Method for manufacturing high-purity iron-nickel alloy, and high-purity iron-nickel alloy manufactured thereby

Abstract

The purpose of the present invention is to provide a high-purity invar alloy, which is the material of a fine metal mask. One implementation of the present invention provides a method for manufacturing a high-purity iron-nickel alloy, comprising the steps of: preparing iron-nickel alloy scrap; forming a melting pool through electron beam cold hearth melting of the iron-nickel alloy scrap; preferably after the melting pool formation step, proceeding with a 1.5-2.5 ratio (kW / kg) of an electron beam output to the weight of a material so as to form a melting pool temperature of 1,800°C or higher, thereby melting and evaporating non-metallic inclusions in the molten pool; performing vacuum induction melting on the alloy in which the non-metallic inclusions have been melted and evaporated, thereby providing a vacuum induction-melted alloy; and performing vacuum arc remelting on the vacuum induction-melted alloy, wherein the number of inclusions having a size of 2 μm or greater in the manufactured alloy is 5.0 / mm2 or less, and preferably, 4.0 / mm2 or less.

Description

Method for producing a high-purity iron-nickel alloy and a high-purity iron-nickel alloy produced thereby

[0001] The present invention relates to a method for producing a high-purity iron-nickel alloy by applying electron beam melting to iron-nickel alloy scrap, and to a high-purity iron-nickel alloy produced thereby.

[0002] Displays utilizing Organic Light-Emitting Diodes (OLEDs) are a representative example of high-resolution displays. The OLED market is steadily growing, rapidly catching up with the market share of Liquid Crystal Displays (LCDs). Recently, research and development are underway on micro OLEDs, which can achieve ultra-high resolutions that go beyond OLED displays and enable augmented reality (AR) and virtual reality (VR) technologies.

[0003] There are several challenges in the research and development of micro OLEDs, and among them, improving the fine metal mask (FMM), a key component for manufacturing OLEDs, is a major task.

[0004] A fine metal mask is a metal plate with microscopic holes. It is used in the pixel deposition stage of the OLED display manufacturing process. This deposition process involves engraving RGB subpixels, the components of a pixel—the smallest unit of an image—onto the substrate. This process involves depositing a specific substance onto the substrate under vacuum conditions, and the fine metal mask serves as a guideline to ensure that the three subpixels are deposited in the correct locations without interfering with each other.

[0005] High display resolution requires a high-purity fine metal mask with numerous, uniform, microscopic holes. Cleanliness is related to the size and number of non-metallic inclusions within the metal plate. To ensure the formation of numerous, uniform microscopic holes, the metal plate itself, the material for the fine metal mask, must contain minimal impurities or non-metallic inclusions.

[0006] In the production of high-purity invar alloys, which are the materials for fine metal masks, it is desirable to use raw materials with extremely low contents of Al, Mg, etc., which are causes of non-metallic inclusions. However, such materials are expensive and their supply is unstable.

[0007] Accordingly, there is an emerging need for a method for manufacturing a high-purity invar alloy (iron-nickel alloy) that can be used as a material for a fine metal mask from low-purity invar alloy (iron-nickel alloy) scrap containing a certain amount of elements such as Al and Mg.

[0008] The purpose of the present invention is to provide a high-purity invar alloy that serves as a material for a fine metal mask.

[0009] One embodiment of the present invention comprises the steps of preparing iron-nickel alloy scrap; forming a melting pool by electron beam cold melting of the iron-nickel alloy; preferably, after the melt is formed, performing the output ratio (kW / kg) of the electron beam melting to the weight of 1.5 to 2.5 to melt and evaporate non-metallic inclusions in the melt; performing vacuum induction melting of the alloy in which the non-metallic inclusions are melted and evaporated to provide a vacuum induction melted alloy; and performing vacuum arc remelting of the vacuum induction melted alloy, wherein the number of inclusions of 2 μm or more in the alloy is 5.0 / mm. 2 A method for producing a high purity iron-nickel alloy is provided.

[0010] At this time, preferably, the number of inclusions larger than 2㎛ is 4.0 / mm 2 A method for producing a high purity iron-nickel alloy is provided.

[0011] The above electron beam cold melting is 10 -3 It can be performed under high vacuum conditions of less than 10 torr and involves casting a vacuum-induction melted iron-nickel alloy in the form of a slab.

[0012] The above electron beam cold hearth melting may include a step of performing electron beam melting on iron-nickel alloy scrap to form a temperature of 1500°C or higher to form a melting pool in which the iron-nickel alloy is melted; and preferably, a step of performing the ratio of output (kW / kg) to the weight of the iron-nickel alloy at 1.5 to 2.5 to form the temperature of the melt at 1800°C or higher to melt and evaporate non-metallic inclusions in the melt.

[0013] The above vacuum induction melting is 10 -2 It can be carried out at ~400 torr, and the components of the vacuum induction melted iron-nickel alloy are in wt%: Ni: 35-37%, C: 0.05% or less, Mn: 0.6% or less, P: 0.015% or less, S: 0.015% or less, Si: 0.4% or less, Cr: 0.25% or less, Co: 0.5% or less, and the remainder is iron and impurities.

[0014] The above vacuum arc remelting may be performed at a melting speed of 2 kg / min to 10 kg / min.

[0015] One embodiment of the present invention is a high-purity iron-nickel alloy manufactured by the above manufacturing method, wherein the number of inclusions of 2㎛ or more in the alloy is 5.0 / mm. 2 Less than, preferably 4.0 / mm 2 It can provide a high purity iron-nickel alloy having a value less than 100%.

[0016] According to the manufacturing method of the present invention, a high-purity iron-nickel alloy with a reduced number of inclusions (2 μm or more) can be provided using iron-nickel alloy scrap.

[0017] Fig. 1 shows a flow chart showing a method for manufacturing a high-purity iron-nickel alloy according to one embodiment of the present invention.

[0018] Figure 2 shows photographs of inclusions in alloys of examples and comparative examples of the present invention.

[0019] Hereinafter, a method for manufacturing a high-purity iron-nickel alloy according to an embodiment of the present invention will be described in more detail with reference to the attached drawings.

[0020] Figure 1 is a flow chart showing a method for manufacturing a high-purity iron-nickel alloy according to one embodiment of the present invention.

[0021] First, referring to FIG. 1, a method for manufacturing a high-purity iron-nickel alloy according to one embodiment of the present invention includes a step of preparing iron-nickel alloy scrap for melting the alloy.

[0022] The above iron-nickel alloy scrap is an iron-nickel alloy having the composition shown in Table 1 below. The form of the iron-nickel alloy is not particularly limited.

[0023]

[0024] A method for producing a high-purity iron-nickel alloy according to one embodiment of the present invention includes a step of subjecting an iron-nickel alloy to electron beam cold hearth melting to provide an electron beam melted alloy.

[0025] For a more desirable degree of cleanliness, the electron beam cold melting includes a step of forming a melting pool; and a step of forming a melting pool temperature of 1,800°C or higher by performing the electron beam melting power ratio (kW / kg) to weight ratio of 1.5 to 2.5 to melt and evaporate non-metallic inclusions in the melt.

[0026] The above electron beam cold melting is 10 -3 It is carried out under high vacuum conditions of 10 torr or less. In this step, the electron beam cold melting is mainly aimed at reducing non-metallic inclusions in the alloy. When the electron beam cold melting step is carried out, an electron beam accelerated in high vacuum is irradiated on the surface of the material, and melting proceeds due to the heat generated at this time. In particular, the vacuum level in this step is 10 -3 This process is performed under a high vacuum of 10 torr or less, which is higher than the other two processes. This high vacuum allows for the removal of oxygen content within inclusions through evaporation and the removal of dissolved oxygen through the removal of gases within the alloy. This step removes non-metallic inclusions or elements that cause inclusions, such as aluminum and magnesium, through evaporation.

[0027] The above inclusions are non-metallic inclusions and include oxides such as MgO and Al2O3.

[0028] A method for producing a high-purity iron-nickel alloy according to one embodiment of the present invention includes a step of vacuum induction melting an electron beam melted alloy to provide a vacuum induction melted alloy.

[0029] Vacuum induction melting can be performed in a conventional manner known to those skilled in the art to produce a melt having sufficient structural integrity to allow stable remelting operation. The vacuum induction melting can be performed at 10 -2The process is performed at ~400 torr, and alternatively, under a partially inert gas atmosphere. This step focuses on controlling the component content through real-time component analysis and controlling impurities through vacuum control. Vacuum is used to prevent and remove the inflow of oxygen, which is the cause of inclusion formation, and the addition of a deoxidizer further controls the oxygen content. The vacuum-induced melting of the alloy is preferably cylindrical in shape to correspond to the cylindrical mold commonly used in the remelting step described below.

[0030] A method for producing a high-purity iron-nickel alloy according to one embodiment of the present invention includes a step of vacuum arc remelting a vacuum-induction melted alloy.

[0031] The above-mentioned vacuum arc remelting step proceeds at a melting rate of 2 kg / min to 10 kg / min. This step primarily aims to remove inclusions through convection. By setting the VAR melting rate to 2 kg / min or higher and increasing the depth of the melt, the resulting convection within the melt pushes internal inclusions outward, resulting in a reduction in inclusions.

[0032] The above vacuum arc remelting step is preferably performed in a cylindrical mold, and the ratio D1 / D2 of the diameter D1 of the vacuum-induced melted alloy to the inner diameter D2 of the mold (the inner diameter of the mold used in the vacuum arc remelting step) is preferably adjusted to 0.80 to 0.95. When D1 / D2 is less than 0.80, heating of the alloy by arc discharge becomes uneven, so that inclusions in the alloy tend to aggregate and coarsen and remain in the alloy. In addition, when D1 / D2 exceeds 0.95, the gap between the alloy and the mold wall becomes excessively narrow, causing arc discharge to occur between the alloy and the mold wall, which causes damage to the mold.

[0033] An iron-nickel alloy manufactured by a method for manufacturing a high-purity iron-nickel alloy according to one embodiment of the present invention has excellent cleanliness. The standard for cleanliness is related to the size or number of inclusions in the manufactured iron-nickel alloy. The inclusions are oxides generated or mixed during the process. An iron-nickel alloy manufactured by one embodiment of the present invention has a number of inclusions having a size of 2 μm or more in the alloy of 5.0 inclusions / mm. 2 Less than, preferably 4.0 / mm 2 It is less than.

[0034]

[0035] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0036] Example 1

[0037] Iron-nickel alloy scrap is prepared for melting the alloy. The composition of the iron-nickel alloy scrap is as described in Table 1 above. The vacuum-induction melted alloy is 10 -3 An electron beam melted alloy was manufactured by electron beam cold hearth melting in a high vacuum of 10 torr or less. Specifically, electron beam melting was performed on 150 kg of iron-nickel alloy scrap to form a melting pool containing the iron-nickel alloy, and electron beam melting was performed at an output of 150 kW to perform a basic refining process. The electron beam melted alloy was subjected to vacuum induction melting at 100 torr to manufacture a vacuum induction melted alloy. The vacuum induction melted alloy was remelted at a melting rate of 8 kg / min to manufacture an iron-nickel alloy.

[0038] Examples 2, 3, and 4

[0039] In Example 1, an iron-nickel alloy was manufactured in the same manner as in Example 1, except that the weight of iron-nickel alloy scrap was 100 kg, and electron beam output was used such that the ratio of electron beam melting output after molten metal formation to weight (kW / kg) was 1.5, 2.0, and 2.5, respectively.

[0040] Examples 5, 6, and 7

[0041] In Example 1, an iron-nickel alloy was manufactured in the same manner as in Example 1, except that the weight of iron-nickel alloy scrap was 150 kg, and an electron beam output was used such that the ratio of electron beam melting output after molten metal formation to weight (kW / kg) was 1.5, 2.0, and 2.5, respectively.

[0042] Examples 8, 9, and 10

[0043] In Example 1, an iron-nickel alloy was manufactured in the same manner as in Example 1, except that 200 kg of iron-nickel alloy scrap was used as the iron-nickel alloy, and electron beam output was used such that the ratio of electron beam melting output after molten metal formation to weight (kW / kg) was 1.5, 2.0, and 2.5, respectively.

[0044] Comparative Example 1

[0045] Compared to Example 1, an iron-nickel alloy was manufactured in the same manner as Example 1, except that the EBCHM process was not performed and iron and nickel raw materials were used as the materials for melting.

[0046] Comparative Example 2

[0047] Compared to Example 1, an iron-nickel alloy was manufactured in the same manner as in Example 1, except that the EBCHM process was not performed.

[0048] Experimental example

[0049] The number of inclusions present in the iron-nickel alloys manufactured in the above examples and comparative examples was evaluated, and the results are shown in Tables 2 and 3 below, and photographs of the inclusions in the alloys are shown in Fig. 2. The evaluation method was to take SEM photographs of 20 random points on the alloy and measure the number of inclusions photographed per unit area. The photograph shown in Fig. 2 is one of the photographs taken by randomly selecting 20 points on the alloy, and the number shown in Table 3 below is the average value of the 20 points.

[0050]

[0051]

[0052] As shown in Table 2, in Comparative Example 2, which did not perform the EBCHM process and used iron and nickel raw materials, the number of inclusions increased by about 2.3 times compared to Comparative Example 1, which did not perform the EBCHM process and used iron-nickel alloy scrap, whereas in Example 1, which performed the EBCHM process, the number of inclusions decreased by 0.78 times. In other words, even when iron-nickel alloy scrap containing elements such as Al and Mg is used, it can be seen that performing the EBCHM process provides a better cleanliness than when using high-purity iron-nickel raw materials.

[0053] In addition, it can be seen that a better cleanliness is achieved when the ratio of the electron beam melting power after molten metal formation to the weight of the melted material (kW / kg) is 1.5 to 2.5. However, when the ratio of the electron beam melting power after molten metal formation to the weight (kW / kg) exceeds 2.5, it is undesirable because it results in a low yield.

Claims

1. Step of preparing iron-nickel alloy scrap; A step of electron beam cold hearth melting of iron-nickel alloy scrap to provide an electron beam melted alloy; A step of vacuum induction melting the electron beam melted alloy to provide a vacuum induction melted alloy; and A step of vacuum arc remelting the above vacuum-induced melted alloy, wherein the number of inclusions of 2㎛ or more in the manufactured alloy is 5.0 / mm. 2 A method for producing a high purity iron-nickel alloy having a lower content.

2. In paragraph 1, A method for producing a high-purity iron-nickel alloy, wherein the components of the above iron-nickel alloy scrap are, in wt%, Ni: 35 to 37%, Al: 0.1% or less, Mg: 0.1% or less, C: 0.05% or less, Mn: 0.6% or less, P: 0.015% or less, S: 0.015% or less, Si: 0.4% or less, Cr: 0.25% or less, Co: 0.5% or less, and the remainder is iron and impurities.

3. In paragraph 1, The above electron beam cold hearth melting is a step of melting iron-nickel alloy scrap to form a melting pool in which iron-nickel alloy is melted at 1500°C or higher; and a step of forming a melt temperature of 1800°C or higher to melt and evaporate non-metallic inclusions in the melt, and the number of inclusions of 2 μm or more in the manufactured alloy is 4.0 / mm. 2 A method for producing a high purity iron-nickel alloy having a lower content.

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