CN112522472A - Method for smelting and denitrifying stainless steel welding material - Google Patents
Method for smelting and denitrifying stainless steel welding material Download PDFInfo
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- CN112522472A CN112522472A CN202011548073.6A CN202011548073A CN112522472A CN 112522472 A CN112522472 A CN 112522472A CN 202011548073 A CN202011548073 A CN 202011548073A CN 112522472 A CN112522472 A CN 112522472A
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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
- C21C7/10—Handling in a vacuum
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
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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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a method for smelting and denitrifying stainless steel welding materials, which comprises the steps of selecting smelting raw materials, smelting 308L stainless steel ingots by adopting a ZG-0.025 type vacuum induction smelting furnace, controlling process parameters, closing a diffusion pump, a Roots pump and a mechanical pump in sequence, filling high-purity argon under vacuum, adding a deoxidizing element silicon and a volatile element manganese, and electromagnetically stirring; reducing power, pouring, cooling, taking out the cast ingot, and cutting off a dead head. The process flow is easy to realize, safe, stable and reliable, and the nitrogen content of the obtained ingot is less than or equal to 0.0015 percent in mass fraction.
Description
Technical Field
The invention relates to a method in the technical field of stainless steel welding material smelting denitrification, in particular to a denitrification method of high vacuum induction smelting, a prefabricated magnesium oxide crucible and high-purity metal chromium.
Background
The 308L stainless steel welding material has good mechanical property and corrosion resistance, and is widely used for preparing the inner wall surfacing layer of the pressure vessel of the pressurized water reactor nuclear power station and the welding line of the safety end of the connecting pipe. However, when the welding material is in service at the ambient temperature of 280-330 ℃ for a long time, the 308L stainless steel welding material is prone to thermal aging, so that the hardness is increased, the toughness is reduced, the corrosion resistance of the welding material is possibly degraded, and the structural integrity of the inner wall surfacing layer and the safety end of the connecting pipe is affected. In addition, the pressure vessel inner wall 308L surfacing layer is in a neutron irradiation environment, and irradiation damage can occur in the service process, so that the corrosion and stress corrosion cracking behaviors of the surfacing layer are influenced.
The pressurized water reactor nuclear power plant has the characteristics of high power density, compact structure, safety, easiness in control, mature technology, relatively low manufacturing cost and power generation cost and the like, so that the pressurized water reactor nuclear power plant is the most widely used commercial nuclear reactor type internationally and occupies 3/4 of the total number of light water reactor nuclear power generating units. The nuclear power station and the submarine in China basically adopt an advanced pressurized water reactor nuclear power unit, and the safety is much higher than that of the Fudao. A pressurized water reactor nuclear power plant is a closed circulation system. The principle flow of the nuclear power station is as follows: the main pump sends high-pressure coolant into the reactor, and the coolant is generally kept at 120-160 atmospheric pressure. In the high pressure case, the coolant temperature does not vaporize even at 300 ℃. The pressurized water reactor consists of two parts, namely a pressure vessel and a reactor core. The pressure container is a sealed, thick and heavy cylindrical large steel shell with the height of tens of meters, the used steel is high-temperature and high-pressure resistant and corrosion resistant, and high-temperature and high-pressure steam for driving the steam turbine to rotate is generated at the position. And a control rod driving mechanism is arranged at the top of the container and used for driving the control rods to move up and down in the reactor core. If the reactor fails, enough control rods are immediately inserted into the reactor core, and the reactor stops working in a short time, so that the operation safety of the reactor is ensured. Pressurized water reactors are relatively widely used nuclear reactors. It is characterized by the fact that the water does not boil inside the core and therefore must be maintained at a high pressure. The water with raised temperature enters a steam generator, a plurality of thin pipes are arranged in the generator, and the water in the thin pipes receives heat and turns into steam to enter a steam turbine for power generation.
Various corrosion failures of a pressurized water reactor nuclear power station occur in decades of operation, the pressurized water reactor nuclear power station is safe and reliable, and is a fundamental stone for the development of the nuclear power station, and the nuclear power safety is always put to the first place in China. It is reasonable to believe that as experience accumulates and technology advances, the safety performance of nuclear power plants will gradually improve further, and the developing third generation reactors and the future fourth generation reactors will create new environments for safe utilization of nuclear energy.
The harm of nitrogen in stainless steel is mainly reflected by: the dissolved nitrogen is precipitated in a gaseous state during the cooling of the molten steel and exists in the steel in a bubble or loose form, thereby destroying the compactness of the steel and causing the macroscopic defect. Nitrogen can form various nitrides in solid steel, such as chromium nitride, aluminum nitride, titanium nitride, and zirconium nitride, as well as the corresponding cyanides, and the like. The presence of these nitrides reduces the plasticity of the alloy, making it brittle. Thereby reducing the processing plasticity and mechanical property of the metal. These nitrides are hard and brittle inclusions, and they do not deform when the metal matrix deforms. Therefore, cracks are easily generated around the nitride, and these cracks develop to cause the metal to break. Nitrogen can reduce the amount of strengthening phases formed in the alloy, thereby reducing the room or high temperature strength of the metal. 308L is used as a welding material for a pressurized water reactor, and the purity of the material has very important influence on the welding quality, so that the control of the impurity content, particularly the nitrogen content, of the welding material has important significance on the improvement of the welding quality. The method can control the impurity elements at a lower level through a special smelting process.
Therefore, the control and reduction of the content of nitrogen elements are the key points of the vacuum smelting related technology, which is the stainless steel welding material technology, and the method is carried out aiming at the technical problem.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for smelting and denitrifying stainless steel welding materials, and the method can be used for obtaining compact alloy ingots with ultra-low nitrogen content.
The invention is realized by the following technical scheme: a method for smelting and denitrifying stainless steel welding materials comprises the following steps:
(1) selecting smelting raw materials including pure iron, aurora nickel, high-purity metal chromium, metal silicon and electrolytic manganese, pickling and derusting the surface of the pure iron, drying the raw materials, and drying an ingot mould, a heat preservation cap and a pouring cup at high temperature;
(2) a ZG-0.025 type vacuum induction smelting furnace is adopted to smelt 308L stainless steel cast ingots, and the technological parameters are as follows: vacuumizing to 0.01Pa, and 15-20 kW: 15-25 min; 25-30 kW until melting; refining for 15min under the condition that the vacuum degree is less than or equal to 0.05Pa and 15-20 kW, and electromagnetically stirring; reducing the vacuum power to 5kW, and reducing the vacuum power for 3-5 min: freezing, discharging air and raising workThe rate is 20kW, and the process is repeated for 2 to 3 times; the diffusion pump, the roots pump and the mechanical pump are closed in sequence, and high-purity argon is filled in the vacuum until the vacuum degree is more than or equal to 103Pa, 10-15 kW, adding a deoxidizing element silicon and a volatile element manganese, and electromagnetically stirring; reducing the power to 10kW, pouring, cooling, taking out the cast ingot, and cutting off a riser.
The stainless steel comprises the following chemical components in percentage by weight: c is less than or equal to 0.03, Si is less than or equal to 1.0, Mn is less than or equal to 2.0, P is less than or equal to 0.005, S is less than or equal to 0.005, Cr: 19.0-21.0, Ni: 10.0-12.5, others are less than or equal to 0.5, Fe: a substrate.
The high-purity metallic chromium contains nitrogen element which is less than or equal to 0.0015 percent in mass fraction.
The prefabricated magnesium oxide crucible is adopted in the smelting process, high-purity metal chromium (less than or equal to 0.0015 percent by mass) can be subjected to nitrogen reduction greatly, refining is carried out under high vacuum, and further sufficient nitrogen removal is carried out by utilizing the electromagnetic stirring effect and a freezing mode, wherein the nitrogen removal is mainly carried out on the upper surface of the alloy liquid.
The invention has the advantages that:
(1) the special smelting process and the prefabricated magnesia crucible are adopted, high-purity metal chromium is used, refining, electromagnetic stirring and freezing treatment are carried out under high vacuum, so that the nitrogen can be greatly removed, and the method plays an important role in obtaining 308L stainless steel with ultralow nitrogen content.
(2) The ultralow nitrogen content of the 308L stainless steel reduces the number of nitride inclusions in the ingot, and greatly improves the mechanical properties of the stainless steel.
(3) The welding material of 308L stainless steel with ultra-low nitrogen content can be applied to important fields such as nuclear power and the like, plays a role in promoting domestic welding materials,
(4) the 308L stainless steel denitrification method is relatively low in cost and relatively easy to realize in process, and further plays a reference role in obtaining the ultra-low nitrogen content for other stainless steels.
Detailed Description
Example (b):
selecting smelting raw materials including pure iron, Jinchuan nickel, high-purity metal chromium, metal silicon and electrolytic manganese, pickling and derusting the surface of pure iron, drying the raw materials, adding the raw materials into a crucible, drying the raw materials at high temperature, putting the raw materials into an ingot mould, a heat preservation cap and a pouring cupIn a hearth, the nitrogen element contained in the high-purity metal chromium is 0.0012 percent by mass fraction. A ZG-0.025 type vacuum induction smelting furnace is adopted to smelt 308L stainless steel cast ingots, and the technological parameters are as follows: vacuumizing to 0.01Pa, 18 kW: 20 min; 28kW until molten; refining for 15min under the vacuum degree of 0.05Pa, and electromagnetically stirring; pre-deoxidizing by using carbon in the raw material; vacuum reduction low power to 5kW, freezing and air release, 3 min: freezing and deflating, increasing the power to 20kW, and repeating for 3 times; the diffusion pump, the roots pump and the mechanical pump are closed in sequence, and high-purity argon is filled in the vacuum until the vacuum degree is 1.5 multiplied by 103Pa, 15kW, adding deoxidizing element silicon and volatile element manganese, and electromagnetically stirring; reducing the power to 10kW, pouring, cooling, taking out the cast ingot, and cutting off a riser. And removing oxide skin on the surface of the cast ingot by a mechanical processing vehicle to obtain a smooth surface cast ingot, analyzing chemical elements, and finally forging, rolling and drawing the smooth surface cast ingot into a welding wire with a certain specification.
The nitrogen element analysis adopts a thermal conductivity method (national standard GB/T223.82-2007), and the analysis precision is 0.0001% (mass fraction).
This example obtained a 308L stainless steel ingot having the following chemical composition in wt% (mass fraction): n: 0.0010, O: 0.0015, H: 0.0002, C: 0.018, Si: 0.50, Mn: 1.5, P: 0.0018, S: 0.0015, Cr: 20.12, Ni: 10.25, Mo: 0.35, Cu: 0.18, Fe: a substrate.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (3)
1. A method for denitrogenating stainless steel smelting welding material is characterized by comprising the following steps:
(1) selecting smelting raw materials including pure iron, aurora nickel, high-purity metal chromium, metal silicon and electrolytic manganese, pickling and derusting the surface of the pure iron, drying the raw materials, and drying an ingot mould, a heat preservation cap and a pouring cup at high temperature;
(2) adopts ZG-0.025 type vacuum induction melting308L stainless steel ingot is smelted in the furnace, and the technological parameters are as follows: vacuumizing to 0.01Pa, and 15-20 kW: 15-25 min; 25-30 kW until melting; refining for 15min under the condition that the vacuum degree is less than or equal to 0.05Pa and 15-20 kW, and electromagnetically stirring; reducing the vacuum power to 5kW, and reducing the vacuum power for 3-5 min: freezing and deflating, then increasing the power to 20kW, and repeating for 2-3 times; the diffusion pump, the roots pump and the mechanical pump are closed in sequence, and high-purity argon is filled in the vacuum until the vacuum degree is more than or equal to 103Pa, 10-15 kW, adding a deoxidizing element silicon and a volatile element manganese, and electromagnetically stirring; reducing the power to 10kW, pouring, cooling, taking out the cast ingot, and cutting off a riser.
2. The method for the smelting denitrification of the stainless steel welding material according to claim 1, wherein the stainless steel comprises the following chemical components in percentage by weight: c is less than or equal to 0.03, Si is less than or equal to 1.0, Mn is less than or equal to 2.0, P is less than or equal to 0.005, S is less than or equal to 0.005, Cr: 19.0-21.0, Ni: 10.0-12.5, others are less than or equal to 0.5, Fe: a substrate.
3. The method for the smelting denitrification of the stainless steel welding material according to claim 1, wherein the nitrogen element contained in the high-purity metallic chromium is less than or equal to 0.0015 percent in mass fraction.
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| CN202011548073.6A CN112522472A (en) | 2020-12-24 | 2020-12-24 | Method for smelting and denitrifying stainless steel welding material |
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| CN202011548073.6A CN112522472A (en) | 2020-12-24 | 2020-12-24 | Method for smelting and denitrifying stainless steel welding material |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113894176A (en) * | 2021-09-30 | 2022-01-07 | 江苏烁石焊接科技有限公司 | Preparation method of heterogeneous high-nitrogen steel wire |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103480975A (en) * | 2013-05-15 | 2014-01-01 | 丹阳市华龙特钢有限公司 | Manufacturing method of nuclear-grade austenitic stainless steel welding wire |
| CN111187929A (en) * | 2020-02-16 | 2020-05-22 | 广东石油化工学院 | Method for denitrifying nickel-based superalloy |
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2020
- 2020-12-24 CN CN202011548073.6A patent/CN112522472A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103480975A (en) * | 2013-05-15 | 2014-01-01 | 丹阳市华龙特钢有限公司 | Manufacturing method of nuclear-grade austenitic stainless steel welding wire |
| CN111187929A (en) * | 2020-02-16 | 2020-05-22 | 广东石油化工学院 | Method for denitrifying nickel-based superalloy |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113894176A (en) * | 2021-09-30 | 2022-01-07 | 江苏烁石焊接科技有限公司 | Preparation method of heterogeneous high-nitrogen steel wire |
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