CN114921722B - Production process for preventing bending degree of medium carbon manganese chromium alloy steel continuous casting billet from exceeding standard - Google Patents
Production process for preventing bending degree of medium carbon manganese chromium alloy steel continuous casting billet from exceeding standard Download PDFInfo
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Abstract
The invention discloses a production process for preventing the bending degree of a medium carbon manganese chromium alloy steel continuous casting blank from exceeding the standard, wherein the medium carbon manganese chromium alloy steel continuous casting blank comprises the following chemical components in percentage by weight: c:0.35 to 0.40 percent, si:0.20 to 0.40 percent, mn:1.80 to 2.00 percent, cr:0.40 to 0.60 percent of Al:0.030 to 0.050 percent, ti:0.030 to 0.060 percent, V:0.030 to 0.060 percent, S is less than or equal to 0.015 percent, P: less than or equal to 0.020 percent, the process comprises the following steps: smelting molten steel, and realizing preliminary dephosphorization and primary adjustment of components to obtain molten steel; adding trace alloy elements into molten steel; pouring the refined molten steel to obtain a high-temperature continuous casting blank of the medium-carbon manganese-chromium alloy steel; cooling the high-temperature continuous casting blank to a preset temperature through a turnover cooling bed, and then conveying the high-temperature continuous casting blank to a heat preservation pit for slow cooling for a preset time to obtain a medium-carbon manganese chromium alloy steel continuous casting blank; the method is used for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting blank from exceeding the standard, and the medium carbon manganese chromium alloy steel continuous casting blank produced by the production process has smaller bending degree, can smoothly enter a steel rolling heating furnace, and does not have the problem of surface longitudinal cracks.
Description
Technical Field
The invention relates to the technical field of alloy steel smelting and continuous casting, in particular to a production process for preventing the bending degree of a medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard.
Background
With the rapid development of the petroleum industry in China, the demand for oil well casings is increasing. The oil well casing belongs to disposable consumable materials, and the consumption of the oil well casing accounts for more than 70% of the total oil well casing. An N80 grade oil well casing is a higher grade oil casing that is required to have high strength, high plasticity, high toughness, low yield ratio, and certain corrosion resistance and hardness. The medium carbon manganese chromium alloy steel is a common steel grade for preparing the N80-grade oil well casing. The steel has coarse grains in the continuous casting high-temperature solidification crystallization process, so that the continuous casting billet is easy to generate high-temperature brittleness and surface longitudinal cracking under the action of cooling stress. The conventional process means is to quickly hoist the continuous casting billet with the surface temperature reaching more than 700 ℃ in the heat preservation pit for slow cooling so as to prevent serious cracking on the surface. However, in the actual production process, the manganese content in the medium carbon manganese chromium alloy steel reaches 1.80-2.00%, the line shrinkage of the high-temperature continuous casting billet in the cooling process is obviously higher than that of other low manganese steel types, and therefore, the bending degree of part of the continuous casting billet exceeds the standard due to overlarge volume shrinkage and uneven cooling, as shown in fig. 1. The continuous casting billet with the standard bending degree cannot enter the steel rolling heating furnace to be scrapped, so that the production cost is increased. In addition, in the process of transporting the continuous casting blank to the heating furnace mouth through the roller way, if the bending degree of the continuous casting blank is too large, the condition that the continuous casting blank is clamped on the roller way wall is very easy to occur, and further the follow-up production is influenced. The space in the factory is limited, and the occupied area of the roller way is enlarged by increasing the width of the roller way, so that the production cost is increased. The new technology and the new technology are adopted, so that the scrapping caused by the exceeding of the bending degree of the continuous casting billet is reduced, the production cost is reduced, and the method becomes the focus of attention of each iron and steel enterprise. Most enterprises improve the problem of exceeding the standard of the bending degree of the continuous casting billet by adding a device for preventing the continuous casting billet from bending.
The Chinese patent with publication number of CN201889408U discloses a device for preventing continuous casting billets from bending, which is used for preventing continuous casting billets from bending and deforming when being slowly cooled in a stamping position. The device has simple structure and low manufacturing cost, but the device has fixed size, can only prevent continuous casting billet bending in the slow cooling process, and is not suitable for continuous casting billets which are bent on a cooling bed. In addition, a gap exists between the device and the continuous casting billet, the continuous casting billet still can be slightly bent, the U-shaped frame structure is easy to clamp after slow cooling is finished, and the device is difficult to take off.
The Chinese patent with publication No. CN205165786U discloses a device for storing hot billets and preventing bending, which provides a door-shaped steel clamp consisting of square steel with the side length of 40mm and is used for clamping 4 uniformly distributed casting billets. Likewise, the device is not suitable for a continuous casting billet which is bent on a cooling bed, and a portal steel clamp is easy to clamp after the slow cooling of the continuous casting billet is finished, so that the device is difficult to remove.
The Chinese patent with publication number of CN211516022U, a device for preventing continuous casting billet from bending, provides a mounting groove for uniformly distributing a plurality of air cylinders, and when the continuous casting billet is placed in the mounting groove, the continuous casting billet can be corrected by pushing the piston rod end of the air cylinder, so that the continuous casting billet is prevented from bending. The device flexible operation is applicable to the continuous casting billet of different crooked degree, but the device occupation space is big, and every continuous casting groove can only correct a hanging continuous casting billet, is unfavorable for the large-scale production of enterprise and uses.
From the above, the device for preventing continuous casting billet bending is mainly suitable for continuous casting billets with small batch and small section, and is difficult to realize industrialized mass production. In addition, the device for preventing the bending of the continuous casting billet can only be passively prevented after continuous casting is finished, and the preventing device can only be taken down after the continuous casting billet is cooled to room temperature, so that the device is not beneficial to fast-paced continuous casting production. Under the large background of cost reduction and efficiency enhancement of the whole steel industry, the development of a production process for preventing the bending degree of the continuous casting billet from exceeding the standard, improving the production efficiency and reducing the production cost becomes a problem to be solved in the industry.
Disclosure of Invention
The invention aims to overcome the defects, and provides a production process for preventing the bending degree of the medium-carbon manganese-chromium alloy steel continuous casting billet from exceeding the standard.
The invention provides a production process for preventing the bending degree of a medium carbon manganese chromium alloy steel continuous casting blank from exceeding the standard, wherein the medium carbon manganese chromium alloy steel continuous casting blank comprises the following chemical components in percentage by weight: c:0.35 to 0.40 percent, si:0.20 to 0.40 percent, mn:1.80 to 2.00 percent, cr:0.40 to 0.60 percent of Al:0.030 to 0.050 percent, ti:0.030 to 0.060 percent, V:0.030 to 0.060 percent, S is less than or equal to 0.015 percent, P: less than or equal to 0.020 percent.
Further, the method comprises the following steps: smelting, namely smelting molten steel, and realizing preliminary dephosphorization and primary adjustment of components to obtain molten steel; a refining step, namely adding trace alloy elements into molten steel for deoxidation and component fine adjustment, wherein the trace alloy elements comprise titanium and vanadium, and the finally obtained refined molten steel comprises the following components in percentage by weight: c:0.35 to 0.40 percent, si:0.20 to 0.40 percent, mn:1.80 to 2.00 percent, cr:0.40 to 0.60 percent of Al:0.030 to 0.050 percent, ti:0.030 to 0.060 percent, V:0.030 to 0.060 percent, S is less than or equal to 0.015 percent, P: less than or equal to 0.020%; and a continuous casting step, namely casting the refined molten steel to obtain a high-temperature continuous casting blank of the medium-carbon manganese-chromium alloy steel.
And further, the method also comprises a cooling step, namely cooling the high-temperature continuous casting blank to a preset temperature through a turnover cooling bed, and then conveying the high-temperature continuous casting blank to a heat preservation pit for slow cooling for a preset time to obtain the medium-carbon manganese chromium alloy steel continuous casting blank.
Further, the predetermined temperature is 400.+ -. 20 ℃.
Further, the predetermined time is 48 hours.
Further, the turnover cooling bed comprises a first toothed plate and a second toothed plate, wherein the upper side of the first toothed plate is provided with a plurality of first V-shaped teeth which are sequentially and equally spaced, and a first spacing part which is arranged between two adjacent first V-shaped teeth; the upper side of the second toothed plate is provided with a plurality of second V-shaped teeth which are arranged at equal intervals in sequence and a second spacing part which is arranged between two adjacent second V-shaped teeth.
Further, the tooth surface of the first V-shaped tooth is formed by a first inclined surface and a second inclined surface, and the included angle between the first inclined surface and the second inclined surface is smaller than 90 degrees; and/or the tooth surface of the second V-shaped tooth is formed by a third inclined surface and a fourth inclined surface, and the included angle between the third inclined surface and the fourth inclined surface is smaller than 90 degrees.
Further, the included angle between the first inclined surface and the vertical direction is smaller than 45 degrees, and the included angle between the second inclined surface and the vertical direction is equal to 45 degrees; and/or the included angle between the third inclined surface and the vertical direction is smaller than 45 degrees, and the included angle between the fourth inclined surface and the vertical direction is equal to 45 degrees.
Further, the first inclined surface is located at the front side of the second inclined surface along the moving direction of the high-temperature continuous casting billet, and the third inclined surface is located at the front side of the fourth inclined surface along the moving direction of the high-temperature continuous casting billet.
Further, the first inclined surface is located at the front side of the second inclined surface along the moving direction of the high-temperature continuous casting billet, and the fourth inclined surface is located at the front side of the third inclined surface along the moving direction of the high-temperature continuous casting billet.
The beneficial effects of the invention are as follows: the production process for preventing the bending degree of the medium-carbon manganese-chromium alloy steel continuous casting billet from exceeding the standard solves the contradiction that the medium-carbon manganese-chromium alloy steel high-temperature continuous casting billet is easy to crack when being cooled fast and easy to bend when being cooled slowly by a microalloying process means and a microalloying cooling mode matched with a turnover cooling bed and a heat preservation pit. The production worker for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard reduces the actual production difficulty, reduces the production cost by 50 yuan/ton, and does not need straightening treatment. The bending problem of the high-temperature continuous casting billet is solved by adding proper titanium and vanadium microelements and adopting a uniform cooling mode of a turnover step cooling bed in the high-temperature cooling stage after the continuous casting billet is removed, and the surface longitudinal crack problem of the continuous casting billet is solved by subsequent slow cooling.
Drawings
FIG. 1 is a schematic diagram of a prior art medium carbon manganese chromium alloy steel continuous casting billet according to the present invention;
FIG. 2 is a flow chart of the operation of the production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard in the embodiment of the invention;
FIG. 3 is a schematic diagram of a turnover cooling bed in accordance with an embodiment of the present invention;
FIG. 4 is a schematic view of the configuration of the first rack and the second rack in cooperation in one embodiment of the invention;
FIG. 5 is a schematic view of the configuration of the first rack and the second rack in accordance with a further embodiment of the present invention; and
fig. 6 is a schematic diagram of the actual production of a continuous casting slab of medium carbon manganese chromium alloy steel by a production process for preventing the bending degree of the continuous casting slab from exceeding the standard in the embodiment of the invention.
In the figure, 1 is a first toothed plate, 11 is a first inclined surface, 12 is a second inclined surface, 2 is a second toothed plate, 21 is a third inclined surface, 22 is a fourth inclined surface, 3 is a driving mechanism, 4 is a collecting table, 5 is a moving direction, and 6 is a high-temperature continuous casting blank.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 2 is a flow chart of the operation of the production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard in the embodiment of the invention.
As shown in fig. 2, the production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard in the embodiment comprises the following steps:
smelting, namely smelting molten steel, and realizing preliminary dephosphorization and primary adjustment of components to obtain molten steel.
A refining step, namely adding trace alloy elements into molten steel for deoxidation and component fine adjustment, wherein the trace alloy elements comprise titanium and vanadium, and the finally obtained refined molten steel comprises the following components in percentage by weight: c:0.35 to 0.40 percent, si:0.20 to 0.40 percent, mn:1.80 to 2.00 percent, cr:0.40 to 0.60 percent of Al:0.030 to 0.050 percent, ti:0.030 to 0.060 percent, V:0.030 to 0.060 percent, S is less than or equal to 0.015 percent, P: less than or equal to 0.020 percent.
And a continuous casting step, namely pouring the refined molten steel to obtain a high-temperature continuous casting blank 6 of the medium-carbon manganese-chromium alloy steel.
And a cooling step, namely cooling the high-temperature continuous casting blank 6 to a preset temperature through a turnover cooling bed, and conveying the high-temperature continuous casting blank to a heat preservation pit for slow cooling for a preset time to obtain the medium-carbon manganese chromium alloy steel continuous casting blank. The preset temperature is 400+/-20 ℃ and the preset time is 48 hours.
Fig. 3 is a schematic structural diagram of a turnover type cooling bed in an embodiment of the present invention.
As shown in fig. 3, the tumble cooling bed includes a first toothed plate 1, a second toothed plate 2, a drive mechanism 3, and a collection table 4.
The upper side of the first toothed plate 1 is provided with a plurality of first V-shaped teeth which are arranged at equal intervals in sequence and a first spacing part which is arranged between two adjacent first V-shaped teeth; the upper side of the second toothed plate 2 has a plurality of second V-shaped teeth arranged at equal intervals in sequence and second spacers arranged between two adjacent second V-shaped teeth.
The tooth surface of the first V-shaped tooth is composed of a first inclined surface 11 and a second inclined surface 12, and the included angle between the first inclined surface 11 and the second inclined surface 12 is smaller than 90 degrees; the tooth surface of the second V-shaped tooth is composed of a third inclined surface 21 and four inclined surfaces, and the included angle between the third inclined surface 21 and the fourth inclined surface 22 is smaller than 90 °.
Specifically, the angle between the first inclined surface 11 and the vertical direction is smaller than 45 °, and the angle between the second inclined surface 12 and the vertical direction is equal to 45 °. The angle between the third inclined surface 21 and the vertical direction is smaller than 45 degrees, and the angle between the fourth inclined surface 22 and the vertical direction is equal to 45 degrees.
When the continuous casting slab is placed on the first V-shaped teeth/second V-shaped teeth, one side of the continuous casting slab is fitted with the second inclined surface 12/fourth inclined surface 22 as shown in the figure. The adjacent other side surface abuts against the junction of the first inclined surface 11/third inclined surface 21 and the spacer, so that a gap exists between the other side surface and the first inclined surface 11/third inclined surface 21.
When the continuous casting blank is cooled, heat is radiated upwards, and when the continuous casting blank is placed in a normal position, the temperature of the two sides is low, the temperature of the upper side is high, and the continuous casting blank is easy to bend sideways. In the scheme, through the first V-shaped teeth and the second V-shaped teeth, the continuous casting blank is placed at an angle of 45 degrees instead of being placed positively, the temperature difference of the whole body of the continuous casting blank is reduced, the high-temperature continuous casting blank 6 is cooled more uniformly, and the side bending condition of the continuous casting blank is reduced.
Moreover, by setting the gaps, continuous casting billets with different sizes can be matched, and the continuous casting billets can be cooled more uniformly. The temperature of the part of the continuous casting blank, which is contacted with the tooth surface, is reduced more rapidly than that of the part of the continuous casting blank, which is exposed to the air, and the contact area is reduced by the arrangement of the gap, so that the cooling speeds of the upper side and the lower side of the continuous casting blank are kept nearly always, and the cooling uniformity is ensured.
The upper surfaces of the first spacing part and the second spacing part are plane.
Fig. 4 is a schematic structural diagram of the first rack and the second rack cooperating in one embodiment of the invention.
As shown in fig. 4, according to an embodiment of the present invention, the first inclined surface 11 is located at the front side of the second inclined surface 12 in the moving direction 5 of the high temperature continuous casting slab 6, and the third inclined surface 21 is located at the front side of the fourth inclined surface 22 in the moving direction 5 of the high temperature continuous casting slab 6. The two toothed plates incline towards the same side, so that continuous casting billets are placed more stably when falling into the other toothed plate from one toothed plate. And, the first pinion rack 1 and the second pinion rack 2 are mutually common, save stock and cost.
Fig. 5 is a schematic structural view of the first rack and the second rack engaged in still another embodiment of the present invention.
As shown in fig. 5, according to still another embodiment of the present invention, the first inclined surface 11 is located at the front side of the second inclined surface 12 in the moving direction 5 of the high temperature continuous casting slab 6, and the fourth inclined surface 22 is located at the front side of the third inclined surface 21 in the moving direction 5 of the high temperature continuous casting slab 6. Through the arrangement, when the continuous casting blank is positioned on the first V-shaped tooth, the gap is positioned on the rear side of the continuous casting blank, and when the continuous casting blank is positioned on the second V-shaped tooth, the gap is positioned on the front side of the continuous casting blank, so that the consistency of the cooling speed of the continuous casting blank is further improved.
The driving mechanism 3 is an existing step-type overturning cooling bed driving mechanism 3, and the structure thereof is not described herein.
The collecting table 4 is located at the front side of the first rack and the second rack in the traveling direction 5 of the strand and is fixedly provided.
The cooling step comprises the steps of: the high-temperature continuous casting billet 6 is arranged on the first V-shaped teeth, the driving mechanism 3 drives the second toothed plate 2 to ascend and the first toothed plate 1 to descend, so that the high-temperature continuous casting billet 6 on the second V-shaped teeth falls onto the first V-shaped teeth, the driving mechanism 3 drives the first toothed plate 1 to retreat for a preset distance, then drives the first toothed plate 1 to ascend and the second toothed plate 2 to descend, so that the high-temperature continuous casting billet 6 on the second V-shaped teeth is transited to the first V-shaped teeth, and then drives the first toothed plate 1 to advance for a preset distance, and drives the high-temperature continuous casting billet 6 to advance for a preset distance. The driving mechanism 3 repeats the above driving steps until the high-temperature continuous casting slab 6 falls onto the collecting table 4, at which time the temperature of the high-temperature continuous casting slab 6 reaches a predetermined temperature.
According to one specific embodiment of the invention, the production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard comprises the following steps of:
in the smelting step of the electric furnace/converter, waste steel and molten iron with qualified components and temperature are added, the total loading of the waste steel and the molten iron is 150 tons, si is less than or equal to 0.60wt percent, P is less than or equal to 0.13wt percent, S is less than or equal to 0.0wt percent and 45 percent, the preliminary dephosphorization and the primary adjustment of the components are realized in the smelting process, and the technical requirements are basically equal to those of the common alloy steel smelting process.
In the refining step, deoxidation and component fine adjustment are carried out in an LF furnace, wherein the adding amount of ferrotitanium is 1.54-3.08 kg/ton, the adding amount of ferrovanadium is 0.63-1.26 kg/ton, the process requirement has no special content, and the key is that the control of the adding amount of trace alloy is strictly executed according to the range requirement, so that the final molten steel components meet the following weight percentage: c:0.35 to 0.40 percent, si:0.20 to 0.40 percent, mn:1.80 to 2.00 percent, cr:0.40 to 0.60 percent of Al:0.030 to 0.050 percent, ti:0.030 to 0.060 percent, V:0.030 to 0.060 percent, S is less than or equal to 0.015 percent, P: less than or equal to 0.020 percent.
And in the continuous casting step, molten steel is cast into a continuous casting blank according to the technological requirement of conventional large square blank (with the cross section size of 300 multiplied by 300 mm) alloy steel continuous casting, a uniform aerosol forced cooling mode is adopted, the pulling speed is 0.90m/min, and a copper pipe of a continuous casting machine adopts a parabolic distributed taper design with the total taper of 0.90-1.00%/m.
The cooling step, the cooling technology of the continuous casting blank adopts a turnover step cooling bed to cool the high-temperature continuous casting blank 6, ensures the periphery of the continuous casting blank at a high temperature section to be uniformly cooled, avoids bending problems, and enters a heat preservation pit for covering and slowly cooling when the surface temperature of the continuous casting blank is reduced to 400+/-20 ℃, and the continuous casting blank is directly transferred to a steel rolling area for rolling production after being cooled for 48 hours.
Mn is the most effective strengthening element of the steel, but the higher content of Mn and Cr can bring about the problems of coarse solidification structure and overlarge line shrinkage caused by structure transformation in the cooling process, and other trace elements are needed to be added to solve the problem of poor continuous casting process performance of the steel. By adding trace elements of titanium and vanadium, the continuous casting billet can be strengthened and toughened more effectively, grains can be refined effectively, the internal structure of the steel is compact, the ageing sensitivity and the cold brittleness are reduced, meanwhile, the welding performance is improved, V, ti can form infinite solid solution with Fe, high-toughness inter-crystal strengthening particles, and the occurrence of cracks is reduced. Meanwhile, by designing the content of titanium element, the plastic deterioration of the continuous casting billet caused by excessive increase of titanium element is avoided.
Meanwhile, the problem of surface longitudinal cracks can occur due to quick cooling of the medium-carbon manganese-chromium alloy steel, but the medium-carbon manganese-chromium alloy steel is put into a heat preservation pit for slow cooling, and the problem of uneven stack cooling and exceeding of curvature degree of the medium-carbon manganese-chromium alloy steel exists. According to the embodiment, the vanadium-titanium microalloying is carried out on the continuous casting billet, so that the high-temperature plasticity and the technological performance of steel are improved, the high-temperature longitudinal crack tendency of the continuous casting billet is solved, and the continuous casting billet can be rapidly cooled in a high-temperature section. Specifically, the overturning step cooling bed and the special tooth-shaped design on the cooling bed ensure that the periphery of the continuous casting billet in the high-temperature section is uniformly cooled, and the problem that the continuous casting billet bends on the cooling bed is avoided. When the surface temperature of the continuous casting billet is reduced to 400+/-20 ℃, the continuous casting billet is put into the pit again for capping and slowly cooling, so that the bending caused by uneven volume shrinkage after the high-temperature continuous casting billet 6 is directly put into the pit is prevented, and the problem that the continuous casting billet is always rapidly cooled on a cooling bed to generate surface longitudinal cracks is avoided.
Fig. 6 is a schematic diagram of the actual production of a continuous casting slab of medium carbon manganese chromium alloy steel by a production process for preventing the bending degree of the continuous casting slab from exceeding the standard in the embodiment of the invention.
The continuous casting slab shown in fig. 6 is a continuous casting slab produced by the production process of the example, and has the chemical components as follows: c:0.370%, si:0.25%, mn:1.83%, cr:0.5%, al:0.034%, S:0.003%, P:0.014%, balance Fe, predetermined temperature 399 ℃. As can be seen from comparison of FIG. 1 and FIG. 6, the continuous casting billet prepared by the production process of the embodiment has smaller curvature, wherein no crack is formed on the surface of the continuous casting billet, and the curvature is measured to be 3.3 mm/m.
Test case one
The medium carbon manganese chromium alloy steel with nine groups of components, each group of which is provided with five continuous casting billets, is produced according to the mode, is cooled to 400 ℃ by a cooling bed, is put into a heat preservation pit for cooling for 48 hours, and comprises the following components:
chemical composition (wt./%) of the carbon manganese chromium alloy steels in table 1.
The average value of the bending degree of each test case is obtained by measurement as follows:
table 2 actual measurement values of the bending degree of continuous casting blanks at different pit entry temperatures.
When the continuous casting billet is cooled, the continuous casting billet needs to be operated into a continuous casting billet heating furnace, and the heating furnace is required to have the bending degree of the continuous casting billet within a certain range. In the existing heating furnace, the curvature of the inlet of a part of the heating furnace is required to be less than 9 (mm/m). After the continuous casting billet produced in the prior art is cooled, the condition that the bending degree of part of the continuous casting billet is too high exists. These continuous casting billets cannot smoothly enter the heating furnace from the inlet of the heating furnace, and the bending condition of the continuous casting billets needs to be corrected by a correction mechanism and the like as described in the background art before the continuous casting billets enter the heating furnace. As can be seen from Table 2, the degree of curvature of the continuous casting billets prepared by the microalloying process in this example was all less than 9 (mm/m). The bending condition of the continuous casting billet is obviously improved, and the probability of blocking in the process of transporting the continuous casting billet to a heating furnace is reduced. The technical means of micro-alloying in the embodiment solves the contradiction that the high-temperature continuous casting blank 6 of the medium-carbon manganese-chromium alloy steel is easy to crack when being cooled quickly and easy to bend when being cooled slowly, and controls the content of vanadium and titanium to be 0.030-0.060 wt percent, and the bending degree of the prepared medium-carbon manganese-chromium alloy steel reaches the standard.
Test case two
In this test example, the chemical composition (wt./%) was C:0.370%, si:0.25%, mn:1.83%, cr:0.5%, al:0.034%, S:0.003%, P:0.014%, and the balance of Fe, cooling the high-temperature continuous casting billet 6 to the following temperature, cooling in a heat preservation pit for 48 hours, measuring the corresponding curvature, and measuring the data as shown in the following table 3:
from the table, the high-temperature continuous casting billet 6 is cooled to 400+/-20 ℃ in the turnover cooling bed and then slowly cooled in the heat preservation pit, so that the problem of bending of the continuous casting billet can be effectively solved, and the probability of blocking in the process of conveying the continuous casting billet to the heating furnace is reduced.
In summary, the present invention is a specific application example, and the protection scope of the present invention is not limited, and the technical scheme of adopting equivalent substitution falls within the protection scope of the present invention.
Claims (5)
1. The production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard is characterized in that the medium carbon manganese chromium alloy steel continuous casting billet comprises the following chemical components in percentage by weight: c: 0.35-0.40%, si: 0.20-0.40%, mn: 1.80-2.00%, cr: 0.40-0.60%, al: 0.030-0.050%, ti: 0.030-0.060%, V: 0.030-0.060%, S is less than or equal to 0.015%, and P: less than or equal to 0.020 percent, and the production process comprises the following steps:
smelting, namely smelting molten steel, and realizing preliminary dephosphorization and primary adjustment of components to obtain molten steel;
a refining step, namely adding trace alloy elements into the molten steel for deoxidation and component fine adjustment, wherein the trace alloy elements comprise titanium and vanadium, and the finally obtained refined molten steel comprises the following components in percentage by weight: c: 0.35-0.40%, si: 0.20-0.40%, mn: 1.80-2.00%, cr: 0.40-0.60%, al: 0.030-0.050%, ti: 0.030-0.060%, V: 0.030-0.060%, S is less than or equal to 0.015%, and P: less than or equal to 0.020%;
a continuous casting step, namely casting the refined molten steel to obtain a high-temperature continuous casting blank of the medium-carbon manganese-chromium alloy steel,
a cooling step, namely cooling the high-temperature continuous casting blank to a preset temperature through a turnover cooling bed, then conveying the high-temperature continuous casting blank to a heat preservation pit for slow cooling for a preset time to obtain a medium-carbon manganese chromium alloy steel continuous casting blank,
wherein the predetermined temperature is 400 + -20 deg.C,
the predetermined time period is 48 hours,
the turnover cooling bed comprises a first toothed plate and a second toothed plate, wherein the upper side of the first toothed plate is provided with a plurality of first V-shaped teeth which are sequentially arranged at equal intervals and a first spacing part which is arranged between two adjacent first V-shaped teeth; the upper side of the second toothed plate is provided with a plurality of second V-shaped teeth which are arranged at equal intervals in sequence, and second spacing parts which are arranged between two adjacent second V-shaped teeth.
2. The production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard according to claim 1, wherein the tooth surface of the first V-shaped tooth is composed of a first inclined surface and a second inclined surface, and the included angle between the first inclined surface and the second inclined surface is smaller than 90 degrees; and/or the tooth surface of the second V-shaped tooth is formed by a third inclined surface and a fourth inclined surface, and the included angle between the third inclined surface and the fourth inclined surface is smaller than 90 degrees.
3. The production process for preventing the bending degree of the medium carbon manganese chromium alloy steel continuous casting billet from exceeding the standard according to claim 2, wherein the included angle between the first inclined surface and the vertical direction is smaller than 45 degrees, and the included angle between the second inclined surface and the vertical direction is equal to 45 degrees; and/or the included angle between the third inclined surface and the vertical direction is smaller than 45 degrees, and the included angle between the fourth inclined surface and the vertical direction is equal to 45 degrees.
4. A production process for preventing a bending degree of a medium carbon manganese chromium alloy steel continuous casting slab from exceeding a standard according to claim 3, wherein the first inclined surface is located on a front side of the second inclined surface in a moving direction of a high temperature continuous casting slab, and the third inclined surface is located on a front side of the fourth inclined surface in a moving direction of a high temperature continuous casting slab.
5. A production process for preventing a bending degree of a medium carbon manganese chromium alloy steel continuous casting slab from exceeding a standard according to claim 3, wherein the first inclined surface is located on a front side of the second inclined surface in a moving direction of a high temperature continuous casting slab, and the fourth inclined surface is located on a front side of the third inclined surface in a moving direction of a high temperature continuous casting slab.
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| CN103266269B (en) * | 2013-05-15 | 2015-04-22 | 武汉钢铁(集团)公司 | HB500 grade hot continuous rolling high strength wear-resisting steel and production method thereof |
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