CN113943902B - Low-gas-content controlled smelting method for high-silicon high-titanium aluminum-containing stainless steel - Google Patents
Low-gas-content controlled smelting method for high-silicon high-titanium aluminum-containing stainless steel Download PDFInfo
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Abstract
The invention discloses a low-gas content controlled smelting method for high-silicon high-titanium aluminum-containing stainless steel, which comprises the following chemical components in percentage by weight: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%, and the balance of Fe and inevitable impurities; the smelting method comprises the following steps: EAF → LF → VOD → LF → VD → ESR. The smelting method can effectively improve the yield strength and the quality stability of the product and improve the primary qualification rate of the product.
Description
Technical Field
The invention belongs to the technical field of metallurgical engineering, and particularly relates to a low-gas-content controlled smelting method for high-silicon high-titanium aluminum-containing stainless steel.
Background
1Cr18Ni11Si4AlTi is a high-silicon, high-titanium and aluminum-containing austenite-ferrite duplex stainless steel, and the steel comprises the following chemical components in percentage by weight: c: 0.10 to 0.18%, Si: 3.40-4.00%, Cr: 17.50-19.50%, S: less than or equal to 0.025%, P: less than or equal to 0.035%, Ni: 10.00-12.00%, Al: 0.10 to 0.30%, Ti: 0.40-0.70%, Mn: less than or equal to 0.80 percent. The 1Cr18Ni11Si4AlTi duplex stainless steel has the characteristics of higher yield strength, good corrosion resistance, good toughness and the like, and is widely applied to the fields of chemical industry, petroleum, energy, marine industry, aerospace, nuclear energy, military industry and the like.
The yield strength sigma 0.2 of the 1Cr18Ni11Si4AlTi duplex stainless steel is more than or equal to 440MPa according to the standards of GB/T1220-92, GJB2294-95 and the like, and is nearly 76 percent higher than the index requirement of the yield strength sigma 0.2 (about 250 MPa) of the similar stainless steel. 1Cr18Ni11Si4AlTi duplex stainless steel produced by a traditional stainless steel smelting method (medium frequency induction furnace + ESR or EAF + AOD) has low yield strength, researchers want measures for improving the strength and toughness of the steel by changing alloy components, a heat treatment system and the like, but the improvement range is very limited after years and multiple rounds of tests. The main reasons are as follows: the smelting method has the advantages that the steel has high contents of nitrogen, hydrogen and oxygen, and is easy to react with elements such as titanium, aluminum and the like in the steel, so that the segregation of the elements such as titanium, silicon and aluminum in a steel ingot is large, and new harmful inclusions are formed in molten steel, and the method is the main reason for causing large fluctuation of yield strength of the steel, poor stability of product quality and low first-pass percent.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the low-gas-content controlled smelting method for the high-silicon high-titanium aluminum-containing stainless steel, which aims to finally improve the yield strength and quality stability of the product and improve the primary qualified rate of the product by improving the metallurgical quality of the product.
The technical scheme of the invention is realized as follows:
a smelting method for controlling the low gas content of high-silicon high-titanium aluminum-containing stainless steel comprises the following chemical components in percentage by weight: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%, and the balance of Fe and inevitable impurities; the smelting method comprises the following steps:
(1) an EAF: after the alloy composition with various metal furnace charges carries out batching calculation, collocation, heat in the electric stove of packing into and melt, blow into oxygen behind the melting down and tentatively degasify, get rid of and mix with, contain the alloy of corresponding element through adding simultaneously, the chemical composition of tentatively adjusting the molten steel is: c: 0.30-0.40%, Cr: 20-20.20%, Ni: 10.00-10.20%, Si: 0.20-0.50%, P: less than or equal to 0.030 percent, adjusting the temperature of the molten steel to be 1600-1650 ℃, and then discharging the molten steel out of the furnace and pouring the molten steel into a ladle;
(2) LF: moving the steel ladle filled with the molten steel in the step (1) to a refining station, reducing Cr element in the electric furnace slag, simultaneously adding alloy containing corresponding elements, and accurately adjusting the chemical components of the molten steel as follows: c: 0.30-0.40%, Cr: 20-20.20%, Ni: 10.00-10.20%, Si: 0.20-0.50%, P: less than or equal to 0.030 percent, and adjusting the temperature of the molten steel to 1590-1620 ℃; hoisting the steel ladle to a slag pit position, driving the steel ladle to incline by using a small hook, introducing Ar for stirring slag, and finally pulling out all steel slag by using a wooden scraper;
(3) VOD: moving the steel ladle filled with the molten steel in the step (2) to a VOD station, blowing oxygen for decarburization on the molten steel under a vacuum condition to remove nitrogen, hydrogen, oxygen and inclusions in the molten steel, and blowing argon from the bottom of the steel ladle to promote the circulation of the molten steel; and (3) finishing VOD oxygen blowing, adding aluminum blocks, ferrosilicon, lime, Cr, Ni and Mn at 1700-1750 ℃, performing vacuum slagging, reduction and alloying, and meeting the control requirement of VOD initial alloying: c: 0.08 to 0.12%, Si: 0.20-0.60%, Cr: 19.00 to 19.50%, Ni: 10.50 to 11.00%, Al: 0.06-0.20%, Mn: 0.35-0.50%, S: less than or equal to 0.025%, P: less than or equal to 0.030 percent; then opening the cover to break vacuum for temperature measurement, and sampling and analyzing the chemical components of the molten steel;
(4) LF: moving the steel ladle filled with the molten steel in the step (3) to a refining station again, adding ferrosilicon, heating, alloying silicon, and heating to 1600-1620 ℃; fine adjustment is carried out on other alloys, and the control targets of the chemical components of the molten steel are as follows: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%;
(5) VD: and (5) moving the steel ladle filled with the molten steel in the step (4) to a VD vacuum treatment station, carrying out vacuum degassing treatment on the molten steel, opening a cover to break vacuum for temperature measurement, and then adding alloy to the target component for fine adjustment, wherein the chemical component control target of the molten steel is as follows: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%; argon blowing treatment is carried out for cooling, and when the temperature is reduced to 1480-1500 ℃, the suspension ladle is cast into an electroslag mother blank;
(6) ESR: and (4) carrying out electroslag remelting on the electroslag mother blank cast in the step (5), remelting and refining the metal material of the electroslag mother blank, and sequentially solidifying to form a steel ingot, wherein the steel ingot is the high-silicon high-titanium aluminum-containing stainless steel.
Further, in the step (3), the temperature is measured after entering the tank to ensure that the temperature of the molten steel is more than or equal to 1550 ℃, the height of the oxygen lance and the pressure of the argon gas are adjusted, and then the oxygen lance is dropped to blow oxygen.
Further, when oxygen is blown, pre-blowing is carried out firstly and then main blowing is carried out, wherein the pre-blowing flow is 450-480 m 3 The flow rate of the main blowing is 550-600 m 3 /h。
Further, in the step (3), the chemical components of the lime are as follows: CaO is more than or equal to 88 percent, SiO 2 ≤5％，S≤0.20％，P≤0.05％，MgO≤3％
Further, the step (5) comprises the following specific steps: argon is communicated, the pressure of the argon is proper to start to fluctuate on the slag surface, the argon reaches the ultimate vacuum degree within 4-7 min, the ultimate vacuum degree is less than or equal to 30Pa, the ultimate vacuum degree is kept for more than or equal to 15min, the cover is opened, the vacuum is broken, the temperature is measured, and alloy is supplemented according to target components for fine adjustment; and then blowing argon to reduce the temperature, so that the temperature of the molten steel is reduced to 1480-1500 ℃, and then carrying out ladle casting.
Further, the slag system adopted in the electroslag remelting in the step (6) comprises: CaF 2 ：51.55～52.45％、CaO：19.55～20.15％、MgO：2.75～3.15％、Al 2 O 3 ：19.55～20.15％、TiO 2 ：3.85～4.25％、Fe 2 O 3 ：≤0.15％。
Compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts multi-connected external refining and vacuum smelting technology, can greatly reduce the content of harmful gas and impurity elements in steel, change the distribution of non-metallic inclusions and improve the metallurgical quality of the high-silicon high-titanium aluminum-containing stainless steel. All indexes of the mechanical property of the final product meet the requirements of the standard (GB/T1220-92 or GJB2294-95), and the one-time qualification rate of the mechanical property sampling detection reaches 100%.
2. Before initial alloying of VOD, Si in molten steel is adjusted and controlled according to the requirements of VOD procedures and residual elements (Si: 0.20-0.50%); and after the VOD initial alloying is finished, adding ferrosilicon in LF, and heating to carry out the final alloying of the Si element. The method avoids the condition that the active element Si is oxidized in a large amount and cannot be reduced and recovered in the VOD oxygen blowing process, increases the reduction task of the Si element in the VOD, and the slag is acidic and erodes the steel ladle of the alkaline furnace lining for a long time; and finally, the silicon element is added in the LF for alloying, the temperature of the LF is relatively low, the time is short, and the corrosion of acid slag on an alkaline furnace lining can be effectively reduced.
3. According to the invention, VOD is adopted to blow oxygen to the molten steel for decarburization under a vacuum condition, argon is blown from the bottom of the steel ladle to promote the circulation of the molten steel, very favorable dynamic conditions can be provided for reaction, and the deoxidation product is CO which is insoluble in the molten steel, so that nitrogen and hydrogen dissolved in the molten steel are diffused into CO bubbles and are exhausted by an air exhaust system at any time, and the floating CO bubbles can also drive suspended inclusions in the molten steel to float up to the slag, thereby obtaining good metallurgical effects of degassing and removing the inclusions.
4. According to the method, nitrogen, hydrogen and oxygen in the molten steel are efficiently removed in the VOD and VD, so that the burning loss of elements such as titanium, aluminum and the like in the subsequent electroslag remelting process can be reduced, harmful impurities are prevented from being generated, and the segregation of the elements such as titanium, silicon and aluminum in the product is small.
Drawings
FIG. 1-distribution of inclusions in the product produced by Process one and Process two.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Preparing main materials and auxiliary materials:
(1) steel material and return material: no rust, no oil stain, no explosive, no closed container, no nonferrous metal and no slag. Steel numbers or codes must be marked, and the materials are stacked in a classified manner, so that the materials cannot be mixed, reliable component analysis results are obtained, and the materials can be used and cannot be mixed and forbidden to be used; the furnace burden is kept dry, and the wet scrap steel cannot enter the furnace; the returned steel and scrap steel are in principle not more than 2 tons, not more than 2000mm long and not more than 500mm wide.
(2) Alloy materials: various alloys must be stacked according to variety and grade, each batch of alloy should have a chemical composition list or a recheck list, and the alloys with similar appearance and section are hung, and the alloys cannot be stacked adjacently and are forbidden to be mixed; the ferroalloy should be kept dry, not stacked in the open air, and must be dried or baked to red for use except cold charging into the furnace.
(3) Auxiliary material
Lime: chemical components: CaO is more than or equal to 88 percent, SiO 2 Less than or equal to 5 percent, less than or equal to 0.20 percent of S, less than or equal to 0.05 percent of P, and less than or equal to 3 percent of MgO; the water content of the lime is less than or equal to 0.50 percent, the block size is 30-100 mm, and the powder and slag inclusion cannot be used.
Fluorite: chemical components: CaF 2 ≥85％，SiO 2 Less than or equal to 14.3 percent and less than or equal to 0.15 percent of S; the fluorite with the water content less than or equal to 0.10 percent and the lumpiness of 0.25-20 mm is used, and the fluorite is cleaned; the appearance quality is emerald green and transparent, and the product is pure and free of impurities. No mountain peel and gangue containing black lead ore, etc. Gangue not more than 5%, high sulfide (black and gray), high Pb (purple), and SiO 2 It is not suitable for use in high patients (opaque white or gray yellow).
Preparing a ladle: cleaning up the residual steel residues at the bottom and on the wall of the steel ladle; when the ladle is baked, the fire is gradually increased from small to large, and the ladle is baked for at least 4 hours at the temperature of more than or equal to 800 ℃ and taken at any time.
A low-gas content controlled smelting method for high-silicon high-titanium aluminum-containing stainless steel comprises the following chemical components in percentage by weight: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%, and the balance of Fe and inevitable impurities; the smelting method comprises the following steps:
(1) an EAF: after the alloy composition with various metal furnace charges carries out batching calculation, collocation, heat in the electric stove of packing into and melt, blow into oxygen behind the melting down and tentatively degasify, get rid of and mix with, contain the alloy of corresponding element through adding simultaneously, the chemical composition of tentatively adjusting the molten steel is: c: 0.30-0.40%, Cr: 20-20.20%, Ni: 10.00-10.20%, Si: 0.20-0.50%, P: less than or equal to 0.030 percent, adjusting the temperature of the molten steel to be 1600-1650 ℃, and then discharging the molten steel out of the furnace and pouring the molten steel into a ladle;
(2) LF: moving the steel ladle filled with the molten steel in the step (1) to a refining station, reducing Cr element in the electric furnace slag, simultaneously adding alloy containing corresponding elements, and accurately adjusting the chemical components of the molten steel as follows: c: 0.30-0.40%, Cr: 20-20.20%, Ni: 10.00-10.20%, Si: 0.20-0.50%, P: less than or equal to 0.030 percent, and adjusting the temperature of the molten steel to 1590-1620 ℃ so as to meet the requirements of the VOD process; hoisting the steel ladle to a slag pit position, driving the steel ladle to incline by using a small hook, turning on Ar to stir and flow slag, and finally pulling out all steel slag by using a wooden scraper;
(3) VOD: moving the steel ladle filled with the molten steel in the step (2) to a VOD station, blowing oxygen for decarburization on the molten steel under a vacuum condition to remove nitrogen, hydrogen, oxygen and inclusions in the molten steel, and blowing argon from the bottom of the steel ladle to promote the circulation of the molten steel; and (3) after VOD oxygen blowing is finished, adding aluminum blocks, ferrosilicon, refined lime, Cr, Ni and Mn at the temperature of 1700-1750 ℃, and carrying out vacuum slagging, reduction and alloying, wherein the VOD initial alloying requirement is as follows: c: 0.08 to 0.12%, Si: 0.20-0.60%, Cr: 19.00 to 19.50%, Ni: 10.50 to 11.00%, Al: 0.06-0.20%, Mn: 0.35-0.50%, S: less than or equal to 0.025%, P: less than or equal to 0.030 percent, then uncovering, breaking vacuum, measuring temperature, sampling and analyzing chemical components of the molten steel;
the VOD method is adopted to blow oxygen to the molten steel for decarburization under the vacuum condition, argon is blown from the bottom of the steel ladle to promote the circulation of the molten steel, very favorable dynamic conditions can be provided for the reaction, and the deoxidation product is CO which is insoluble in the molten steel, so that nitrogen and hydrogen dissolved in the molten steel are diffused into CO bubbles, and the floating CO bubbles can also drive and suspend inclusions in the molten steel to float into slag along with the discharge of an air pumping system, thereby obtaining good metallurgical effects of degassing and removing the inclusions.
The selected lime comprises the following chemical components: CaO is more than or equal to 88 percent, SiO 2 Less than or equal to 5 percent, less than or equal to 0.20 percent of S, less than or equal to 0.05 percent of P, and less than or equal to 3 percent of MgO.
(4) LF: moving the steel ladle filled with the molten steel in the step (3) to a refining station again, adding ferrosilicon, heating, alloying silicon, and heating to 1600-1620 ℃; fine adjustment is carried out on other alloys, and the control targets of the chemical components of the molten steel are as follows: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%;
after VOD initial alloying, adding ferrosilicon in LF and heating for a short time to carry out final alloying of Si element, thereby avoiding that the slag is acidic due to a large amount of oxidation of active element Si in the VOD method and corroding an alkaline lining steel ladle for a long time; meanwhile, the reduction task of the Si element by the VOD method can be reduced; the silicon element is added at the end of the LF for alloying, the temperature of the LF is relatively low, and the time is short, so that the contact time of the acid slag and the alkaline furnace lining is short, and the corrosion to the alkaline furnace lining can be effectively reduced.
(5) VD: and (3) moving the steel ladle filled with the molten steel in the step (4) to a VD vacuum treatment station, carrying out vacuum degassing treatment on the molten steel, opening a cover to break vacuum and measuring temperature, and then adding alloy to target components to carry out fine adjustment, wherein the chemical component control target of the molten steel is as follows: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%; argon blowing treatment is carried out for cooling, and when the temperature is reduced to 1480-1500 ℃, the suspension ladle is cast into an electroslag mother blank;
the molten steel is further subjected to vacuum degassing, and gas and inclusions in the molten steel are further removed, so that the quality of the product is improved.
(6) ESR: and (4) carrying out electroslag remelting on the electroslag mother blank cast in the step (5), remelting and refining the metal material of the electroslag mother blank, and sequentially solidifying to form a steel ingot, wherein the steel ingot is the high-silicon high-titanium aluminum-containing stainless steel. Thus, the produced metal material is pure, and the hairline of the metal material can be improved or eliminated.
In the specific implementation, in the step (3), the temperature is measured after the steel is put into the tank to ensure that the temperature of the molten steel is more than or equal to 1550 ℃, and the height of the oxygen lance and the pressure of argon are adjusted; dropping the gun to blow oxygen, comprehensively controlling the oxygen consumption, and stopping blowing oxygen according to the lower limit of internal control; observing the boiling condition of argon, keeping the vacuum degree less than or equal to 300pa, and keeping vacuum carbon deoxidation for 8 minutes; then adding aluminum blocks, ferrosilicon, selected lime, Cr, Ni and Mn, and carrying out vacuum slagging, reduction and alloying.
In the specific implementation, during oxygen blowing, pre-blowing is firstly carried out and then main blowing is carried out, wherein the pre-blowing flow rate is 450-480 m 3 The flow rate of the main blowing is 550-600 m 3 /h。
When the method is specifically implemented, in the step (5), argon is connected, the pressure of the argon is proper to start to fluctuate on the slag surface, the argon reaches the ultimate vacuum degree within 4-7 min, the ultimate vacuum degree is less than or equal to 30Pa, the ultimate vacuum degree is kept for more than or equal to 15min, the cover is opened, the vacuum is broken, the temperature is measured, and alloy is supplemented according to target components for fine adjustment; and then blowing argon to reduce the temperature, so that the temperature of the molten steel is reduced to 1480-1500 ℃, and then carrying out ladle casting.
In specific implementation, the electroslag remelting adopted slag system in the step (6) comprises the following components: CaF 2 ：51.55～52.45％、CaO：19.55～20.15％、MgO：2.75～3.15％、Al 2 O 3 ：19.55～20.15％、TiO 2 ：3.85～4.25％、Fe 2 O 3 ：≤0.15％。
In use, the purchased CaF 2 、CaO、MgO、Al 2 O 3 、TiO 2 The raw materials are prepared in the production field according to the proportion of a slag system, and then the raw materials are preserved for 4-6 hours at 850 ℃ by using a resistance furnace.
The high-silicon high-titanium aluminum-containing stainless steel is produced by adopting the smelting method and a traditional stainless steel smelting method (medium frequency induction furnace + ESR), wherein the method is marked as method one, and the traditional stainless steel smelting method (medium frequency induction furnace + ESR) is marked as method two.
1. Sampling and observing non-metallic inclusions in the products obtained by the first and second methods, observing under a magnifying glass (with a magnification of 500 times), wherein the distribution diagram of the inclusions is shown in fig. 1, wherein fig. 1a is the distribution diagram of the inclusions in the products obtained by the first method, and fig. 1b is the distribution diagram of the inclusions in the products obtained by the second method, and as can be seen from fig. 1, the inclusions in the products obtained by the first method are fine and uniformly dispersed, and the inclusions in the products obtained by the second method are in a stacking state. And detecting the contents of gas and inclusions in the high-silicon high-titanium aluminum-containing stainless steel produced by the first analysis method and the second analysis method, wherein the analysis and comparison data of the gas and the inclusions are shown in table 1.
TABLE 1 analysis of gas and inclusions
As can be seen from Table 1, the content of gas and impurities in steel can be greatly reduced by carrying out vacuum degassing treatment on VOD and VD duplex molten steel, and compared with the second method, the denitrification rate of the first method is more than or equal to 50 percent; the dehydrogenation rate is more than or equal to 35 percent; the deoxidation rate is more than or equal to 50 percent; the removal rate of the D-type inclusions is more than or equal to 50 percent.
2. The products produced by methods one and two were analyzed and the chemical composition data are shown in table 2.
Table 2 chemical composition data
As can be seen from Table 2, the product obtained by the invention has stable chemical composition and yield, and the segregation of the chemical composition of the head and the tail of the ingot is small. Therefore, in the process of smelting the high-silicon high-titanium aluminum-containing stainless steel by the smelting method, the optimal alloy element adding range scheme can be formulated according to the influence degree of each alloy element in the steel on the structure and the performance: the gamma forming element in the high-silicon high-titanium aluminum-containing stainless steel is matched according to the lower limit, the alpha forming element is matched according to the upper limit, the realization of the optimal design adjustment of the alloy elements is ensured, and the sufficient alpha phasor in the steel structure is ensured from the beginning.
3. The mechanical properties and yield of the high-silicon high-titanium aluminum-containing stainless steel obtained by the first method and the second method are shown in Table 3.
TABLE 3 mechanical Properties and yield
As can be seen from Table 3, the mechanical properties of the product obtained by the first method meet the requirements of the standard (GB/T1220-92 or GJB2294-95), and compared with the second method, the yield strength of the high-silicon high-titanium aluminum-containing stainless steel obtained by the first method is improved by 107MPa, the tensile strength is improved by 40MPa, the first pass rate is increased by 43.77%, the first pass rate reaches 100%, and the yield of steel ingots is increased by 8.02%.
According to the characteristics (the silicon content is too high) of the high-silicon high-titanium aluminum-containing stainless steel, the alloying of the Si element is carried out in the LF furnace finally, so that the silicon content in the steel is prevented from being too high, the loss of active element Si due to large oxidation in a VOD method is avoided, the slag is acidic, and the alkaline lining steel ladle is corroded for a long time; meanwhile, the reduction task of Si element by VOD method is reduced, and the loss of Si alloy is reduced. The method flexibly applies various multi-connected molten steel external refining means, has stronger molten steel refining capability, not only improves the metallurgical quality of products, but also reduces the production cost, saves energy and improves the overall production efficiency. The requirements that all indexes of the final product meet the standards are met; the one-time qualification rate of mechanical property sampling detection reaches 100%, the supply of materials urgently needed by users is guaranteed, and the method has great economic benefit.
Finally, it should be noted that the above-mentioned examples of the present invention are only examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. Variations and modifications in other variations will occur to those skilled in the art upon reading the foregoing description. Not all embodiments are exhaustive. All obvious changes and modifications of the present invention are within the scope of the present invention.
Claims (6)
1. A low-gas content controlled smelting method for high-silicon high-titanium aluminum-containing stainless steel comprises the following chemical components in percentage by weight: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%, and the balance of Fe and inevitable impurities; the method is characterized by comprising the following steps:
(1) an EAF: after the alloy composition with various metal furnace charges carries out batching calculation, collocation, heat in the electric stove of packing into and melt, blow into oxygen behind the melting down and tentatively degasify, get rid of and mix with, contain the alloy of corresponding element through adding simultaneously, the chemical composition of tentatively adjusting the molten steel is: c: 0.30-0.40%, Cr: 20-20.20%, Ni: 10.00-10.20%, Si: 0.20-0.50%, P: less than or equal to 0.030 percent, adjusting the temperature of the molten steel to be 1600-1650 ℃, and then discharging the molten steel out of the furnace and pouring the molten steel into a ladle;
(2) LF: moving the steel ladle filled with the molten steel in the step (1) to a refining station, reducing Cr element in the electric furnace slag, simultaneously adding alloy containing corresponding elements, and accurately adjusting the chemical components of the molten steel as follows: c: 0.30-0.40%, Cr: 20-20.20%, Ni: 10.00-10.20%, Si: 0.20-0.50%, P: less than or equal to 0.030 percent, and adjusting the temperature of the molten steel to 1590-1620 ℃; hoisting the steel ladle to a slag pit position, driving the steel ladle to incline by using a small hook, introducing Ar for stirring slag, and finally pulling out all steel slag by using a wooden scraper;
(3) VOD: moving the steel ladle filled with the molten steel in the step (2) to a VOD station, blowing oxygen for decarburization on the molten steel under a vacuum condition to remove nitrogen, hydrogen, oxygen and inclusions in the molten steel, and blowing argon from the bottom of the steel ladle to promote the circulation of the molten steel; and (3) finishing VOD oxygen blowing at the temperature of 1700-1750 ℃, adding aluminum blocks, ferrosilicon, lime, Cr, Ni and Mn, and carrying out vacuum slagging, reduction and alloying, wherein the control requirement of VOD initial alloying is as follows: c: 0.08 to 0.12%, Si: 0.20-0.60%, Cr: 19.00 to 19.50%, Ni: 10.50 to 11.00%, Al: 0.06-0.20%, Mn: 0.35-0.50%, S: less than or equal to 0.025%, P: less than or equal to 0.030 percent; then opening the cover to break vacuum for temperature measurement, and sampling and analyzing the chemical components of the molten steel;
(4) LF: moving the steel ladle filled with the molten steel in the step (3) to a refining station again, adding ferrosilicon, heating, alloying silicon, and heating to 1600-1620 ℃; fine adjustment is carried out on other alloys, and the control targets of the chemical components of the molten steel are as follows: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%;
(5) VD: and (3) moving the steel ladle filled with the molten steel in the step (4) to a VD vacuum treatment station, carrying out vacuum degassing treatment on the molten steel, opening a cover to break vacuum and measuring temperature, and then adding alloy to target components to carry out fine adjustment, wherein the chemical component control target of the molten steel is as follows: c: 0.14 to 0.15%, Si: 3.90-3.95%, Cr: 19.20 to 19.30%, Ni: 10.20-10.30%, Al: 0.18 to 0.25%, Mn: 0.40-0.50%, S: less than or equal to 0.020%, P: less than or equal to 0.030 percent, Ti: 0.55-0.65%; argon blowing treatment is carried out for cooling, and when the temperature is reduced to 1480-1500 ℃, the suspension ladle is cast into an electroslag mother blank;
(6) ESR: and (4) carrying out electroslag remelting on the electroslag mother blank cast in the step (5), remelting and refining metal materials of the electroslag mother blank, and sequentially solidifying to form a steel ingot, wherein the steel ingot is the high-silicon high-titanium aluminum-containing stainless steel.
2. The controlled smelting method for the high-silicon high-titanium aluminum-containing stainless steel with low gas content according to claim 1, wherein in the step (3), the temperature is measured after entering the tank to ensure that the temperature of the molten steel is more than or equal to 1550 ℃, the height of the oxygen lance and the pressure of the argon gas are adjusted, and then oxygen is blown by falling the oxygen lance.
3. The low-gas-content controlled smelting method for the high-silicon high-titanium aluminum-containing stainless steel according to claim 2, characterized in that pre-blowing is performed before main blowing during oxygen blowing, wherein the pre-blowing flow rate is 450-480 m 3 The flow rate of the main blowing is 550-600 m 3 /h。
4. The low-gas-content controlled smelting method for the high-silicon high-titanium aluminum-containing stainless steel according to claim 1, wherein in the step (3), the chemical components of the lime are as follows: CaO is more than or equal to 88 percent, SiO 2 ≤5%，S≤0.20%，P≤0.05%，MgO≤3%。
5. The low-gas-content controlled smelting method for the high-silicon high-titanium aluminum-containing stainless steel according to claim 1, characterized in that the step (5) comprises the following specific steps: argon is communicated, the pressure of the argon is proper to start to fluctuate on the slag surface, the argon reaches the ultimate vacuum degree within 4-7 min, the ultimate vacuum degree is less than or equal to 30Pa, the ultimate vacuum degree is kept for more than or equal to 15min, the cover is opened, the vacuum is broken, the temperature is measured, and alloy is supplemented according to target components for fine adjustment; and then blowing argon to reduce the temperature, so that the temperature of the molten steel is reduced to 1480-1500 ℃, and then carrying out ladle casting.
6. The low-gas-content controlled smelting method for the high-silicon high-titanium aluminum-containing stainless steel according to claim 1, wherein the electroslag remelting in the step (6) adopts a slag system comprising: CaF 2 ：51.55～52.45%、CaO：19.55～20.15%、MgO：2.75～3.15%、Al 2 O 3 ：19.55～20.15%、TiO 2 ：3.85～4.25%、Fe 2 O 3 ：≤0.15%。
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