CN108715913B - Method for smelting 9Ni steel by electric furnace - Google Patents
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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
- C21C5/52—Manufacture of steel in electric furnaces
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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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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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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- 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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Abstract
The invention discloses a method for smelting 9Ni steel by an electric furnace, which comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace; in the vacuum residual oxygen decarburization process of the VD furnace, a steel ladle enters the VD furnace, the vacuum degree reaches less than or equal to 200Pa, the vacuum is relieved, and carbon in the molten steel is decarburized: c is less than or equal to 0.01 percent. The invention adopts EAF furnace for primary smelting, controls the temperature and components of the molten steel, then enters VD vacuum decarburization, enters LF furnace refining process for deoxidation and component adjustment, and finally controls the pouring temperature reasonably through VD furnace vacuum treatment. The 9Ni steel produced by the invention has qualified components and few inclusions, the thickness of the rolled steel plate is less than or equal to 50mm, the yield strength Rp0.2 is more than or equal to 515MPa, and the tensile strength Rm: 690-825 MPa; the minimum impact energy is more than or equal to 21J at the temperature of minus 196 ℃, and the lateral expansion is more than or equal to 0.381 mm.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a method for smelting 9Ni steel by an electric furnace.
Background
The 9Ni steel has good obdurability at ultralow temperature (below minus 196 ℃) and good processing and welding performance, and is an ideal material for low-temperature high-alloy pressure vessels such as LNG storage tanks. The alloy has high content (about 9 percent of Ni), the impact energy at the temperature of 196 ℃ below zero is required to be more than or equal to 21J transversely, P, S in steel is required to be as low as possible, and the main elements are C: 0.05 to 0.07 percent, Si: 0.16-0.30%, Mn: 0.70-0.80%, P is less than or equal to 0.007%, S is less than or equal to 0.003%, Ni: 9.1 to 9.4 percent. The alloy addition amount is large, the control difficulty of electric furnace smelting C, P is large, and the requirement on inclusion is strict.
Because the carbon content of the 9Ni steel is low, if the 9Ni steel is directly smelted after the electric furnace steel is tapped, the C of the molten steel is required to be less than 0.02 percent, and the molten steel is seriously oxidized at the moment, a large amount of deoxidizers are required to be consumed, and the deoxidizers increase the pollution to the molten steel; the LF refining furnace has large alloy adding amount and long power transmission time, and carbon falling off from electrodes makes the C of molten steel easily exceed the upper limit to judge waste.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for smelting 9Ni steel by an electric furnace, which adopts an EAF furnace to create a condition for decarburization, performs VD decarburization until C is less than or equal to 0.01 percent, adjusts alloy components in LF, performs deoxidation and removes inclusions, and finally performs high-vacuum degassing and removes inclusions, so that the components of molten steel before casting are qualified, and the purity is high; the produced 9Ni steel has qualified components, few inclusions, high flaw detection qualification rate of rolled steel plates and performance meeting requirements.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for smelting 9Ni steel by an electric furnace comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace; in the vacuum residual oxygen decarburization process of the VD furnace, a steel ladle enters the VD furnace, the vacuum degree reaches less than or equal to 200Pa, the vacuum is relieved, and carbon in the molten steel is decarburized: c is less than or equal to 0.01 percent.
According to the EAF furnace primary smelting process, when C is more than or equal to 0.02% and less than or equal to 0.05%, P is less than or equal to 0.004%, molten steel is slightly oxidized and is tapped without slag, the temperature of the molten steel tapped to a ladle is controlled to be 1590-1630 ℃, and 2-3 kg/t of lime is added during tapping.
In the LF furnace refining process, molten steel enters an LF furnace, is firstly electrified to heat and slag, and alloy Ni of 40-50 kg/t steel is added when the temperature reaches 1630 ℃; continuously heating to 1630 ℃ again, and adding 40-50 kg/t of steel alloy Ni; then feeding 1.4-1.8 kg/t steel of strong deoxidizer aluminum wire when the temperature reaches more than 1600 ℃; feeding electricity, deoxidizing by using 0.2-0.5 kg/t steel aluminum particles or 0.2-0.5 kg/t steel aluminum powder, whitening the furnace slag within 5min, keeping white slag, adjusting Si and Mn components, carrying out strong stirring for 2-4 min when the temperature reaches 1620-1640 ℃, desulfurizing to remove impurities, keeping molten steel from being exposed, and continuing strong stirring if S is more than 0.004%; when the white slag is kept for more than or equal to 25min, the molten steel C: 0.03-0.05%, Si: 0.16-0.20%, Mn: 0.70-0.80%, S is less than or equal to 0.004%, Ni: 9.1-9.3%, the temperature reaches 1660-1680 ℃, and LF refining is finished; and (5) pouring 30-60% of furnace slag, and entering a VD procedure.
In the VD vacuum treatment process, after the molten steel components are finely adjusted, the flow of argon is 160-300 NL/min, and the vacuum degree is less than or equal to 66.7Pa for treatment for more than or equal to 20 min; after VD, weakly stirring for 8-15 min, and not exposing molten steel; and when the molten steel reaches the casting requirement temperature, the ladle is cast into an ingot blank.
The molten steel is slightly over oxidized, namely the C content of the molten steel is less than or equal to 0.05 percent, and the oxygen content is 100-500 ppm.
The strong stirring refers to the argon flow rate of 800-1500 NL/min, and the weak stirring refers to the argon flow rate of 20-50 NL/min.
The 9Ni steel produced by the method of the invention comprises the following chemical components: c: 0.05 to 0.07%, Si: 0.16-0.30%, Mn: 0.70-0.80%, P is less than or equal to 0.007%, S is less than or equal to 0.003%, and Ni: 9.1-9.4%, and the balance of Fe and inevitable impurity elements;
the thickness of the 9Ni steel plate produced by the method is less than or equal to 50 mm.
The 9Ni steel plate produced by the method has the following properties: yield strength Rp0.2 is more than or equal to 515MPa, tensile strength Rm: 690-825 MPa; the minimum impact energy is more than or equal to 21J at the temperature of minus 196 ℃, and the lateral expansion is more than or equal to 0.381 mm.
The flaw detection qualification rate of the 9Ni steel plate produced by the method is more than or equal to 99.4 percent.
The invention relates to a method for smelting 9Ni steel by an electric furnace, wherein the 9Ni steel product standard refers to ASTM A20; product performance testing methods standard reference ASTM a 370; the product flaw detection standard is referred to A578/A578M.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: 1. the invention adopts the VD furnace to perform vacuum residual oxygen decarburization, utilizes the characteristic that carbon-oxygen reaction is easy to carry out in vacuum, and carbon-oxygen products CO are easy to discharge, and simultaneously can carry other harmful gases N, H to discharge molten steel, thereby reducing the consumption of LF deoxidizer later and purifying the molten steel. 2. According to the invention, refining is carried out by an LF furnace, the temperature is raised by electricity at the beginning stage, and is not deoxidized, and carbon falling off from an electrode is oxidized by slag or oxygen in molten steel in the temperature raising process because the molten steel and the slag are not deoxidized, so that the molten steel does not expand carbon or slightly expands carbon; the alloy is added in two times, so that the problems that the temperature of molten steel slag is too low, the fluidity of the slag is poor, and the carbon of molten steel rises too fast during power transmission can be avoided. 3. According to the invention, only aluminum particles or aluminum powder is used for deoxidation, so that the deoxidation capability is enhanced, and the slag is promoted to adsorb impurities. 4. The invention controls the vacuum treatment and the argon stirring strength after the vacuum treatment through high vacuum degassing, can improve the degassing effect, promotes slag to adsorb impurities, and avoids secondary oxidation of molten steel. 5. The 9Ni steel produced by the invention has qualified components and few inclusions, and the flaw detection qualification rate of the rolled steel plate reaches more than 99.4 percent. 6. The thickness of the 9Ni steel plate produced by the method is less than or equal to 50mm, the yield strength Rp0.2 is more than or equal to 515MPa, and the tensile strength Rm: 690-825 MPa, the minimum impact energy at-196 ℃ is more than or equal to 21J, and the lateral expansion is more than or equal to 0.381 mm.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
The method for smelting 9Ni steel by the electric furnace comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace, and comprises the following specific process steps:
(1) the primary smelting process of the EAF furnace comprises the following steps: tapping 100t, namely tapping the steel until the temperature of molten steel reaches 1590 ℃, adding 2kg/t of steel by lime during tapping, and adding molten steel C: 0.02%, P: 0.004%, oxygen content 100 ppm;
(2) a VD furnace vacuum residual oxygen decarburization process: the steel ladle enters a VD furnace, the vacuum degree is 200Pa, the vacuum is relieved, and the carbon in the steel ladle is removed: c: 0.01 percent;
(3) and (3) refining in an LF furnace: feeding molten steel into an LF furnace, firstly, supplying electricity to heat and slagging, and adding 40kg/t of steel alloy Ni when the temperature reaches 1630 ℃; then, continuously heating to 1640 ℃, and adding 50kg/t of steel alloy Ni; feeding 1.4kg/t of aluminum wire when the temperature of molten steel reaches 1610 ℃; feeding electricity, deoxidizing with 0.5kg/t steel aluminum particles, whitening the slag within 5min, keeping the white slag, adjusting Si and Mn components, and strongly stirring for 3min with argon flow 1100NL/min when the temperature reaches 1620 ℃; and when white slag is kept for 25min, molten steel C: 0.04%, Si: 0.16%, Mn: 0.70%, S: 0.004%, Ni: 9.1 percent, the temperature reaches 1660 ℃, and LF refining is finished; pouring 50% of slag, and entering a VD process;
(4) VD vacuum treatment process: finely adjusting the components of the molten steel, treating for 20min with the vacuum degree less than or equal to 66.7Pa and the argon flow of 160 NL/min; and D, finishing the argon flow 35NL/min weak stirring for 8min by VD, and when the temperature of the molten steel reaches the required temperature, pouring the molten steel into an ingot blank by a ladle.
Example 9Ni steel product: ni: 9.10%, C: 0.06%, P: 0.006%, S: 0.002%, Si: 0.16%, Mn: 0.70 percent, and the balance of Fe and inevitable impurity elements.
In the embodiment, the thickness of the finished Ni steel product is 14mm, and the flaw detection qualification rate of the steel plate is 100%; the performance of the finished product is as follows: yield strength rp 0.2: 560MPa, tensile strength Rm: 705MPa, minimum impact energy at-196 ℃: 30J, lateral expansion: 0.68 mm.
Example 2
The method for smelting 9Ni steel by the electric furnace comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace, and comprises the following specific process steps:
(1) the primary smelting process of the EAF furnace comprises the following steps: tapping 100t, the temperature of molten steel to a ladle is 1630 ℃, adding 3kg/t of steel by lime during tapping, and adding molten steel C: 0.03%, P: 0.003% and an oxygen content of 300 ppm;
(2) a VD furnace vacuum residual oxygen decarburization process: the steel ladle enters a VD furnace, the vacuum degree is 200Pa, the vacuum is relieved, and the carbon in the steel ladle is removed: c: 0.008 percent;
(3) and (3) refining in an LF furnace: feeding molten steel into an LF furnace, firstly, supplying power, heating and slagging, and adding 50kg/t of steel alloy Ni when the temperature reaches 1640 ℃; then, continuously heating to 1650 ℃, and adding 42kg/t of alloy Ni; feeding 1.8kg/t steel by an aluminum wire when the temperature of the molten steel reaches 1620 ℃; powering on, deoxidizing with 0.2kg/t steel aluminum powder, whitening the slag within 5min, keeping white slag, adjusting Si and Mn components, and strongly stirring for 2min with argon flow of 1200NL/min when the temperature reaches 1640 ℃; when white slag is kept for 32min, molten steel C: 0.03%, Si: 0.18%, Mn: 0.80%, S: 0.003%, Ni: 9.25 percent, the temperature reaches 1680 ℃, and LF refining is finished; pouring 50% of slag, and entering a VD process;
(4) VD vacuum treatment process: finely adjusting the components of the molten steel, treating for 20min with the vacuum degree less than or equal to 66.7Pa and the argon flow rate of 300 NL/min; and VD, finishing argon flow 40NL/min weak stirring for 12min, and when the temperature of the molten steel reaches the required temperature, pouring the molten steel into an ingot blank by a ladle.
Example 9Ni steel product: ni: 9.25%, C: 0.050%, P: 0.005%, S: 0.0015%, Si: 0.18%, Mn: 0.80 percent, and the balance of Fe and inevitable impurity elements.
In the embodiment, the thickness of the finished Ni steel product is 20mm, and the flaw detection qualification rate of the steel plate is 100%; the performance of the finished product is as follows: yield strength rp 0.2: 620MPa, tensile strength Rm: 770MPa, minimum impact energy at-196 ℃: 40J, lateral expansion: 0.50 mm.
Example 3
The method for smelting 9Ni steel by the electric furnace comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace, and comprises the following specific process steps:
(1) the primary smelting process of the EAF furnace comprises the following steps: tapping 100t, leading the temperature of molten steel to a ladle to be 1610 ℃, adding 2.5kg/t of steel into lime during tapping, leading the molten steel C: 0.04%, P: 0.004%, and the oxygen content is 200 ppm;
(2) a VD furnace vacuum residual oxygen decarburization process: the steel ladle enters a VD furnace, the vacuum degree is 200Pa, the vacuum is relieved, and the carbon in the steel ladle is removed: c: 0.01 percent;
(3) and (3) refining in an LF furnace: feeding molten steel into an LF furnace, firstly, supplying electricity to heat and slagging, and adding 45kg/t of steel alloy Ni when the temperature reaches 1635 ℃; then continuously heating to 1635 ℃, and adding 46kg/t of steel alloy Ni; feeding 1.6kg/t steel by an aluminum wire when the temperature of the molten steel reaches 1620 ℃; powering on, deoxidizing with 0.2kg/t steel aluminum particles, whitening the slag within 5min, keeping white slag, adjusting Si and Mn components, and strongly stirring for 4min with argon flow of 1000NL/min when the temperature reaches 1630 ℃; when white slag is kept for 26min, molten steel C: 0.05%, Si: 0.20%, Mn: 0.75%, S: 0.0025%, Ni: 9.15 percent, the temperature reaches 1675 ℃, and LF refining is finished; pouring out 60% of slag, and entering a VD process;
(4) VD vacuum treatment process: finely adjusting the components of molten steel to an internal control range, treating for 20min, wherein the vacuum degree is less than or equal to 66.7Pa, and the argon flow is 260 NL/min; and D, finishing the argon flow 30NL/min weak stirring for 15min by VD, and when the temperature of the molten steel reaches the required temperature, pouring the molten steel into an ingot blank by a ladle.
Example 9Ni steel product: ni: 9.20%, C: 0.062%, P: 0.006%, S: 0.002%, Si: 0.30%, Mn: 0.75 percent, and the balance of Fe and inevitable impurity elements.
In the embodiment, the thickness of the finished product of the Ni steel is 50mm, and the flaw detection qualification rate of the steel plate is 99.5%; the performance of the finished product is as follows: yield strength rp 0.2: 600MPa, tensile strength Rm: 730MPa, minimum impact energy at-196 ℃: 55J, lateral expansion: 0.53 mm.
Example 4
The method for smelting 9Ni steel by the electric furnace comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace, and comprises the following specific process steps:
(1) the primary smelting process of the EAF furnace comprises the following steps: tapping 100t, namely tapping the steel at the temperature of 1600 ℃ from the molten steel to the ladle, adding 2.8kg/t of steel into lime during tapping, and adding the molten steel C: 0.05%, P: 0.002% and oxygen content 400 ppm;
(2) a VD furnace vacuum residual oxygen decarburization process: the steel ladle enters a VD furnace, the vacuum degree is 200Pa, the vacuum is relieved, and the carbon in the steel ladle is removed: c: 0.007%;
(3) and (3) refining in an LF furnace: feeding molten steel into an LF furnace, firstly, supplying electricity to heat and slagging, and adding alloy Ni of 48kg/t steel when the temperature reaches 1630 ℃; then, continuously heating to 1645 ℃, and adding 43kg/t of alloy Ni; feeding 1.55kg/t of aluminum wire when the temperature of the molten steel reaches 1620 ℃; powering on, deoxidizing with 0.5kg/t steel aluminum powder, whitening the slag within 5min, keeping white slag, adjusting Si and Mn components, and strongly stirring for 3min with argon flow of 1500NL/min when the temperature reaches 1640 ℃; and when the white slag is kept for 30min, the molten steel C: 0.045%, Si: 0.16%, Mn: 0.70%, S: 0.004%, Ni: 9.1 percent, the temperature reaches 1660 ℃, and LF refining is finished; pouring out 40% of slag, and entering a VD process;
(4) VD vacuum treatment process: finely adjusting the components of molten steel to an internal control range, treating for 20min, wherein the vacuum degree is less than or equal to 66.7Pa, and the argon flow is 280 NL/min; and D, finishing the argon flow of 20NL/min by VD, weakly stirring for 10min, and when the temperature of the molten steel reaches the required temperature, pouring the molten steel into an ingot blank by a ladle.
Example 9Ni steel product: ni: 9.18%, C: 0.06%, P: 0.006%, S: 0.002%, Si: 0.16%, Mn: 0.70 percent, and the balance of Fe and inevitable impurity elements.
In the embodiment, the thickness of the finished product of the Ni steel is 40mm, and the flaw detection qualification rate of the steel plate is 99.6 percent; the performance of the finished product is as follows: the performance of the finished product is as follows: yield strength rp 0.2: 715MPa, tensile strength Rm: 761MPa, minimum impact energy at-196 ℃: 35J, lateral expansion: 0.49 mm.
This example 5
The method for smelting 9Ni steel by the electric furnace comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace, and comprises the following specific process steps:
(1) the primary smelting process of the EAF furnace comprises the following steps: tapping 105t, wherein the temperature of molten steel to a ladle is 1630 ℃, adding 3.0kg/t of steel into lime during tapping, and adding molten steel C: 0.03%, P: 0.002% and oxygen content 500 ppm;
(2) a VD furnace vacuum residual oxygen decarburization process: the steel ladle enters a VD furnace, the vacuum degree reaches 180Pa, the vacuum is relieved, and carbon in the steel ladle is removed: c: 0.005 percent;
(3) and (3) refining in an LF furnace: feeding molten steel into an LF furnace, firstly, supplying power, heating and slagging, and adding 46kg/t of steel alloy Ni when the temperature reaches 1640 ℃; then continuously heating to 1630 ℃, and adding 40kg/t of steel alloy Ni; feeding 1.7kg/t of aluminum wire when the temperature of molten steel reaches 1600 ℃; feeding electricity, deoxidizing with 0.4kg/t steel aluminum particles, whitening the slag within 5min, keeping the white slag, adjusting the components of Si and Mn, and strongly stirring for 3min with argon flow of 800NL/min when the temperature reaches 1625 ℃; when white slag is kept for 28min, molten steel C: 0.05%, Si: 0.17%, Mn: 0.72%, S: 0.003%, Ni: 9.3 percent, when the temperature reaches 1680 ℃, finishing LF refining, pouring 30 percent of slag, and entering a VD procedure;
(4) VD vacuum treatment process: finely adjusting the components of molten steel to an internal control range, treating for 25min, wherein the vacuum degree is less than or equal to 66.7Pa, and the argon flow is 220 NL/min; and VD, finishing argon flow 50NL/min weak stirring for 13min, and when the temperature of the molten steel reaches the required temperature, pouring the molten steel into an ingot blank by a ladle.
Example 9Ni steel product: ni: 9.4%, C: 0.07%, P: 0.007%, S: 0.003%, Si: 0.20%, Mn: 0.75 percent, and the balance of Fe and inevitable impurity elements.
In the embodiment, the thickness of the finished product of the Ni steel is 28mm, and the flaw detection qualification rate of the steel plate is 99.5%; the performance of the finished product is as follows: the performance of the finished product is as follows: yield strength rp 0.2: 705MPa, tensile strength Rm: 756MPa, minimum impact energy at-196 ℃: 26J, lateral expansion: 0.53 mm.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.
Claims (5)
1. A method for smelting 9Ni steel in an electric furnace, wherein the chemical composition of the 9Ni steel is as follows: c: 0.05 to 0.07%, Si: 0.16-0.30%, Mn: 0.70-0.80%, P is less than or equal to 0.007%, S is less than or equal to 0.003%, and Ni: 9.1-9.4%, and the balance of Fe and inevitable impurity elements, and is characterized in that the method comprises the working procedures of primary smelting in an EAF furnace, vacuum residual oxygen decarburization in a VD furnace, refining in an LF furnace and vacuum treatment in the VD furnace; in the vacuum residual oxygen decarburization process of the VD furnace, a steel ladle enters the VD furnace, the vacuum degree reaches less than or equal to 200Pa, the vacuum is relieved, and carbon in the molten steel is decarburized: c is less than or equal to 0.01 percent; in the EAF furnace primary smelting process, when C is more than or equal to 0.02% and less than or equal to 0.05%, P is less than or equal to 0.004%, molten steel is slightly peroxide and slag-free to be tapped, the temperature of the molten steel in tapping to a ladle is controlled to be 1590-1630 ℃, and 2-3 kg/t of lime is added during tapping; the molten steel is slightly over oxidized, namely the C content of the molten steel is less than or equal to 0.05 percent, and the oxygen content is 100-500 ppm; in the LF furnace refining process, molten steel enters an LF furnace, electricity is firstly supplied to heat and slag is formed, and alloy Ni of 40-50 kg/t steel is added when the temperature reaches 1630 ℃; continuously heating to 1630 ℃ again, and adding 40-50 kg/t of steel alloy Ni; then feeding 1.4-1.8 kg/t steel of strong deoxidizer aluminum wire when the temperature reaches more than 1600 ℃; powering on, deoxidizing by using 0.2-0.5 kg/t steel aluminum particles or 0.2-0.5 kg/t steel aluminum powder, whitening the slag within 5min, keeping the white slag, and adjusting the components of Si and Mn; when the temperature reaches 1620-1640 ℃, carrying out strong stirring for 2-4 min, removing sulfur and impurities, and if S is more than 0.004%, continuing to carry out strong stirring; when the white slag is kept for more than or equal to 25min, the molten steel C: 0.03-0.05%, Si: 0.16-0.20%, Mn: 0.70-0.80%, S is less than or equal to 0.004%, Ni: 9.1-9.3%, the temperature reaches 1660-1680 ℃, and LF refining is finished; and pouring 30-60% of slag, and entering a vacuum treatment process of a VD furnace, wherein strong stirring is argon flow of 800-1500 NL/min.
2. The method for smelting 9Ni steel by using the electric furnace as claimed in claim 1, wherein in the VD furnace vacuum treatment process, after the molten steel components are finely adjusted, the flow of argon is 160-300 NL/min, and the vacuum degree is less than or equal to 66.7Pa, and the treatment time is more than or equal to 20 min; and (5) finishing the vacuum treatment process of the VD furnace, weakly stirring for 8-15 min without exposing molten steel, wherein the weak stirring is 20-50 NL/min of argon flow.
3. The method for smelting 9Ni steel by an electric furnace according to claim 1 or 2, wherein the thickness of the 9Ni steel plate produced by the method is less than or equal to 50 mm.
4. The method for smelting 9Ni steel by an electric furnace according to claim 3, wherein the 9Ni steel plate produced by the method has the following properties: yield strength Rp0.2 is more than or equal to 515MPa, tensile strength Rm: 690-825 MPa; the minimum impact energy is more than or equal to 21J at the temperature of minus 196 ℃, and the lateral expansion is more than or equal to 0.381 mm.
5. The method for smelting 9Ni steel by an electric furnace according to claim 4, wherein the flaw detection qualification rate of the 9Ni steel plate produced by the method is more than or equal to 99.4%.
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| CN201810580966.5A CN108715913B (en) | 2018-06-07 | 2018-06-07 | Method for smelting 9Ni steel by electric furnace |
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| CN101653822A (en) * | 2009-05-25 | 2010-02-24 | 莱芜钢铁股份有限公司 | Electric furnace continuous casting short process production method of oil well pipe billets |
| CN101705423A (en) * | 2009-11-25 | 2010-05-12 | 首钢总公司 | Low-cost steel plate for building structure and manufacturing method thereof |
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| CN102978332A (en) * | 2012-12-26 | 2013-03-20 | 首钢总公司 | Smelting method of 9Ni steel |
| CN104032226B (en) * | 2013-09-26 | 2015-11-11 | 北大方正集团有限公司 | A kind of non-hardened and tempered steel and production technique thereof |
| CN103602888B (en) * | 2013-12-02 | 2015-05-27 | 南京钢铁股份有限公司 | Manufacturing method for low-compression ratio hot-rolled 9Ni steel thick plate |
| CN103642978B (en) * | 2013-12-09 | 2015-12-30 | 莱芜钢铁集团有限公司 | A kind of electric furnace short route smelts the method containing nickel steel |
| CN104894460A (en) * | 2014-03-05 | 2015-09-09 | 鞍钢股份有限公司 | Ni content control method of 9Ni steel |
| CN104018091B (en) * | 2014-06-18 | 2016-11-23 | 江苏省沙钢钢铁研究院有限公司 | A kind of reinforcing bar and preparation method thereof |
| CN104438334B (en) * | 2014-09-19 | 2016-11-23 | 衡阳华菱钢管有限公司 | Medium caliber 9Ni low temperature seamless steel pipe and production method |
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