阅读说明：本技术 一种稀土合金化预应力盘条用钢及其制造方法 (Steel for rare earth alloying prestressed wire rod and manufacturing method thereof ) 是由 李文双 牛树林 俞飞 冯治胜 王勇 张楠 顾凤义 于 2021-09-08 设计创作，主要内容包括：本发明涉及预应力盘条用钢制造技术领域,特别是涉及一种稀土合金化预应力盘条用钢及其制造方法。钢的牌号为SWRH82BRe,包含：碳0.79％～0.85％,硅0.15％～0.35％,锰0.60％～0.90％,铬0.20％～0.30％,镍≤0.10％,铜≤0.20％,磷≤0.020％,硫≤0.025％,稀土Re0.010％～0.050％,余量为铁和其他不可避免的元素。本发明通过稀土对钢进行微合金化处理,保证预应力用钢SWRH82BRe具有更高的强度和良好的塑性指标,更短的时效时间,更高的洁净度和更高的组织均匀性。(The invention relates to the technical field of manufacturing of steel for a prestressed wire rod, in particular to rare earth alloying steel for the prestressed wire rod and a manufacturing method thereof. The steel grade is SWRH82BRe, comprising: 0.79 to 0.85 percent of carbon, 0.15 to 0.35 percent of silicon, 0.60 to 0.90 percent of manganese, 0.20 to 0.30 percent of chromium, less than or equal to 0.10 percent of nickel, less than or equal to 0.20 percent of copper, less than or equal to 0.020 percent of phosphorus, less than or equal to 0.025 percent of sulfur, 0.010 to 0.050 percent of rare earth Re0, and the balance of iron and other inevitable elements. According to the invention, the steel is subjected to microalloying treatment by rare earth, so that the steel for prestress SWRH82BRe has higher strength and good plasticity index, shorter aging time, higher cleanliness and higher tissue uniformity.)

1. A steel for a rare earth alloying prestressed wire rod is characterized in that: the grade of the steel is SWRH82BRe, and the steel comprises the following components in percentage by mass: 0.79 to 0.85 percent of carbon, 0.15 to 0.35 percent of silicon, 0.60 to 0.90 percent of manganese, 0.20 to 0.30 percent of chromium, less than or equal to 0.10 percent of nickel, less than or equal to 0.20 percent of copper, less than or equal to 0.020 percent of phosphorus, less than or equal to 0.025 percent of sulfur, 0.010 to 0.050 percent of rare earth Re, and the balance of iron and other inevitable elements.

2. The steel for a rare earth alloyed prestressed wire rod as claimed in claim 1, wherein the tensile strength Rm of the steel for a rare earth alloyed prestressed wire rod is: 1200 MPa-1260 MPa, and the reduction of area Z is more than or equal to 30 percent.

3. The steel for rare earth alloyed prestressed wire rod as claimed in claim 1, wherein T [ O ] of said steel for rare earth alloyed prestressed wire rod]The content is controlled to be less than or equal to 15 multiplied by 10^-6The content of N is controlled to be less than or equal to 30 multiplied by 10^-6。

4. The steel for a rare earth alloyed prestressed wire rod as claimed in claim 1, wherein the steel for a rare earth alloyed prestressed wire rod has a net carbide grade of 0.5 or less and a martensite grade of 0.5 or less.

5. The steel for a rare earth alloyed prestressed wire rod as claimed in claim 1, wherein the non-metallic inclusions of the steel are classified by GBT10561 as class A inclusions or less of 1.0 grade, class B inclusions or less of 0.5 grade, class C inclusions or less of 0.5 grade, class D inclusions or less of 1.0 grade, and class Ds inclusions or less of 1.0 grade.

6. The method of manufacturing a steel for a rare earth alloyed prestressed wire rod according to claim 1, characterized by comprising the steps of:

s1, adding a special dephosphorization agent at the earlier stage of converter smelting to ensure the dephosphorization capability of the converter smelting, adding 0.8kg/t of silicon-calcium-barium deoxidizer at one time during tapping, namely tapping omega (C) of high-carbon-drawing tapping, wherein the carburant is a low-nitrogen carburant;

s2, adopting a medium-low alkalinity refining slag system as the refining slag system, wherein the binary alkalinity R of the slag is 1-2.5, and the total amount of lime is added according to 6.0-9.0 kg/t; 200 kg of low-alkalinity premelting slag refining slag per furnace, 10-40 kg of fluorite per furnace are added for slag adjustment, rare earth alloy is added under the condition of good deoxidation and desulfurization of molten steel, a Ca-Si wire is fed into the furnace at 150m per last stage of LF refining, and the soft blowing time is more than or equal to 15 min;

s3, casting a 150-square small square billet in the continuous casting process, wherein the constant superheat degree is guaranteed in the continuous casting process, and the superheat degree is controlled to be 15-25 ℃; electromagnetic stirring is adopted in the continuous casting process;

s4, controlling a neutral atmosphere of a rolling heating furnace, wherein the heating time is 90-110 min, and the temperature of a soaking section is 1200 ℃; controlling the descaling pressure of high-pressure water to be more than or equal to 12MPa, the descaling rate to be more than or equal to 95%, the steel tapping temperature to be 1030 plus 1070 ℃, the finish rolling temperature to be 900-920 ℃, the spinning temperature to be 840-860 ℃, the speed of a first-stage roller way to be 0.70m/s, and in a standard cooling mode, starting 100% of fans 1-6%, and completely opening heat-insulating covers.

7. The method for manufacturing steel for a rare earth alloyed prestressed wire rod as claimed in claim 6, wherein in S1, said specific ingredients of said special dephosphorizing agent are lime CaO and iron scale Fe₂O₃According to the mass ratio of 1:2, the phosphorus content of the steel isThe steel tapping temperature is controlled to be 1600-1630 ℃, and a deoxidizer, namely silicon-aluminum-barium, is added into the steel tapping at one time, wherein the amount is controlled to be less than or equal to 0.013%, the proportion of scrap steel is controlled to be less than or equal to 25%, and the steel tapping temperature is controlled to be 0.8 kg/t.

8. The method of manufacturing a steel for a rare earth alloyed prestressed wire rod as set forth in claim 6, wherein in S2, the timing of addition of the rare earth alloy is: during the refining process, molten steel is deoxidized and desulfurized to ensure that O is less than or equal to 8ppm and S is less than or equal to 0.010 percent, then pure rare earth is rapidly added, and the adding amount of rare earth alloy is controlled to be 15-25 kg/furnace.

9. The method of manufacturing a steel for a rare earth alloyed prestressed wire rod as set forth in claim 6, wherein: s3, in the continuous casting process, crystallizer electromagnetic stirring and tail end electromagnetic stirring are adopted, the current of the crystallizer electromagnetic stirring is 300A, and the frequency is 5 Hz; the current for electromagnetic stirring at the end was 400A and the frequency was 8 Hz.

Technical Field

The invention relates to the technical field of manufacturing of steel for a prestressed wire rod, in particular to rare earth alloying steel for the prestressed wire rod and a manufacturing method thereof.

Background

The steel for the prestressed wire rod is mainly applied to manufacturing prestressed wires such as steel strands, steel wire ropes, elevator ropes and the like. The abnormal structure can often cause drawing brittle failure in the drawing process of manufacturing the steel wire by the wire rod, the prestressed wire rod belongs to high-carbon steel, and the high-carbon steel is easy to form central carbon segregation in the continuous casting process, so that reticular carbide and central martensite appear in the wire rod rolled by a subsequent high-speed wire rod, which is the abnormal structure causing the wire drawing brittle failure of the prestressed wire rod, and meanwhile, the plasticity of the prestressed wire rod of a common Mn-Cr component system is obviously reduced along with the increase of the strength, and the difficulty is brought to the manufacture of the high-strength steel wire.

The patent with the application number of CN201810573584.X discloses a steel for rare earth alloying grinding balls and a manufacturing method thereof, the steel for the rare earth grinding balls is a bar product, belongs to different steel types with the steel for the rare earth alloying prestressed wire rod, and has completely different component systems; the invention solves the problem that how to design the steel for the prestressed wire rod with more uniform structure, higher strength, excellent plasticity index, shorter aging time and higher cleanliness according to the fact that the original component system is not suitable for the invention and achieves the expected performance.

Disclosure of Invention

Aiming at the defects, the invention provides the steel for the rare earth alloying prestressed wire rod and the manufacturing method thereof, the grade of the steel is SWRH82BRe, alloying is carried out by adding rare earth Re and key process control points are optimized, so that the SWRH82BRe is effectively ensured to have more uniform structure, higher strength and excellent plasticity index, shorter aging time and higher cleanliness.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the steel for the rare earth alloying prestressed wire rod is the steel with the grade of SWRH82BRe, and comprises the following components in percentage by mass: 0.79 to 0.85 percent of carbon, 0.15 to 0.35 percent of silicon, 0.60 to 0.90 percent of manganese, 0.20 to 0.30 percent of chromium, less than or equal to 0.10 percent of nickel, less than or equal to 0.20 percent of copper, less than or equal to 0.020 percent of phosphorus, less than or equal to 0.025 percent of sulfur, 0.010 to 0.050 percent of rare earth Re, and the balance of iron and other inevitable elements.

As a preferred rare earth Re element: the rare earth is called as 'industrial monosodium glutamate', and trace rare earth can play a role in obviously improving the performance of steel. The rare earth element has extremely strong chemical activity due to a unique electronic shell structure, the energy valence state of the 4f shell structure is variable, the size of a large atom is large, the rare earth element is an extremely strong purifying agent for steel and an effective modifier for clean steel inclusion, and the rare earth element is a strong inhibitor for effectively controlling a weakening source in steel and reducing the energy state of a local area and local weakening of the steel. The concrete functions are as follows:

1. deep purification, control of the weakening source: the main points are as follows: can deeply reduce the content of oxygen and sulfur, and reduce the harmful effects of low-melting-point elements such as phosphorus, sulfur, hydrogen, arsenic, antimony, bismuth, lead, tin and the like. The segregation of sulfur and rare earth elements on the grain boundary of high-speed steel is studied by Auger spectroscopy and an ion probe. The rare earth elements reduce the segregation of the grain boundary P, eliminate the harmful effect of weakening the grain boundary caused by Fe3P, and improve the state of the grain boundary, thereby strengthening the grain boundary, hindering intergranular fracture and increasing the transgranular fracture fraction.

2. Coagulation "tissue control": the size of the secondary dendrite spacing will affect microsegregation, inclusion and porosity, thus affecting the mechanical properties. The rare earth forms a compound with a higher melting point in steel, and is precipitated before the molten steel is solidified, and the compound is distributed in the molten steel in a fine particle form and serves as a heterogeneous nucleation center, so that the supercooling degree of the molten steel crystal is reduced, the solidification structure of the steel can be refined, the segregation is reduced, and the solidification structure control is realized.

3. Micro-alloying action: rare earth has purification and obvious modification effects in steel. The cleanliness of steel is continuously improved, and the microalloy strengthening effect of rare earth elements is increasingly prominent. The microalloying of the rare earth comprises solid solution strengthening of trace rare earth elements, interaction of the rare earth elements and other solute elements or compounds, size, shape and distribution of existing states (atoms, inclusions or compounds) of rare earth atoms, particularly segregation in grain boundaries, influence of the rare earth on the steel surface and matrix structure and the like.

Preferably, the tensile strength Rm of the steel for a rare earth alloyed prestressed wire rod is: 1200 MPa-1260 MPa, and the reduction of area Z is more than or equal to 30 percent, so that the prestressed wire rod can have more balanced mechanical properties, namely, good drawing performance can be considered under the condition of high strength.

Preferably, T [ O ] of the steel for a rare earth alloyed prestressed wire rod]The content is controlled to be less than or equal to 15 multiplied by 10^-6The content of N is controlled to be less than or equal to 30 multiplied by 10^-6。

Preferably, the steel for the rare earth alloying prestressed wire rod has a net carbide grade of less than or equal to 0.5 and a martensite grade of less than or equal to 0.5.

Preferably, the steel for the rare earth alloying prestressed wire rod has the non-metallic inclusions which are rated according to GBT10561 and reach the levels that A type inclusions are less than or equal to 1.0, B type inclusions are less than or equal to 0.5, C type inclusions are less than or equal to 0.5, D type inclusions are less than or equal to 1.0, and Ds type inclusions are less than or equal to 1.0.

The invention also provides a manufacturing method of the steel for the rare earth alloying prestressed wire rod, which comprises the following steps:

s1, adding a special dephosphorization agent at the earlier stage of converter smelting to ensure the dephosphorization capability of the converter smelting, adding 0.8kg/t of silicon-calcium-barium deoxidizer at one time during tapping, namely tapping omega (C) of high-carbon-drawing tapping, wherein the carburant is a low-nitrogen carburant;

s2, adopting a medium-low alkalinity refined slag system as a refined slag system, adding lime according to the total amount of 6.0-9.0 kg/t, adding 200 kg/furnace of low-alkalinity premelted slag refined slag, adding 10-40 kg/furnace of fluorite for slag regulation, adding rare earth alloy under the condition of good molten steel deoxidation and desulfurization, feeding a Ca-Si wire 150 m/furnace at the end of LF refining, and enabling the soft blowing time to be more than or equal to 15 min;

s3, casting a 150-square small square billet in the continuous casting process, wherein the constant superheat degree is guaranteed in the continuous casting process, the superheat degree is controlled to be 15-25 ℃, and crystallizer electromagnetic stirring (current: 300A, frequency: 5Hz) and tail end electromagnetic stirring (current: 400A, frequency: 8Hz) are adopted in the continuous casting process, so that the equiaxed crystal area in the center is enlarged, the grain size is obviously refined, the macrostructure of a casting blank is obviously improved, and the segregation index is obviously reduced;

s4, controlling a neutral atmosphere of a rolling heating furnace, heating for 90-110 min, controlling the temperature of a soaking section to be 1200 ℃, promoting high-temperature diffusion of C and Cr elements, reducing a segregation index, controlling the neutral atmosphere of the heating furnace, preventing steel from decarbonizing, controlling the high-pressure water descaling pressure to be more than or equal to 12MPa, controlling the descaling rate to be more than or equal to 95%, controlling the tapping temperature to be 1030-1070 ℃, controlling the finish rolling temperature to be 900-920 ℃, controlling the spinning temperature to be 840-860 ℃, controlling the speed of a first section of roller bed to be 0.70m/S, controlling a standard cooling mode, starting a fan 1-6 # by 100%, and completely opening a heat preservation cover.

Preferably, in S1, the special dephosphorizing agent specifically comprises lime CaO and iron scale Fe₂O₃According to the mass ratio of 1:2, after the dephosphorizing agent is used, the dephosphorization can be rapidly carried out at the earlier stage of converter smelting, the phosphorus content in the steel tapping is controlled to be less than or equal to 0.013%, the proportion of scrap steel is controlled to be less than or equal to 25%, the steel tapping temperature is controlled to be 1600-1630 ℃, and 0.8kg/t of deoxidizer silicon aluminum barium is added into the steel tapping at one time.

Preferably, in S2, the rare earth alloy is added at the following timing: during the refining process, molten steel is deoxidized and desulfurized to ensure that O is less than or equal to 8ppm and S is less than or equal to 0.010 percent, then pure rare earth is rapidly added, and the adding amount of rare earth alloy is controlled to be 15-25 kg/furnace.

Preferably, in S3, the crystallizer electromagnetic stirring and the end electromagnetic stirring are adopted in the continuous casting process, the current of the crystallizer electromagnetic stirring is 300A, and the frequency is 5 Hz; the current for electromagnetic stirring at the end was 400A and the frequency was 8 Hz.

The invention has the beneficial effects that:

the invention provides a steel for a rare earth alloying prestressed wire rod, which is provided with the grade of SWRH82BRe and a manufacturing method thereof, alloying is carried out by adding rare earth Re, the proportion of various alloy elements is reasonably controlled, a key process control point and a scientific heat treatment system are optimized, the SWRH82BRe is effectively ensured to be more uniform in structure, higher in strength and excellent in plasticity index, shorter in aging time and higher in cleanliness.

The specific implementation mode is as follows:

in order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The steel for the rare earth alloying prestressed wire rod designed in the embodiment, which is under the steel designation SWRH82BRe, specifically comprises the following components by mass percent:

0.79 to 0.85 percent of carbon, 0.15 to 0.35 percent of silicon, 0.60 to 0.90 percent of manganese, 0.20 to 0.30 percent of chromium, less than or equal to 0.10 percent of nickel, less than or equal to 0.20 percent of copper, less than or equal to 0.020 percent of phosphorus, less than or equal to 0.025 percent of sulfur, 0.010 to 0.050 percent of rare earth Re, and the balance of iron and other inevitable elements, such as tin, antimony, bismuth and the like.

Based on the above component design, the measured values of component control in the implementation process are shown in table 1:

TABLE 1 EXAMPLE 1 chemical composition control/wt%

Serial number	C	Si	Mn	P	S	Cr	Cu	Ni	Re
										1	0.81	0.22	0.73	0.013	0.005	0.23	0.018	0.008	0.015

This example provides a method for producing the above steel for rare earth alloyed prestressed wire rod SWRH82BRe according to the composition control and dosage of table 1:

s1, adding a special dephosphorizing agent at the early stage of converter smelting, wherein the specific component of the dephosphorizing agent isCaO of lime and iron scale Fe₂O₃According to the mass ratio of 1:2, after the dephosphorizing agent is used, the dephosphorization can be rapidly carried out at the early stage of the converter smelting, so that the dephosphorization capability of the converter smelting is ensured, and the phosphorus content is 0.013%; 0.8kg/t of deoxidizer silicon calcium barium is added at one time during tapping; high-carbon-pulling steel tapping, namely steel tapping omega (C) is 0.35 percent; controlling the proportion of scrap steel to be less than or equal to 25 percent and controlling the tapping temperature to 1620 ℃; the carburant is a low-nitrogen carburant;

s2, adopting a medium and low alkalinity refining slag system as the refining slag system, wherein the binary alkalinity R of the slag is 1.9, and adding the total amount of lime according to 7.0 kg/t; 200 kg of low-alkalinity premelting slag refining slag per furnace, and adding 30 kg of fluorite per furnace for slag adjustment; adding rare earth alloy with the addition amount of 20 kg/furnace under the conditions of good deoxidation and desulfurization of molten steel (less than or equal to 8ppm of [ O ] and less than or equal to 0.010 percent of [ S ]), wherein the supply unit of the rare earth alloy is the metal institute of Chinese academy; feeding a Ca-Si wire at 150 m/furnace at the final stage of LF refining, wherein the soft blowing time is 16 min;

s3, casting a 150-square small square billet in the continuous casting process, wherein the constant superheat degree is guaranteed in the continuous casting process, the superheat degree is controlled to be 20 ℃, and the secondary cooling specific water amount is 0.9L/kg; in the continuous casting process, crystallizer electromagnetic stirring (current: 300A, frequency: 5Hz) and end electromagnetic stirring (current: 400A, frequency: 8Hz) are adopted, so that the area of an equiaxial crystal area in the center is enlarged, the grain size is obviously refined, the macrostructure of a casting blank is obviously improved, and the segregation index is obviously reduced;

s4, controlling a neutral atmosphere of the rolling heating furnace to prevent the steel from decarbonizing; the heating time is 100min, the temperature of the soaking section is 1200 ℃, the high-temperature diffusion of C and Cr elements is promoted, and the segregation index is reduced; controlling the descaling pressure of high-pressure water to be 14MPa, and the descaling rate to be more than or equal to 95 percent; controlling the tapping temperature 1050 ℃, the finish rolling temperature 910 ℃, the spinning temperature 850 ℃, the first-stage roller speed 0.70m/s, the standard cooling mode, the fan No. 1-6 opening 100%, and the heat-insulating cover opening completely.

Through inspection, the final performance indexes of the product obtained in the embodiment are as follows: the tensile strength Rm is 1230MPa, the reduction of area Z is 34%, the martensite is 0.5, the network carbide is 0 grade, T [ O ] is 14ppm, N is 28ppm, the performance index of the common SWRH82B product is compared with that of the embodiment shown in Table 2.

TABLE 2 comparison of the common SWRH82B with the SWRH82B Performance index of example 1

	Rm/MPa	Z/％	Martensite/grade	Network carbide/grade	T[O]/ppm	N/ppm
							Common SWRH82B	1170	19	2.0	2.5	25×10-6	43×10-6
Example 1	1230	34	0.5	0	14×10-6	28×10-6

As can be seen from Table 2, the newly designed rare earth-titanium microalloyed steel has higher strength, plasticity and better structural uniformity.

The nonmetallic inclusion of the steel for the rare earth alloying prestressed wire rod reaches the level that A type inclusion is less than or equal to 1.0, B type inclusion is less than or equal to 0.5, C type inclusion is less than or equal to 0.5, D type inclusion is less than or equal to 1.0 and Ds type inclusion is less than or equal to 1.0 according to the GBT10561 rating.

Example 2

Table 3, example 2 chemical composition control value/wt%

Serial number	C	Si	Mn	P	S	Cr	Cu	Ni	Re
										1	0.79	0.15	0.60	0.010	0.008	0.20	0.018	0.008	0.010

According to the composition control and the dosage of table 3, this example provides a method for manufacturing a steel SWRH82BRe for a rare earth alloyed prestressed wire rod:

s1, adding a special dephosphorizing agent into the converter at the earlier stage of smelting, wherein the dephosphorizing agent comprises the specific components of lime CaO and iron scale Fe₂O₃According to the mass ratio of 1:2, after the dephosphorizing agent is used, the dephosphorization can be rapidly carried out at the earlier stage of the converter smelting, so that the dephosphorization capability of the converter smelting is ensured, and the phosphorus content is 0.011%; 0.8kg/t of deoxidizer silicon calcium barium is added at one time during tapping; high-carbon-pulling steel tapping, namely steel tapping omega (C) is 0.32%; controlling the proportion of scrap steel to be less than or equal to 25 percent and controlling the tapping temperature to be 1600 ℃; the carburant is a low-nitrogen carburant;

s2, adopting a medium-low alkalinity refining slag system as a refining slag system, wherein the binary alkalinity R of the slag is 1.0, and adding the total amount of lime according to 6.0 kg/t; 200 kg of low-alkalinity premelting slag refining slag per furnace, and 10 kg of fluorite per furnace is added for slag adjustment; adding rare earth alloy under the conditions of good deoxidation and desulfurization of molten steel (less than or equal to 8ppm of [ O ] and less than or equal to 0.010%), wherein the addition amount is 15 kg/furnace, and the supply unit of the rare earth alloy is the metal institute of Chinese academy of sciences; feeding a Ca-Si wire at 150 m/furnace at the final stage of LF refining, wherein the soft blowing time is 15 min;

s3, casting a 150-square small square billet in the continuous casting process, wherein the constant superheat degree is guaranteed in the continuous casting process, the superheat degree is controlled to be 15 ℃, and the secondary cooling specific water amount is 0.9L/kg; in the continuous casting process, crystallizer electromagnetic stirring (current: 300A, frequency: 5Hz) and end electromagnetic stirring (current: 400A, frequency: 8Hz) are adopted, so that the area of an equiaxial crystal area in the center is enlarged, the grain size is obviously refined, the macrostructure of a casting blank is obviously improved, and the segregation index is obviously reduced;

s4, controlling a neutral atmosphere of the rolling heating furnace to prevent the steel from decarbonizing; the heating time is 90min, the temperature of the soaking section is 1200 ℃, the high-temperature diffusion of C and Cr elements is promoted, and the segregation index is reduced; controlling the descaling pressure of high-pressure water to be 12MPa, and the descaling rate to be more than or equal to 95 percent; controlling the tapping temperature to be 1030 ℃, the finish rolling temperature to be 900 ℃, the spinning temperature to be 840 ℃, the speed of a first-section roller way to be 0.70m/s, and in a standard cooling mode, starting 100% of fans 1-6%, and completely opening heat-insulating covers.

Through inspection, the final performance indexes of the product obtained in the embodiment are as follows: the tensile strength Rm is 1200MPa, the reduction of area Z is 38%, the martensite is 0, the network carbide is 0 grade, T [ O ] is 15ppm, N is 29ppm, the performance index of the common SWRH82B product is compared with the performance index of the embodiment shown in Table 4.

TABLE 4 comparison of the common SWRH82B with the SWRH82B Performance index of example 2

	Rm/MPa	Z/％	Martensite/grade	Network carbide/grade	T[O]/ppm	N/ppm
							Common SWRH82B	1170	19	2.0	2.5	25×10-6	43×10-6
Example 1	1200	38	0	0	15×10-6	29×10-6

As can be seen from Table 4, the newly designed rare earth-titanium microalloyed steel has higher strength, plasticity and better structural uniformity.

The nonmetallic inclusion of the steel for the rare earth alloying prestressed wire rod reaches the level that A type inclusion is less than or equal to 1.0, B type inclusion is less than or equal to 0.5, C type inclusion is less than or equal to 0.5, D type inclusion is less than or equal to 1.0 and Ds type inclusion is less than or equal to 1.0 according to the GBT10561 rating.

Example 3

Table 5, example 3 chemical composition control value/wt%

Serial number	C	Si	Mn	P	S	Cr	Cu	Ni	Re
										1	0.85	0.35	0.90	0.010	0.010	0.30	0.015	0.009	0.050

This example provides a method for producing a steel SWRH82BRe for a rare earth alloyed prestressed wire rod, according to the composition control and dosage of table 5:

s1, adding a special dephosphorizing agent into the converter at the earlier stage of smelting, wherein the dephosphorizing agent comprises the specific components of lime CaO and iron scale Fe₂O₃According to the mass ratio of 1:2, after the dephosphorizing agent is used, the dephosphorization can be rapidly carried out at the early stage of the converter smelting, so that the dephosphorization capability of the converter smelting is ensured, and the phosphorus content is 0.009%; 0.8kg/t of deoxidizer silicon calcium barium is added at one time during tapping; high-carbon-pulling steel, namely steel omega (C) is 0.39%; controlling the proportion of scrap steel to be less than or equal to 25 percent and controlling the tapping temperature to be 1630 ℃; the carburant is a low-nitrogen carburant;

s2, adopting a medium-low alkalinity refining slag system as a refining slag system, wherein the binary alkalinity R of the slag is 2.5, and adding the total amount of lime according to 9.0 kg/t; 200 kg of low-alkalinity premelting slag refining slag per furnace, and adding 40 kg of fluorite per furnace for slag adjustment; under the condition of good deoxidation and desulfurization of molten steel (O is less than or equal to 8ppm, S is less than or equal to 0.010%), adding rare earth alloy, the adding quantity is 25 kg/furnace, and the supply unit of the rare earth alloy is the metal institute of Chinese academy of sciences; feeding a Ca-Si wire at 150 m/furnace at the final stage of LF refining, and carrying out soft blowing for 19 min;

s3, casting a 150-square small square billet in the continuous casting process, wherein the constant superheat degree is guaranteed in the continuous casting process, the superheat degree is controlled to be 25 ℃, and the secondary cooling specific water amount is 0.9L/kg; in the continuous casting process, crystallizer electromagnetic stirring (current: 300A, frequency: 5Hz) and end electromagnetic stirring (current: 400A, frequency: 8Hz) are adopted, so that the area of an equiaxial crystal area in the center is enlarged, the grain size is obviously refined, the macrostructure of a casting blank is obviously improved, and the segregation index is obviously reduced;

s4, controlling a neutral atmosphere of the rolling heating furnace to prevent the steel from decarbonizing; the heating time is 110min, the temperature of the soaking section is 1200 ℃, the high-temperature diffusion of C and Cr elements is promoted, and the segregation index is reduced; controlling the descaling pressure of high-pressure water to be 15MPa, and the descaling rate to be more than or equal to 95 percent; controlling the tapping temperature 1070 ℃, the finish rolling temperature 920 ℃, the spinning temperature 860 ℃, the first-stage roller speed 0.70m/s, the standard cooling mode, starting 100% of fans 1-6%, and completely opening the heat-insulating covers.

Through inspection, the final performance indexes of the product obtained in the embodiment are as follows: the tensile strength Rm is 1260MPa, the reduction of area Z is 32%, the martensite is 0.5, the network carbide is 0 grade, T [ O ] is 11ppm, N is 25ppm, the performance index of the common SWRH82B product is compared with that of the present example, see Table 4.

TABLE 6 comparison of the common SWRH82B with the SWRH82B Performance index of example 3

	Rm/MPa	Z/％	Martensite/grade	Network carbide/grade	T[O]/ppm	N/ppm
							Common SWRH82B	1170	19	2.0	2.5	25×10-6	43×10-6
Example 1	1260	32	0	0.5	11×10-6	25×10-6

As can be seen from Table 6, the newly designed rare earth-titanium microalloyed steel has higher strength, plasticity and better structural uniformity.

The nonmetallic inclusion of the steel for the rare earth alloying prestressed wire rod reaches the level that A type inclusion is less than or equal to 1.0, B type inclusion is less than or equal to 0.5, C type inclusion is less than or equal to 0.5, D type inclusion is less than or equal to 1.0 and Ds type inclusion is less than or equal to 1.0 according to the GBT10561 rating.

The rare earth alloying steel for the prestressed wire rod is provided with the grade of SWRH82BRe and the manufacturing method thereof, alloying is carried out by adding rare earth Re, the proportion of various alloy elements is reasonably controlled, a key process control point is optimized, and a scientific heat treatment system is optimized, so that the SWRH82BRe is effectively ensured to be more uniform in structure, higher in strength and excellent in plasticity index, shorter in aging time and higher in cleanliness.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.