CN111719079A - Control method for cold heading steel flocculation flow - Google Patents
Control method for cold heading steel flocculation flow Download PDFInfo
- Publication number
- CN111719079A CN111719079A CN201910218034.0A CN201910218034A CN111719079A CN 111719079 A CN111719079 A CN 111719079A CN 201910218034 A CN201910218034 A CN 201910218034A CN 111719079 A CN111719079 A CN 111719079A
- Authority
- CN
- China
- Prior art keywords
- steel
- aluminum
- cold
- slag
- cold heading
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- 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
- 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
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
-
- 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
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
-
- 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
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Analytical Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention relates to the field of cold heading steel, in particular to a cold heading steel flocculation flow control method. The cold heading steel ML08AL comprises the following chemical components in percentage by mass: c0.06-0.09; si is less than or equal to 0.08; 0.35-0.45% of Mn; p is less than or equal to 0.017; s is less than or equal to 0.015; 0.02-0.05 of Als; n is 0.03-0.05; the balance being Fe. The production process route is as follows: the hot metal mixer → the hot metal pretreatment → the top and bottom combined blown converter → the molten steel pre-deoxidation → the LF furnace refining → the billet continuous casting. During refining in the LF furnace, slag blocking and tapping are performed, the thickness of slag in a steel ladle is controlled to be not more than 50mm, carbide slag and aluminum particles are mixed and deoxidized, the atmosphere in the LF furnace is controlled to be a reducing atmosphere, and bottom argon blowing and stirring are performed. The invention solves the problem of cold upsetting cracking of the cold upsetting steel Ml08AL caused by more inclusions in the steel, grades the non-metallic inclusions, mainly grades 0.5 and 1.0, wherein the grade 1.5 and above accounts for less than 5 percent of the total detected amount, the grain size reaches more than 8.5, and the cold upsetting performance meets the requirement of 1/4.
Description
Technical Field
The invention relates to the field of cold heading steel, in particular to a cold heading steel flocculation flow control method.
Background
The cold heading steel is steel for standard parts, which is produced by utilizing the plasticity of metal and adopting a cold heading forming process and has higher interchangeability. The cold heading steel is commonly used for manufacturing various mechanical standard parts and fasteners by cold heading forming, such as various fasteners of bolts, nuts, screws, rivets, self-tapping screws and the like and various cold heading formed spare and accessory parts. The cold heading steel product is mainly used in the industries of automobiles, shipbuilding, equipment manufacturing, electronics, household appliances, bicycles, tools, light steel structures, buildings and the like. The steel grade of the cold heading steel wire rod is generally low-medium carbon high-quality carbon structural steel and alloy structural steel. Because the cold-forming performance of the cold-heading steel is good, cold heading is used for replacing a hot-rolled material cold cutting machine for machining in the machining industry, a large amount of working hours are saved, metal consumption can be reduced by 10% -30%, and the product has the characteristics of high dimensional precision, good surface finish, high productivity, high tensile strength and the like.
The deep processing procedure of the wire rod for the cold forging steel at the later stage is basically as follows: wire rod → recrystallization annealing → cold drawing → spheroidizing annealing → cold heading forming. Because of large deformation amount and high deformation speed in the processing process, the alloy material is required to have good cold upsetting performance, plasticity, toughness and lower strength and hardness. Because the steel is a square billet with low silicon and aluminum, the casting is difficult, and the steel belongs to a typical steel grade with high production difficulty and high added value. Due to high aluminum control and the existence of a large amount of inclusions, metal-to-metal discontinuity occurs in metal crystals, the discontinuity between metal structures cannot bear or can bear only small stress during the cold heading deformation of the material, stress concentration is inevitably caused around defects, the cold workability of the material is deteriorated, the problem of upset cracking occurs, and the problem of upset cracking from 1/2 to 1/3 and 1/4 is more serious as the cold heading deformation is increased. Therefore, for the cold forging steel ML08Al, the aluminum content of the molten steel and the inclusions in the steel must be strictly controlled, and high melting point Al is particularly required2O3Less inclusions, and the steel grade is largely deoxidized with aluminum, and calcium treatment is required to change Al in order to prevent nozzle clogging2O3The existence form of the inclusions improves the castability of the molten steel.
In the initial production stage, a slag surface pre-deoxidation process is not adopted after the converter adjusts the aluminum, and the molten steel and the converter slag have strong oxidizability, so that the refining deoxidation is difficult, and the whole deoxidation process is performed, so that the control fluctuation of the refined aluminum is large, the upward floating of a deoxidation product is insufficient, the castability of the molten steel is poor, the flocculation problem frequently occurs, the corresponding cold upsetting performance of a rolled material cannot meet the requirement, and the 1/2 upsetting cracking problem occurs.
Disclosure of Invention
The invention aims to provide a method for controlling the flocculation flow of cold heading steel, which solves the problem of cold heading cracking of the cold heading steel Ml08AL caused by more inclusions in the steel, grades the non-metallic inclusions, mainly grades 0.5 and 1.0, the grade 1.5 and above accounts for less than 5% of the total amount to be detected, the grain size reaches more than 8.5, and the cold heading performance meets the requirements of 1/4.
The technical scheme of the invention is as follows:
the method for controlling the flocculation flow of the cold forging steel comprises the following chemical components in percentage by mass: c0.06-0.09; si is less than or equal to 0.08; 0.35-0.45% of Mn; p is less than or equal to 0.017; s is less than or equal to 0.015; 0.02-0.05 of Als; n is 0.03-0.05; the balance being Fe.
According to the control method of the cold heading steel flocculation flow, the elongation is more than or equal to 40 percent, the tensile strength is less than or equal to 470MPa, and the reduction of area is more than or equal to 60 percent.
According to the control method of the cold heading steel floc flow, the ML08AL production process route is as follows: hot metal mixer → hot metal pretreatment → 120 ton top-bottom combined blown converter → molten steel pre-deoxidation → 120 ton LF furnace refining → 150mm × 150mm square billet continuous casting.
The method for controlling the cold heading steel floc flow comprises the steps of pre-deoxidizing in a 120-ton top-bottom combined blown converter, adding 30-40 kg of aluminum particles into a steel ladle before the tapping of the converter is finished, and supplementing aluminum wires by using a wire feeder after the tapping is finished, so that the aluminum content of molten steel is in the range of 0.020% -0.050%; and after the aluminum wire is supplemented, argon is blown for 4-6 min, so that the deoxidation product can fully float upwards.
According to the control method of the cold forging steel floc flow, during refining in an LF furnace, slag blocking and steel tapping are performed, the thickness of slag in a ladle is controlled to be not more than 50mm, carbide slag and aluminum particles are mixed for deoxidation, the atmosphere in the LF furnace is controlled to be a reducing atmosphere, and argon is blown at the bottom for stirring; the LF slag composition is controlled as follows according to mass percentage: SiO22，2.45～5.06；CaO，49.02～55.54；Al2O321.96-30.08, TFe, 1.82-3.00; the slag alkalinity is 8.93-13.62.
According to the method for controlling the flocculation flow of the cold forging steel, in the cold forging steel ML08AL, the weight ratio of acid-soluble aluminum [ Al ] s to total aluminum [ Al ] t is as follows: [ Al ] s/[ Al ] t is not less than 0.9.
According to the control method of the cold heading steel flocculation flow, calcium treatment is carried out during LF furnace refining, the wire feeding depth of a calcium iron wire is 300-400 mm deep from the bottom of a steel ladle, the wire feeding speed is 2.5-3.5 m/s, and the calcium iron wire is 300-400 m/furnace.
According to the method for controlling the cold forging steel flocculation flow, after the calcium treatment of the refining LF furnace is finished, soft argon blowing treatment is carried out on molten steel; when the flow of argon gas is 70-110L/min, the effect of removing the inclusions in the steel is the best, and the removal index is 0.97-1.0.
The design idea of the invention is as follows:
in the initial production stage, a slag surface pre-deoxidation process is not adopted after the converter adjusts the aluminum, and the molten steel and the converter slag have strong oxidizability, so that the refining deoxidation is difficult, and the whole deoxidation process is performed, so that the control fluctuation of the refined aluminum is large, the upward floating of a deoxidation product is insufficient, the castability of the molten steel is poor, the flocculation problem frequently occurs, the corresponding cold upsetting performance of a rolled material cannot meet the requirement, and the 1/2 upsetting cracking problem occurs. Aiming at the problem, the deoxidation link is advanced, a pre-deoxidation process is adopted in a converter, a remarkable effect is achieved, the aluminum content in steel is stable, the oxidability of molten steel is weakened, the refining deoxidation pressure is reduced, the aluminum grain usage amount and the aluminum content control are greatly reduced, and the castability of the molten steel is ensured.
The refining process plays a key role in the production process of the cold heading steel and is responsible for the important tasks of reducing the cost, effectively controlling the aluminum content and the calcium treatment amount, removing impurities, ensuring the castability of molten steel and ensuring the cold heading performance. The method is characterized in that the aluminum content is controlled within a certain range, the deoxidation mode can effectively reduce deoxidation products, the aluminum deoxidation products can be denatured and floated only when the calcium treatment amount reaches a certain proportion, the argon flow is determined in a static blowing link, the influence of the argon blowing time on the removal of impurities is ensured, and the castability of molten steel is ensured. Through research, the acid-soluble aluminum control process, reasonable component control, the calcium treatment inclusion deformation process, argon blowing inclusion floating and refining secondary treatment effect are determined.
The invention has the advantages and beneficial effects that:
⑴ the present invention is directed to ML08The flocculation problem of Al molten steel, the deoxidation process is moved to the rear of a converter, so that the deoxidation product becomes Al with larger volume2O3SiO22MnO inclusions can float upwards, the total oxygen content of the molten steel is reduced, and the refining pressure is relieved.
After the carbide slag and the aluminum particles are mixed and deoxidized in the LF furnace refining process, the consumption of a single aluminum particle furnace is reduced by 123-132 kg, the content of molten steel [ Al ] s is reduced by 0.012-0.019%, the content of molten steel [ Al ] t is reduced by 0.018-0.028%, the ratio of the molten steel [ Al ] s/[ Al ] t is gradually improved from 0.85 in 2011 to 0.97 in 2014, and the cost is greatly reduced.
⑶ the invention optimizes LF refining ML08Al molten steel Als]Content and calcium treatment process, promotes inclusion floating through static blowing link, and enables [ Al]s/[Al]t is not less than 0.9, and the purpose of calcium treatment [ Ca ]]/[A12O3]The molten steel castability is good, and the dosage of the calcium and iron wires is reduced by 227-478 meters per furnace from 2012 to 2011.
According to the invention, through a series of research works on the production process of the cold heading steel, the cold heading steel ML08Al is produced in batch, and the cold upsetting performance can not meet the requirement of 1/2 from the beginning, so that the requirements of both 1/3 and 1/4 can be met at present.
Through the research and successful production of the flocculation control technology of the cold heading steel ML08Al, the development progress of cold heading series steel grades is accelerated, the quality of the cold heading steel is improved, the technical economic benefit and the social benefit are remarkable, and the market prospect is wide.
Sixthly, performing deoxidation and forward movement, and performing pre-deoxidation slag modification after tapping of a converter is finished, so that not only is the integral deoxidation product of molten steel reduced, but also the refining pressure is reduced, and the aluminum content of the molten steel is stabilized.
The invention optimizes an LF refining white slag process, a deoxidation process and a calcium treatment process, improves the purity of molten steel, enables an aluminum deoxidation product to be fully denatured and floated through calcification treatment, and ensures smooth pouring and stable improvement of steel quality.
The key technical research of LF refining of the invention is as follows: the content of Al s in the steel is reasonably controlled, so that the total oxygen content in the steel is reduced, excessive secondary oxidation products generated in the continuous casting process caused by high content are avoided, and the effect of refining grains is fully played.
The self-bearing cold heading steel ML08AL of the invention is as follows: wire → recrystallization annealing → cold drawing → spheroidizing annealing → cold heading forming, and manufacturing various mechanical standard parts and fasteners, such as various fasteners of bolts, nuts, screws, rivets, self-tapping screws and the like and various cold heading formed spare and accessory parts, wherein the product is mainly used in the industries of automobiles, shipbuilding, equipment manufacturing, electronics, household appliances, bicycles, tools, light steel structures, buildings and the like.
Drawings
FIG. 1 shows the relationship between acid-soluble aluminum and inclusions in steel.
FIG. 2 is a graph showing the relationship between total oxygen and the total amount of inclusions in steel.
FIG. 3 is an equilibrium diagram of [ S ] - [ Ca ] at different temperatures.
FIG. 4 is a graph showing the relationship between the wire feeding speed and the recovery rate of the calcium iron wire.
Fig. 5 is a metallographic structure examination chart.
Detailed Description
In the specific implementation process, the production process route of the control method of the cold heading steel ML08AL floc flow is as follows:
the mixer → the molten iron pretreatment (S removal and slag removal) → 120-ton top-bottom combined blown converter → molten steel pre-deoxidation → 120-ton LF furnace refining → 150mm × 150mm square billet continuous casting.
The method for controlling the cold heading steel ML08AL flocculation flow comprises the following steps:
1. calcium treatment and inclusion denaturation theory of cold forging steel
The control of the form and the components of the inclusions in the cold forging steel is shown by domestic and foreign expert research: when the aluminum deoxidized product is converted into 12CaO 7Al by calcium treatment2O3However, since its melting point is only 1455 ℃, it is easily floated and adsorbed into slag. When calcium treatment is carried out, the reaction product should be deformed in the direction of CA 6-CA 2-CA-C12A 7 theoretically, and in order to ensure the modification treatment of inclusions, the calcium content of the added molten steel must be controlled, if Ca is insufficient, Al is insufficient2O3Cannot be converted into liquid calcium aluminate; ca plusThe excessive amount of the added water can generate CaS, and the water gap is easily blocked and the water gap erosion is easily increased. In calcium treatment, parameters such as wire feeding amount, wire feeding speed, temperature and feeding depth need to be optimized to ensure that [ Ca ] in steel]/[Al]And the indexes are equal to ensure that the generated calcium aluminate is in a low melting point region, so that the inclusion is easy to float upwards and be removed in the molten steel. The calcium aluminate properties are shown in table 1.
TABLE 1 various calcium aluminates physical Properties
| Inclusions | Crystal structure | Density, g/cm3 | Melting temperature of |
| Al2O3 | Trigonometric system | 3.96 | 2052 |
| CaO·6Al2O3 | System of cubes | 3.28 | 1850 |
| CaO·2Al2O3 | Monoclinic system | 2.91 | 1750 |
| CaO·Al2O3 | Cube | 2.98 | 1605 |
| 12CaO·7Al2O3 | Cube | 2.83 | 1455 |
| 3CaO·Al2O3 | Cube | 3.04 | 1535 |
2. Cold heading steel aluminum control and inclusion control theory
Aluminum is a strong deoxidizing element in steel-making production, and most of steel is deoxidized by aluminum or a compound deoxidizer containing aluminum. Compared with the silicon-manganese deoxidation, the final deoxidation by using the aluminum can keep the oxygen content in the steel to be low concentration all the time during tapping, casting and solidification, thus not only effectively reducing the oxygen in the steel, but also refining the crystal grains of the steel, improving the toughness and preventing the aging. Therefore, the aluminum added in Ml08Al forms Al partially2O3Or containing Al2O3The inclusions are partially dissolved in the solid iron and then either form dispersed AlN in the solid state or remain in solid solution as heating and cooling conditions vary.
As aluminum has a special function in steel and controls the form and components of inclusions in cold forging steel, the research of experts at home and abroad shows that: in the production of Ml08Al, the control of the content of acid-soluble aluminum in steel is diverged. Some think that the higher the control is, the better the control is, because the current continuous casting implements full-protection casting, the dissolved oxygen in acid-soluble aluminum in steel is low, and the secondary oxidation of aluminum is less; however, as the amount of aluminum added increases, there are increased costs and defects in the cast slab. The final deoxidizer mainly containing aluminum can control the total amount of inclusions in steel by adjusting Als in the steel. Therefore, controlling the Als too high or too low can cause the total amount of the inclusions to increase, and controlling the Als well is a key process for reducing the inclusions.
3. Study of converter Pre-deoxidation
(1) Reasons and purposes of converter pre-deoxidation
The cold forging steel ML08AL is difficult to cast in a square billet because the aluminum content of the molten steel is high, so that the molten steel needs to be deoxidized to be reductive white slag. Therefore, more aluminum deoxidation products are contained in the molten steel, and if the molten steel does not float upwards sufficiently, the deoxidation products in the water mouth deposit flocculation flow and even the molten steel stops casting. In the refining area for deoxidation, the deoxidation product particles formed in the early stage are larger, and pure alumina inclusions generated in the middle and later deoxidation are fine particle inclusions, which are not beneficial to aggregation and floating. And the deoxidation product is Al with larger volume after the converter is deoxidized2O3SiO2 MnO and Al2O3CaO-SiO2The floating is easy, thereby reducing the total oxygen content of the molten steel and stabilizing the aluminum content of the molten steel. Therefore, after the deoxidation is moved to the converter, the refining pressure is relieved, and the molten steel flocculation flow is reduced.
(2) Converter pre-deoxidation measure and effect thereof
The converter pre-deoxidation is to add 30-40 kg of aluminum particles into a ladle before the converter tapping is finished, and supplement aluminum wires by using a wire feeder after the tapping is finished and oxygen is determined, so that the aluminum content of molten steel is in the range of 0.020% -0.050%. And blowing argon for 5min after the aluminum wire is supplemented, so that the deoxidized product can fully float upwards, the oxidability of the slag is reduced, the average components of the slag before and after slag changing and the aluminum content of the molten steel are shown in table 2, and it can be seen that the oxidability of the ladle slag after the converter furnace is obviously reduced after pre-deoxidation, and the molten steel [ Al ] t tends to be stable due to argon blowing stirring and slag pre-deoxidation, and the difference between the molten steel [ Al ] t and refined slag aluminum is smaller according to the actual control condition.
TABLE 2 converter Pre-deoxidation before and after improvement of ladle slag composition and aluminium control
| Composition of | SiO2 | CaO | MgO | TFe | Al2O3 | Basicity R | Highest Alt | Lowest Alt | Average Alt |
| Before improvement | 18.52 | 45.53 | 8.54 | 13.72 | 11.69 | 2.46 | 0.096 | 0.055 | 0.072 |
| After improvement | 11.84 | 43.48 | 8.26 | 7.55 | 27.43 | 3.67 | 0.058 | 0.028 | 0.034 |
4. Study of LF refining Process
(1) Purpose and means of external refining
The molten steel secondary refining is to transfer the molten steel primarily refined in the steelmaking furnace to a ladle or other special containers for refining, and is also called secondary refining.
The purpose of external refining is as follows: deep decarburization, desulfurization, deoxidation, degassing, component adjustment and temperature adjustment and homogenization, inclusion removal, inclusion shape and composition change and the like are carried out under the conditions of vacuum, inert atmosphere or controllable atmosphere. The external refining of molten steel is an essential process for meeting the requirements of improving the variety and quality of steel, producing new steel and rationalizing the production process, and meeting the strict requirements of continuous casting on the connection of molten steel components, temperature, purity, time and the like, and becomes an important link in modern steelmaking and continuous casting production.
The LF furnace is called as a ladle furnace, is successfully developed in Japan in the early 70 s of the 20 th century, is popularized and applied in a large quantity, and becomes the most main external refining equipment in the present time. The LF furnace strengthens thermodynamic and kinetic conditions by means of arc heating, reducing atmosphere in the furnace, white slag refining, gas stirring and the like, so that the molten steel can achieve comprehensive refining effects of deoxidation, desulfurization, alloying, temperature rise and the like in a short time. The method ensures that the purposes of accurate molten steel components, uniform temperature, full floating of impurities and molten steel purification are achieved, simultaneously well coordinates the steelmaking and continuous casting processes, and ensures the smooth operation of multi-furnace continuous casting.
The refining function is strong, the effects of deoxidation, desulfurization and molten steel purification are good, and the quality of steel is obviously improved; it is suitable for producing ultra-low sulfur and ultra-low oxygen steel.
Secondly, the electric arc heating device has the function of electric arc heating, and is high in heat efficiency, large in temperature rise range and high in temperature control precision.
And thirdly, the stirring and alloying functions are realized, narrow component control is easy to realize, and the stability of the product is improved.
Fourthly, the slag steel refining process is adopted, and the refining cost is low.
Simple equipment and low investment.
The LF furnace has four unique refining functions: submerged arc heating, argon stirring, reducing atmosphere in a furnace and white slag refining. The four refining functions of the LF furnace are mutually permeated and promoted. The reducing atmosphere in the furnace is subjected to argon blowing and stirring under the heating condition, so that the refining capacity of the white slag is improved, and an ideal refining environment is created, so that the quality of the steel is obviously improved.
(2) Deoxygenation control
The LF furnace argon blowing operation is that a certain amount of argon is blown into molten steel through a bottom argon blowing device of a ladle in the refining process to drive the molten steel to circulate, so that the components and the temperature are uniform, and the gathering and floating of inclusions are promoted. Thereby achieving the purposes of homogenizing the temperature and the components of the molten steel, stabilizing the casting process, reducing the content of impurities and gas in the steel and improving the quality of the steel.
The key points of the LF white slag refining process are as follows:
firstly, slag blocking and tapping are carried out, and the thickness of slag in a steel ladle is controlled to be not more than 50 mm.
Modifying the ladle slag and controlling the alkalinity of the ladle slag.
And thirdly, the carbide slag is used for foaming, and good fluidity of the slag is kept through aluminum particle deoxidation, so that the desulfurization and deoxidation effects are ensured.
Fourthly, controlling the atmosphere in the LF furnace to be a reducing atmosphere so as to avoid secondary oxidation of the molten steel.
And fifthly, well bottom blowing argon stirring to ensure that the furnace has higher mass transfer speed.
In a word, the slag forming of the LF furnace requires fast, white and stable. The 'fast' means that white slag is manufactured in a short time, the treatment period is fixed, the earlier the white slag is formed, the longer the refining time is, and the better the refining effect is; "white" means that omega (FeO) is required to be reduced to less than 3.0 wt% to form a strong reducing atmosphere; the stability has two meanings, namely, the slag properties between furnaces need to be stable and cannot be greatly different; secondly, after the white slag of the same heat is manufactured, the omega (FeO) in the slag needs to be kept less than or equal to 3.0wt percent, the refining effect is improved, and the inspection result of the refining slag is shown in Table 3.
TABLE 3 statistical 100 furnace LF slag composition results
The aluminum particles are used for deoxidation, and the aluminum particles have no foaming function, so that the aluminum particles on the slag surface partially enter molten steel to increase aluminum in the molten steel, the deoxidation efficiency is reduced, and the aluminum content of the molten steel is in an unstable state due to aluminum increase. The carbide slag and the aluminum particles are used for mixed deoxidation, so that the foaming function of the carbide slag is utilized, the submerged arc effect of the slag is improved, and the reaction formula that the carbide slag deoxidation is rapidly increased on a slag steel reaction interface due to the exposure of molten steel is reduced:
CaC2+3[O]＝CaO(s)+2CO(g)△G＝-75300-37.51T
CaC2+3(FeO)＝CaO+3Fe+2CO(g)
(3) research on acid-soluble aluminum control process
Too low control of Als increases the dissolved oxygen content, which not only increases the oxides in the steel, but also affects the structural properties of the steel. With the increase of Als, on one hand, the dissolved oxygen can be rapidly reduced to a lower level, and the crystal grains of the steel are refined; on the other hand, higher Als can increase the secondary oxidation of molten steel during casting, and Al retained in the steel is generated2O3The inclusion causes flocculation flow during molten steel pouring, and the generated AlN is precipitated at grain boundaries during casting blank solidification to easily cause cracks.
The relationship between [ Al ] and T [ O ] in steel is complex, and the aluminum deoxidation capacity at normal pressure can be calculated by the following formula:
2[Al]+3[O]＝(Al2O3)
lnk0＝64000/T-20.57
as the amount of Als in the steel increases, the amount of dissolved oxygen decreases significantly, i.e., the amount of Als in the steel has a significant effect on inclusions, as shown in fig. 1. As is clear from fig. 1, the control range of the acid-soluble aluminum in the steel is defined to be 0.020% or more. In addition, in order to control the total amount of inclusions, it is important to reduce the total oxygen content in the steel, and the relationship between total oxygen and inclusions in the steel is shown in FIG. 2. To reduce the total amount of inclusions in steel, and most importantly, to reduce T [ O ], the final deoxidizer, which is mainly aluminum, can control the total amount of inclusions in steel by adjusting Als in steel.
After the acetylene sludge deoxidation and the effective acid-soluble aluminum control are adopted, the aluminum content of the molten steel is gradually reduced in recent years, and the specific table is shown in table 4.
TABLE 4 comparative table of Al content control of Ml08AL molten steel in recent years
| Constituent aluminum control | 2011 year | 2012 of the year | 2013 | 2014 |
| [Al]s，％ | 0.057 | 0.045 | 0.042 | 0.038 |
| [Al]t，％ | 0.067 | 0.049 | 0.045 | 0.039 |
| [Al]s/[Al]t | 0.85 | 0.91 | 0.94 | 0.97 |
As can be seen from Table 4, from 2012 onward, the amounts of [ Al ] s and [ Al ] t of molten steel were respectively reduced by 0.012%, 0.015% and 0.019% and 2011, respectively. Further, as can be seen from Table 4, in 2011, the smaller the [ Al ] s/[ Al ] t, the more the alumina content in the molten steel, which is also the main cause of the molten steel floc flow.
5. Composition control process
The cold heading steel mainly comprises carbon, silicon, manganese and aluminum alloy elements and impurity elements such as phosphorus, sulfur, nitrogen, oxygen and the like, and the elements exist in the material in different forms to influence the plasticity of the material. The influence factors of other elements except aluminum on the cold forging steel ML08Al are as follows:
carbon: carbon mainly cementite (Fe) as a compound in cold forging steel3C) The higher the carbon content, the more cementite, the lower the plasticity of the steel, and the higher the strength.
Silicon: silicon can increase the elastic limit of the material but reduce the cold deformability of the material.
Manganese: manganese can improve the work hardening of the material, thereby reducing the plasticity of the material and improving the strength. However, manganese can react with FeS to form MnS, thereby improving the thermoplasticity of the material.
Phosphorus: phosphorus is an impurity element in steel, can be dissolved in ferrite, reduces the plasticity of the steel, and improves the strength and the hardness of the steel. Phosphorus has a large segregation ability, and becomes brittle even when the segregation content of local phosphorus in steel is high.
Sulfur: sulfur is also a harmful impurity element in steel, is insoluble in ferrite, and generates FeS. FeS and FeO form eutectic and distribute in grain boundaries, causing hot brittleness of the steel.
Nitrogen: nitrogen has a high solubility in austenite and a low solubility in ferrite, and decreases with a decrease in temperature, and when steel having a high nitrogen content is cooled from a high temperature quickly, nitrogen in ferrite is supersaturated and dissolved in the steel since it is not precipitated. At room temperature or slightly elevated temperature, nitrogen will precipitate in the form of FeN, increasing the strength, hardness and reducing the plasticity of the steel.
In order to obtain proper cold heading performance, the components must be controlled within a reasonable range, and by means of micro-positive pressure operation, the actual component control condition of the cold heading steel ML08AL is shown in Table 5, and the performance index of the cold heading steel ML08AL is shown in Table 6.
TABLE 5 control of actual composition of cold heading Steel ML08AL
| Examples | C，％ | Si，％ | Mn，％ | P，％ | S，％ | Als，％ | N，％ | Fe |
| Highest point of the design | 0.08 | 0.07 | 0.42 | 0.016 | 0.007 | 0.05 | 0.0046 | Surplus |
| Lowest level of | 0.05 | 0.02 | 0.35 | 0.006 | 0.004 | 0.028 | 0.0038 | Surplus |
| Average | 0.065 | 0.044 | 0.38 | 0.011 | 0.005 | 0.038 | 0.0042 | Surplus |
TABLE 6 Performance index of Cold heading Steel ML08AL
| Rolling number | Elongation/percent | Tensile strength/MPa | Reduction of area/%) |
| W30013712 | 42.8 | 367 | 77 |
| W30013708 | 47 | 369 | 79 |
| W30013714 | 46.5 | 364 | 79 |
| W30013701 | 48.2 | 377 | 78 |
| W30013705 | 46.5 | 359 | 78 |
| W30013711 | 47.2 | 364 | 79 |
| W30013703 | 46.3 | 360 | 79 |
| W30013707 | 45 | 357 | 79 |
| W30013709 | 44.6 | 374 | 79 |
| W30013702 | 43 | 376 | 79 |
| Mean value of | 45.7 | 366.7 | 78.6 |
6. Theoretical study on calcium treatment and inclusion denaturation
Oxygen has very low solubility in steel, mainly Al2O3The forms of nonmetallic inclusions such as FeO, SiO2, CaO and the like exist in steel, and a part of nonmetallic compounds of sulfur and nitrogen exist, and the inclusions destroy the continuity of a matrix of a material, cause crack sources of cracking during cold heading, and particularly, the inclusions near the surface are affected more seriously by the action of stress concentration and tangential tensile stress. The non-metallic inclusion is one of the main causes of cold heading cracking, and the larger the inclusion particle is, the more easily the inclusion particle is cracked.
After the calcium treatment, the following three types of inclusions were found in molten steel.
(l)Al2O3A CaO (CaS) calcium aluminate inclusion. The molten steel rarely has high melting pointPure Al of dots2O3Most of the inclusions were changed to (CaO) x (Al)2O3) y inclusion and individual Al2O3CaO-CaS impurities. Such inclusions account for 75.7% of the inclusions observed.
(2)Al2O3A CaO-SiO 2 inclusion. The number of such inclusions is not large and is only 8.1%. Is a composite inclusion formed by combining calcium aluminate and silicon oxide, and the main component is Al2O3And CaO, SiO2 are low, typically less than 10%.
(3)Al2O3CaO-SiO 2-MnO based inclusions. Such inclusions account for 10.8%, and since the inclusions contain about 20% of Mn and generally have a diameter of 20 μm or more, the inclusions are presumed to be secondary oxidation products. The air brought in and the [ Mn ] are simultaneously fed with the calcium and iron wires]MnO is generated by the reaction.
In addition, in order to avoid the generation of CaS inclusion after the calcium treatment, clear requirements on the sulfur content of the molten steel are required, the balance relation at different temperatures is shown in figure 3, and the figure shows that when the temperature reaches 1600 ℃, the [ S ] which is balanced with the calcium content is less than or equal to 0.005 percent in order to avoid the generation of CaS inclusion.
Calcium iron wire feeding point determination:
the horizontal position of the wire feeding is related to the argon blowing position of the ladle. For feeding Ca-Fe wire, the vapor pressure of Ca is very large, and even if the Ca is liquid, the density of the Ca is much smaller than that of molten steel, and is only 1.48g/cm3(450 ℃) and therefore the buoyancy to which the liquid Ca is subjected in the molten steel is also considerable. Therefore, the horizontal position of the calcium iron wire feeding point is selected to be at the central position of the molten steel descending flow, so that the Ca enters the molten steel in a gas state or a liquid state, is forced to descend under the action of the descending flow and then floats upwards, or is brought into the ascending flow of the air brick along with the ladle bottom suction flow, thereby prolonging the retention time of the Ca in the molten steel and fully playing the role.
Calcium treatment depth determination:
the proper feed depth is related to the melt-down depth of the core-spun yarn. The core-spun yarn begins to melt down when being fed to a certain depth, and the depth of the core-spun yarn ensures that calcium bubbles dispersed by melting down are subjected to larger hydrostatic pressure of molten steel, so that the calcium bubbles are completely consumed as far as possible before floating to the molten steel surface. The wire feeding depth is preferably 300-400 mm deep from the bottom of the ladle. In order to ensure the wire feeding depth, a vertical lifting guide pipe which can approach the liquid level of the steel is adopted, the guiding depth of the lifting guide pipe is much larger than that of the common lifting guide pipe which can not approach the liquid level of the steel and can not be fixed at the front end, and the yield is about 20 percent higher.
Determination of the wire feeding speed:
the proper wire feeding speed can improve the yield of calcium. If the speed is too high, on one hand, the molten steel is violently stirred up due to a large amount of calcium vapor locally generated, and the large amount of calcium vapor is directly exposed and volatilized into the air, and on the other hand, the molten steel floats up due to the fact that the calcium vapor is not dissolved in time, so that the yield of the molten steel is reduced; on the contrary, if the speed is too slow, the feeding depth is insufficient, and the feeding liquid floats to the molten steel surface before being completely dissolved in the molten steel, so that the feeding liquid is wasted. Through experiments, the optimum wire feeding speed is determined to be between 2.5 and 3.5m/s, and the relationship between the wire feeding speed and the calcium recovery rate is shown in figure 4.
Determination of calcium treatment amount:
theoretically calculated [ Ca ] for generating 12CaO 7A1203]-[Al]Curves and measured values. The calcium content in the steel is too low, the average content is 20ppm, almost all actual measuring points are positioned below the theoretical curve, the ideal inclusion form control effect is not achieved, and the flocculation problem is caused. According to ML08AI pair [ Als]Required, [ Als ]]/[Alt]Not less than 0.9, the calcium treatment being aimed at [ Ca ] in order to ensure that all acid-insoluble aluminum is denatured]/[A12O3]The castability of the molten steel is more than or equal to 1, and the castability of the molten steel is good after the theoretical calculation and control.
7. Argon blowing upward floating theory research
After the calcium treatment of the refining LF furnace is finished, the molten steel needs to be subjected to soft argon blowing treatment. The stirred molten steel promotes the non-metallic inclusion in the steel to collide and grow, the floating argon bubbles can absorb gas in the steel, and the inclusion suspended in the molten steel is adhered to the surface of the molten steel and is absorbed by a slag layer. The soft argon blowing treatment is an argon blowing mode of firstly blowing in the middle and then blowing in the weak state, and the stirring intensity of argon is gradually reduced. Domestic research data show that large-particle impurities larger than 7.5 mu m are eliminated after LF treatment and soft argon blowing.
The soft argon blowing flow has great influence on the floating removal of inclusions in the steel; when the flow of argon gas is 70-110L/min, the effect of removing inclusions in steel is the best, and the removal index is 0.97-1.0; the removal index of the inclusions is decreased as the soft-blowing flow rate is increased, and the removal index of the inclusions is 0.94 when the soft-blowing argon flow rate is 120L/min; and when the soft argon blowing amount was increased to 220L/min, the inclusion removal index was decreased to 0.79.
Research shows that when the flow of the soft argon blowing is small, the argon bubbles in the molten steel are uniform, fine, large in quantity and dispersed, so that the capture and floating removal of fine inclusions in the steel are facilitated, but when the flow of the argon is too small, the quantity of the argon bubbles entering the molten steel in unit time is reduced, and the removal effect of the inclusions is also influenced; when the flow of the soft argon blowing gas is maximum, the bubbles are collided with each other to synthesize large bubbles after being separated from the air brick, so that the argon bubbles in the molten steel are concentrated and the quantity of the argon bubbles is reduced, thereby influencing the capturing and removing efficiency of the impurities. Meanwhile, the surface of the molten steel can be blown away by large soft argon blowing flow to cause secondary oxidation of the molten steel, and when the soft argon blowing flow is too large, the molten steel in the ladle is easy to form a circular flow, so that the treated very fine inclusions enter the steel slag along a circular flow track. Therefore, in order to minimize inclusions in molten steel, a reasonable soft argon blowing rate should be maintained to secure the number of argon bubbles introduced into molten steel.
Therefore, the soft argon blowing flow is controlled to 110L/min at the early stage, and is controlled to 70L/min at the later stage to remove the inclusions in the steel most effectively.
Through the research of the flocculation control technology, the inclusion control level of the cold forging steel ML08Al is obviously improved, and the specific detection results are shown in Table 7. From the detection point of view, the grade is mainly 0.5 and 1.0.
TABLE 7 examination of the grade of nonmetallic inclusions
| Categories | A | B | C | D |
| Detecting quantity/item | 130 | 130 | 130 | 130 |
| 0.5 order frequency/%) | 118 | 91 | 102 | 121 |
| 1.0 order frequency/%) | 12 | 27 | 20 | 9 |
| 1.5 order frequency/%) | 0 | 12 | 8 | 0 |
By metallographic examination of the ML08AL wire rod, the examination results are shown in table 8, and the improved grain size is seen to be higher.
TABLE 8 metallographic examination of a certain pour before process modification
As shown in figure 5, the metallographic structure of the cold forging steel ML08Al is composed of ferrite and pearlite, the grain size is 8.5-9.0 grade, and the grain size is more uniform and finer.
The results of the examples show that:
⑴ aiming at the problem of ML08Al molten steel flocculation flow, the deoxidation process is moved to the rear of the converter, so that the deoxidation product becomes Al with larger volume2O3SiO22MnO inclusions can float upwards, the total oxygen content of the molten steel is reduced, and the refining pressure is relieved.
Secondly, through a series of research works on the production process flow of the cold forging steel, the cold forging steel ML08Al is produced in batch, and the cold upsetting performance can meet the requirements of both 1/3 and 1/4 at present from the initial requirement that 1/2 cannot be met.
The research and the successful production of the flocculation control technology of the cold heading steel ML08Al are realized, the development progress of cold heading series steel is accelerated, the quality of the cold heading steel is improved, the technical economic benefit and the social benefit are obvious, and the market prospect is wide.
Claims (8)
1. The method for controlling the cold heading steel flocculation flow is characterized in that the cold heading steel ML08AL comprises the following chemical components in percentage by mass: c0.06-0.09; si is less than or equal to 0.08; 0.35-0.45% of Mn; p is less than or equal to 0.017; s is less than or equal to 0.015; 0.02-0.05 of Als; n is 0.03-0.05; the balance being Fe.
2. The method for controlling the flow of cold heading steel flocs according to claim 1, wherein the elongation is not less than 40%, the tensile strength is not more than 470MPa, and the reduction of area is not less than 60% by mass.
3. The method for controlling the cold heading steel floc flow according to claim 1, wherein the ML08AL production process route is as follows: hot metal mixer → hot metal pretreatment → 120 ton top-bottom combined blown converter → molten steel pre-deoxidation → 120 ton LF furnace refining → 150mm × 150mm square billet continuous casting.
4. The method for controlling the floc flow of cold-heading steel according to claim 3, wherein a 120-ton top-bottom combined blown converter is used for pre-deoxidation, 30-40 kg of aluminum particles are added into a ladle before the tapping of the converter is finished, and a wire feeder is used for supplementing aluminum wires after the tapping is finished, so that the aluminum content of molten steel is in the range of 0.020% -0.050%; and after the aluminum wire is supplemented, argon is blown for 4-6 min, so that the deoxidation product can fully float upwards.
5. The method for controlling the flocculated flow of the cold forging steel according to claim 1, wherein during the refining in the LF furnace, the slag is stopped and the steel is tapped, the slag thickness in a ladle is controlled to be not more than 50mm, the carbide slag and the aluminum particles are mixed and deoxidized, the atmosphere in the LF furnace is controlled to be a reducing atmosphere, and argon is blown from bottom for stirring; the LF slag composition is controlled as follows according to mass percentage: SiO22，2.45～5.06；CaO，49.02～55.54；Al2O321.96-30.08, TFe, 1.82-3.00; the slag alkalinity is 8.93-13.62.
6. The method for controlling the flocculation flow of cold heading steel according to claim 1, wherein the weight ratio of acid-soluble aluminum [ Al ] s to total aluminum [ Al ] t in the cold heading steel ML08AL is: [ Al ] s/[ Al ] t is not less than 0.9.
7. The method for controlling the flocculation flow of the cold heading steel according to claim 1, wherein calcium treatment is performed during refining in an LF furnace, the wire feeding depth of the calcium iron wire is 300-400 mm from the bottom of the ladle, the wire feeding speed is 2.5-3.5 m/s, and the calcium iron wire is 300-400 m/furnace.
8. The method for controlling the flocculation flow of the cold forging steel as claimed in claim 1, wherein after the calcium treatment of the refining LF furnace is finished, the molten steel is subjected to soft argon blowing treatment; when the flow of argon gas is 70-110L/min, the effect of removing the inclusions in the steel is the best, and the removal index is 0.97-1.0.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910218034.0A CN111719079A (en) | 2019-03-21 | 2019-03-21 | Control method for cold heading steel flocculation flow |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910218034.0A CN111719079A (en) | 2019-03-21 | 2019-03-21 | Control method for cold heading steel flocculation flow |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111719079A true CN111719079A (en) | 2020-09-29 |
Family
ID=72562657
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910218034.0A Pending CN111719079A (en) | 2019-03-21 | 2019-03-21 | Control method for cold heading steel flocculation flow |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111719079A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112251661A (en) * | 2020-10-28 | 2021-01-22 | 湖南华菱湘潭钢铁有限公司 | Production method of low-carbon low-silicon cold heading steel |
| CN112609131A (en) * | 2020-10-27 | 2021-04-06 | 河钢股份有限公司承德分公司 | Low-carbon aluminum killed cold forging steel and production method thereof |
| CN113122679A (en) * | 2021-04-19 | 2021-07-16 | 广东韶钢松山股份有限公司 | Calcium treatment method for molten steel and steel prepared by using calcium treatment method |
| CN114871397A (en) * | 2022-03-28 | 2022-08-09 | 本钢板材股份有限公司 | High-quality steel wire rod for cold heading and preparation method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105543675A (en) * | 2015-12-21 | 2016-05-04 | 中天钢铁集团有限公司 | Cold heading steel with refined crystalline grains and production process thereof |
| CN106957942A (en) * | 2017-03-06 | 2017-07-18 | 河钢股份有限公司邯郸分公司 | A kind of low carbon low silicon aluminium killed steel that improves directly starts to walk to open the method for pouring success rate |
| CN108085600A (en) * | 2017-12-28 | 2018-05-29 | 常熟市龙腾特种钢有限公司 | A kind of large deformation standard component cold-forging steel and its production method |
| CN108977612A (en) * | 2018-09-28 | 2018-12-11 | 邢台钢铁有限责任公司 | The smelting process of high-strength weather-resistant bolt steel |
-
2019
- 2019-03-21 CN CN201910218034.0A patent/CN111719079A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105543675A (en) * | 2015-12-21 | 2016-05-04 | 中天钢铁集团有限公司 | Cold heading steel with refined crystalline grains and production process thereof |
| CN106957942A (en) * | 2017-03-06 | 2017-07-18 | 河钢股份有限公司邯郸分公司 | A kind of low carbon low silicon aluminium killed steel that improves directly starts to walk to open the method for pouring success rate |
| CN108085600A (en) * | 2017-12-28 | 2018-05-29 | 常熟市龙腾特种钢有限公司 | A kind of large deformation standard component cold-forging steel and its production method |
| CN108977612A (en) * | 2018-09-28 | 2018-12-11 | 邢台钢铁有限责任公司 | The smelting process of high-strength weather-resistant bolt steel |
Non-Patent Citations (2)
| Title |
|---|
| 蔡开科: "《连铸坯质量控制》", 31 May 2010, 冶金工业出版社 * |
| 裘文: "冷镦冷挤压用钢ML08Al的质量控制", 《金属世界》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112609131A (en) * | 2020-10-27 | 2021-04-06 | 河钢股份有限公司承德分公司 | Low-carbon aluminum killed cold forging steel and production method thereof |
| CN112609131B (en) * | 2020-10-27 | 2022-03-15 | 河钢股份有限公司承德分公司 | Low-carbon aluminum killed cold forging steel and production method thereof |
| CN112251661A (en) * | 2020-10-28 | 2021-01-22 | 湖南华菱湘潭钢铁有限公司 | Production method of low-carbon low-silicon cold heading steel |
| CN113122679A (en) * | 2021-04-19 | 2021-07-16 | 广东韶钢松山股份有限公司 | Calcium treatment method for molten steel and steel prepared by using calcium treatment method |
| CN114871397A (en) * | 2022-03-28 | 2022-08-09 | 本钢板材股份有限公司 | High-quality steel wire rod for cold heading and preparation method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111719079A (en) | Control method for cold heading steel flocculation flow | |
| JP5262075B2 (en) | Method for producing steel for pipes with excellent sour resistance | |
| CN103160729B (en) | Medium-carbon microalloyed steel for engineering machinery caterpillar chain piece and production process thereof | |
| CN102816979B (en) | Production method of low-carbon sulfur series free-cutting steel continuous casting billet | |
| CN109252008A (en) | A kind of production method of low carbon, low nitrogen ultralow-sulfur steel | |
| CN103334050B (en) | Process utilizing sheet billet continuous casting to manufacture low aluminum silicon calm carbon structural steel | |
| CN112899560B (en) | High-strength gear steel 23CrMnMoS and manufacturing method thereof | |
| CN114318154B (en) | High-cleanliness welding wire steel L-S3 and preparation method thereof | |
| CN101736194B (en) | Wheel steel and preparation method as well as wheel thereof | |
| CN108893682B (en) | Die steel billet and preparation method thereof | |
| CN111471920B (en) | Non-quenched and tempered steel for U-shaped bolt and production method thereof | |
| CN111411304A (en) | Q460-grade hot-rolled angle steel and preparation method thereof | |
| CN114480987A (en) | Rare earth-containing NM600 wear-resistant steel plate and preparation method thereof | |
| CN113652511A (en) | Smelting method for controlling nitrogen content in silicon-aluminum killed steel to be less than or equal to 0.0013% | |
| CN106011373B (en) | A kind of production method carrying out molten steel Calcium treatment using residual calcium in Antaciron | |
| CN112626312A (en) | Low-carbon aluminum killed steel Al for reducing RH single process2O3Method of inclusion | |
| KR100368239B1 (en) | A process of refining molten steel for high clean steel | |
| CN112981250A (en) | Control method for corner crack of low-carbon low-titanium niobium-containing steel sheet billet with low molten iron unit consumption | |
| CN113122679A (en) | Calcium treatment method for molten steel and steel prepared by using calcium treatment method | |
| CN102211155A (en) | Calcium treatment method of low-carbon low silicon aluminium killed steels under CSP (Cast Steel Plate) condition | |
| CN112322833A (en) | Method for alloying ultrahigh aluminum steel | |
| CN116574965B (en) | Method for improving inclusion level of wind power steel | |
| CN108342656A (en) | A kind of superhigh intensity automobile structural steel and its production method | |
| CN117248167B (en) | Corrosion-resistant I-steel and production method thereof | |
| CN117925947B (en) | High-purity low-temperature steel and production method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200929 |