Rare earth intermediate alloy for nickel-based heat-resistant alloy and use method of rare earth intermediate alloy

Abstract

The invention discloses a rare earth intermediate alloy for a nickel-based heat-resistant alloy and a use method, and aims to solve the problems of high burning loss of yttrium element and difficulty in accurate control of components in the smelting process of the nickel-based heat-resistant alloy through reasonable component design. According to the technical scheme, the yttrium-aluminum intermediate alloy capable of being used for adding the yttrium element in the N06025 alloy smelting process is designed according to the proportion characteristics of main element components of the N06025 alloy and in combination with binary alloy phase diagram parameters, production process feasibility and other factors; the use method comprises the following steps: controlling the oxygen content to be less than 20 * 10 <-6 > before the yttrium-aluminum intermediate alloy is added, wrapping the yttrium-aluminum intermediate alloy with aluminum-foil paper, and inserting the yttrium-aluminum intermediate alloy into a deeper position of a steel ladle. The method has the advantages that the yttrium-aluminum intermediate alloy capable of being used for adding the yttrium element in the N06025 alloy smelting process is designed, the stability of the yield of the yttrium element is effectively controlled, the yield of the yttrium element is stabilized at 50%-60%, and the content of a finished product is stabilized at 0.06%-0.09%.

Description

Technical Field

[0001] The invention belongs to the field of corrosion-resistant alloy manufacturing, and relates to a rare earth master alloy for nickel-based heat-resistant alloy and a use method, in particular to a yttrium-containing rare earth master alloy. Background Art

[0002] N06025 is a nickel-based heat-resistant alloy containing the rare earth element yttrium (0.05% to 0.12%, wt). The alloy currently has outstanding performance among various commercially produced high-temperature oxidation-resistant and high-strength nickel-based alloys. The chemical composition of N06025 alloy includes carbon, nickel, chromium, iron, manganese, aluminum, titanium, yttrium, zirconium and other elements. As a rare earth element, yttrium can first strengthen the grain boundary and improve the high-temperature creep performance and endurance strength of the alloy. Secondly, it can also refine the grains and improve the corrosion resistance and oxidation resistance of the alloy. In addition, the combined action of the three antioxidant elements yttrium, aluminum and chromium significantly improves the oxidation resistance of the alloy at high temperatures above 1150℃. Based on the excellent oxidation resistance and thermal strength of the alloy, it is widely used in heating furnaces and other industries. Whether vacuum induction furnace or non-vacuum induction furnace is used to smelt N06025 alloy, due to the high chemical activity of yttrium, it is very easy to react chemically with oxidizing elements during the smelting production process. Practice has proved that when using metal yttrium to smelt N06025 alloy, the burnout ratio is relatively large (generally more than 90%). Due to the high price of metal yttrium, a large amount of burnout will lead to cost increase; in addition, the density of metal yttrium is low (only 4.86g / cm 2 ), high melting point (about 2410℃), when using metal yttrium to adjust the yttrium content in the smelting process of N06025 alloy, the raw material is very easy to float and cannot be quickly dissolved in the alloy steel liquid (generally around 1150℃), resulting in large fluctuations in the actual yttrium content in the N06025 alloy steel liquid smelted in different batches, and the low stability significantly increases the difficulty of controlling the smelting process. Therefore, it is urgent to develop an intermediate alloy product that can not only improve the yttrium control level in the N06025 alloy, but also ensure that the chemical composition of the alloy meets the standard, thereby reducing the burnout of the yttrium element, reducing the difficulty of controlling the smelting chemical composition, and reducing cost consumption. Summary of the invention

[0003] The invention discloses a rare earth master alloy for nickel-based heat-resistant alloy, aiming to solve the problems of high yttrium element burnout and difficulty in precise composition control in the nickel-based heat-resistant alloy smelting process through reasonable composition design.

[0004] Technical solution of the present invention:

[0005] 1. According to the main element composition ratio characteristics of N06025 alloy, combined with the binary alloy phase diagram parameters, production process feasibility and other factors, a yttrium-aluminum master alloy that can be used to add yttrium element in the smelting process of N06025 alloy is designed. The specific composition is shown in Table 1.

[0006] Table 1

[0007]

[0008] 2. Specific application process measures

[0009] ⑴The chemical composition of N06025 alloy shall comply with the requirements of Table 2.

[0010] Table 2

[0011]

[0012] ⑵Technological process: batching → charging → power on → charging → full melting → stirring → standing → adjusting ingredients → pouring.

[0013] ① Calculate the amount of various raw materials required for smelting according to the alloy composition control requirements; select high-quality refined steel, metal nickel, metal chromium, metal aluminum, metal titanium, yttrium aluminum master alloy, and sponge zirconium to ensure accurate chemical composition, and keep all raw materials entering the furnace clean and oil-free.

[0014] ② Adding sequence: retain yttrium aluminum master alloy and sponge zirconium during the charging period, give priority to adding industrial pure iron and metallic nickel, cover the slag in time during the charging process to prevent the molten steel from direct contact with the atmosphere, and hammer the slag surface frequently to prevent crusting; add metallic chromium after 80% of the full melting, cover the slag in time to prevent nitrogen absorption; after full melting, add metallic aluminum in two to three batches, with a single addition amount not exceeding 10kg, and stir for 5min to 10min after each addition; then add metallic titanium all at once to ensure the recovery rate of aluminum and titanium and the deoxidation effect.

[0015] ③ The refining period is not less than 40 minutes, and the refining temperature is controlled at 1480℃~1500℃. During this period, the gas content in the molten steel is monitored. After the refining period, the gas oxygen content in the steel is ensured to be less than 20×10 -6 , and then wrap the yttrium aluminum master alloy and zirconium sponge with aluminum foil respectively as preparation before joining.

[0016] ④ Conditions for casting molded ingots: first measure the temperature of the molten steel, and control the pouring temperature at 1510℃~1530℃. After measuring the temperature, insert the zirconium sponge and stir for 5 minutes; insert the yttrium aluminum master alloy into the bottom of the molten steel, and stir for 3 minutes to achieve the purpose of component homogenization, and add 2kg~3kg of aluminum-calcium oxide agent to the slag surface to further cover the slag surface to prevent air inhalation.

[0017] ⑤ Pouring: Pour all the molten steel into the tundish and quickly transfer the ladle to the pouring position. After the water outlet of the ladle is aligned with the inlet of the center pouring pipe, the pouring operation is carried out under argon protection.

[0018] Description of the invention:

[0019] ① Yttrium aluminum master alloy, the specific composition is shown in Table 1;

[0020] ②N06025 alloy contains 1.8% to 2.4% aluminum. When yttrium is added to the yttrium master alloy, the aluminum that enters the molten steel with the master alloy can also be effectively utilized without affecting the chemical composition and quality of the alloy.

[0021] ③ The yttrium-aluminum master alloy is designed to contain 80% yttrium and 20% aluminum. The theoretical melting point is about 1100°C, which is much lower than the smelting temperature of N06025 alloy, 1500°C. It can be melted quickly during the smelting process, making it easy for the yttrium element to be quickly homogenized in the molten steel;

[0022] ④Control the oxygen content before adding yttrium aluminum master alloy to less than 20×10 -6 The yttrium-aluminum master alloy is wrapped in aluminum foil and inserted into a deeper position of the ladle, which effectively controls the stability of the yttrium element yield. The yttrium element yield is stable at 50% to 60%, and the finished product content is stable at 0.06% to 0.09%.

[0023] Advantages of the present invention:

[0024] A yttrium-aluminum master alloy for adding yttrium element in the smelting process of N06025 alloy is designed, which effectively controls the stability of the yield of yttrium element. The yield of yttrium element is stable at 50%-60%, and the content of yttrium element in finished product is stable at 0.06%-0.09%. DETAILED DESCRIPTION

[0025] The present invention is described in detail below by way of examples.

[0026] Embodiment 1 and Embodiment 2 are implemented together:

[0027] Process flow: batching → charging → power on → charging → full melting → stirring → standing → adjusting ingredients → pouring.

[0028] Process steps: Calculate the amount of various raw materials required for smelting based on the alloy composition control requirements.

[0029] ① Select high-quality refined steel, metal nickel, metal chromium, metal aluminum, metal titanium, yttrium aluminum master alloy, and sponge zirconium to ensure accurate chemical composition. All raw materials entering the furnace are kept clean and oil-free.

[0030] ② Adding sequence: During the smelting period, retain the yttrium aluminum master alloy and sponge zirconium, give priority to adding industrial pure iron and metal nickel, cover the slag in time during the smelting process to prevent the molten steel from directly contacting the atmosphere, and frequently hammer the slag surface to prevent crusting. Add metal chromium after 80% of the total melting, cover the slag in time to prevent nitrogen absorption. After the total melting, add metal aluminum in two or three batches, with a single addition amount of no more than 10kg, and stir for 5min to 10min after each addition; add metal titanium at one time. Ensure the recovery rate of aluminum and titanium and the deoxidation effect.

[0031] ③ The refining period is not less than 40 minutes, and the refining temperature is controlled at 1480℃~1500℃. During this period, the gas content in the molten steel is monitored; after the refining period, the gas oxygen content in the steel is ensured to be less than 20×10 -6 , and then wrap the yttrium aluminum master alloy and zirconium sponge with aluminum foil respectively as preparation before joining.

[0032] ⑤ Conditions for casting molded ingots: first measure the temperature of the molten steel, and control the pouring temperature at 1510℃~1530℃. After measuring the temperature, insert the zirconium sponge and stir for 5 minutes; insert the yttrium aluminum master alloy into the bottom of the molten steel, and stir for 3 minutes to achieve the purpose of uniform composition, and add 2kg~3kg of aluminum-calcium oxide agent to the slag surface to further cover the slag surface to prevent air inhalation.

[0033] ⑥ Pouring: Pour all the molten steel into the tundish and quickly transfer the ladle to the pouring position. After the lower water outlet of the ladle is aligned with the inlet position of the center pouring pipe, the pouring operation is carried out under the protection of argon gas.

[0034] Example 1

[0035] N06025 alloy, injection molded ingot type 710kg.

[0036] Process steps:

[0037] ① The actual ingredients are as per Table 3.

[0038] Table 3

[0039]

[0040] ② Sampling and analysis of gas, oxygen content 17×10 -6 .

[0041] ③ The temperature before pouring is 1515℃, yttrium aluminum master alloy is added at one time according to the calculated amount, and stirred for 3 minutes after adding.

[0042] ④Pouring 710kg injection molding ingot

[0043] ⑤Ingredient analysis:

[0044] The composition of the cast mold ingot was analyzed and the results are shown in Table 4.

[0045] Table 4

[0046]

[0047] Example 2

[0048] N06025 alloy, injection molded ingot type 710kg.

[0049] Process steps:

[0050] ① The actual ingredients are as per Table 5.

[0051] Table 5

[0052]

[0053] ② Sampling and analysis of gas, oxygen content 17×10 -6 .

[0054] ③ The temperature before pouring is 1520℃, yttrium aluminum master alloy is added at one time according to the calculated amount, and stirred for 3 minutes after adding.

[0055] ④Pouring 710kg injection molding ingot

[0056] ⑤Ingredient analysis:

[0057] The composition of the cast mold ingot was analyzed and the results are shown in Table 6.

[0058] Table 6

[0059]

Claims

1. A rare earth master alloy for nickel-based heat-resistant alloy, characterized in that: Yttrium aluminum master alloy that can be used to add yttrium element in the smelting process of N06025 alloy, the specific composition is shown in Table 1. Table 1 2. The specific application of the rare earth master alloy for nickel-based heat-resistant alloy according to claim 1, characterized in that: Process flow: batching → charging → power supply → charging → full melting → stirring → standing → adjusting ingredients → pouring; ⑴ Calculate the amount of various raw materials required for smelting according to the N06025 alloy composition control requirements; select high-quality refined steel, metal nickel, metal chromium, metal aluminum, metal titanium, yttrium aluminum master alloy, and sponge zirconium to ensure accurate chemical composition, and keep all raw materials entering the furnace clean and oil-free; ⑵ Adding sequence: industrial pure iron and nickel should be added first during the chemical process. During the chemical process, the slag should be covered in time to prevent the molten steel from directly contacting the atmosphere. The slag surface should be hammered frequently to prevent crusting. After 80% of the raw materials are melted, add chromium and cover the slag in time to prevent nitrogen absorption. After the whole melting, aluminum should be added in two or three batches. The single addition amount should not exceed 10kg. Stir for 5 to 10 minutes after each addition. Add titanium at one time to ensure the recovery rate of aluminum and titanium and the deoxidation effect. ⑶ The refining period is not less than 40 minutes, and the refining temperature is controlled at 1480℃~1500℃. During this period, the gas content in the molten steel is monitored. After the refining period, the gas oxygen content in the steel is ensured to be less than 20×10 -6 , and then wrap the yttrium aluminum master alloy and zirconium sponge with aluminum foil respectively to prepare for joining; (4) Conditions for casting mold ingots: first measure the temperature of the molten steel, and control the pouring temperature at 1510℃~1530℃. After measuring the temperature, insert the zirconium sponge and stir for 5 minutes; insert the yttrium aluminum master alloy into the bottom of the molten steel, stir for 3 minutes to achieve the purpose of component homogenization, and add 2kg~3kg of aluminum-calcium oxide agent to the slag surface to further cover the slag surface to prevent air inhalation; ⑸ Pouring: Pour all the molten steel into the tundish and quickly transfer the ladle to the pouring position. After the water outlet of the ladle is aligned with the inlet of the center pouring pipe, the pouring operation is carried out under the protection of argon gas.

3. The specific application of the rare earth master alloy for nickel-based heat-resistant alloy according to claim 2, characterized in that: Injection molding N06025 alloy ingot 710kg process steps: ⑴The actual ingredients are as per Table 2; Table 2 ⑵ Sampling and analysis of gas, oxygen content 17×10 -6 ; ⑶ The temperature before pouring is 1515℃, yttrium aluminum master alloy is added at one time according to the calculated amount, and stirred for 3 minutes after adding; (4) Casting 710kg injection molding ingot; ⑸ The composition of the casting mold ingot was analyzed. The results are shown in Table 3. Table 3

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