CN115161535A - Manufacturing method for smelting low-nitrogen stainless steel ingot by vacuum induction furnace - Google Patents
Manufacturing method for smelting low-nitrogen stainless steel ingot by vacuum induction furnace Download PDFInfo
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- CN115161535A CN115161535A CN202210641823.7A CN202210641823A CN115161535A CN 115161535 A CN115161535 A CN 115161535A CN 202210641823 A CN202210641823 A CN 202210641823A CN 115161535 A CN115161535 A CN 115161535A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/005—Manufacture of stainless steel
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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Abstract
The invention discloses a method for manufacturing low-nitrogen stainless steel ingots by smelting in a vacuum induction furnace, which comprises the following steps: adding a steelmaking raw material into a vacuum induction furnace for smelting, wherein the smelting sequentially comprises the following steps: melting, refining and casting, wherein in the melting step, raw material metal chromium is not added, and metal raw materials of iron, nickel and molybdenum are added into a vacuum induction furnace in batches to be melted; in the refining treatment step, the molten steel which is melted completely is refined, then metallic chromium is added into the molten steel in batches and is melted, and then the content of the alloy elements in the molten steel is finely adjusted after the content of the nitrogen elements in the molten steel is qualified so that the content of the components in the molten steel meets the requirement. The low-nitrogen stainless steel ingot manufactured by the invention has the advantages of chemical components meeting the requirements, low nitrogen content and short smelting time.
Description
Technical Field
The invention relates to a manufacturing method of a metal material, in particular to a manufacturing method for smelting a low-nitrogen stainless steel ingot in a vacuum induction furnace.
Background
With the rapid development of the current industrialization, the requirements on metal materials are higher and higher, especially in some special environments, such as oceans, plateaus and low-temperature environments, metal materials needing corrosion resistance, high toughness and high strength are often involved, and in the current common steel, only high-strength, high-toughness and corrosion-resistant stainless steel can meet the use requirements, but the stainless steel has strict requirements on chemical components, especially requires lower nitrogen content.
At present, the stainless steel is smelted by adopting a vacuum induction furnace internationally and domestically, and the standard of the stainless steel generally requires the chemical composition Cr:12-14%, mo:2-4%, less than or equal to 0.04%, 8-12% of Ni, less than or equal to 0.001%, less than or equal to 0.003% of S, and less than or equal to 0.004% of P, in order to ensure the high strength and toughness of the steel, the contents of carbon and nitrogen in the steel are limited: c is less than or equal to 0.04 percent, N is less than or equal to 0.001 percent, and simultaneously, in order to ensure that the steel has higher corrosion resistance, the chromium content in the steel is higher: 12 to 14 percent of Cr.
Because the combination ability of chromium element and nitrogen element is stronger, the nitrogen content of the raw material metal chromium for increasing the chromium element is between 0.008% and 0.015% when the stainless steel is smelted by a vacuum induction furnace, and the carbon content of the main denitrification element of the stainless steel in the smelting process of the vacuum induction furnace is lower, thus bringing greater difficulty to denitrification of the stainless steel in the smelting process of the vacuum induction furnace.
At present, domestic enterprises adopt molten steel to smelt for a long time under high vacuum degree (less than or equal to 5 pa) when producing the stainless steel, and utilize the molten steel to smelt and denitrify under the vacuum environment, the time of the smelting and manufacturing method is generally 25-30h, and because the smelting time of the manufacturing method is longer, a large amount of energy is consumed, and the risk is brought to the quality of steel.
Therefore, a manufacturing method capable of shortening the process of smelting the low-nitrogen stainless steel ingot in a vacuum induction furnace is needed.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provides a manufacturing method for smelting low-nitrogen stainless steel ingots by a vacuum induction furnace, so as to shorten the smelting time for smelting the low-nitrogen stainless steel ingots by the vacuum induction furnace in the conventional process.
The inventor of the invention finds that metallic chromium is not added in the melting period of the vacuum induction furnace smelting, other metal materials are slowly added in batches for melting and denitrification, the metallic chromium is added and melted in a specific mode in the refining period of the vacuum induction furnace smelting, molten steel is poured in a specific mode in the pouring period of the vacuum induction furnace smelting, and finally the stainless steel ingot with qualified components and low nitrogen element is obtained in a short time.
In order to achieve the above purpose, the following technical scheme is adopted.
A manufacturing method for smelting a low-nitrogen stainless steel ingot by a vacuum induction furnace comprises the following components in percentage by mass: 12-14%, mo:2-4%, C is less than or equal to 0.04%, ni:8-12%, N is less than or equal to 0.001%, S is less than or equal to 0.003%, P is less than or equal to 0.004%, and the balance is Fe and inevitable impurities, and the preparation method comprises the following steps: adding steelmaking raw materials into a vacuum induction furnace for smelting, wherein the smelting sequentially comprises the following steps: melting treatment, refining treatment and casting molding, wherein,
in the step of melting treatment, raw material chromium is not added, and the metal raw materials of iron, nickel and molybdenum are added into a vacuum induction furnace in batches to be melted;
in the refining treatment step, the molten steel (molten steel) which is completely melted after the melting treatment is firstly refined, then metallic chromium is added into the molten steel in batches and is melted, and then the content of the alloy element of the molten steel is finely adjusted after the content of the nitrogen element in the molten steel is qualified so that the content of the component of the molten steel meets the requirement.
In the above manufacturing method, as a preferred embodiment, in the melting step, pure iron is added to melt, then metal nickel is added to melt, and finally metal molybdenum is added to melt.
In the above manufacturing method, as a preferred embodiment, in the melting step, the melting conditions are: the material melting power is 400-600kW and is not equal to 600kW, the vacuum degree is not more than 5Pa, and the melting treatment time is 6-8h.
In the invention, the purpose of controlling the melting power in the melting treatment is to ensure that the metal raw material can be completely melted.
In the above manufacturing method, as a preferred embodiment, in the melting treatment step, the same kind of metal raw material is added to the molten steel in divided amounts of 3 to 5 times in the storage bin, each time in an amount of 1/5 to 1/3 of the total weight of the same kind of metal raw material in the storage bin.
In the prior art, the material melting power of a furnace body is generally set to be 600-1000kW. In the present invention, the use of low power and small batch feeds ensures that the gases are adequately removed during the melting stage.
In the above-described manufacturing method, as a preferred embodiment, in the melting step, the raw material for smelting is brought into a fully molten state at a later stage of the melting process, and the temperature of the fully molten steel is preferably controlled to be in a range of 1500 to 1600 ℃ (e.g., 1510 ℃, 1520 ℃, 1550 ℃, 1570 ℃, 1580 ℃, 1590 ℃), and more preferably 1580 to 1590 ℃ (e.g., 1582 ℃, 1585 ℃, 1587 ℃, 1588 ℃, 1589 ℃).
In the above manufacturing method, as a preferred embodiment, the steelmaking material includes metallic nickel, metallic chromium, metallic molybdenum, and pure iron; the metal nickel, the metal chromium, the metal molybdenum and the pure iron can be various metals which are conventional in the field and are used for refining stainless steel, for example, the metal nickel is 1# Ni and the like;
preferably, the pure iron is a metal material which is smelted and purified by EAF + LF + VOD to remove harmful elements such as C, si, mn, S, P and the like; more preferably, in the pure iron, the mass percentage of N is less than 0.015 percent, the mass percentage of S is less than 0.003 percent, the mass percentage of P is less than 0.005 percent, the mass percentage of Mn is less than 0.03 percent, and the mass percentage of Si is less than 0.05 percent;
preferably, the metallic chromium is conventional metallic chromium, and the nitrogen content in the metallic chromium is 0.008-0.015wt%. The conventional chromium metal can reduce the raw material cost of the low-nitrogen stainless steel ingot.
In the above manufacturing method, as a preferred embodiment, in the refining step, the refining conditions are: the power is 200-400kW, (for example, 220kW, 250kW, 280kW, 300kW, 350kW, 370kW, 390 kW), the vacuum degree is less than or equal to 3Pa (for example, 1.5Pa, 1.2Pa, 1Pa, 0.5Pa, 0.1 Pa), preferably, the vacuum degree is less than or equal to 2Pa, the temperature is 1580-1590 ℃, and the time under power frequency stirring is 10-20min.
In the present invention, the purpose of controlling the power in the refining process is to control the refining temperature.
In the above production method, as a preferable embodiment, in the refining treatment, metallic chromium is added to the molten steel when the degree of vacuum of refining is 2Pa or less.
In the above manufacturing method, as a preferred embodiment, in the refining step, the metal chromium is divided into 2 parts on average, each part of the metal chromium is added into the refined molten steel 3 times, and 1/4 to 1/3 of the total weight of each part of the metal chromium is added each time; preferably, after the first part of the chromium metal is added for smelting for 1 hour, adding a second part of the chromium metal for further smelting for 1 hour; still preferably, during the addition of the metallic chromium, the power is 300-400kW (e.g., 310kW, 320kW, 350kW, 370kW, 380kW, 390 kW), the smelting temperature is 1580-1590 ℃ (e.g., 1582 ℃, 1585 ℃, 1587 ℃, 1588 ℃, 1589 ℃), the degree of vacuum is less than or equal to 5Pa (e.g., 4Pa, 3Pa, 2Pa, 1 Pa), more preferably the degree of vacuum is less than or equal to 3Pa.
The invention adopts high smelting temperature (namely high smelting temperature) to slowly feed under high vacuum, thereby ensuring that nitrogen in the metal chromium is fully removed.
In the prior art, metallic chromium is added in the melting treatment stage, and the smelting temperature during the addition of the metallic chromium is 1540-1560 ℃.
In the above production method, as a preferred embodiment, in the refining step, after each part of the chromium metal is added, the alloy is smelted under line frequency stirring for 10 to 20min (e.g., 12min, 15min, 18 min).
In the above production method, as a preferred embodiment, in the refining treatment, the total refining time is 5 to 10 hours (e.g., 6 hours, 7 hours, 8 hours, and 9 hours).
In the above manufacturing method, as a preferred embodiment, in the casting molding step, inert gas is simultaneously filled into the vacuum chamber and the mold injection chamber of the vacuum induction furnace to make the pressures of the vacuum chamber and the mold injection chamber consistent, and then casting is performed to obtain a stainless steel ingot; preferably, the inert gas is argon, and more preferably, argon with the pressure of 20-50Pa is simultaneously filled into a vacuum chamber and a die-casting chamber of the vacuum induction furnace, so that the liquid level of molten steel is stabilized during casting, and molten steel is prevented from splashing and blocking; more preferably, the tapping temperature during casting is 1540-1560 ℃.
In the above production method, as a preferred embodiment, the total time for the melting in the production method is 15 to 20 hours.
The method for smelting the low-nitrogen stainless steel ingot by the vacuum induction furnace can obtain the high-strength, high-toughness and corrosion-resistant stainless steel ingot with qualified chemical components, low nitrogen content and short smelting time, the high-strength, high-toughness and corrosion-resistant stainless steel ingot smelted by the method has the gas nitrogen content of less than or equal to 0.0010%, the chemical components meet the requirements, and the smelting time is 15-20 hours.
In the invention, the technical characteristics can be freely combined to form a new technical scheme under the condition of not conflicting with each other.
Compared with the prior art, the invention has the following beneficial technical effects:
the low-nitrogen stainless steel ingot manufactured by the invention meets the requirements on chemical components, has low nitrogen content and shortens smelting time by a large amount.
Detailed Description
The present invention will be described in detail below with reference to examples thereof. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are given by way of illustration and explanation only, not limitation. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and equivalents thereof.
A manufacturing method for smelting low-nitrogen stainless steel ingots by a vacuum induction furnace comprises the following steps: adding a steelmaking raw material into a vacuum induction furnace for smelting, wherein the smelting comprises the steps of sequentially carrying out melting treatment, refining treatment and casting molding, wherein,
the steel-making raw materials are mixed so that the obtained steel ingot contains: cr:12-14%, mo:2-4%, less than or equal to 0.04% of C, 8-12% of Ni, less than or equal to 0.001% of N, less than or equal to 0.003% of S and less than or equal to 0.004% of P;
the melting process includes: completely reserving metal chromium, adding pure iron, metal molybdenum and metal nickel in batches for melting, wherein the adding amount of each time is 1/5-1/3 of the total weight of the metal materials in a storage bin, the melting power in the melting period is 400-600kW and is not equal to 600kW (for example, 420kW, 450kW, 500kW, 550kW and 580 kW), adding pure iron for melting firstly, adding metal nickel for melting, and finally adding metal molybdenum for melting;
the refining treatment comprises the following steps: after all the metal materials in the melting period are melted, adding metal chromium, wherein the metal chromium is added in two parts on average, each part of the metal chromium is added into the molten steel for 3 times, and the weight of each addition is 1/4-1/3; adding a second part of metal chromium after the first part of metal chromium is added and smelted for 1 hour, wherein the adding mode of the second part of metal chromium is the same as that of the first part; the smelting temperature during the addition of the metal chromium is 1580-1590 deg.C (for example, 1582 deg.C, 1585 deg.C, 1586 deg.C, 1588 deg.C);
the cast molding comprises: after the chemical components and the nitrogen content meet the requirements, argon is simultaneously filled into a vacuum chamber and a mold injection chamber of the vacuum induction furnace to ensure that the air pressure is 20-50Pa, and finally the steel ingot is cast into the required steel ingot.
According to the invention, the steelmaking raw materials comprise metallic nickel, metallic chromium, metallic molybdenum and pure iron. The metal nickel, the metal chromium, the metal molybdenum and the pure iron can be various metals which are conventional in the field and are used for refining stainless steel, for example, the metal nickel is 1# Ni and the like; the pure iron is a metal material which is smelted and purified by EAF + LF + VOD to remove harmful elements such as C, si, mn, S, P and the like; the steel-making raw materials are prepared into the following components in the finally obtained steel ingot: cr:12-14%, mo:2-4%, less than or equal to 0.04% of C, 8-12% of Ni, less than or equal to 0.001% of N, less than or equal to 0.003% of S and less than or equal to 0.004% of P.
According to the invention, the melting treatment in the vacuum induction furnace is a process of adding the steelmaking metal materials except the metal chromium into the vacuum induction furnace, and then performing melting and mixing on the steelmaking raw materials in different types and in batches by adjusting a certain vacuum degree and melting power; preferably, the conditions of the melting process include: the chemical material power is 400-600kW (for example, 420kW, 450kW, 500kW, 550kW, 580 kW), the vacuum degree is less than or equal to 5Pa (for example, 4Pa, 3Pa, 2Pa, 1 Pa), and the time is 6-8h (for example, 6.5h, 7h, 7.5 h); the adding amount of the metal material is 1/5-1/3 of the total weight of the metal material in the storage bin every time, and the metal material is added in 3-5 times; the smelting raw material is brought into a fully molten state at the latter stage of the melting treatment, and the temperature of the fully molten steel is preferably controlled within a range of 1500 to 1600 ℃ (e.g., 1510 ℃, 1520 ℃, 1550 ℃, 1570 ℃, 1580 ℃, 1590 ℃), more preferably 1580 to 1590 ℃ (e.g., 1582 ℃, 1585 ℃, 1586 ℃, 1588 ℃).
And after the melting treatment is finished, refining the fully molten steel.
Preferably, the refining conditions include: the power is 200-400kW (e.g., 220kW, 250kW, 300kW, 350kW, 380 kW), the degree of vacuum is less than or equal to 3Pa, preferably, the degree of vacuum is less than or equal to 2Pa, the temperature is 1580-1590 ℃ (e.g., 1582 ℃, 1585 ℃, 1586 ℃, 1588 ℃), and the time under power frequency stirring is 10-20min (e.g., 12min, 15min, 17min, 19 min).
The molten steel (namely, molten steel) after the refining treatment has more uniform components, and metal chromium needs to be added into the refined molten steel in a specific adding mode that the metal chromium is averagely added into the molten steel in two parts, and each part of the metal chromium is added into the molten steel 3 to 4 times, and the weight of each part of the metal chromium is 1/4 to 1/3. After the first part of the chromium metal is added and smelted for 1 hour, the second part of the chromium metal is added and then smelting is continued for 1 hour, and the adding mode is the same as that of the first part of the chromium metal.
And casting and molding the refined molten steel, wherein the casting and molding are to cast the molten steel into an ingot mold. The casting conditions preferably include: tapping temperature is 1540-1560 deg.C (e.g., 1545 deg.C, 1550 deg.C, 1555 deg.C, 1558 deg.C). In the invention, in order to obtain lower gas nitrogen content and qualified chemical components, argon gas is generally simultaneously filled into a vacuum chamber and a mold injection chamber of the vacuum induction furnace, so that the gas pressure is 20-50Pa (for example, 25Pa, 30Pa, 35Pa, 40Pa and 45 Pa) to ensure that molten steel can be stably injected into an ingot mold, and the phenomena of splashing and blockage of the molten steel are avoided.
The low-nitrogen stainless steel ingot manufactured by the invention has the advantages of chemical components meeting the requirements, low nitrogen content and short smelting time.
Example 1
In this example, the method for producing a low-nitrogen stainless steel ingot produced by the present invention will be described by taking 0Cr13Ni8Mo as an example of the production in a 6-ton vacuum induction furnace.
Melting period (melting treatment): the steel ingot contains the following components in percentage by weight: ni:8.5%, cr:12.5%, mo:2.0%, C:0.03%, S:0.002%, P:0.005 percent of the raw materials are prepared, wherein the chromium metal is reserved completely; under the vacuum degree of 5Pa and the electric power of 400KW, adding pure iron, wherein the total amount of pure iron is 4500kg, the pure iron is placed into a bin of a vacuum induction furnace for three times, 1500kg is placed into the bin each time, the pure iron in the bin is added into a crucible of the vacuum induction furnace for 3 times to be formed into molten iron, and 500kg is added into the bin each time; adding metal nickel into the molten steel by three times, wherein the total amount of the metal nickel is 600kg, adding the metal nickel into a bin of a vacuum induction furnace by three times, adding 200kg of the metal nickel into the molten steel each time, adding 200kg of the metal molybdenum finally, and adding the molybdenum plates into the bin of the vacuum induction furnace by three times. After the molten steel is melted, the temperature is controlled to be 1580-1590 ℃, and the melting period is 8 hours.
Refining period (refining treatment): refining the molten steel under the condition that the high vacuum degree is less than or equal to 3Pa, wherein the power in the refining period is 300kW, and the refining temperature is 1580-1590 ℃; when the vacuum degree is less than or equal to 2Pa, adding 800kg of metal chromium at the temperature of 1580-1590 ℃, refining at the temperature, dividing the metal chromium into two parts, each part being 400kg, firstly adding 400kg of metal chromium into a storage bin, adding 400kg of metal chromium into molten steel for three times, adding 140kg for the first time, adding 130kg again after melting, adding 130kg after melting, and smelting for 10-20min under power frequency stirring after each part of metal chromium is added; melting the first part of 400kg of metallic chromium, stirring for 1 hour, and adding the second part of 400kg of metallic chromium in the same manner as the first part; stirring for 1 hour after all the materials are added, and sampling; after the gaseous nitrogen element is qualified, finely adjusting the alloy element, reducing the temperature to 1550 ℃, and preparing for casting, wherein the refining period time is 8h.
Casting period (casting molding): in the casting period, argon is simultaneously filled into a vacuum chamber and a mold injection chamber of the vacuum induction furnace, so that the air pressure of the vacuum chamber and the mold injection chamber reaches 20-50Pa, and after the pressure of the vacuum chamber and the pressure of the mold injection chamber are consistent, an ingot mold vehicle is started for casting; the casting period time is 1h, and the components of the obtained steel ingot and the smelting time are shown in Table 1.
TABLE 1 chemical composition and smelting time of the steel ingots obtained in example 1
| C | S | P | Cr | Ni | Mo | N | Time of smelting |
| 0.03 | 0.002 | 0.005 | 12.5 | 8.5 | 2.0 | 0.0009 | 17h |
Comparative example 1
The comparative example is illustrated by taking 0Cr13Ni8Mo smelted in a 6-ton vacuum induction furnace as an example, and the comparative example is a manufacturing method for smelting low-nitrogen stainless steel ingots by a conventional smelting method, and the differences from the example 1 are as follows: 1) Adding metal chromium in the melting period and adding no metal chromium in the refining period; 2) Adding metallic nickel and metallic molybdenum into the molten steel at one time; 3) The refining temperature is controlled according to 1540-1560 ℃; 4) Argon is not filled in the pouring period, and vacuum pouring is adopted; in particular, the amount of the solvent to be used,
melting period: metal nickel, metal chromium, metal molybdenum and pure iron are added according to the proportion of the obtained steel ingot: ni:8.5%, cr:12.5%, mo:2.0%, C:0.03%, S:0.002%, P:0.005 percent of the raw materials are mixed. Under the vacuum degree of 5Pa and the electric power of 900kW, adding pure iron, wherein the total amount of pure iron is 4500kg, completely putting the pure iron into a bin of a vacuum induction furnace, adding the pure iron into a crucible of the vacuum induction furnace for 3 times to form molten iron, and adding 1500kg each time; adding metal nickel after pure iron is completely melted, wherein the total amount of the metal nickel is 600kg, the metal nickel is added into a bin of a vacuum induction furnace once, then the metal nickel is added into molten steel once, then the metal chromium is added, the total amount of the metal chromium is 800kg, the metal chromium is added into the bin of the vacuum induction furnace once, then the metal chromium is added into the molten steel 2 times, each time, 400kg is added, finally, the total amount of the metal molybdenum is 200kg, the metal molybdenum is added into the bin of the vacuum induction furnace once, and the metal molybdenum is added into the molten steel once; after the molten steel is melted, the temperature is controlled to be 1540-1560 ℃, and the melting period time is 6h.
And (3) refining period: refining and denitrifying the molten steel under the condition that the high vacuum degree is less than or equal to 3pa, wherein the power in the refining period is 300kW, the nitrogen element is reduced by 0.0003-0.0005 wt% per hour, the alloy elements are finely adjusted after the gaseous nitrogen element is qualified, pouring is prepared, and the time in the refining period is 22h.
Pouring period: casting the vacuum chamber of the vacuum induction furnace and the injection molding chamber in vacuum in the casting period; the composition of the obtained steel ingot is shown in table 2, because molten steel is splashed and blocked, and the casting period is 2 hours.
Table 2 chemical composition and smelting time of steel ingot obtained in comparative example 1
| C | S | P | Cr | Ni | Mo | N | Time of smelting |
| 0.033 | 0.002 | 0.005 | 12.45 | 8.47 | 2.14 | 0.0010 | 30h |
Comparative example 2
The comparative example illustrates the method for manufacturing the low-nitrogen stainless steel ingot smelted by the invention by taking 0Cr13Ni8Mo smelted in a 6-ton vacuum induction furnace as an example, and is different from the example 1 in that the refining process adopts a lower refining temperature. In particular, the amount of the solvent to be used,
melting period (melting treatment): the steel ingot contains the following components in percentage by weight: ni:8.5%, cr:12.5%, mo:2.0%, C:0.03%, S:0.002%, P:0.005 percent of the raw materials are prepared, wherein the chromium metal is reserved completely; under the vacuum degree of 5Pa and the electric power of 400kW, adding pure iron, wherein the total amount of pure iron is 4500kg, the pure iron is placed into a bin of the vacuum induction furnace for three times, 1500kg is placed into the bin each time, the pure iron in the bin is added into a crucible of the vacuum induction furnace for 3 times to form molten iron, and 500kg is added into the crucible each time; adding metal nickel into the molten steel by three times, wherein the total amount of the metal nickel is 600kg, adding the metal nickel into a bin of a vacuum induction furnace by three times, adding 200kg of the metal nickel into the molten steel each time, adding 200kg of the metal molybdenum finally, and adding the molybdenum plates into the bin of the vacuum induction furnace by three times. After the molten steel is melted, the temperature is controlled to be 1520-1530 ℃, and the melting period time is 10 hours.
Refining period (refining treatment): refining the molten steel under the condition that the high vacuum degree is less than or equal to 3Pa, wherein the power in the refining period is 300kW, and the refining temperature is 1520-1530 ℃; when the vacuum degree is less than or equal to 2Pa, adding 800kg of metallic chromium at the temperature of 1520-1530 ℃ and refining at the temperature, dividing the metallic chromium into two parts, each part being 400kg, firstly adding 400kg of metallic chromium into a storage hopper, adding 400kg of metallic chromium into molten steel for three times, adding 140kg of metallic chromium for the first time, adding 130kg of metallic chromium again after melting, adding 130kg of metallic chromium after melting, and smelting for 10-20min under power frequency stirring after each part of metallic chromium is added; melting the first part of 400kg of metallic chromium, stirring for 1 hour, and adding the second part of 400kg of metallic chromium in the same manner as the first part; stirring for 1 hour after all the materials are added, and sampling; the nitrogen content is 0.003ppm, the power of the refining period is 300kW, the nitrogen element is reduced by 0.0003 to 0.0005 weight percent per hour, the alloy element is finely adjusted after the gaseous nitrogen element is qualified, the temperature is raised to 1550 ℃, the casting is prepared, and the time of the refining period is 14 hours.
Casting period (casting molding): in the casting period, argon is simultaneously filled into a vacuum chamber and a die casting chamber of the vacuum induction furnace to ensure that the air pressure reaches 20-50Pa, and an ingot mould vehicle is started for casting after the pressure of the vacuum chamber and the pressure of the die casting chamber are consistent; the casting period time is 1h, and the components of the obtained steel ingot and the smelting time are shown in Table 3.
TABLE 3 chemical composition and smelting time of steel ingot obtained in comparative example 2
| C | S | P | Cr | Ni | Mo | N | Time of smelting |
| 0.031 | 0.002 | 0.005 | 12.46 | 8.48 | 2.17 | 0.0010 | 25h |
Comparative example 3
This comparative example illustrates the method for manufacturing a low-nitrogen stainless steel ingot by smelting 0Cr13Ni8Mo in a 6-ton vacuum induction furnace, and differs from example 1 in that chromium metal is added at one time during the refining period.
Melting period (melting treatment): the steel ingot contains the following components in percentage by weight: ni:8.5%, cr:12.5%, mo:2.0%, C:0.03%, S:0.002%, P:0.005 percent of the raw materials are prepared, wherein the chromium metal is reserved completely; under the vacuum degree of 5Pa and the electric power of 400kW, adding pure iron, wherein the total amount of pure iron is 4500kg, the pure iron is put into a bin of the vacuum induction furnace three times, 1500kg is put into the bin each time, the pure iron in the bin is added into a crucible of the vacuum induction furnace 3 times to be molten iron, and 500kg is added into the bin each time; adding metal nickel after pure iron is completely melted, wherein the total amount of the metal nickel is 600kg, adding the metal nickel into a bin of a vacuum induction furnace once, then adding the metal nickel into molten steel by three times, each time adding 200kg, finally adding metal molybdenum, the total amount of the molybdenum plates is 200kg, adding the metal molybdenum into the bin of the vacuum induction furnace once, and then adding the metal molybdenum and the molybdenum plates into the molten steel by three times. After the molten steel is melted, the temperature is controlled to be 1580-1590 ℃, and the melting period is 8 hours.
Refining period (refining treatment): refining the molten steel under the condition that the high vacuum degree is less than or equal to 3Pa, wherein the power in the refining period is 300kW, and the refining temperature is 1580-1590 ℃; when the vacuum degree is less than or equal to 2Pa, adding 800kg of metal chromium at 1580-1590 ℃ at one time, refining at the temperature, stirring for 1 hour after all the metal chromium is added, and sampling; the nitrogen content is 0.0045ppm, the molten steel is refined and denitrified, the power in the refining period is 300kW, the nitrogen element is reduced by 0.0003 to 0.0005 weight percent per hour, the alloy elements are finely adjusted after the gaseous nitrogen element is qualified, the temperature is reduced to 1550 ℃, the casting is prepared, and the time in the refining period is 24 hours.
Casting period (casting molding): in the casting period, argon is simultaneously filled into a vacuum chamber and a mold injection chamber of the vacuum induction furnace, so that the air pressure of the vacuum chamber and the mold injection chamber reaches 20-50Pa, and after the pressure of the vacuum chamber and the pressure of the mold injection chamber are consistent, an ingot mold vehicle is started for casting; the casting period time is 1h, and the components of the obtained steel ingot and the smelting time are shown in Table 4.
TABLE 4 chemical composition and smelting time of steel ingot obtained in comparative example 3
| C | S | P | Cr | Ni | Mo | N | Time of smelting |
| 0.034 | 0.002 | 0.005 | 12.47 | 8.46 | 2.1 | 0.0010 | 33h |
Claims (10)
1. The manufacturing method for smelting the low-nitrogen stainless steel ingot in the vacuum induction furnace is characterized in that the stainless steel ingot comprises the following components in percentage by mass: 12-14%, mo:2-4%, C is less than or equal to 0.04%, ni:8-12%, N is less than or equal to 0.001%, S is less than or equal to 0.003%, P is less than or equal to 0.004%, and the balance of Fe and inevitable impurities, and the preparation method comprises the following steps: adding steelmaking raw materials into a vacuum induction furnace for smelting, wherein the smelting sequentially comprises the following steps: melting treatment, refining treatment and casting molding, wherein,
in the step of melting treatment, raw material chromium is not added, and metal raw materials of iron, nickel and molybdenum are added into a vacuum induction furnace in batches to be melted;
in the refining treatment step, the molten steel (molten steel) which is completely melted after the melting treatment is firstly refined, then metallic chromium is added into the molten steel in batches and is melted, and then the content of the alloy element of the molten steel is finely adjusted after the content of the nitrogen element in the molten steel is qualified so that the content of the component of the molten steel meets the requirement.
2. The manufacturing method for smelting low-nitrogen stainless steel ingots by using the vacuum induction furnace according to claim 1, wherein in the melting treatment step, pure iron is added firstly for melting, then metal nickel is added for melting, and finally metal molybdenum is added for melting; the conditions of the melting treatment are as follows: the material melting power is 400-600kW and is not equal to 600kW, the vacuum degree is less than or equal to 5Pa, and the melting treatment time is 6-8h.
3. The method of manufacturing a low-nitrogen stainless steel ingot by vacuum induction furnace according to claim 1, wherein in the melting step, the same kind of metal raw material is added to the molten steel in the bunker 3 to 5 times, each time in an amount of 1/5 to 1/3 of the total weight of the same kind of metal raw material in the bunker.
4. The manufacturing method for smelting a low-nitrogen stainless steel ingot by using a vacuum induction furnace according to claim 1, wherein in the melting treatment step, the smelting raw materials reach a full-melting state in the later stage of the melting treatment, and the temperature of the fully-melted molten steel is preferably controlled within the range of 1500-1600 ℃, and is preferably 1580-1590 ℃.
5. The method for manufacturing a low-nitrogen stainless steel ingot by vacuum induction furnace smelting according to claim 1, wherein the steelmaking raw materials include metallic nickel, metallic chromium, metallic molybdenum, and pure iron;
preferably, the metallic nickel, metallic chromium, metallic molybdenum, pure iron may be various metals conventionally used in the art for the refining of stainless steel;
preferably, the pure iron is a metal material which is smelted and purified by EAF + LF + VOD to remove harmful elements such as C, si, mn, S, P and the like; more preferably, in the pure iron, the mass percent of N is less than 0.015 percent, the mass percent of S is less than 0.003 percent, the mass percent of P is less than 0.005 percent, the mass percent of Mn is less than 0.03 percent, and the mass percent of Si is less than 0.05 percent;
preferably, the metallic chromium is conventional metallic chromium, and the nitrogen content in the metallic chromium is 0.008-0.015wt%.
6. The method for manufacturing a low-nitrogen stainless steel ingot by vacuum induction furnace smelting according to claim 1, wherein in the refining treatment step, the refining treatment conditions are as follows: the power is 200-400kW, the vacuum degree is less than or equal to 3Pa, preferably, the vacuum degree is less than or equal to 2Pa, the temperature is 1580-1590 ℃, and the time is 10-20min under power frequency stirring.
7. The manufacturing method for smelting a low-nitrogen stainless steel ingot by using the vacuum induction furnace according to claim 1, wherein in the refining treatment, when the vacuum degree of refining is less than or equal to 2Pa, metallic chromium is added into molten steel;
preferably, in the refining treatment step, the metal chromium is averagely divided into 2 parts, each part of the metal chromium is added into the refined molten steel for 3 times, and each time, the metal chromium is added into the molten steel for 1/4-1/3 of the total weight of each part of the metal chromium;
preferably, after the first part of the metal chromium is added and smelted for 1 hour, adding a second part of the metal chromium and continuing smelting for 1 hour;
preferably, during the period of adding the metal chromium, the power is 300-400kW, the smelting temperature is 1580-1590 ℃, the vacuum degree is less than or equal to 5Pa, and more preferably the vacuum degree is less than or equal to 3Pa;
preferably, in the refining treatment step, after each part of chromium metal is added, smelting is carried out for 10-20min under power frequency stirring.
8. The method for manufacturing a low-nitrogen stainless steel ingot by vacuum induction furnace smelting according to claim 1, wherein in the refining treatment, the total refining time is 5-10 hours.
9. The manufacturing method of smelting a low-nitrogen stainless steel ingot by a vacuum induction furnace according to claim 1, wherein in the casting molding step, inert gas is simultaneously filled into a vacuum chamber and a mold injection chamber of the vacuum induction furnace to make the pressures of the vacuum chamber and the mold injection chamber consistent, and then casting is performed to obtain the stainless steel ingot;
preferably, the inert gas is argon, and further preferably, argon with the pressure of 20-50Pa is simultaneously filled in a vacuum chamber and a mold injection chamber of the vacuum induction furnace;
more preferably, the tapping temperature during casting is 1540-1560 ℃.
10. A manufacturing method of a vacuum induction furnace for melting ingots of low-nitrogen stainless steel according to any of claims 1 to 9, characterized in that in the manufacturing method, the total time of the melting is 15 to 20 hours.
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| CN115404394A (en) * | 2022-08-18 | 2022-11-29 | 山西太钢不锈钢股份有限公司 | Smelting method of Fe-Cr soft magnetic alloy material 12FM |
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| JP2002161306A (en) * | 2000-11-24 | 2002-06-04 | Kawasaki Steel Corp | Refining process with decarburization for chromium- containing molten ferrous alloy |
| CN105970074A (en) * | 2016-05-30 | 2016-09-28 | 河北钢铁股份有限公司 | Method for quickly smelting low-nitrogen stainless steel through vacuum induction furnace |
| CN114032441A (en) * | 2021-10-21 | 2022-02-11 | 重庆大学 | Method for smelting ultra-low carbon stainless steel in vacuum induction furnace |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH11140530A (en) * | 1997-11-10 | 1999-05-25 | Nippon Steel Corp | Production of ultra-low nitrogen stainless steel |
| JP2002161306A (en) * | 2000-11-24 | 2002-06-04 | Kawasaki Steel Corp | Refining process with decarburization for chromium- containing molten ferrous alloy |
| CN105970074A (en) * | 2016-05-30 | 2016-09-28 | 河北钢铁股份有限公司 | Method for quickly smelting low-nitrogen stainless steel through vacuum induction furnace |
| CN114032441A (en) * | 2021-10-21 | 2022-02-11 | 重庆大学 | Method for smelting ultra-low carbon stainless steel in vacuum induction furnace |
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| CN115404394A (en) * | 2022-08-18 | 2022-11-29 | 山西太钢不锈钢股份有限公司 | Smelting method of Fe-Cr soft magnetic alloy material 12FM |
| CN115404394B (en) * | 2022-08-18 | 2023-08-18 | 山西太钢不锈钢股份有限公司 | Smelting method of Fe-Cr soft magnetic alloy material 12FM |
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