CN113881829A - Treatment method for reducing hydrogen content of steel - Google Patents

Treatment method for reducing hydrogen content of steel Download PDF

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Publication number
CN113881829A
CN113881829A CN202111064477.2A CN202111064477A CN113881829A CN 113881829 A CN113881829 A CN 113881829A CN 202111064477 A CN202111064477 A CN 202111064477A CN 113881829 A CN113881829 A CN 113881829A
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steel
hydrogen content
treatment method
reducing
molten steel
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王艳林
张灵通
陈晓华
王自东
张博炜
郑志浩
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University of Science and Technology Beijing USTB
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University of Science and Technology Beijing USTB
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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
    • C21C7/076—Use of slags or fluxes as treating agents
    • 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
    • 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
    • C21C7/0025—Adding carbon material
    • 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
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • 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
    • 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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • 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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Abstract

A treatment method for reducing the hydrogen content of steel products is characterized in that molten steel in a primary smelting furnace is subjected to degassing and dehydrogenation treatment, and the hydrogen content in the steel products is reduced to be less than or equal to 2 ppm; in the LF refining process, a strong carbide forming element is added, the non-reversible hydrogen reaction of the billet in the heating process is inhibited, and the defect of center hairline of the round steel is overcome. The invention adopts a unique dehydrogenation and degassing innovative control method in the smelting process, and adds the elements for forming the reinforced carbide, thereby effectively improving the low-power quality of the round steel and leading the rolled round steel with the compression ratio less than 3 to obtain compact low-power structure and good flaw detection quality.

Description

Treatment method for reducing hydrogen content of steel
Technical Field
The invention belongs to the technical field of steel rolling forming, and particularly relates to a treatment method for reducing the hydrogen content of steel.
Background
The rolling compression ratio is a key process parameter for determining the texture performance of a rolled piece, and is the ratio of the cross section area of a billet to the cross section area of round steel. The product quality of the continuous casting alloy steel is high and difficult to control and guarantee, the quality of a casting blank is improved during production, and the continuous casting alloy steel is produced by adopting large-compression-ratio steel rolling, so that the section of the cast continuous casting blank is large, and the continuous casting blank is required to be rolled into a material after cogging. In the prior production, the problem of rolling of phi 500mm continuous casting billets is solved
Figure BDA0003257672230000011
And the compression ratio of the round steel with the above specification is less than 3 (because the casting process of the continuous casting billet can form the defect of loose core part, the round steel can be effectively welded through the subsequent rolling with large compression ratio, the general compression ratio is guaranteed to be more than or equal to 7, the compression ratio is less than 3, and the loose of the casting billet is not easy to weld), so that the round steel has the defects of loose grade more than 1.5 and residual shrinkage cavity; and because the molten steel is not subjected to vacuum treatment in the smelting process, the content of free hydrogen in the molten steel is more than 6ppm, so that the rolled round steel is easy to generate the defect of center hairline.
Disclosure of Invention
The invention provides a treatment method for reducing the hydrogen content of steel, which is used for overcoming the defects in the prior art.
The invention is realized by the following technical scheme:
a treatment method for reducing the hydrogen content of steel,
degassing and dehydrogenating molten steel in the primary smelting furnace to reduce the hydrogen content in the steel to less than or equal to 2 ppm;
in the LF refining process, a strong carbide forming element is added, the non-reversible hydrogen reaction of the billet in the heating process is inhibited, and the defect of center hairline of the round steel is overcome.
In the above method for reducing the hydrogen content of steel, the molten steel in the primary smelting furnace is degassed and dehydrogenated, and Ca-containing and C-containing agents are added into the molten steel in the primary smelting furnace.
The treatment method for reducing the hydrogen content of the steel material is characterized in that the preparation containing Ca and C is a high-efficiency degassing composite material, and the CaC of the preparation2Not less than 78%, and the granularity is 85% in the range of 5-20 mm.
In the treatment method for reducing the hydrogen content of the steel, the additive amount of the preparation containing Ca and C is 0.5 kilogram of steel per ton and 0.5 kilogram of steel per ton.
In the above treatment method for reducing the hydrogen content of steel, the strong carbide forming element is Cr.
The treatment method for reducing the hydrogen content of the steel material is characterized in that the addition amount of the strong carbide forming element is 0.15-0.25 percent of the mass of the molten steel.
The invention has the advantages that:
1. the invention adopts a unique dehydrogenation and degassing innovative control method in the smelting process, and adds the elements for forming the reinforced carbide, thereby effectively improving the low-power quality of the round steel and leading the rolled round steel with the compression ratio less than 3 to obtain compact low-power structure and good flaw detection quality.
2. For the hairline at the center of the round steel, VD/RH vacuum treatment is generally adopted at present to avoid the hairline. Aiming at the current situation that the compression ratio of a round steel product is less than 3, the preparation containing Ca and C is added, so that free hydrogen in steel is effectively removed; meanwhile, by adding the element Cr for forming the reinforced carbide, the non-reversible hydrogen reaction of the steel billet is inhibited, and finally, the low-power center porosity of the round steel is less than or equal to 1.0 grade without the center hairline defect.
3. According to the invention, a preparation containing Ca and C is added after the primary smelting furnace, the Ca and C react with dissolved oxygen in molten steel to generate a slagging material CaO, and free hydrogen atoms in the steel are removed through kinetic conditions generated by generated CO and CO2, so that the hydrogen in the molten steel is controlled to be less than 2 ppm.
4. The invention adds the strong carbide forming element Cr to ensure that the billet forms a CrC compound in the heating process, thereby inhibiting C + H ═ CH4↓ reaction, thereby avoiding methaneThe generation of qi causes a defect in the hairline of the heart.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic diagram of the collision of free hydrogen with CO, CO2 bubbles according to the present invention;
FIG. 2 is a heating profile of a steel slab in example 2 of the present invention;
FIG. 3 is a cross-sectional view of a round steel before the smelting control is adopted in example 3 of the present invention;
FIG. 4 is a cross-sectional view of a round steel after the smelting control in example 4 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The method comprises the following steps: the smelting process flow of the 45 steel comprises the following steps: converter + LF + continuous casting;
the chemical composition requirements are as follows: carbon 043-0.47%, silicon 0.20-0.33%, manganese 0.52-0.60%, chromium 0.10-0.13%, phosphorus less than or equal to 0.015%, sulfur less than or equal to 0.005%, copper less than or equal to 0.10%, and the balance of iron and inevitable impurities.
The specific smelting process comprises the following steps:
a converter part:
1. the raw materials comprise: the steel is composed of molten iron, pig iron blocks and scrap steel, and the scrap steel containing more Ni and Cu cannot be added. Slag steel and raw ore must not be used. Smelting hot charging molten iron, wherein the proportion of the molten iron is more than or equal to 60 percent.
2. The tapping temperature is more than or equal to 1620 ℃. The converter tapping adopts the earlier stage of a tapping hole, and the slag discharging amount is strictly controlled. Controlling the steel tapping amount and preventing the alloy components from being qualified. (molten steel amount: 90 to 100 tons).
3. Proper amounts of Si-Mn, high-Cr, carburant, Al ingot and other alloys are added in sequence, and the adjustment can be carried out according to the actual molten steel amount change and other conditions.
4. The addition sequence is as follows: when tapping 1/5, the materials are added in sequence along with the steel flow, the high-efficiency degassing composite material, the carburant, the silicon-manganese, the high-chromium and other alloys and the lime are added in 600 kg/furnace.
5. When the alloy is placed into a ladle, the two argon supply air bricks of the ladle are used for supplying air and stirring simultaneously, the argon pressure is controlled moderately, and the argon pressure is properly reduced when the argon blowing station is reached.
LF part
1. If the fluidity of the slag surface in the ladle is good, the slag can be poured and then hung in an LF station; otherwise, the molten steel is transmitted to a station, and a proper amount of fluorite is added for slagging and then deslagging is carried out.
2. 200 kg of lime is added continuously in the process of putting the ladle into an LF furnace and supplying power for heating, 300 kg of sintering refining slag is melted in each furnace, and proper amount of fluorite is added according to the slag condition for slag mixing.
3. Ensuring that the white slag time is more than or equal to 15 minutes, measuring the temperature to determine the soft blowing time after the components meet the requirements, wherein the temperature is required to be more than or equal to 15 minutes, measuring the temperature and sampling after the soft blowing is finished, adding carbonized rice hulls into the mixture after the components are qualified, wherein the carbonized rice hulls are more than or equal to 5 bags (baked), and ensuring that the slag surface is completely covered. After the components and the temperature are proper, the ladle is hung on the bench for continuous casting.
Continuous casting section
1. Temperature of the steel water upper stage: the first ladle is 1560-1575 ℃ and the continuous casting ladle is 1545-1555 ℃. Controlling the superheat degree of the tundish: the first package superheat degree is less than or equal to 40 ℃, and the superheat degrees of the other packages are controlled to be 20-30 ℃.
2. Before casting, the tundish is filled with argon, the baking effect of the tundish and the centering condition of a stopper rod and a bowl opening area are carefully checked, the fact that a water outlet of the tundish is free of blockage is ensured, and the baking temperature of the tundish is higher than 1100 ℃. Controlling the superheat degree of the molten steel to be 20-30 ℃ and a crystallizerThe amount of cooling water is controlled at 220m3Controlling the secondary cooling water amount to be 0.16L/KG, controlling the pulling speed according to 0.285-0.30m/min, and controlling the crystallizer electric stirring parameter to be 400A/2HZ and the tail end electric stirring parameter to be 320A/5 HZ.
Example 2
Dehydrogenation and degassing control method for primary molten steel
Aiming at the molten steel tapped from a 120-ton converter, the molten steel amount is 89-95 tons, the tapping temperature is 160-. When the steel output reaches 10-15 tons, 30-50Kg of preparation containing Ca and C is added, and the following reaction occurs in the molten steel:
ca + T [ O ] dissolved CaO (CaO)
C + T [ O ] dissolution ═ CO ≠ ②
C+T[O]Dissolved as CO2↑ ③
The formed compound CaO is floated into slag through low argon blowing in the LF external refining process to form a good slag component;
the reaction II and III forms gas, and the most important function is to promote the removal of the gas in the molten steel along with the upward floating of the gas. Mainly depends on formed CO and CO2Flotation of bubbles, free H atoms with CO, CO2The bubbles collide and adhere to the bubble walls and are then removed as the bubbles float upward. The principle of collision is shown in figure 1.
Example 3
Irreversible hydrogen reaction control method for effectively inhibiting billet heating process by adding strong carbide forming element Cr in LF external refining process
For continuous casting round billets with the diameter of 500mm, in a heating furnace, the heating process of figure 2 is needed,
during the heating process, due to the activity of free hydrogen, the following reaction can occur with C in the matrix:
C+H＝CH4↑④
the formed methane gas can irregularly diffuse along the loose center part of the billet, thereby generating irregular tiny center hairline defects and bringing round steel in along with the rolling processAnd (5) finishing. 0.15-0.25% of Cr element is added in the external refining process of LF furnace and reacts with C in steel to form Cr23C6、Cr7C3And the like, thereby inhibiting the reaction (iv) from proceeding and avoiding the generation of hairline defects.
Example 4
Analysis in a specific implementation
Change of free hydrogen in smelting process
In the present embodiment, the change of free hydrogen in 10-furnace molten steel before and after the addition of the preparation was compared and shown in Table 1. It can be seen that the hydrogen content in the steel is significantly reduced after the formulation is added, indicating that the dehydrogenation effect is good.
TABLE 1 measured H content ppm of molten steel
Figure BDA0003257672230000061
(II) analysis of macrostructure of the bar before and after the bar is applied
Analyzing macrostructures of the round steel before and after smelting control, wherein the bar before implementation is shown in figure 3, and the bar after implementation is shown in figure 4, and as can be seen from figures 3 and 4, the bar before implementation has a center hairline defect; the implemented bar round steel has good macrostructure, and the center porosity is less than 1.0 grade, thereby proving that the macrostructure of the bar round steel can be effectively improved after the implementation, and the level of the center porosity is reduced.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (6)

1. A treatment method for reducing the hydrogen content of steel is characterized by comprising the following steps:
degassing and dehydrogenating molten steel in the primary smelting furnace to reduce the hydrogen content in the steel to less than or equal to 2 ppm;
in the LF refining process, a strong carbide forming element is added, the non-reversible hydrogen reaction of the billet in the heating process is inhibited, and the defect of center hairline of the round steel is overcome.
2. The treatment method for reducing the hydrogen content of steel according to claim 1, wherein the treatment method comprises the following steps: the primary smelting furnace molten steel is degassed and dehydrogenated, and Ca-containing and C-containing preparations are added into the primary smelting furnace molten steel.
3. The treatment method for reducing the hydrogen content of steel according to claim 2, wherein: the preparation containing Ca and C is a high-efficiency degassing composite material, and the CaC of the preparation2Not less than 78%, and the granularity is 85% in the range of 5-20 mm.
4. A treatment method for reducing the hydrogen content of steel according to claim 2 or 3, characterized in that: the addition amount of the preparation containing Ca and C is 0.5 kg per ton of steel.
5. The treatment method for reducing the hydrogen content of steel according to claim 1, wherein the treatment method comprises the following steps: the strong carbide forming element is Cr.
6. A treatment method for reducing the hydrogen content of steel according to claim 1 or 5, characterized in that: the addition amount of the strong carbide forming elements is 0.15-0.25% of the mass of the molten steel.
CN202111064477.2A 2021-09-10 2021-09-10 Treatment method for reducing hydrogen content of steel Pending CN113881829A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101368251A (en) * 2008-09-28 2009-02-18 舞阳钢铁有限责任公司 Steel plate for large-thickness hydrogen-contacting equipment and its production technology
CN105969932A (en) * 2016-06-30 2016-09-28 山东钢铁股份有限公司 Steelmaking hydrogen control method
RU2015122359A (en) * 2015-06-10 2017-01-10 Открытое акционерное общество "Волжский трубный завод" Method for out-of-furnace steel processing
CN109355562A (en) * 2018-11-09 2019-02-19 丹阳市曙光特钢有限公司 A kind of production method of high-strength special type steel
CN112831625A (en) * 2021-01-04 2021-05-25 南京钢铁股份有限公司 Smelting process for controlling hydrogen content of molten steel of non-vacuum steel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101368251A (en) * 2008-09-28 2009-02-18 舞阳钢铁有限责任公司 Steel plate for large-thickness hydrogen-contacting equipment and its production technology
RU2015122359A (en) * 2015-06-10 2017-01-10 Открытое акционерное общество "Волжский трубный завод" Method for out-of-furnace steel processing
CN105969932A (en) * 2016-06-30 2016-09-28 山东钢铁股份有限公司 Steelmaking hydrogen control method
CN109355562A (en) * 2018-11-09 2019-02-19 丹阳市曙光特钢有限公司 A kind of production method of high-strength special type steel
CN112831625A (en) * 2021-01-04 2021-05-25 南京钢铁股份有限公司 Smelting process for controlling hydrogen content of molten steel of non-vacuum steel

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