,800

Comparative Examples 23 to 24

It was prepared in the same manner as in Example 2, except that centrifugal casting was carried out under the conditions of Table 6.

Example 2 Comparative Example 23 Comparative Example 24 Rotation speed(rpm) 2,032 1,850 2,350

Comparative Examples 25 to 26

In the third step, the ladle and the injection basin were prepared in the same manner as in Example 2, except that the preheating treatment was performed under the conditions of Table 7.

Example 2 Comparative Example 25 Comparative Example 26 Temperature(℃) 300 200 400

Comparative Example 27

It was prepared in the same manner as in Example 2, except that an anti-oxidation atmosphere was not created with argon gas.

Comparative Example 28

It was prepared in the same manner as in Example 2, except that strontium was not inoculated in the third step (3), and was mixed with the alloy raw materials for producing a nickel-based superheat-resistant alloy in the first step (1).

[Experimental Example]

Experimental Example 1: Degree of formation of oxides or slag by melting temperature

In preparing the nickel-based superheat-resistant alloys of Example 2 and Comparative Examples 20 to 22, the molten metal state is shown in FIG. 3.

3, in the case of Comparative Example 20 in which the temperature of the molten metal was formed at 1,450° C. and Comparative Example 21 in which the temperature of the molten metal was formed at 1,550° C., an excess amount of oxide or It can be seen that slag is formed.

That is, according to FIG. 3, it means that the molten metal temperature is preferably 1,600°C or higher.

Experimental Example 2: Evaluation of the internal structure of a nickel-based superheat-resistant alloy according to the timing of strontium inoculation

The internal structures of the nickel-based super-heat-resistant alloy according to Example 2 and the nickel-based super-heat-resistant alloy according to Comparative Example 28 are shown in FIG. 4. In FIG. 4, (a) is a cross-section of a nickel-based superheat-resistant alloy according to Example 2, and (b) is a cross-section of a nickel-based superheat-resistant alloy according to Comparative Example 28.

4, after tapping a molten metal formed of an alloy raw material containing carbon, sulfur, manganese, chromium, molybdenum, tungsten, titanium, niobium, aluminum and nickel according to this embodiment, a molten metal inoculated with strontium was used. In the case of Example 2, it can be seen that grain boundary refinement is induced and the internal structure is uniformly formed in an equiaxed crystal shape.

On the other hand, unlike this Example, in the case of Comparative Example 28 using a molten metal in which strontium was mixed with carbon, sulfur, manganese, chromium, molybdenum, tungsten, titanium, niobium, aluminum and nickel, grain boundary refinement was not sufficiently induced. In addition, it can be seen that it has an internal structure in which the columnar and equiaxed crystal forms are mixed.

Experimental Example 3: Mechanical properties at room temperature

According to the method specified in KS B 0801, room temperature tensile strength, room temperature yield strength, and room temperature elongation of the nickel-based superheat-resistant alloys of Examples and Comparative Examples were measured, and are shown in Table 8.

Room temperature Tensile strength (MPa) Yield strength (Mpa) Elongation (%) Example 1 760 660 7.40 Example 2 816 670 7.82 Example 3 770 665 7.54 Example 4 840 705 8.50 Example 5 820 680 7.91 Example 6 845 710 9.00 Comparative Example 1 690 580 6.20 Comparative Example 2 675 590 6.00 Comparative Example 3 660 570 6.30 Comparative Example 4 670 560 7.00 Comparative Example 5 650 600 6.45 Comparative Example 6 660 590 6.10 Comparative Example 7 610 545 5.85 Comparative Example 8 650 560 6.00 Comparative Example 9 680 575 6.20 Comparative Example 10 670 580 6.30 Comparative Example 11 630 570 6.50 Comparative Example 12 645 560 6.60 Comparative Example 13 630 580 6.40 Comparative Example 14 650 585 6.30 Comparative Example 15 680 545 6.45 Comparative Example 16 690 555 6.50 Comparative Example 17 675 560 6.70 Comparative Example 18 680 575 6.55 Comparative Example 19 811 655 7.40 Comparative Example 20 580 490 5.40 Comparative Example 21 590 505 5.58 Comparative Example 22 605 510 5.79 Comparative Example 23 610 560 6.00 Comparative Example 24 630 570 6.30 Comparative Example 25 570 495 5.50 Comparative Example 26 630 520 6.00 Comparative Example 27 420 315 4.58 Comparative Example 28 457 486 5.00

Referring to Table 8, it can be seen that according to this embodiment, the tensile strength, yield strength, and elongation at room temperature are more excellent.

Experimental Example 4: Mechanical properties at high temperature

According to the method specified in KS B 0801, the high temperature (650°C) tensile strength, high temperature (650°C) yield strength and high temperature (650°C) elongation of the nickel-based superheat-resistant alloys of Examples and Comparative Examples were measured. Shown in.

High temperature (650 ℃) Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 1 850 690 5.50 Example 2 879 699 6.80 Example 3 860 698 6.00 Example 4 895 720 8.10 Example 5 880 701 7.50 Example 6 899 730 8.80 Comparative Example 1 725 580 4.20 Comparative Example 2 730 600 4.30 Comparative Example 3 715 610 4.51 Comparative Example 4 720 605 4.59 Comparative Example 5 730 590 4.28 Comparative Example 6 730 605 4.30 Comparative Example 7 745 610 4.44 Comparative Example 8 750 600 4.58 Comparative Example 9 750 580 4.95 Comparative Example 10 740 595 4.90 Comparative Example 11 720 585 5.00 Comparative Example 12 735 600 4.84 Comparative Example 13 740 590 4.95 Comparative Example 14 745 600 5.00 Comparative Example 15 750 580 4.84 Comparative Example 16 745 600 4.99 Comparative Example 17 720 575 4.75 Comparative Example 18 725 595 4.80 Comparative Example 19 786 691 4.00 Comparative Example 20 600 460 3.50 Comparative Example 21 605 465 3.60 Comparative Example 22 630 490 4.00 Comparative Example 23 620 510 4.00 Comparative Example 24 640 545 4.83 Comparative Example 25 570 410 3.80 Comparative Example 26 640 550 5.00 Comparative Example 27 540 375 2.74 Comparative Example 28 591 420 4.18

Referring to Table 9, it can be seen that according to this embodiment, the tensile strength, yield strength, and elongation at high temperature are more excellent.

Through the above Experimental Examples 3 and 4, it can be seen that according to the present embodiment, excellent tensile strength, yield strength, and elongation can be achieved at both room temperature and high temperature. That is, according to the present embodiment, it means that excellent mechanical properties can be realized at both room temperature and high temperature.

Experimental Example 5: Evaluation of machinability

Each nickel-based superheat-resistant alloy according to Examples and Comparative Examples was processed on a general-purpose lathe using a TiAlN-PVD-coated carbide tool (CNMG 120408 TT5080) to a depth of cut of 40 mm to a depth of 0.2 mm, Surface roughness was measured using Mitutoyo Surftest SJ301.

In the experiment, if the wear length of the clearance surface of the tool exceeded 0.3 mm, it was judged that the life of the tool was over and the experiment was stopped.

variable experiment condition (test condition) Cutting depth [mm] 0.2 sample Examples 1 to 5 and Comparative Examples 1 to 19 Cutting distance [mm] 45 Feed speed [mm/rev] 0.108 Tool type CNMG120408 TT5080 Spindle rotation speed (RPM) 336 Cutting speed [m/min] 80.4 Cutting time [min] 1.24 Cutting distance per turn [m] 99.7 Cutting environment Dry cutting

At this time, the tool life test was conducted according to the conditions of Table 10 above, and the total cutting distance (unit: m), tool wear depth (unit: μm), and one cut (99.7 m) at the end of the experiment. The surface roughness (Rz, unit: μm) is shown in Table 11.

Total cutting distance (m) Tool wear depth (μm) Surface roughness (μm) Example 1 854 530 1.58 Example 2 1705 201 0.81 Example 3 1617 253 0.90 Example 4 1894 168 0.56 Example 5 1760 194 0.81 Example 6 1900 160 0.55 Comparative Example 1 736 830 1.78 Comparative Example 2 720 825 1.70 Comparative Example 3 308 1205 2.15 Comparative Example 4 405 1114 2.08 Comparative Example 5 354 1306 2.10 Comparative Example 6 410 1281 2.00 Comparative Example 7 690 795 1.94 Comparative Example 8 663 780 1.88 Comparative Example 9 708 820 1.81 Comparative Example 10 681 800 1.76 Comparative Example 11 741 750 1.63 Comparative Example 12 708 700 1.61 Comparative Example 13 750 690 1.72 Comparative Example 14 725 687 1.94 Comparative Example 15 699 749 1.88 Comparative Example 16 700 725 1.90 Comparative Example 17 630 777 1.91 Comparative Example 18 620 763 1.96 Comparative Example 19 299 1515 2.10 Comparative Example 20 340 980 1.90 Comparative Example 21 350 950 1.89 Comparative Example 22 315 930 1.74 Comparative Example 23 360 945 2.00 Comparative Example 24 400 1005 2.05 Comparative Example 25 410 1200 2.14 Comparative Example 26 355 929 1.94 Comparative Example 27 380 976 2.00 Comparative Example 28 420 865 1.89

As disclosed in Table 11, according to this embodiment, the total cutting distance (m) is long, the tool wear depth (μm) is low, and the surface roughness Rz value (μm) is low. It can be seen that machinability is excellent.

When the results of Experimental Examples 1 to 5 are summarized, in the case of this example, centrifugal casting according to specific conditions is performed in the atmosphere without vacuum casting, so that mechanical properties at room temperature and high temperature are excellent. In addition, it is possible to manufacture a nickel-based superheat-resistant alloy with remarkably excellent machinability.

As described above, the description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains can easily transform into other specific forms without changing the technical spirit or essential features of the present invention. You can understand. Therefore, the embodiments described above are illustrative in all respects and should be understood as non-limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

Claims (8)

In the method of producing a nickel-based superheat-resistant alloy by centrifugal casting,
Carbon (C), sulfur (S), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), titanium (Ti), niobium (Nb), aluminum (Al) and nickel (Ni) And a first step of preparing an alloy raw material for producing a nickel-based superheat-resistant alloy containing inevitable impurities;
A second step of injecting the alloy raw material into a solubility crucible and melting the alloy raw material to form a molten metal;
A third step of injecting the molten metal into a mold for centrifugal casting after tapping the molten metal from the solubility crucible;
A fourth step of performing centrifugal casting by rotating the centrifugal casting mold; And
A fifth step of removing oxides or slag after separating the casting formed by the centrifugal casting from the mold for centrifugal casting; and
In the first step, the alloy raw material for producing the nickel-based superheat-resistant alloy is carbon (C): 0.01 to 0.30 wt%, sulfur (S): 0.10 to 0.50 wt%, manganese (Mn): 0.1 to 1.0 wt%, based on the total weight. %, chromium (Cr) 10.0 to 15.0 wt%, molybdenum (Mo) 2.0 to 7.0 wt%, tungsten (W) 0.1 to 5.0 wt%, titanium (Ti) 0.1 to 2.0 wt%, niobium (Nb): 1.0 to 5.0% by weight, aluminum (Al): 3.0 to 10.0% by weight and the remaining amount of nickel (Ni) and inevitable impurities,
The third step includes a 3-1 step of tapping the molten metal from the solubility crucible using a ladle; A 3-2 step of inoculating strontium (Sr) into the molten metal tapped from the solubility crucible; And a 3-3 step of injecting the molten metal into the centrifugal casting mold by moving the molten metal inoculated with the strontium (Sr) into a pouring basin, and injecting the molten metal into the centrifugal casting mold using a centrifugal casting method. A method of manufacturing a nickel-based superheat-resistant alloy with excellent machinability and mechanical properties.
The method of claim 1,
The alloy raw material for manufacturing the nickel-based super heat-resistant alloy
Nickel base having excellent machinability and mechanical properties using a centrifugal casting method, characterized in that it further comprises at least one selected from the group consisting of silicon (Si), boron (B), zirconium (Zr) and iron (Fe) A method of manufacturing a super heat-resistant alloy.
The method of claim 1,
In the second step
A method for producing a nickel-based super-heat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method, characterized in that the alloy raw material for producing the nickel-based super-heat-resistant alloy is heat-treated at a temperature of 1,600 to 1,700°C.
delete The method of claim 1,
Before performing step 3-1 above,
Method for producing a nickel-based superheat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method, characterized in that preheating the ladle and the injection basin to 250 ~ 350 ℃.
The method of claim 1,
In the 3-2 step
A nickel-based super-heat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method, characterized in that the strontium (Sr): 0.001 to 1.0% by weight is inoculated based on the total weight of the alloy raw material for producing the nickel-based super-heat-resistant alloy. How to manufacture.
The method of claim 1,
In the fourth step
The centrifugal casting is a method for producing a nickel-based superheat-resistant alloy having excellent machinability and mechanical properties by using a centrifugal casting method, characterized in that it is carried out under the conditions of rotational speed: 1,950 ~ 2,250 rpm and gravity multiple: 80 ~ 160.
The method of claim 1,
The third and fourth steps
Machinability and machinability using a centrifugal casting method, characterized in that it is carried out in an antioxidant atmosphere composed of at least one process gas selected from the group consisting of argon (Ar) gas, hydrogen (H ₂ ) gas, and carbon monoxide (CO) gas. A method of manufacturing a nickel-based superheat-resistant alloy with excellent mechanical properties.

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