CN114855064A - Method for improving surface quality of microalloyed steel continuous casting wide and thick plate blank - Google Patents

Method for improving surface quality of microalloyed steel continuous casting wide and thick plate blank Download PDF

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CN114855064A
CN114855064A CN202210447071.0A CN202210447071A CN114855064A CN 114855064 A CN114855064 A CN 114855064A CN 202210447071 A CN202210447071 A CN 202210447071A CN 114855064 A CN114855064 A CN 114855064A
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李烈军
许博
陈松军
彭政务
张伟鹏
张鑫奎
黄思铭
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South China University of Technology SCUT
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    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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    • C21—METALLURGY OF IRON
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    • 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
    • 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
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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    • 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
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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Abstract

The invention discloses a method for improving the surface quality of a microalloy steel continuous casting wide and thick plate blank. The method improves the surface quality of the microalloy steel continuous casting wide and thick plate blank through alloy component optimization, and specifically comprises the following steps: (1) in the converter tapping process, the consumption of aluminum and iron is reduced; (2) in the LF and RH refining process, the usage amount of aluminum slag balls is kept, but aluminum wires are not added into the molten steel any more, so that the aluminum content in the molten steel is greatly reduced; (3) in the LF + RH refining process, the content of titanium in the molten steel is increased; (4) in the whole production process, the contact between molten steel and air is isolated by adopting the covering slag, the denitrification is enhanced in the RH refining, and the nitrogen content is controlled within 0.006 percent. The microalloyed steel continuous casting wide and thick plate blank produced by the method has good high-temperature plasticity, low crack sensitivity and greatly improved surface quality.

Description

Method for improving surface quality of microalloyed steel continuous casting wide and thick plate blank
Technical Field
The invention relates to the technical field of component optimization of steel making, in particular to a method for improving the surface quality of a microalloyed steel continuous casting wide and thick plate blank.
Background
In order to improve various properties of steel, researchers have proposed microalloying techniques for steel. One or more alloy elements are added into the steel, and the total content of the added alloy elements is below 0.20 percent, so that the weldability, the formability, the toughness, the strength and other properties of the steel are improved. Due to the excellent toughness and higher strength of microalloyed low alloy steel, the microalloyed low alloy steel is widely applied to industries such as petroleum pipelines, bridge construction, transportation, mechanical manufacturing and the like.
At present, the microalloying of low alloy steel is mainly to add Nb, Ti, V and other alloy elements into steel, and the alloy elements can react with C, N strongly to form compound precipitation. The Nb, Ti and V elements are separated out at austenite crystal boundary to inhibit the growth of austenite and strengthen fine grains, and these elements can also separate out nano-scale precipitate in ferrite grain or crystal boundary to block dislocation motion and strengthen precipitate, so that the strength of steel material is increased without lowering the toughness of steel material. However, the micro-alloy elements are precipitated at the grain boundary at high temperature, so that the continuity of the grain boundary is damaged, the crack sensitivity of the casting blank is increased, and the high-temperature plasticity of the casting blank is reduced.
Al element mainly exists in steel as AlO and AlN, and AlN precipitated phase has obvious edge angles, is mostly quadrangular, hexagonal or irregular and has smaller size. In general, AlN precipitates at about 900 ℃ to greatly reduce the ductility of the austenite region, and causes the third brittleness to be widened and the valleys to be deepened, so that it has a certain adverse effect on the fracture toughness of the steel.
The binding capacity of Ti element with carbon and nitrogen in molten steel is stronger than that of niobium, vanadium and aluminum, TiN phase can be precipitated at high temperature, the nitrogen content of steel is reduced, and the nitrogen fixation effect is achieved, so that the precipitation of Nb (C, N) and AlN at austenite grain boundary is reduced, and the influence of the precipitation of second phase in a third brittle zone is reduced. Meanwhile, TiN has a pinning effect on austenite grain boundaries, prevents the growth of the austenite grain boundaries, refines austenite grains, and reduces the prerequisite condition of crack generation, thereby improving the high-temperature plasticity of a casting blank. At a relatively low temperature, the precipitated particles of titanium are large and distributed scattered, and thus can serve as nucleation sites for precipitates such as niobium and vanadium to form composite carbonitride, thereby reducing the adverse effect of niobium, Nb and vanadium V on the high-temperature plasticity of the steel.
Continuous casting technology, i.e. continuous casting technology, allows the continuous production of cast slabs compared to the traditional casting process, with the following advantages: (1) the casting process is reduced, and the casting process is shortened; (2) the yield of the metal is improved; (3) the energy consumption is reduced; (4) the automation degree is continuously improved; (5) the quality of continuous casting billets is increasingly improved. The continuous casting technology is used for producing the microalloyed steel, and the advantages of the microalloyed steel and the microalloyed steel can be greatly exerted.
But because the microalloy elements are precipitated at high temperature, the high-temperature thermoplasticity of the casting blank is deteriorated; the micro-alloy steel continuous casting wide and thick plate blank has serious surface defects due to the reasons of large sectional area of the wide and thick plate, serious turbulence, uneven temperature distribution, uneven stress of the casting blank and the like, so that serious resource waste is generated, and the economic benefit is reduced.
In the patent of a test method for improving the surface quality of a microalloyed steel continuous casting slab, a Gleeble3800 thermal test machine is used for researching a brittle temperature zone of microalloyed steel, and an idea is provided for the specification of continuous casting straightening temperature. But the simulation of the continuous casting process is only carried out from the test point of view, the actual production test is not carried out, and the generation of continuous casting billet cracks is not improved from the source.
Disclosure of Invention
In order to overcome the adverse effect of microalloy elements on the high-temperature plasticity of a continuous casting blank, the invention aims to provide the method for improving the surface quality of the microalloy steel continuous casting wide and thick plate blank. The production cost of enterprises can be reduced, and the production efficiency is stabilized and improved.
The purpose of the invention is realized by the following technical scheme.
The production process flow of the microalloy steel continuous casting wide and thick plate blank comprises the following steps: molten iron pretreatment → converter steelmaking → LF + RH refining → continuous casting. A method for improving the surface quality of a microalloy steel continuous casting wide and thick plate blank comprises the following steps:
(1) in the converter tapping process, the consumption of aluminum and iron is reduced;
(2) in the LF + RH refining process, the increase of aluminum wires is removed;
(3) in the LF + RH refining process, the content of titanium in the molten steel is increased;
(4) and controlling the increase of nitrogen elements in the molten steel in the whole production process.
Further, the reduction of the consumption of aluminum and iron in the step (1) specifically comprises the following steps: during the tapping process of the converter, the content of the ferro-aluminum in the deoxidizer is reduced, while the content of the silicon-manganese alloy is unchanged, so as to keep the overall deoxidizing effect of the steel unchanged, but reduce the content of the aluminum in the molten steel.
Further, the removing of the increase of the aluminum wire in the step (2) specifically comprises: the consumption of the aluminum slag balls is kept in the LF and RH refining process, so that the increase of the oxygen content in the molten steel is prevented, but aluminum wires are not added into the molten steel in the LF refining process, and the content of acid-soluble aluminum in the molten steel is greatly reduced.
Further, through the steps (1) and (2), the aluminum content in the molten steel is controlled to be 0% -0.008%.
Further, in the step (3), the main tasks of the LF + RH refining are deoxidation, desulfurization, inclusion removal and molten steel alloying, and in the alloying process, the use of titanium alloy is increased, so that the titanium content in the molten steel is increased and stabilized to be about 0.020%.
Further, through the step (3), the titanium content in the molten steel is controlled within the range of 0.018-0.028%.
Further, the step (4) of controlling the contact between the molten steel and the air specifically comprises the following steps: in the whole production process, the contact between the molten steel and air is isolated by adopting the covering slag, so that the molten steel is prevented from absorbing nitrogen in the air. Meanwhile, in the RH refining process, the refining vacuum degree is controlled within 300Pa, denitrification is carried out, the nitrogen content in the molten steel is controlled within 0.006 percent, and the nitrogen increase of the molten steel in the subsequent continuous casting process is not obvious.
The invention provides a microalloyed steel continuous casting wide and thick plate blank with excellent surface quality, which is obtained by the method, and the surface quality rate is 81-89%.
Compared with the prior art, the invention has the following advantages:
(1) the invention utilizes the microalloy steel continuous casting wide and thick plate blank produced by the optimized process. The negative influence of Al element on the steel performance is removed, the influence of Ti element on the steel performance is enhanced, the influence of N element on the steel performance is strictly controlled, and the precipitation strengthening and fine grain strengthening of microalloy element titanium at the high-temperature section of the continuous casting billet are improved, so that the thermoplasticity of the continuous casting billet at the high-temperature section is improved.
(2) The microalloy steel continuous casting wide and thick slab produced by the method has good high-temperature plasticity, high casting blank surface quality, and good surface rate of 81-89%, and is stabilized at about 83%. Under the condition of better nitrogen control, the hot charging can be directly carried out by heat, and the production efficiency of a steel mill is greatly improved.
Drawings
FIG. 1 is a flow chart of the manufacturing process of micro alloy steel continuous casting wide and thick slabs in examples 1-3;
FIG. 2 is a high-temperature plasticity comparison diagram of a microalloyed steel Q390GJC continuous casting wide and thick plate blank before and after the process improvement in example 1;
FIG. 3 is a fracture morphology diagram of a microalloyed steel Q390GJC continuous casting wide and thick slab tensile sample at 750 ℃ before process improvement in example 1;
FIG. 4 is a fracture morphology diagram of a microalloyed steel Q390GJC continuous casting wide and thick slab tensile sample at 750 ℃ after the process improvement in example 1.
Detailed Description
The following further describes embodiments of the present invention with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.
Example 1
According to the production process flow chart of figure 1, the steel grade is Q390GJC, and the production process flow is as follows: molten iron pretreatment → converter steelmaking → LF + RH refining → continuous casting, more specifically: molten iron pre-desulfurization treatment → converter steelmaking → LF refining → RH refining → continuous casting, and wide and thick slabs with the thickness of 270mm and the width of 2260mm are manufactured.
In the production process, the method for improving the surface quality of the microalloyed steel Q390GJC continuous casting wide and thick plate blank comprises the following steps:
(1) during the tapping process of the converter, the content of the silicon-manganese alloy in the deoxidizer is unchanged, while the content of the aluminum and the iron is reduced from 150kg to 120 kg.
(2) In the LF and RH refining process, the usage amount of aluminum slag balls is kept, but aluminum wires are not added any more, so that the content of acid-soluble aluminum in the molten steel is greatly reduced while the increase of oxygen in the molten steel is prevented, and the content of Als is reduced from about 0.020% to about 0.005%.
(3) In the LF refining and RH refining, the molten steel is sufficiently desulfurized, deoxidized, inclusion-removed, and alloyed, and in the alloying, the content of the titanium alloy is increased to increase the target content of Ti in the molten steel from the vicinity of the former 0.01% to the vicinity of 0.020%. The fluctuation is allowed in the actual production, and the fluctuation range is 0.018 to 0.028 percent.
(4) In the whole production process, the contact between the molten steel and air is isolated by adopting the covering slag, the contact between the molten steel and the air is strictly controlled, and the molten steel is prevented from being sucked into N elements in the air. Meanwhile, in the RH refining process, the refining vacuum degree is 266Pa, and denitrification is carried out, so that the nitrogen content in the molten steel is controlled within 0.006 percent.
By adopting the improved production process, the microalloyed steel Q390GJC continuous casting wide and thick plate blank with the target component can be smoothly produced, the chemical components and the contents of the part of the casting blank before and after the improvement are shown in the table 1, and the rest is Fe and contains a small amount of inclusions.
TABLE 1
Chemical composition C Si Mn P≤ S≤ Als N Nb Ti Cu
Before improvement% 0.160 0.30 1.46 0.020 0.006 0.021 0.0076 0.030 0.010 0.028
After improvement% 0.158 0.31 1.45 0.020 0.006 0.002 0.0053 0.029 0.023 0.030
The quality of the microalloyed steel Q390GJC continuous casting wide and thick plate blank prepared in the embodiment is detected.
(1) And (3) surface quality detection:
after the micro-alloy steel Q390GJC continuous casting wide and thick plate blank is produced, the surface quality of the plate blank needs to be checked, so that the plate blank is prevented from generating serious surface defects in subsequent hot rolling, causing product scrap and wasting productivity. The surface quality inspection method mainly adopts a flame skinning method, 4-6 continuous casting wide and thick plate blanks are produced by one furnace steel approximately, 2 plate blanks are drawn out for skinning inspection, one deep skinning and one shallow skinning. The superficial raking uses a flame gun to clean the surface once, approximately removes a 4mm thick surface steel layer, and the deep raking uses a flame gun to rake again on the basis of the superficial raking, approximately removes an 8mm thick surface steel layer. And after peeling, carrying out detailed searchlighting inspection on the whole surface of the casting blank by using an LED strong light flashlight, wherein the inspection time of one plate blank is 5-8 minutes. When the defects of surface transverse cracks, angular cracks, reticular cracks, slag inclusion and the like appear, marking the corresponding defect positions, and judging that the casting blank is bad if the number of the defects is more than 1. If one slab in the spot check has a problem, other slabs of the whole furnace steel need to be scalped for inspection, defective casting blanks are refitted after scalping, and then are sent to hot rolling, and if the problem is serious, the whole casting blank is scrapped.
Before the process is improved, the surface quality improvement rate of the microalloy steel Q390GJC continuous casting wide and thick plate blank is about 56 percent, more surface defects exist, more continuous casting blanks need to be scalped, inspected and refitted, the productivity is seriously wasted, the production period is prolonged, and the production efficiency of a steel mill is influenced. After the process is improved, the surface quality improvement rate of the microalloyed steel Q390GJC continuous casting wide and thick plate blank is about 87%, if the nitrogen control condition is excellent, the surface quality of the microalloyed steel Q390GJC continuous casting wide and thick plate blank is excellent, hot charging can be directly carried out, the links of slow cooling, peeling detection and heating in the middle are reduced, and the production efficiency of a steel mill is greatly improved.
(2) And (3) high-temperature plasticity detection:
FIG. 2 is a comparison graph of high-temperature plasticity of a microalloy steel Q390GJC continuous casting wide and thick plate blank before and after process improvement, and it can be seen from the graph that the fracture shrinkage rate of a steel sample after the improvement is obviously higher than that of the steel sample before the improvement within a brittleness range of 650-950 ℃, and is improved by 15% -30%, and the fracture shrinkage rate is an index for evaluating the plasticity of the steel. Therefore, the improved steel has more excellent plasticity, thereby ensuring that the cracks of the casting blank are reduced in the production process. Fig. 3 is a fracture morphology diagram of a microalloyed steel Q390GJC continuous casting wide and thick slab tensile sample at 750 ℃ before process improvement, fig. 4 is a fracture morphology diagram of a microalloyed steel Q390GJC continuous casting wide and thick slab tensile sample at 750 ℃ after process improvement, and a comparison between fig. 3 and fig. 4 shows that the fracture forms of the two steels are different, and the microalloyed steel Q390GJC continuous casting wide and thick slab after process improvement has certain ductile fracture, shows stronger high-temperature plasticity, and further illustrates that the success rate of process improvement is remarkable.
Example 2
According to the production process flow chart of fig. 1, the production process flow of the steel grade Q420GJC comprises the following steps: molten iron pretreatment → converter steelmaking → LF + RH refining → continuous casting, more specifically: molten iron pre-desulfurization treatment → converter steelmaking → LF refining → RH refining → continuous casting, and wide and thick slabs with the thickness of 270mm and the width of 2260mm are manufactured.
In the production process, the method for improving the surface quality of the microalloyed steel Q420GJC continuous casting wide and thick slabs comprises the following steps:
(1) during the tapping process of the converter, the content of the silicon-manganese alloy in the deoxidizer is unchanged, while the content of the aluminum and the iron is reduced from 150kg to 120 kg.
(2) In the LF and RH refining process, the usage amount of aluminum slag balls is kept, but aluminum wires are not added any more, so that the content of acid-soluble aluminum in the molten steel is greatly reduced while the increase of oxygen in the molten steel is prevented, and the content of Als is reduced from about 0.020% to about 0.005%.
(3) In the LF refining and RH refining processes, molten steel is sufficiently desulfurized, deoxidized, inclusion-removed, and alloyed, and in the alloying process, the content of titanium alloy is increased to increase the Ti content in the molten steel from the former vicinity of 0.01% to the vicinity of 0.020%.
(4) In the whole production process, the contact between the molten steel and air is isolated by adopting the covering slag, the contact between the molten steel and the air is strictly controlled, and the molten steel is prevented from being sucked into N elements in the air. Meanwhile, in the RH refining process, the refining vacuum degree is 275Pa, denitrification is carried out, and the nitrogen content in the molten steel is controlled within 0.006 percent.
By adopting the improved production process, the microalloyed steel Q420GJC continuous casting wide and thick plate blank with the target component can be smoothly produced, the chemical components and the contents of the part of the casting blank before and after the improvement are shown in the table 2, and the rest is Fe and contains a small amount of inclusions.
TABLE 2
Chemical composition C Si Mn P≤ S≤ Als N Nb Ti Cu
Before improvement% 0.154 0.30 1.45 0.020 0.006 0.020 0.0068 0.038 0.011 0.029
After improvement% 0.157 0.31 1.45 0.020 0.006 0.003 0.0044 0.040 0.024 0.030
According to the detection method in the example 1, the surface quality condition of the produced microalloy steel Q420GJC continuous casting wide and thick slab is checked, and the surface improvement rates of two casting blanks before and after the process improvement are compared. Before the process is improved, the surface quality improvement rate of the microalloyed steel Q420GJC continuous-casting wide and thick plate blank is about 43%, and after the process is improved, the surface quality improvement rate of the microalloyed steel Q420GJC continuous-casting wide and thick plate blank is about 81%. Due to the influence of high Nb content, the surface quality of the microalloy steel Q420GJC continuous casting wide and thick slabs is slightly poor, but the surface quality of the casting slabs is still obviously improved compared with that before the improvement.
Example 3
According to the production process flow chart of fig. 1, the production process flow of the steel grade Q345GJB is as follows: molten iron pretreatment → converter steelmaking → LF + RH refining → continuous casting, more specifically: molten iron pre-desulfurization treatment → converter steelmaking → LF refining → RH refining → continuous casting, and wide and thick slabs with the thickness of 270mm and the width of 2260mm are manufactured.
In the production process, the method for improving the surface quality of the microalloyed steel Q345GJB continuous casting wide and thick plate blank comprises the following steps:
(1) during the tapping process of the converter, the content of the silicon-manganese alloy in the deoxidizer is unchanged, while the content of the aluminum and the iron is reduced from 150kg to 120 kg.
(2) In the LF and RH refining process, the usage amount of aluminum slag balls is kept, but aluminum wires are not added any more, so that the content of acid-soluble aluminum in the molten steel is greatly reduced while the increase of oxygen in the molten steel is prevented, and the content of Als is reduced from about 0.020% to about 0.005%.
(3) In the LF refining and RH refining processes, molten steel is sufficiently desulfurized, deoxidized, inclusion-removed, and alloyed, and in the alloying process, the content of titanium alloy is increased to increase the Ti content in the molten steel from the former vicinity of 0.01% to the vicinity of 0.020%.
(4) In the whole production process, the contact between the molten steel and air is isolated by adopting the covering slag, the contact between the molten steel and the air is strictly controlled, and the molten steel is prevented from being sucked into N elements in the air. Meanwhile, in the RH refining process, the refining vacuum degree is 261Pa, denitrification is carried out, and the nitrogen content in the molten steel is controlled within 0.006 percent.
By adopting the improved production process, the microalloyed steel Q345GJB continuous casting wide and thick slab with the target component can be smoothly produced, the chemical components and the contents of the casting blank before and after improvement are shown in Table 3, and the balance is Fe and contains a small amount of impurities.
TABLE 3
Figure BDA0003617369030000061
Figure BDA0003617369030000071
According to the detection method in the example 1, the surface quality of the produced microalloyed steel Q345GJB continuous casting wide and thick slab is checked, and the surface quality of the casting blank before and after the process improvement is compared. Before the process is improved, the surface quality improvement rate of the micro-alloy steel Q345GJB continuous casting wide and thick plate blank is about 55%, after the process is improved, the surface quality improvement rate of the micro-alloy steel Q345GJB continuous casting wide and thick plate blank is about 86%, and the surface quality of the micro-alloy steel Q345GJB continuous casting wide and thick plate blank is obviously improved.

Claims (10)

1. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick plate blank is characterized in that the production process flow of the microalloyed steel continuous casting wide and thick plate blank is as follows: molten iron pretreatment → converter steelmaking → LF + RH refining → continuous casting; the method for improving the surface quality of the microalloy steel continuous casting wide and thick plate blank comprises the following steps:
(1) in the converter tapping process, the consumption of aluminum and iron is reduced;
(2) in the LF + RH refining process, the increase of aluminum wires is removed;
(3) in the LF + RH refining process, the content of titanium in the molten steel is increased;
(4) and controlling the increase of nitrogen elements in the molten steel in the whole production process.
2. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick plate blank according to claim 1, wherein the step (1) of reducing the consumption of aluminum and iron specifically comprises the following steps: the content of aluminum and iron in the deoxidizer is reduced, the content of the silicon-manganese alloy is unchanged so as to maintain the overall deoxidizing effect of the steel, but the content of aluminum in the molten steel is reduced.
3. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick slab as claimed in claim 1, wherein the step (2) of removing the increase of the aluminum wires comprises the following specific steps: the amount of aluminum slag balls is kept in the external refining, so that the oxygen content of the molten steel is prevented from increasing, but aluminum wires are not added into the molten steel in the LF refining process, so that the aluminum content in the molten steel is reduced.
4. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick slab as claimed in claim 1, wherein the aluminum content in the molten steel is controlled to be 0-0.008% through the steps (1) and (2).
5. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick plate blank according to claim 1, characterized in that in the step (3), the main tasks of LF and RH refining are deoxidation, desulfurization, inclusion removal and molten steel alloying, and in the alloying process, the dosage of the titanium alloy is increased to increase the titanium content in the molten steel.
6. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick slab as claimed in claim 1, wherein the titanium content in the molten steel is controlled to be in the range of 0.018 to 0.028 percent through the step (3).
7. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick plate blank according to claim 1, wherein the nitrogen content in the molten steel is controlled in the step (4), and the method comprises the following specific steps: in the whole production process, the contact between the molten steel and air is isolated by adopting the covering slag, so that the molten steel is prevented from absorbing nitrogen in the air; and in the RH refining process, the refining vacuum degree is controlled within 300Pa to denitrify.
8. The method for improving the surface quality of the microalloyed steel continuous casting wide and thick slab according to claim 1, wherein the nitrogen content in the molten steel is controlled within 0.006% through the step (4).
9. A micro-alloyed steel continuously cast wide and thick slab produced by the method of any one of claims 1 to 8.
10. The microalloyed steel continuous casting wide and thick slab as claimed in claim 9, wherein the surface quality of the microalloyed steel continuous casting wide and thick slab is 81-89%.
CN202210447071.0A 2022-04-26 2022-04-26 Method for improving surface quality of microalloyed steel continuous casting wide and thick plate blank Pending CN114855064A (en)

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Citations (1)

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Publication number Priority date Publication date Assignee Title
CN113699431A (en) * 2021-08-26 2021-11-26 广东韶钢松山股份有限公司 Method for reducing surface cracks of low alloy steel

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113699431A (en) * 2021-08-26 2021-11-26 广东韶钢松山股份有限公司 Method for reducing surface cracks of low alloy steel

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Application publication date: 20220805