Rare earth weather-proof angle steel and manufacturing method thereof

Abstract

The invention relates to the technical field of steel production, in particular to rare earth weather-proof angle steel and a manufacturing method thereof, and the manufacturing method comprises the steps of converter / electric furnace steelmaking, LF refining, non-metallic inclusion modification treatment, continuous casting and hot rolling. During steelmaking, the temperature of molten iron entering a furnace is not less than 1250 DEG C, and S is not more than The steel-making end point is controlled to be 0.04%-0.07% of C and 0.005%-0.015% of P; after refining is finished, a Si-Ca wire or a Ca wire is fed for non-metallic inclusion modification treatment, and Ca / Al in molten steel reaches 0.08-0.12; during continuous casting, 0.10-0.16 kg of rare earth elements are added into each ton of steel by adopting a method of feeding rare earth wires into a crystallizer, and the carbon content in the steel is 0.07%-0.14%; and selecting continuous casting crystallizer casting powder matched with the steel grade. By adding La or / and Ce and combining specific operation condition control, the rare earth weather-proof angle steel with a good anti-corrosion effect is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and in particular to a rare earth weathering angle steel and a manufacturing method thereof. Background Art

[0002] Angle steel is a long steel strip with two sides perpendicular to each other, mainly used in construction, machinery manufacturing, bridges, ships and other fields. The iron towers used in overhead line power transmission projects are mainly fixed and supported by angle steel. The iron towers are exposed to wind and rain outdoors all year round and need to have sufficient mechanical strength and corrosion resistance. The traditional anti-corrosion method is to hot-dip galvanize the surface of the angle steel, but this operation will cause a certain degree of environmental pollution. Another method is to use weather-resistant angle steel that is exempt from subsequent hot-dip galvanizing treatment. The commonly used chemical elements to improve the weather resistance of steel are mostly Cu, P, Cr, and Ni. Adding rare earth elements in the preparation of weather-resistant steel is a new attempt.

[0003] CN113637903A discloses a rare earth-containing cold-rolled automotive weathering steel with a yield strength of 310MPa and a production method. Its main components and their mass percentages are C: ≤0.09%, Si: 0.10~0.40%, Mn: 0.15~0.35%, P: 0.05~0.11%, S≤0.015%, Als: 0.010~0.030%, Cu: 0.2~0.35%, RE: 0.04~0.09%, and its steel grain size is above 10 levels. The atmospheric corrosion resistance is ≤50% relative to the corrosion rate of Q235, ensuring good corrosion resistance. However, the specific types of rare earth elements added are not specified, and it is in a cold-rolled state. The internal components of automobiles generally have surface coating or structural coating, and the air fluidity is poor, which is not a typical application scenario for weathering steel.

[0004] CN113737105A discloses a rare earth-containing weathering steel and a preparation method thereof. The main components and their mass percentages are: one or more of Al 4-11%, Si 0.25-1.8%, P 0.05-0.30%, Cu 0.1-0.55%, Mn 3-30%, RE 0.025-0.55%, C 0.05-0.45%, Ti 0.01-0.125%, Nb 0.03-0.12% and V 0.03-0.12% and the balance Fe. The rare earth content is too high and a large amount of Al element is added. The feasibility and economy of the preparation method are questionable.

[0005] CN115747644A discloses a rare earth weathering steel for photovoltaic brackets and a production method thereof. The main components and their mass percentages are: C: 0.06~0.12%, Si: 0.30~0.50%, Mn: 0.8~1.0%, P: ≤0.018%, S: ≤0.005%, Cu: 0.20~0.35%, Cr: 0.40~0.55%, Ni: 0.05~0.15%, Ti: 0.020~0.030%, La: 15~25ppm, Alt: 0.020~0.050%. The produced rare earth weathering steel is applied to photovoltaic brackets. By alloying with trace amounts of La and other elements and controlling the morphology of inclusions, the elongation reaches 30%, but the relevant indicators of atmospheric corrosion resistance are not reflected, and it is difficult to ensure the service life. Summary of the invention

[0006] In view of the technical problem that the corrosion resistance of rare earth-containing steels used in specific weather-resistant scenarios such as iron towers needs to be improved, the present invention provides a rare earth weather-resistant angle steel and a manufacturing method thereof. A small amount of rare earth La and / or Ce is added during the preparation, and specific operating conditions are controlled. For example, during continuous casting, a continuous casting crystallizer protective slag matching the steel grade is selected. The obtained rare earth weather-resistant angle steel has excellent mechanical properties and good anti-corrosion effect.

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for manufacturing rare earth weathering angle steel, comprising the steps of converter / electric furnace steelmaking, LF refining, non-metallic inclusion modification treatment, continuous casting and hot rolling; When making steel in a converter, the temperature of the molten iron entering the furnace is ≥1250℃, and S≤0.025%; after splashing slag to protect the furnace, the furnace is shaken to first load scrap steel, and then add molten iron. The steelmaking endpoint is controlled at C 0.04%~0.07%, P 0.005%~0.015%, and the molten steel temperature is 1630~1660℃; electric furnace steelmaking can also be used, and the endpoint control is the same as that of converter steelmaking; After LF refining, Si-Ca wire or Ca wire is fed to perform non-metallic inclusion modification treatment, and the Ca / Al ratio in the molten steel reaches 0.08~0.12. The molten steel is soft-blown and allowed to stand, and then the ladle is placed on the continuous casting table for pouring; During continuous casting, the pouring temperature of the continuous casting tundish is 1530~1565℃. In the production process, the method of feeding rare earth wires into the continuous casting crystallizer is adopted to add rare earth elements to the steel. The added amount is 0.10~0.16kg / ton, and the carbon content in the steel is 0.07%~0.14%. The width-to-thickness ratio of the continuous casting billet is controlled to be 1:1~2. The continuous casting crystallizer protection slag matching the steel grade is selected. Controlled rolling and controlled cooling process is adopted during hot rolling.

[0008] Furthermore, during the steel-making process of converter / electric furnace, aluminum blocks / aluminum particles are added for deoxidation, steel slag is mixed and flushed, and then ferroalloy materials are added for alloying.

[0009] Furthermore, the rare earth element added to the steel is at least one of La and Ce.

[0010] Furthermore, during continuous casting, in addition to Fe and inevitable impurities, the chemical composition of the steel by mass percentage includes C 0.08% - 0.12%, Si 0.35% - 0.40%, Mn 1.10% - 1.35%, P 0.018% - 0.021%, S 0.002% - 0.004%, Alt 0.036% - 0.045%, Ni 0.12% - 0.13%, Cr 0.52% - 0.55%, Cu 0.26% - 0.29%, La 0.0034% - 0.0038%, Ce 0.0074% - 0.0090% and Ca 0.0030% - 0.0040%.

[0011] The carbon (C) content is controlled within 0.08% - 0.12%. Since the corrosion - resistant elements Ni, Cr, and Cu contained in the steel can also play a strengthening role, but will increase the carbon equivalent and the welding susceptibility index. In order to reasonably control the material strength range, and more importantly, to ensure good plasticity, impact toughness, and welding performance, the C content range is lower than that of the conventional low - alloy steel Q355 and the ordinary carbon steel Q235.

[0012] The silicon (Si) content is controlled within 0.35% - 0.40%. It can, on the premise of ensuring smooth production, not only exert its solid - solution strengthening ability but also be beneficial to improving the material's corrosion resistance. If the Si content is too high, when producing thick - section angle steel, it is easy to cause internal quality problems in the material during the controlled cooling process and lead to a decline in welding performance.

[0013] The manganese (Mn) content is controlled within 1.10% - 1.35%. Mn has a solid - solution strengthening effect, can improve the material's tensile strength, can lower the starting temperature Ar3 of austenite phase transformation, moderately increase the hardenability, and reduce the hot brittleness and cold brittleness caused by sulfur.

[0014] The phosphorus (P) content is within 0.018% - 0.021%. P increases the material's cold brittleness and weldability, and at the same time, the effects of solid - solution strengthening and improving corrosion resistance are significant.

[0015] The sulfur (S) content is controlled within 0.002% - 0.004%. S forms sulfide inclusions in the steel, reducing the material's toughness, and the lower it is in structural steel, the better.

[0016] Rare earth elements (REM) are controlled at 0.006%~0.030%. It should be emphasized that the rare earth content here refers to the rare earth content in the steel, not the amount added. And Ce and La are selected to be added, which can be added alone or in combination. The addition of rare earth to steel has the following effects: (1) promoting the spheroidization of sulfides, reducing the anisotropy of the material, and especially improving the transverse impact resistance of the rolled material; (2) refining the cast structure, austenite grains, pearlite structure, and lath martensite structure; (3) reducing the grain boundary segregation of P; and (4) improving the corrosion resistance of the material, which is specifically manifested in the following two aspects: on the one hand, rare earth sulfides, solid-solution rare earths, and rare earth-containing metal compounds are chemically active in the corrosive medium. After decomposition, they will release rare earth cations and precipitate in the cathode area with a relatively high pH value, which will hinder the electrochemical corrosion reactions of the cathode and the anode, slowing down the further progress of corrosion; on the other hand, the phosphorus-rare earth element composite has a good inhibitory effect on the anode and cathode reactions of the corrosion reaction, and the material changes from local corrosion to uniform corrosion, so that the pH value of the micro-area on the surface of the matrix remains at a weak acidity, promoting the formation of a stable and dense rust layer structure α-FeOOH.

[0017] The calcium (Ca) content is controlled at 0.0030%~0.0040%, and the Ca / Al ratio of molten steel is required to reach 0.08~0.12 after refining. At present, most steel production uses Al as a deoxidizer in molten steel, and weathering angle steel with high quality requirements is no exception. 2 O 3 High-melting-point compounds with high content are easy to block the water outlet of the middle ladle during the continuous casting process. Ca treatment can form calcium aluminate with a lower melting point, thereby ensuring the smooth progress of the continuous casting process. In addition, Ca treatment can form CaS inclusions in the steel that are difficult to deform during hot working, weaken the effect of MnS and improve the anisotropy of the material. Therefore, for the continuous casting production of weather-resistant angle steel, Ca treatment after refining is required, and the molten steel must contain a certain amount of Ca.

[0018] Further, when the chemical composition of the steel, excluding Fe and unavoidable impurities, includes C 0.11%~0.12%, Si 0.36%~0.40%, Mn 1.10%, P 0.018%~0.021%, S 0.003%~0.004%, Alt 0.036%~0.042%, Ni 0.12%, Cr 0.52%, Cu 0.26%~0.29%, La 0.0034%~0.0038%, Ce 0.0084%~0.0090% and Ca 0.0030%~0.0034% by mass percentage, the requirements for continuous casting mold protection slag are: The basicity is 1.0~1.2, the viscosity at 1300℃ is 0.70~0.75Pa•s, and the melting temperature is 1150±30℃; When the chemical composition of the steel, excluding Fe and unavoidable impurities, includes C 0.08-0.10%, Si 0.35%~0.40%, Mn 1.10%~1.35%, P 0.018%~0.021%, S 0.002%~0.004%, Alt 0.02%~0.05%, Ni0.12%~0.13%, Cr 0.52%~0.55%, Cu 0.26%~0.29%, La 0.0034%~0.0038%, Ce 0.0084%~0.0090% and Ca 0.0030%~0.0040% by mass percentage, the requirements for continuous casting mold protection slag are: The basicity is 0.85~1.05, the viscosity is 1.00~1.10Pa•s at 1300℃, and the melting temperature is 1170±30℃.

[0019] Furthermore, the continuous casting mold protection slag composition includes SiO 2 25%~33%, CaO30%~35%, Al 2 O 3 8%~9%, carbon powder 10%~16%, the rest is MgO, Na 2 O and F.

[0020] Furthermore, the continuous casting billet is cut into fixed lengths and then cooled down off the production line to check the surface quality; the fixed length of the continuous casting billet is 4.5~16m.

[0021] Furthermore, during hot rolling, the heating temperature is 1160~1250℃, and the heating time is 1.0~3.8 hours. The starting rolling temperature is 1020~1150℃, the final rolling temperature is 850~900℃, and the final cooling temperature is 550~700℃.

[0022] In a second aspect, the present invention provides a rare earth weathering angle steel prepared by the above manufacturing method. The rare earth weathering angle steel is subjected to a 72-hour periodic immersion test, and the average corrosion rate is ≤1.9509g / (m 2 h).

[0023] Furthermore, the yield strength of the rare earth weathering angle steel is ≥370MPa, the tensile strength is 470-680MPa, the elongation is ≥20%, the impact energy at 20℃ is ≥80J, the impact energy at 0℃ is ≥60J, the impact energy at -20℃ is ≥40J, and the impact energy at -40℃ is ≥35J.

[0024] The beneficial effects of the present invention are: The present invention provides a method for manufacturing rare earth weathering angle steel. On the one hand, by adding a small amount of rare earth elements La or / and Ce to the chemical composition of steel, the corrosion resistance and impact resistance of the weathering angle steel are improved. On the other hand, when preparing peritectic steel, an iron-carbon alloy with a certain carbon content is prone to non-equilibrium structure after crystallization, resulting in surface depressions, promoting the formation of cracks, and seriously affecting the surface quality of the steel, thereby affecting its mechanical strength and corrosion resistance. The control of surface defects in the continuous casting of peritectic steel is a difficult problem in the steel production industry. Therefore, in the continuous casting process, in order to avoid defects in the finished product, when setting the chemical composition of the steel, the added content of the C element is controlled to be outside the range of forming peritectic steel. The added amount of the C element is limited and cannot meet the market demand for the diversity of steel. The manufacturing method provided by the present invention achieves the quality control of the continuous casting billet with a C content of 0.07% to 0.14% by determining the condition requirements of the continuous casting crystallizer protective slag, thereby ensuring the quality of the finished rare earth weathering angle steel.

[0025] The rare earth weathering angle steel prepared by the present invention meets the requirements of Q355 and Q420 series in YB / T 4835. After a 72-hour periodic immersion test, the average corrosion rate is ≤1.9509g / (m 2 h), and has excellent mechanical properties. It is mainly used in transmission tower construction projects, and can also be used in other tower mast structures, workshops, factories, warehouses and other public buildings' steel frame support structures. From the perspective of corrosion protection, sandblasting and rust removal, anti-corrosion layer spraying or hot-dip galvanizing can be omitted during structural processing and installation. After the structure is installed, no anti-corrosion operation is required during use. When used, it can be painted and maintained less or even maintenance-free. In other atmospheric environments except marine environments and industrial heavy corrosion environments, it can replace the existing Q355 and Q420 series angle steels and their components for corrosion protection. It is an economical and environmentally friendly steel with significant economic significance, environmental significance and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 It is the microstructure diagram of the rare earth weathering angle steel of Example 1; wherein, (a) is the microstructure diagram of the cross section of the rare earth weathering angle steel, and (b) is the microstructure diagram of the longitudinal section of the rare earth weathering angle steel.

[0028] Figure 2 It is the microstructure diagram of the rare earth weathering angle steel of Example 2; wherein, (a) is the microstructure diagram of the cross section of the rare earth weathering angle steel, and (b) is the microstructure diagram of the longitudinal section of the rare earth weathering angle steel.

[0029] Figure 3 These are microstructure diagrams of the rare earth weathering angle steel of Example 3, wherein (a) is the microstructure diagram of the cross section of the rare earth weathering angle steel, and (b) is the microstructure diagram of the longitudinal section of the rare earth weathering angle steel. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] Example 1 A rare earth weathering angle steel and a manufacturing method thereof, comprising the steps of converter steelmaking, LF refining, non-metallic inclusion modification treatment, billet continuous casting and hot rolling; Specifically: (1) Converter steelmaking: The temperature of the molten iron entering the converter is ≥1250℃, S≤0.025%. After the converter is splashed with slag to protect the furnace, the furnace is shaken to first load scrap steel and then add molten iron. The scrap steel accounts for 10%. Converter steelmaking, P and C removal, the steelmaking end point is controlled at C 0.07%, P 0.014%, the molten steel temperature is 1630℃, and the slag is blocked for tapping. During the tapping process, aluminum particles are added for deoxidation, steel slag is mixed and flushed, and ferroalloy materials are added for alloying. After tapping, a small amount of refined reducing slag is added to cover the surface of the molten steel, and the argon is blown and stirred to the LF refining furnace; (2) LF refining: First, the top slag is melted and heated, then the temperature is measured and samples are taken. According to the test results, slag conditions, and molten steel temperature, alloys, slag materials, and temperature are added according to conventional process control requirements; (3) Non-metallic inclusion modification treatment: After LF refining, Si-Ca wire or Ca wire is fed to perform non-metallic inclusion modification treatment according to the Al content in the molten steel, so that the Ca / Al ratio in the molten steel reaches 0.08. The molten steel is then soft-blown and allowed to stand for 15 minutes before being placed on the continuous casting table for casting; (4) Billet continuous casting: The pouring temperature of the continuous casting tundish is 1530°C. During the production process, the method of feeding rare earth wire into the continuous casting crystallizer is adopted. La-Ce alloy wire is added to the steel in an amount of 0.15 kg / ton. Except for Fe and unavoidable impurities, the chemical composition of the steel is shown in Table 1. Requirements for continuous casting mold protection slag: The mass percentage of the components of the continuous casting mold protection slag is SiO 2 25.66%, CaO 30.40%, Al 2 O 38.12%, carbon powder 15.34%, MgO 7.34%, Na 2 O 6.37%, the remainder is F, the basicity of the continuous casting mold protection slag is 1.18, the viscosity at 1300℃ is 0.725Pa•s, and the melting temperature is 1170℃. Under this condition, the surface defects of the continuous casting of rare earth peritectic steel (C content is between 0.10% and 0.14%, belonging to peritectic steel containing rare earth components) can be effectively controlled; The billet is cut into 4.5m lengths, cooled down and inspected for surface quality before being transferred to the rolling line. (4) Hot rolling: The controlled rolling and controlled cooling process is adopted. After high-pressure water descaling, rough rolling, finishing rolling, controlled cooling after rolling, coiling and finishing, the finished rare earth weathering angle steel is obtained. The hot rolling process parameters are shown in Table 2. The square billet is heated at 1250°C for 1.0 hour and then taken out of the furnace.

[0032] The microstructure of rare earth weathering angle steel is as follows Figure 1 The mechanical properties are shown in Table 3. It can be seen from Table 3 that the mechanical properties of the rare earth weathering angle steel manufactured by the present invention are significantly better than the existing national standard requirements. The TB / T 1979-2023 "Atmospheric Corrosion Resistant Steel for Special Metal Materials for Locomotives and Vehicles" standard is adopted for a 72-hour periodic infiltration test, and the corrosion resistance test results are shown in Table 4.

[0033] Table 1 Chemical composition of steel (wt%)

[0034] Table 2 Hot rolling process parameters

[0035] Table 3 Mechanical properties of steel

[0036] Table 4 Test results of atmospheric corrosion resistance (weekly immersion accelerated corrosion test)

[0037] Example 2 A rare earth weathering angle steel and a manufacturing method thereof, comprising the steps of converter steelmaking, LF refining, non-metallic inclusion modification treatment, billet continuous casting and hot rolling; Specifically: (1) Converter steelmaking: The temperature of the molten iron entering the converter is ≥1250℃, S≤0.025%. After the converter is splashed with slag to protect the furnace, the furnace is shaken to first load scrap steel and then add molten iron. The scrap steel accounts for 15%. Converter steelmaking, P and C removal, the steelmaking end point is controlled at C 0.07%, P 0.014%, the molten steel temperature is 1630℃, and the slag is blocked for tapping. During the tapping process, aluminum particles are added for deoxidation, steel slag is mixed and flushed, and ferroalloy materials are added for alloying. After the tapping is completed, a small amount of refined reducing slag is added to cover the surface of the molten steel, and the argon is blown and stirred to lift the ladle to the LF refining furnace; (2) LF refining: First, the top slag is melted and heated, then the temperature is measured and samples are taken. According to the test results, slag conditions, and molten steel temperature, alloys, slag materials, and temperature are added according to conventional process control requirements; (3) Non-metallic inclusion modification treatment: After LF refining, Si-Ca wire or Ca wire is fed to modify non-metallic inclusions according to the Al content in the molten steel, so that the Ca / Al ratio in the molten steel reaches 0.12. Then the molten steel is soft-blown and allowed to stand for 15 minutes before being placed on the continuous casting table for casting; (4) Billet continuous casting: The pouring temperature of the continuous casting tundish is 1565°C. During the production process, the method of feeding rare earth wire into the continuous casting crystallizer is adopted. La-Ce alloy wire is added to the steel in an amount of 0.15 kg / ton. Except for Fe and unavoidable impurities, the chemical composition of the steel is shown in Table 1. Requirements for continuous casting mold protection slag: The mass percentage of the components of continuous casting mold protection slag is SiO 2 25.66%, CaO 30.40%, Al 2 O 3 8.12%, carbon powder 15.34%, MgO 7.34%, Na 2 O 6.37%, the remainder is F, the basicity of the continuous casting mold protection slag is 1.18, the viscosity at 1300℃ is 0.725Pa•s, and the melting temperature is 1120℃. Under this condition, the surface defects of the continuous casting of rare earth peritectic steel can be effectively controlled; The billet is cut into 16m lengths, cooled down and inspected for surface quality before being transferred to the rolling line. (4) Hot rolling: The controlled rolling and controlled cooling process is adopted. After high-pressure water descaling, rough rolling, finishing rolling, controlled cooling after rolling, coiling and finishing, the finished hot-rolled coil is obtained. The hot rolling process parameters are shown in Table 2. The square billet is heated at 1220°C for 1.5 hours and then taken out of the furnace.

[0038] The microstructure of the prepared rare earth weathering angle steel is as follows: Figure 2 The mechanical properties are shown in Table 3. The TB / T1979-2023 "Atmospheric Corrosion Resistant Steel for Special Metal Materials for Locomotives and Vehicles" standard was used for a 72-hour periodic infiltration test, and the corrosion resistance test results are shown in Table 4.

[0039] Example 3 A rare earth weathering angle steel and a manufacturing method thereof, comprising the steps of converter steelmaking, LF refining, non-metallic inclusion modification treatment, rectangular billet continuous casting and hot rolling; Specifically: (1) Converter steelmaking: The temperature of the molten iron entering the converter is ≥1250℃, S≤0.025%. After the converter is splashed with slag to protect the furnace, the furnace is shaken to first load scrap steel and then add molten iron. The scrap steel accounts for 10%. Converter steelmaking, P and C removal, the steelmaking end point is controlled at C 0.04%, P 0.015%, the molten steel temperature is 1660℃, and the slag is blocked for tapping. During the tapping process, aluminum particles are added for deoxidation, steel slag is mixed and flushed, and ferroalloy materials are added for alloying. After tapping, a small amount of refined reducing slag is added to cover the surface of the molten steel, and the argon blowing and stirring ladle is hoisted to the LF refining furnace; (2) LF refining: First, the top slag is melted and heated, then the temperature is measured and samples are taken. According to the test results, slag conditions, and molten steel temperature, alloys, slag materials, and temperature are added according to conventional process control requirements; (3) Non-metallic inclusion modification treatment: After LF refining, Si-Ca wire or Ca wire is fed to perform non-metallic inclusion modification treatment according to the Al content in the molten steel, so that the Ca / Al ratio in the molten steel reaches 0.08. The molten steel is then soft-blown and allowed to stand for 15 minutes before being placed on the continuous casting table for casting; (4) Rectangular billet continuous casting: The pouring temperature of the continuous casting tundish is 1530°C. During the production process, the method of feeding rare earth wire into the continuous casting crystallizer is adopted. La-Ce alloy wire is added to the steel in an amount of 0.15 kg / ton. Except for Fe and unavoidable impurities, the chemical composition of the steel is shown in Table 1. Among them, the C element is less than 0.10%, which belongs to low-carbon rare earth steel. In the continuous casting process of rectangular billets containing rare earths, no peritectic reaction will occur, and there will be no surface defects in the continuous casting of rare earth peritectic steel. At this time, the continuous casting mold protection slag conditions are: the mass percentage of the components of the continuous casting mold protection slag is SiO 2 32.70%, CaO 33.20%, Al 2 O 3 8.40%, carbon powder 11.50%, MgO 7.17%, Na 2 O 5.37%, the balance is F, the basicity of the continuous casting mold protection slag is 1.02, the viscosity at 1300℃ is 1.05Pa•s, the melting temperature is 1170℃, 0.07%~0.10%; The rectangular billet is cut into 8.2m fixed lengths, cooled down and inspected for surface quality before being transferred to the rolling line; (4) Hot rolling: The controlled rolling and controlled cooling process is adopted. After high-pressure water descaling, rough rolling, finishing rolling, controlled cooling after rolling, coiling and finishing, the finished rare earth weathering angle steel is obtained. The hot rolling process parameters are shown in Table 2. The square billet is heated at 1160°C for 3.8 hours and then taken out of the furnace.

[0040] The microstructure of rare earth weathering angle steel is as follows Figure 3 The mechanical properties are shown in Table 3. The TB / T 1979-2023 "Atmospheric Corrosion Resistant Steel for Special Metal Materials for Locomotives and Vehicles" standard was used for a 72-hour periodic infiltration test, and the corrosion resistance test results are shown in Table 4.

[0041] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A method for manufacturing rare earth weathering angle steel, characterized in that: It includes the steps of converter / electric furnace steelmaking, LF refining, non-metallic inclusion modification treatment, continuous casting and hot rolling; When making steel in a converter, the temperature of the molten iron entering the furnace is ≥1250℃, and S≤0.025%; after splashing slag to protect the furnace, the furnace is shaken to first load scrap steel, and then add molten iron. The steelmaking endpoint is controlled at C 0.04%~0.07%, P 0.005%~0.015%, and the molten steel temperature is 1630~1660℃; electric furnace steelmaking can also be used, and the endpoint control is the same as that of converter steelmaking; After LF refining, Si-Ca wire or Ca wire is fed to perform non-metallic inclusion modification treatment, and the Ca / Al ratio in the molten steel reaches 0.08~0.

12. The molten steel is soft-blown and allowed to stand, and then the ladle is placed on the continuous casting table for pouring; During continuous casting, the pouring temperature of the continuous casting tundish is 1530~1565℃. In the production process, the method of feeding rare earth wires into the continuous casting crystallizer is adopted to add rare earth elements to the steel. The added amount is 0.10~0.16kg / ton, and the carbon content in the steel is 0.07%~0.14%. The width-to-thickness ratio of the continuous casting billet is controlled to be 1:1~2. The continuous casting crystallizer protection slag matching the steel grade is selected. Controlled rolling and controlled cooling process is adopted during hot rolling.

2. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: During the steel-making process of converter / electric furnace, aluminum blocks / aluminum particles are added for deoxidation, steel slag is mixed and then ferroalloy materials are added for alloying.

3. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: The rare earth element added to the steel is at least one of La and Ce.

4. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: During continuous casting, in addition to Fe and inevitable impurities, the chemical composition of the steel includes C 0.08%~0.12%, Si 0.35%~0.40%, Mn1.10%~1.35%, P 0.018%~0.021%, S 0.002%~0.004%, Alt 0.036%~0.045%, Ni 0.12%~0.13%, Cr 0.52%~0.55%, Cu 0.26%~0.29%, La 0.0034%~0.0038%, Ce 0.0074%~0.0090% and Ca0.0030%~0.0040% by mass percentage.

5. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: When the chemical composition of the steel, excluding Fe and unavoidable impurities, includes C 0.11%~0.12%, Si 0.36%~0.40%, Mn 1.10%, P 0.018%~0.021%, S 0.003%~0.004%, Alt 0.036%~0.042%, Ni 0.12%, Cr 0.52%, Cu 0.26%~0.29%, La 0.0034%~0.0038%, Ce 0.0084%~0.0090% and Ca 0.0030%~0.0034% by mass percentage, the requirements for continuous casting mold protection slag are: The basicity is 1.0~1.2, the viscosity at 1300℃ is 0.70~0.75Pa•s, and the melting temperature is 1150±30℃; When the chemical composition of the steel, excluding Fe and unavoidable impurities, includes C 0.08-0.10%, Si 0.35%~0.40%, Mn 1.10%~1.35%, P 0.018%~0.021%, S 0.002%~0.004%, Alt 0.02%~0.05%, Ni0.12%~0.13%, Cr 0.52%~0.55%, Cu 0.26%~0.29%, La 0.0034%~0.0038%, Ce 0.0084%~0.0090% and Ca 0.0030%~0.0040% by mass percentage, the requirements for continuous casting mold protection slag are: The basicity is 0.85~1.05, the viscosity is 1.00~1.10Pa•s at 1300℃, and the melting temperature is 1170±30℃.

6. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: The components of the continuous casting mold protection slag include SiO2 25%~33%, CaO 30%~35%, Al2O3 8%~9%, carbon powder 10%~16%, and the remainder is MgO, Na2O and F by mass percentage.

7. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: After the continuous casting billet is cut into fixed length, it is cooled down and the surface quality is checked; the fixed length of the continuous casting billet is 4.5~16m.

8. The method for manufacturing rare earth weathering angle steel according to claim 1, characterized in that: During hot rolling, the heating temperature is 1160~1250℃, and the heating time is 1.0~3.8 hours. The starting rolling temperature is 1020~1150℃, the final rolling temperature is 850~900℃, and the final cooling temperature is 550~700℃.

9. A rare earth weathering angle steel prepared by the manufacturing method according to any one of claims 1 to 8, characterized in that: After 72 hours of periodic immersion test, the average corrosion rate of rare earth weathering angle steel is ≤1.9509g / (m 2 h).

10. The rare earth weathering angle steel according to claim 9, characterized in that: The yield strength of rare earth weathering angle steel is ≥370MPa, the tensile strength is 470~680MPa, the elongation is ≥20%, the impact energy at 20℃ is ≥80J, the impact energy at 0℃ is ≥60J, the impact energy at -20℃ is ≥40J, and the impact energy at -40℃ is ≥35J.

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