A vacuum induction furnace bottom air blowing deoxidation device and method

Abstract

The present invention discloses a blowing deoxidation device for the bottom of a vacuum induction furnace, comprising: a gas source, including a methane gas source, an argon gas source and a compressed air gas source; a gas circuit, including a methane gas circuit connected to the methane gas source, an argon gas circuit connected to the argon gas source and a compressed air gas circuit connected to the compressed air gas source; a mixed gas bag connected to the methane gas circuit and the argon gas circuit; a bottom blowing mechanism connected to the mixed gas bag through a conveying gas circuit, for deoxidizing the molten steel in the test furnace from the bottom; the conveying gas circuit is connected to the compressed air gas circuit; a control cabinet, for controlling the opening and closing of the gas circuit. The present invention blows deoxidizing gas methane into the molten steel under vacuum conditions to achieve the purpose of deoxidation, solves the drawbacks of the existing deoxidation methods, reduces the inclusion content in the steel, expands the smelting varieties of vacuum induction furnaces, improves the quality of steel, and improves the level of steelmaking logistics.

Description

Technical Field

[0001] The invention relates to a rapid deoxidation technology in the smelting process of an induction furnace in the metallurgical industry, and more specifically to an air blowing deoxidation device and method for a vacuum induction furnace bottom. Background Art

[0002] There are two traditional deoxidation methods for vacuum induction furnace smelting. One is to use deoxidized alloy blocks (granules) for direct deoxidation. The direct deoxidation speed is fast but there are many oxidized inclusions. The other is to use vacuum carbon deoxidation. The product of this deoxidation method is CO, which is discharged outside the furnace under vacuum conditions and will not pollute the purity of the molten steel. However, because vacuum deoxidation requires the control of the vacuum degree, it is easy to cause molten steel splashing, thereby affecting the vacuum treatment of the molten steel. The above two deoxidation methods are not completely suitable for the smelting of vacuum induction furnaces. Therefore, it is the research goal of various metallurgical enterprises to seek a deoxidation technology that can remove oxygen from molten steel, does not cause secondary pollution to the molten steel, and is suitable for vacuum induction furnaces. Summary of the invention

[0003] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a vacuum induction furnace bottom blowing deoxidation device and method, which blows deoxidizing gas methane into molten steel under vacuum conditions to achieve the purpose of deoxidation, solve the drawbacks of existing deoxidation methods, reduce the inclusion content in steel, expand the vacuum induction furnace smelting varieties, improve steel quality, and improve the level of steelmaking logistics.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] On the one hand, a vacuum induction furnace bottom blowing deoxidation device comprises:

[0006] Gas sources, including methane, argon and compressed air;

[0007] a gas circuit, comprising a methane gas circuit connected to the methane gas source, an argon gas circuit connected to the argon gas source, and a compressed air gas circuit connected to the compressed air gas source;

[0008] A mixed gas bag, connected to the methane gas circuit and the argon gas circuit;

[0009] A bottom blowing mechanism is connected to the mixed gas bag through a conveying gas path, and is used to deoxidize the molten steel in the test furnace from the bottom of the test furnace; the conveying gas path is connected to the compressed air path;

[0010] The methane gas circuit, the argon gas circuit, the compressed air gas circuit, and the conveying gas circuit are respectively provided with a plurality of valves;

[0011] The control cabinet is used to control the opening and closing of multiple valves in the gas circuit so that the deoxidation rate of the vacuum induction furnace bottom blowing deoxidation is greater than 71%.

[0012] Preferably, the methane gas line is provided with a first ball valve, a first pressure gauge, a first check valve, a first shut-off valve, a first pressure transmitter, a first mass flow meter, a first flow regulating valve and a second check valve in sequence; and / or

[0013] The argon gas path is provided with a second ball valve, a second pressure gauge, a second shut-off valve, a second pressure transmitter, a second mass flow meter, a second flow regulating valve and a third check valve in sequence; and / or

[0014] The compressed air circuit is provided with an eighth ball valve, a third pressure gauge, a seventh shut-off valve, an eighth check valve, a ninth ball valve and a third anti-flashback valve in sequence; and / or

[0015] The gas delivery line is provided with a fifth ball valve, a fifth shut-off valve, a sixth check valve, a sixth shut-off valve, a sixth ball valve, a seventh check valve, a seventh ball valve and a second anti-backfire valve in sequence.

[0016] Preferably, the gas circuit also includes a cleaning and replacement gas circuit for connecting the argon gas circuit with the methane gas circuit, and connecting the delivery gas circuit with the test furnace, and using argon gas to clean and replace the gas remaining in the gas circuit.

[0017] Preferably, a third shut-off valve and a fourth check valve are sequentially provided on the cleaning and replacement gas path connecting the argon gas path and the methane gas path;

[0018] The cleaning and replacement gas path connecting the delivery gas path and the test furnace is provided with a fourth shut-off valve, a third ball valve, a fifth check valve, a fourth ball valve and a first anti-flashback valve in sequence.

[0019] Preferably, the test furnace is a vacuum induction furnace.

[0020] Preferably, the control cabinet is also connected to an alarm.

[0021] Preferably, the bottom blowing mechanism adopts an integrated bottom blowing element and / or a split bottom blowing element;

[0022] The integrated bottom blowing element is made of high temperature resistant non-magnetic stainless steel and is coated with chrome corundum castable on the outside;

[0023] The blowing port of the integrated bottom blowing element is a slit type;

[0024] The split bottom blowing element comprises a bottom brick and a bottom blowing element body arranged thereon;

[0025] The inner core of the bottom-blown element body is made of chrome corundum castable material, the outer portion is made of high-temperature resistant non-magnetic stainless steel clamp, and the bottom brick is made of chrome corundum castable material.

[0026] On the other hand, a method for air blowing deoxidation of the vacuum induction furnace bottom is provided for the air blowing deoxidation device of the vacuum induction furnace bottom. The air blowing deoxidation device of the vacuum induction furnace bottom is cleaned and replaced. After the replacement is completed, all valves are closed in reverse order, the test furnace is started, argon is filled in the vacuum chamber, the temperature is adjusted to the target temperature, the oxygen content of the molten steel is adjusted to the target value, the bottom blowing mechanism is closed, and the test is started.

[0027] Preferably, the gas supply intensity of the bottom blowing mechanism is 5 to 1000 L / t·min, and the gas pressure is 0.1 to 1.0 MPa;

[0028] The ratio of argon / methane is (0-100)% / (100-0)%;

[0029] The argon filling pressure in the vacuum chamber is 400-600Pa.

[0030] The present invention provides a vacuum induction furnace bottom blowing deoxidation device and method, which has the following beneficial effects:

[0031] 1) No need for metal deoxidizer, saving costs;

[0032] 2) Since the deoxidation product is gas, the inclusions in the steel are significantly reduced;

[0033] 3) The deoxidation efficiency is above 70%, and the cleanliness of the molten steel is stable and controllable;

[0034] 4) The ratio of methane and argon can be adjusted arbitrarily, and the gas volume can be adjusted in a wide range;

[0035] 5) Saves time for adding vacuum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall framework of the air blowing deoxidation device of the present invention;

[0037] Figure 2 It is a schematic diagram of the framework of the air blowing deoxidation device of the present invention;

[0038] Figure 3 It is a schematic structural diagram of an integrated bottom blowing element in the air blowing deoxidation device of the present invention;

[0039] Figure 4 yes Figure 3 Schematic diagram of the A direction;

[0040] Figure 5 It is a schematic diagram of the structure of the bottom brick in the air blowing deoxidation device of the present invention;

[0041] Figure 6 It is a schematic structural diagram of the bottom blowing element body in the air blowing deoxidation device of the present invention. DETAILED DESCRIPTION

[0042] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0043] Combination Figure 1 and Figure 2 As shown, the present invention provides a vacuum induction furnace bottom blowing deoxidation device, comprising:

[0044] Gas sources, including a methane gas source 1, an argon gas source 2 and a compressed air gas source 3;

[0045] A gas circuit, comprising a methane gas circuit connected to a methane gas source 1, an argon gas circuit connected to an argon gas source 2, and a compressed air gas circuit connected to a compressed air gas source 3;

[0046] The mixed gas bag 4 is connected with the methane gas path and the argon gas path;

[0047] The bottom blowing mechanism 5 is connected to the mixed gas bag 4 through the conveying gas path, and is used to deoxidize the molten steel in the test furnace from the bottom of the test furnace, and is also connected to the compressed air path;

[0048] Multiple valves are respectively provided on the methane gas circuit, the argon gas circuit, the compressed air gas circuit, and the conveying gas circuit;

[0049] The control cabinet 6 is used to control the opening and closing of multiple valves in the gas circuit so that the deoxidation rate of the vacuum induction furnace bottom blowing deoxidation is greater than 71%.

[0050] Hydrogen-containing gas is a hydrocarbon that cracks into carbon and hydrogen at high temperatures. Carbon and hydrogen can react with oxygen in molten steel to generate carbon monoxide and water vapor. Carbon monoxide and water vapor are gaseous and will not pollute the molten steel when discharged from the furnace under vacuum. At the same time, the CO reaction can be accelerated under vacuum conditions and H can be removed. Therefore, the use of methane in a vacuum induction furnace to deoxidize molten steel is an effective method for producing clean, high-quality steel.

[0051] The methane gas line is provided with a first ball valve 7, a first pressure gauge 8, a first check valve 9, a first shut-off valve 10, a first pressure transmitter 11, a first mass flow meter 12, a first flow regulating valve 13 and a second check valve 14 in sequence.

[0052] The argon gas line is provided with a second ball valve 15 , a second pressure gauge 16 , a second cut-off valve 17 , a second pressure transmitter 18 , a second mass flow meter 19 , a second flow regulating valve 20 and a third check valve 21 in sequence.

[0053] The gas delivery path is provided with a fifth ball valve 29 , a fifth shut-off valve 30 , a sixth check valve 31 , a sixth shut-off valve 32 , a sixth ball valve 33 , a seventh check valve 34 , a seventh ball valve 35 and a second anti-flashback valve 36 in sequence.

[0054] The test furnace is a vacuum induction furnace 38.

[0055] The gas circuit also includes a cleaning and replacement gas circuit for connecting the argon gas circuit with the methane gas circuit, and connecting the delivery gas circuit with the test furnace to prevent the oxygen in the air retained in the pipeline from interfering with the test structure and causing an explosion.

[0056] A third shut-off valve 22 and a fourth check valve 23 are provided in sequence on the cleaning and replacement gas path connecting the argon gas path and the methane gas path;

[0057] A fourth shut-off valve 24 , a third ball valve 25 , a fifth check valve 26 , a fourth ball valve 27 and a first anti-flashback valve 28 are sequentially provided on the cleaning and replacement gas path connecting the delivery gas path and the test furnace.

[0058] Taking into account the flammability of methane gas, the methane gas line was cleaned before the test. The methane gas source 1 was closed first, and then the second ball valve 15, the second pressure gauge 16, the third shut-off valve 22, the fourth check valve 23, the first pressure transmitter 11, the first mass flow meter 12, the first flow regulating valve 13 and the second check valve 14 were opened to enter the mixed gas bag 4, and then connected to the bottom gas supply original of the vacuum induction furnace 38 through the fifth ball valve 29, the fifth shut-off valve 30, the sixth check valve 31, the fourth shut-off valve 24, the third ball valve 25, the fifth check valve 26, the fourth ball valve 27 and the first anti-flashback valve 28. After cleaning and replacement, the corresponding valves were closed to ensure that no air would remain in the pipeline.

[0059] Similarly, the argon gas line needs to be cleaned and replaced before the test, and the operating steps are the same as those for cleaning the methane gas line.

[0060] The compressed air circuit is provided with an eighth ball valve 39, a third pressure gauge 40, a seventh shut-off valve 41, an eighth check valve 42, a ninth ball valve 43 and a third anti-flashback valve 44 in sequence and connected to the test furnace (the bottom gas supply component 3801 of the vacuum induction furnace 38). Its function is to use compressed air to blow open the bottom gas supply component if the bottom gas supply component is blocked during the test.

[0061] The control cabinet 6 is also connected with three alarms 45 for detecting leakage of the methane gas circuit, the argon gas circuit and the compressed air gas circuit respectively. Once a gas leakage occurs, the alarm 45 will sound an alarm.

[0062] The bottom blowing mechanism 5 adopts an integrated bottom blowing element and / or a split bottom blowing element;

[0063] Combination Figure 3 and Figure 4 As shown, the integrated bottom blowing element is made of high temperature resistant non-magnetic stainless steel 501 and is coated with chrome corundum castable 502 on the outside.

[0064] The blowing port position 503 of the integrated bottom blowing element is a slit type.

[0065] Combination Figure 5 and Figure 6 As shown, the split bottom blowing element comprises a bottom brick 504 and a bottom blowing element body 505 arranged thereon.

[0066] The inner core of the bottom blowing element body 505 is made of chrome corundum castable material 506, the outer portion is made of high temperature resistant non-magnetic stainless steel clamp 507, and the bottom brick 504 is made of chrome corundum castable material.

[0067] The difference between the integrated type and the split type is that in actual use, the integrated type is used for induction furnaces and is replaced with the furnace body. The split type is mostly used for large-scale production and can be easily replaced.

[0068] The advantage of high temperature resistant non-magnetic stainless steel is that during the smelting process, the induction furnace cannot induce heating on it, ensuring that the components are not damaged or deformed.

[0069] Chrome corundum castable is used for high temperature resistance, and can be used at 1500℃~1800℃.

[0070] The purpose of the slit type is to ensure the smoothness and flow of air flow. At the same time, due to the size of the slit type, it can effectively prevent the backflow of molten steel.

[0071] The present invention also provides a method for deoxidizing the bottom of a vacuum induction furnace by blowing. After cleaning and replacement are completed using the air blowing deoxidation device for the bottom of a vacuum induction furnace of the present invention, all valves are closed in reverse order, the test furnace is powered on to start melting, argon is filled in the vacuum chamber to 400-600 Pa, the temperature is adjusted to the target temperature, the oxygen content of the molten steel is adjusted to the target value, the bottom blowing mechanism is closed, and the test is started.

[0072] The gas supply intensity of the bottom blowing mechanism is 5 to 1000 L / t·min, and the gas pressure is 0.1 to 1.0 MPa, which can be further set to 0.1 to 0.15 MPa according to the capacity of the vacuum induction furnace.

[0073] The ratio of argon / methane is (0~100)% / (100~0)%.

[0074] The results of the induction furnace methane injection test for molten steel deoxidation are shown in Table 1.

[0075] Table 1

[0076]

[0077] Example 1

[0078] The free oxygen is 500-550 ppm, the molten steel temperature is 1597°C, and the vacuum degree is 300 Torr.

[0079] First, purge the pipeline: set the ratio of argon / methane to 100 / 0, the pressure to 0.2Kpa, and the flow rate to 100L / min. Open the manual valve beside the furnace and press the one-button purge. After 2 minutes of purge, close the manual valve beside the furnace and then close the one-button purge.

[0080] Pre-evacuate to the limit, then fill with argon to 100 torr, turn on the power to raise the temperature, after a certain amount of molten pool is formed at the bottom, set the mixed gas ratio of argon / methane to 0 / 100, the flow rate to 3L / minute, the pressure to 0.15kpa, and the spraying time to 15 minutes. Press one button to spray, slowly open the manual valve beside the furnace, and adjust the opening according to the tumbling situation until it is fully opened. After all the melt is clear, close the manual valve beside the furnace and turn off the one-button spray. Measure the temperature and determine the oxygen, and adjust the temperature to 1600°±10°.

[0081] Set process parameters: argon and methane pressure: 0.14Kpa, mixed gas flow rate 10L / min, blowing time 8 minutes, the mixing ratio is dynamically adjusted during the blowing process, starting argon / methane 1 / 9, blowing for 2 minutes 3 / 7, blowing for 4 minutes 5 / 5, blowing for 5 minutes 7 / 3.

[0082] Press the one-button spray, slowly open the manual valve beside the furnace, and adjust the opening according to the tumbling situation until it is fully open. After the spray is completed, blow argon for 2 minutes.

[0083] Measure temperature, take samples and determine oxygen, adjust composition and temperature, tap steel, and it’s over.

[0084] Example 2

[0085] Free oxygen 250~500PPm, molten steel temperature 1620℃, vacuum degree 250 Torr.

[0086] First, purge the pipeline: set the ratio of argon / methane to 100 / 0, the pressure to 0.2Kpa, and the flow rate to 100L / min. Open the manual valve beside the furnace and press the one-button purge. After 2 minutes of purge, close the manual valve beside the furnace and then close the one-button purge.

[0087] Pre-evacuate to the limit, then fill with argon to 250 torr, turn on the power to raise the temperature, after a certain amount of molten pool is formed at the bottom, set the mixed gas ratio of argon / methane to 0 / 100, the flow rate to 3L / minute, the pressure to 0.15kpa, and the spraying time to 15 minutes. Press one button to spray, slowly open the manual valve beside the furnace, and adjust the opening according to the tumbling situation until it is fully opened. After all the melt is clear, close the manual valve beside the furnace and turn off the one-button spray. Measure the temperature and determine the oxygen, and adjust the temperature to 1620°±10°.

[0088] Set process parameters: argon and methane pressure: 0.15Kpa, mixed gas flow rate 6L / min, blowing time 6 minutes, the mixing ratio is dynamically adjusted during the blowing process, starting argon / methane 1 / 9, blowing for 2 minutes 3 / 7, blowing for 4 minutes 5 / 5, blowing for 5 minutes 7 / 3, blowing argon alone for 1 minute after the blowing is completed.

[0089] Press the one-button spray, slowly open the manual valve beside the furnace, and adjust the opening according to the tumbling situation until it is fully open. After the spray is completed, blow argon for 1 minute.

[0090] Measure temperature, take samples and determine oxygen, adjust composition and temperature, tap steel, and it’s over.

[0091] Example 3

[0092] Free oxygen 100~200PPm, molten steel temperature 1590℃, vacuum degree 100 Torr.

[0093] First, purge the pipeline: set the ratio of argon / methane to 100 / 0, the pressure to 0.2Kpa, and the flow rate to 100L / min. Open the manual valve beside the furnace and press the one-button purge. After 2 minutes of purge, close the manual valve beside the furnace and then close the one-button purge.

[0094] Pre-evacuate to the limit, then fill with argon to 100 torr, turn on the power to raise the temperature, after a certain amount of molten pool is formed at the bottom, set the mixed gas ratio of argon / methane to 0 / 100, the flow rate to 3L / minute, the pressure to 0.15kpa, and the spraying time to 15 minutes. Press one button to spray, slowly open the manual valve beside the furnace, and adjust the opening according to the tumbling situation until it is fully opened. After all the melt is clear, close the manual valve beside the furnace and turn off the one-button spray. Measure the temperature and determine the oxygen, and adjust the temperature to 1590°±10°.

[0095] Set the process parameters: argon and methane pressure: 0.15Kpa, mixed gas flow rate 6L / min, blowing time 4 minutes, the mixing ratio is dynamically adjusted during the blowing process, starting argon / methane 1 / 9, blowing for 2 minutes 3 / 7, and blowing argon alone for 2 minutes after the end of the blowing.

[0096] Press the one-button spray, slowly open the manual valve beside the furnace, and adjust the opening according to the tumbling situation until it is fully open. After the spray is completed, blow argon for 1 minute.

[0097] Measure temperature, take samples and determine oxygen, adjust composition and temperature, tap steel, and it’s over.

[0098] It is very common to use vacuum induction furnaces for metallurgical activities, especially in laboratories for steel grade and process research and development. Due to the limitation of deoxidation technology, the improvement of vacuum induction furnace smelting technology has also limited the limitations of induction furnace smelting steel grades. The technology of the present invention is conducive to improving induction furnace smelting technology, expanding induction furnace steelmaking varieties, and improving steelmaking quality. Therefore, the technology of the present invention can be widely used in vacuum induction furnace smelting, and can also be extended to large vacuum refining furnaces.

[0099] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A vacuum induction furnace bottom blowing deoxidation device, characterized in that: include: Gas sources, including methane, argon and compressed air; a gas circuit, comprising a methane gas circuit connected to the methane gas source, an argon gas circuit connected to the argon gas source, and a compressed air gas circuit connected to the compressed air gas source; A mixed gas bag, connected to the methane gas circuit and the argon gas circuit; A bottom blowing mechanism is connected to the mixed gas bag through a conveying gas path, and is used to deoxidize the molten steel in the test furnace from the bottom of the test furnace; the conveying gas path is connected to the compressed air path; The methane gas circuit, argon gas circuit, compressed air gas circuit, and delivery gas circuit are respectively provided with a plurality of valves. The control cabinet is used to control the opening and closing of multiple valves in the gas circuit. The deoxidation rate of the vacuum induction furnace bottom blowing deoxidation is greater than 71%. The methane gas line is provided with a first ball valve, a first pressure gauge, a first check valve, a first cut-off valve, a first pressure transmitter, a first mass flow meter, a first flow regulating valve and a second check valve in sequence; The argon gas path is provided with a second ball valve, a second pressure gauge, a second cut-off valve, a second pressure transmitter, a second mass flow meter, a second flow regulating valve and a third check valve in sequence; The compressed air circuit is provided with an eighth ball valve, a third pressure gauge, a seventh cut-off valve, an eighth check valve, a ninth ball valve and a third anti-backfire valve in sequence; The gas delivery path is provided with a fifth ball valve, a fifth shut-off valve, a sixth check valve, a sixth shut-off valve, a sixth ball valve, a seventh check valve, a seventh ball valve and a second anti-flashback valve in sequence. The gas circuit also includes a cleaning and replacement gas circuit, which is used to connect the argon gas circuit with the methane gas circuit, and connect the delivery gas circuit with the test furnace, and use argon gas to clean and replace the gas remaining in the gas circuit. The cleaning and replacement gas path connecting the argon gas path and the methane gas path is provided with a third shut-off valve and a fourth check valve in sequence; The cleaning and replacement gas path connecting the delivery gas path and the test furnace is provided with a fourth shut-off valve, a third ball valve, a fifth check valve, a fourth ball valve and a first anti-flashback valve in sequence. The control cabinet is also connected to three alarms to detect the leakage of methane gas circuit, argon gas circuit and compressed air gas circuit respectively. Once a gas leak occurs, the alarm will sound an alarm. The vacuum induction furnace bottom air blowing deoxidation device performs the following vacuum induction furnace bottom air blowing deoxidation method: the gas retained in the air path of the vacuum induction furnace bottom air blowing deoxidation device is purged and replaced, and after the purging and replacement is completed, all valves are reversely closed in sequence, the test furnace is started, argon is filled in the vacuum chamber, the temperature is adjusted to the target temperature, the oxygen content of the molten steel is adjusted to the target value, the bottom blowing mechanism is closed, and the test is started.

2. The air blowing deoxidation device for the bottom of a vacuum induction furnace according to claim 1, characterized in that: The test furnace is a vacuum induction furnace.

3. The air blowing deoxidation device for the bottom of a vacuum induction furnace according to claim 1, characterized in that: The bottom blowing mechanism adopts an integrated bottom blowing element or a split bottom blowing element; The integrated bottom blowing element is made of high temperature resistant non-magnetic stainless steel and is coated with chrome corundum castable on the outside; The blowing port of the integrated bottom blowing element is a slit type; The split bottom blowing element comprises a bottom brick and a bottom blowing element body arranged thereon; The inner core of the bottom-blown element body is made of chrome corundum castable material, the outer portion is made of high-temperature resistant non-magnetic stainless steel clamp, and the bottom brick is made of chrome corundum castable material.

4. A method for deoxidizing a vacuum induction furnace bottom using a deoxidizing device for deoxidizing a vacuum induction furnace bottom according to any one of claims 1 to 3, characterized in that: The gas retained in the gas path of the air blowing deoxidation device at the bottom of the vacuum induction furnace is cleaned and replaced. After the cleaning and replacement is completed, all valves are reversely closed in sequence, the test furnace is started, argon is filled in the vacuum chamber, the temperature is adjusted to the target temperature, the oxygen content of the molten steel is adjusted to the target value, the bottom blowing mechanism is closed, and the test is started. The gas supply intensity of the bottom blowing mechanism is 5-1000L / (t•min), and the gas pressure is 0.1-1.0MPa; The ratio of argon / methane is (0~100)% / (100~0)%; The argon filling pressure in the vacuum chamber is 400-600Pa.

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