WO2017166962A1 - Melting process for nickel-based alloy containing aluminum, titanium, boron, and zirconium - Google Patents

Abstract

Disclosed is a melting process for a nickel-based alloy containing aluminum, titanium, boron, and zirconium, comprising: adding graphite accounting for 50% of a total carbon-containing mass of an alloy into a crucible of a vacuum furnace and placing the graphite at the bottommost portion of the crucible, and adding all elements, except for aluminum, titanium, boron, zirconium, and nickel, in the alloy into the crucible of the vacuum furnace to be molten; raising the temperature, adding the remaining graphite into the crucible, and carrying out refining and then cooling; adding calcium metal into the crucible, and after the calcium metal is completely molten, carrying out refining and then cooling; adding aluminum and titanium into the crucible, and raising the temperature until the aluminum and the titanium are completely molten; adding a nickel-boron alloy and zirconium into the crucible, and raising the temperature until the nickel-boron alloy and the zirconium are completely molten; and cooling the molten metal, filtering, and carrying out tapping and pouring. The process method reduces the content of harmful gas and low-melting-point harmful impurities in an alloy, and achieves the purposes of purifying an alloy melt, reducing segregation of alloy elements, and ensuring alloy performance.

Description

Smelting process of nickel-based alloy containing aluminum titanium boron zirconia Technical field

The invention relates to an alloy smelting process, in particular to a smelting process of a nickel-based alloy containing aluminum titanium boron zirconia.

Background technique

The technical difficulty in vacuum smelting of aerospace and civil superalloys is that the gas content (oxygen, nitrogen, hydrogen) in the alloy is strictly controlled. At present, according to the enterprise standard, the oxygen and nitrogen contents of many alloys are generally around 20 ppm. Only by reducing the content of harmful impurities in the alloy, reducing the segregation of alloying elements, and improving the purity of the alloy melt can improve the performance and life of the alloy. However, the vacuum smelting process is a very complicated thermal processing process, and the design of any one process step will have an important influence on the gas content of the alloy, the impurity content and the properties of the alloy.

O, N, S in the alloy will form non-metallic inclusions in the alloy solution, such as (Al ₂ O ₃ ), (Ti, Ta) C / N, the number of non-metallic inclusions in the (Ti, Ta)S alloy Both the form and the form have a major impact on the overall performance of the alloy. In addition, the purity of the alloy melt is an important indicator for measuring the quality and manufacturing level of the master alloy ingot. In vacuum smelting, carbon is the main deoxidizing element. Due to the decomposition reaction of carbon, the oxygen of the metal solution is removed, thereby reducing the gas content in the alloy, purifying the metal solution, and improving the quality of the alloy. As the carbon deoxygenation reaction progresses, the carbon monoxide gas overflows, and the hydrogen and nitrogen harmful gases in the alloy are carried out. The lower the oxygen content, the more easily the metal melt evaporates, and the low melting point harmful impurity elements in the alloy are also easily eliminated. Therefore, deoxidation is a key step in the vacuum smelting process. The deoxidation effect directly determines the content of harmful impurities in the alloy, which determines whether the alloy performance and life can be improved.

In alloys used in aviation, the components generally include several low melting point elements such as aluminum, titanium, boron, and zirconium. When these low-melting-point elements are added for alloying treatment, if the timing, temperature, and degree of vacuum are not strictly controlled, large burning and volatilization occur, and the chemical composition of the alloy is difficult to control, resulting in waste. Specifically, when aluminum, titanium, boron, and zirconium are added, the degree of vacuum is too low or the equipment leak rate is large, and a large amount of aluminum, titanium, boron, and zirconium elements are oxidized and burned, and the composition is difficult to control. When aluminum and titanium are added, the temperature of the molten metal is too high, and a large amount of aluminum and titanium are burnt and volatilized due to the exothermic release. When aluminum or titanium is added to the molten metal, a severe exothermic reaction occurs, and especially when the amount of addition is large, the exothermic reaction of the molten metal is large. Even if the temperature of the molten metal is suitable when aluminum and titanium are added, the chemical composition of the alloy is hard to control because the amount of the primary addition is too large, and the burning and vacuum volatilization are also caused. In addition, since aluminum, titanium, boron, and zirconium are lighter in themselves and have a low density, they float on the surface of the molten metal after being added to the molten metal. If sufficient agitation is not performed, segregation is easily generated, which seriously affects the synthesis of the alloy. performance. In particular, the addition time of boron is also very important. It is too early to be burned, and it is easy to burn. It is too late to be distributed, so it is very important to master the time of boron addition.

In view of the current state of the art, it is urgent to develop a smelting process of a nickel-based alloy containing aluminum, titanium, boron, and zirconium, which has uniform chemical composition, low melting point and low volatilization, and long-lasting properties of the alloy and tensile properties at room temperature.

Summary of the invention

SUMMARY OF THE INVENTION The object of the present invention is to provide a smelting process of a nickel-based alloy containing aluminum-titanium-boron-zirconium having uniform chemical composition, low-melting-point element burning loss and low volatilization, long-lasting properties of the alloy and high tensile properties at room temperature.

The smelting process of the nickel-based alloy containing aluminum titanium boron borax according to the present invention comprises the following steps:

(1) First step carbon deoxidation:

Adding 50% of the total carbon content of the superalloy to the vacuum furnace, placing it at the bottom of the crucible, adding all the elements in the superalloy except aluminum, titanium, boron, zirconium and nickel into the vacuum furnace. Smelting;

(2) The second step of carbon deoxidation:

The temperature is raised to 1570 ~ 1590 ° C, the remaining graphite is added to the crucible, refined, and then cooled;

(3) Metal calcium deoxidation:

Adding metal calcium, after melting all, heating to 1550 ~ 1570 ° C, refining, shaking in the refining process, so that the floating slag floating up to the molten metal surface is discharged to the back of the wall;

(4) Add aluminum and titanium:

Cooling to 1370 ~ 1390 ° C, adding aluminum, titanium, heating up to aluminum, titanium all melted;

(5) Adding nickel-boron alloy and zirconium:

Maintaining a temperature of 1410 to 1430 ° C, adding a nickel-boron alloy and zirconium thereto, and heating the mixture to a nickel-boron alloy and zirconium;

(6) Frozen metal melt, filtration, tapping and pouring:

Cool down, wait until the temperature drops to 1360 ~ 1380 ° C, and then heat up to 1450 ~ 1470 ° C, using a ceramic filter while filtering and tapping.

among them:

Step (1) Graphite is a particle in which the spectral graphite electrode is broken up to 2 to 5 mm.

Step (1) The smelting temperature is 1560 to 1580 ° C, and the smelting time is 20 to 30 min.

Step (2) The temperature is raised to 1570 to 1590 ° C, and the remaining graphite is added to the crucible, and refined at a power of 80 KW for 20 to 30 minutes.

After all the metal calcium added in step (3) is melted, the temperature is raised to 1550 to 1570 ° C, and refining is carried out at 80 KW for 10 min. After refining for 5 min, the crucible is started to be shaken, so that the scum floating up to the molten metal level is discharged. The rear part of the wall is slag-treated.

Step (3) The amount of metal calcium is 0.02 to 0.05% of the total mass of the superalloy. If the amount of calcium added is too large, deoxidation inclusions will form in the molten metal, so the amount of metal calcium added must be strictly controlled. It is also important to carry out slagging treatment after adding metal calcium for deep deoxidation.

Step (4) is heated until aluminum and titanium are all melted, and then stirred for 3 to 5 minutes.

Step (5) is heated to a nickel-boron alloy, and the zirconium is melted, and then stirred for 3 to 5 minutes.

The degree of vacuum when adding aluminum, titanium, nickel boron alloy, or zirconium is ≤ 0.1 Pa. Boron should be added in the late stage of smelting before tapping. When aluminum and titanium are added in a large amount, they should be added in two or more batches. When aluminum is about 3 wt.%, and titanium is about 3 wt.%, it can be added twice. If more aluminum and titanium content should be considered, more times should be added.

Step (6) Cooling the molten metal melt can be in the form of natural cooling after power failure, and other cooling forms can also be used. The invention preferably takes the form of a natural cooling of power outages.

The beneficial effects of the present invention are as follows:

The invention adopts a secondary carbon deep deoxidation process and a metal calcium deoxidation process, and adds one-half of the graphite which accounts for the total carbon content of the alloy before the start of the high-temperature alloy smelting, and the graphite is added to the bottom of the crucible. After the metal is completely melted, it is raised to a certain temperature, and subjected to a secondary carbon addition operation to further perform deep deoxidation, and then metal calcium is added for calcium deoxidation; at the same time, the chemical composition of the alloy is controlled by controlling the timing and temperature of the addition of aluminum, titanium, boron, and zirconium. More uniform, low melting point elements burn less and less volatile; frozen metal melt makes the harmful gas dissolved in the molten metal float in the process of cooling and solidification of the molten metal, and the negative pressure difference generated by vacuum furnace smelting will be harmful gas Further removed. After filtering with a ceramic filter, the metal melt is further purified to obtain a high-quality high-temperature alloy, and the content of harmful gases such as O, N, H and low-melting harmful impurities in the high-temperature alloy are minimized to achieve a pure alloy. The melt reduces the segregation of alloying elements and ensures the properties of the alloy. The invention improves the long-term performance and the tensile property at room temperature of the high-temperature alloy, and the comprehensive mechanical properties of the alloy and the quality of the alloy all reach the level of high-quality alloys at home and abroad.

detailed description

The invention will be further described below in conjunction with the embodiments.

Example 1

According to the standard of K418B alloy, the vacuum smelting process of the present invention is used for production, and the chemical composition thereof is shown in Table 1, and the performance parameters are shown in Table 2.

Taking a 200 Kg vacuum furnace as an example, the vacuum smelting process of the present invention is as follows:

(1) First step carbon deoxidation:

Adding 50% of the total carbon content of the superalloy to the vacuum furnace, placing it at the bottom of the crucible, adding all the elements in the superalloy except aluminum, titanium, boron, zirconium and nickel into the vacuum furnace. Smelting; graphite is a graphite electrode crushed to 2 ~ 5mm particles; smelting temperature 1570 ± 10 ° C, smelting time 25min;

(2) The second step of carbon deoxidation:

The temperature was raised to 1580±10 ° C, and the remaining graphite was added into the crucible, and refined at a power of 80 KW for 25 min, and then cooled;

(3) Metal calcium deoxidation:

Adding metal calcium, after melting all, heating to 1560 ± 10 ° C, refining at 80 KW for 10 min, refining for 5 min, starting to shake the crucible, so that the scum floating up to the molten metal surface is discharged to the back of the crucible wall; The amount of calcium used is 0.03% of the total mass of the superalloy.

(4) Add aluminum and titanium:

Cooling to 1380 ± 10 ° C, adding aluminum, titanium, heating to aluminum, titanium all melted, and then stirred for 5 min;

(5) Adding nickel-boron alloy and zirconium:

Maintaining a temperature of 1420 ± 10 ° C, adding nickel boron alloy, zirconium, heating to nickel boron alloy melting, and stirring for 3 min;

(6) Frozen metal melt, filtration, tapping and pouring:

Cool down, wait until the temperature drops to 1370 ± 10 ° C, and then heat up to 1460 ± 10 ° C, using a ceramic filter while filtering and tapping.

The degree of vacuum when adding aluminum, titanium, nickel boron alloy, or zirconium is ≤ 0.1 Pa.

Table 1 Example 1 alloy composition parameter table

element C Si Mn P S Cr Fe range 0.03/0.07 ≤0.50 ≤0.25 ≤0.015 ≤0.015 11.0/13.0 ≤0.5 Measured 0.054 0.037 0.050 0.0065 0.0013 11.78 0.15 element Mo Cu Nb Ti Co Al Zr range 3.80/5.20 ≤0.5 1.50/2.50 0.40/1.00 ≤1.0 5.50/6.50 0.05/0.15 Measured 4.71 0.038 2.21 0.82 0.49 6.13 0.080 element B Pb Ag Bi Ni O ppm N ppm range 0.005/0.015 ≤0.0010 ≤0.0005 ≤0.00020 Yu —— —— Measured 0.013 0.0005 0.00003 0.00005 Yu 7.5 6.8

It was measured by a German imported ON900 type oxygen nitrogen analyzer: oxygen (O) 7.5 ppm nitrogen (N) 6.8 ppm.

Table 2 Example 1 alloy performance parameter table

Room temperature tensile properties σ _b /MPa σ _0.2 /MPa δ _S /% standard ≥760 ≥690 ≥5.0 Measured 892 756 7.5

Example 2

The vacuum smelting process of the present invention was carried out in accordance with the standard of the K418B alloy, and the chemical composition thereof is shown in Table 3, and the performance parameters are shown in Table 4.

Taking a 200 Kg vacuum furnace as an example, the vacuum smelting process of the present invention is as follows:

(1) First step carbon deoxidation:

Adding 50% of the total carbon content of the superalloy to the vacuum furnace, placing it at the bottom of the crucible, adding all the elements in the superalloy except aluminum, titanium, boron, zirconium and nickel into the vacuum furnace. Smelting; graphite is broken by spectral graphite electrode to 2 ~ 5mm particles; smelting temperature is 1580 ± 10 ° C, smelting time 20min;

(2) The second step of carbon deoxidation:

The temperature was raised to 1570±10 ° C, and the remaining graphite was added into the crucible, and refined at a power of 80 KW for 20 min, and then cooled;

(3) Metal calcium deoxidation:

Adding metal calcium, after melting all, heating to 1570±10 ° C, refining at 80 KW for 10 min, refining for 5 min, starting to shake the crucible, so that the scum floating up to the molten metal surface is discharged to the back of the crucible wall; The amount of calcium used is 0.04% of the total mass of the superalloy.

(4) Add aluminum and titanium:

Cooling to 1390 ± 10 ° C, adding aluminum, titanium, heating to aluminum, titanium all melted, and then stirred for 3 min;

(5) Adding nickel-boron alloy and zirconium:

Maintaining a temperature of 1410 ± 10 ° C, adding nickel boron alloy, zirconium, heating to nickel boron alloy melting, and stirring for 5 min;

(6) Frozen metal melt, filtration, tapping and pouring:

Cool down, wait until the temperature drops to 1360 ± 10 ° C, and then heat up to 1470 ± 10 ° C, using a ceramic filter while filtering and tapping.

The degree of vacuum when adding aluminum, titanium, nickel boron alloy, or zirconium is ≤ 0.1 Pa. The rest is as in Example 1.

Table 3 Example 2 alloy composition parameter table

element C Si Mn P S Cr Fe range 0.03/0.07 ≤0.50 ≤0.25 ≤0.015 ≤0.015 11.0/13.0 ≤0.5 Measured 0.055 0.039 0.050 0.0067 0.0013 11.81 0.18 element Mo Cu Nb Ti Co Al Zr range 3.80/5.20 ≤0.5 1.50/2.50 0.40/1.00 ≤1.0 5.50/6.50 0.05/0.15 Measured 4.75 0.035 2.29 0.78 0.52 6.18 0.083 element B Pb Ag Bi Ni O ppm N ppm range 0.005/0.015 ≤0.0010 ≤0.0005 ≤0.00020 Yu —— —— Measured 0.010 0.0004 0.00003 0.00004 Yu 7.7 6.5

It was measured by a German imported ON900 type oxygen nitrogen analyzer: oxygen (O) 7.7 ppm nitrogen (N) 6.5 ppm.

Table 4 Example 2 alloy performance parameter table

Room temperature tensile properties σ _b /MPa σ _0.2 /MPa δ _S /% standard ≥760 ≥690 ≥5.0 Measured 895 761 8.2

Example 3

According to the standard of K418B alloy, the vacuum smelting process of the present invention is used for production, and the chemical composition thereof is shown in Table 5, and the performance parameters are shown in Table 6.

Taking a 200 Kg vacuum furnace as an example, the vacuum smelting process of the present invention is as follows:

(1) First step carbon deoxidation:

Adding 50% of the total carbon content of the superalloy to the vacuum furnace, placing it at the bottom of the crucible, adding all the elements in the superalloy except aluminum, titanium, boron, zirconium and nickel into the vacuum furnace. Smelting; graphite is broken by spectral graphite electrode to 2 ~ 5mm particles; smelting temperature is 1560 ± 10 ° C, smelting time 30min;

(2) The second step of carbon deoxidation:

The temperature was raised to 1590±10 ° C, and the remaining graphite was added into the crucible, and refined at a power of 80 KW for 30 min, and then cooled;

(3) Metal calcium deoxidation:

Adding metal calcium, after melting all, heating to 1550 ± 10 ° C, refining at 80 KW for 10 min, refining for 5 min, starting to shake the crucible, so that the scum floating up to the molten metal surface is discharged to the back of the crucible wall; The amount of calcium used is 0.05% of the total mass of the superalloy.

(4) Add aluminum and titanium:

Cooling to 1370 ± 10 ° C, adding aluminum, titanium, heating to aluminum, titanium all melted, and then stirred for 4 min;

(5) Adding nickel-boron alloy and zirconium:

Maintaining a temperature of 1430 ± 10 ° C, adding nickel boron alloy, zirconium, heating to nickel boron alloy melting, and stirring for 4 min;

(6) Frozen metal melt, filtration, tapping and pouring:

Cool down, wait until the temperature drops to 1380 ± 10 ° C, and then heat up to 1450 ± 10 ° C, using a ceramic filter while filtering and tapping.

The degree of vacuum when adding aluminum, titanium, nickel boron alloy, or zirconium is ≤ 0.1 Pa. The rest is as in Example 1.

Table 5 Example 3 alloy composition parameter table

element C Si Mn P S Cr Fe range 0.03/0.07 ≤0.50 ≤0.25 ≤0.015 ≤0.015 11.0/13.0 ≤0.5 Measured 0.057 0.041 0.049 0.0061 0.0014 11.95 0.17 element Mo Cu Nb Ti Co Al Zr range 3.80/5.20 ≤0.5 1.50/2.50 0.40/1.00 ≤1.0 5.50/6.50 0.05/0.15 Measured 4.82 0.039 2.35 0.85 0.58 6.25 0.091 element B Pb Ag Bi Ni O ppm N ppm range 0.005/0.015 ≤0.0010 ≤0.0005 ≤0.00020 Yu —— —— Measured 0.99 0.0006 0.00004 0.00003 Yu 7.6 6.7

It was measured by a German imported ON900 type oxygen nitrogen analyzer: oxygen (O) 7.6 ppm nitrogen (N) 6.7 ppm.

Table 6 Example 3 alloy performance parameter table

Room temperature tensile properties σ _b /MPa σ _0.2 /MPa δ _S /% standard ≥760 ≥690 ≥5.0 Measured 890 764 7.7

As can be seen from Table 1-6, the content of oxygen and nitrogen in the K418B alloy is very low. Due to the secondary carbon deep deoxidation process, the metal calcium deoxidation process, the alloying process, the frozen metal melt process, and the filtration process, the content of other harmful impurities in the alloy is significantly reduced. The most prominent is that the alloy's room temperature tensile properties and high temperature durability are greatly improved.

Claims (9)

A smelting process for a nickel-based alloy containing aluminum titanium boron zirconia, comprising the steps of: (1) First step carbon deoxidation: Adding 50% of the total carbon content of the superalloy to the vacuum furnace, placing it at the bottom of the crucible, adding all the elements in the superalloy except aluminum, titanium, boron, zirconium and nickel into the vacuum furnace. Smelting; (2) The second step of carbon deoxidation: The temperature is raised to 1570 ~ 1590 ° C, the remaining graphite is added to the crucible, refined, and then cooled; (3) Metal calcium deoxidation: Adding metal calcium, after melting all, heating to 1550 ~ 1570 ° C, refining, shaking in the refining process, so that the floating slag floating up to the molten metal surface is discharged to the back of the wall; (4) Add aluminum and titanium: Cooling to 1370 ~ 1390 ° C, adding aluminum, titanium, heating up to aluminum, titanium all melted; (5) Adding nickel-boron alloy and zirconium: Maintaining a temperature of 1410 to 1430 ° C, adding a nickel-boron alloy and zirconium thereto, and heating the mixture to a nickel-boron alloy and zirconium; (6) Frozen metal melt, filtration, tapping and pouring: Cool down, wait until the temperature drops to 1360 ~ 1380 ° C, and then heat up to 1450 ~ 1470 ° C, using a ceramic filter while filtering and tapping. The smelting process for a nickel-based alloy containing aluminum-titanium-boron-zirconium according to claim 1, wherein the step (1) graphite is a particle in which the spectral graphite electrode is broken to 2 to 5 mm. The smelting process of the aluminum-based boron-zirconium-containing nickel-based alloy according to claim 1, characterized in that the step (1) smelting temperature is 1560 to 1580 ° C, and the smelting time is 20 to 30 min. The smelting process of the aluminum-based boron-zirconium-containing nickel-based alloy according to claim 1, wherein the temperature of the step (2) is raised to 1570 to 1590 ° C, and the remaining graphite is added to the crucible, and refined at a power of 80 KW. ~30min. The smelting process of a nickel-based alloy containing aluminum titanium borate and zirconium according to claim 1, wherein after the metal calcium added in the step (3) is completely melted, the temperature is raised to 1550 to 1570 ° C, and the temperature is 80 KW. After refining for 10 min, when refining for 5 min, the crucible is started to be shaken, so that the scum floating up to the molten metal level is discharged to the rear of the crucible wall. The smelting process for a nickel-based alloy containing aluminum-titanium-boron-zirconium according to claim 1, wherein the amount of the metal calcium in the step (3) is 0.02 to 0.05% of the total mass of the high-temperature alloy. The smelting process of the aluminum-based boron-zirconium-containing nickel-based alloy according to claim 1, wherein the step (4) is heated until the aluminum and the titanium are all melted, and then stirred for 3 to 5 minutes. The smelting process of the aluminum-based boron-zirconium-containing nickel-based alloy according to claim 1, wherein the step (5) is heated until the nickel-boron alloy and the zirconium are all melted, and then stirred for 3 to 5 minutes. The smelting process for a nickel-based alloy containing aluminum-titanium-boron-zirconium according to any one of claims 1 to 8, characterized in that the degree of vacuum when aluminum, titanium, nickel-boron alloy or zirconium is added is ≤ 0.1 Pa.