Corrosion-resistant rail and manufacturing method thereof

Abstract

The present invention belongs to the field of rail manufacturing and specifically discloses a corrosion-resistant rail and a manufacturing method thereof. The method comprises the following steps: obtaining a corrosion-resistant rail ingot through converter smelting, LF refining, RH vacuum degassing, and continuous casting; heating the corrosion-resistant rail ingot until it is easily deformable, placing it on a slab mill for rolling and forming, and obtaining a rail product; after rough rolling, placing the rail product on a universal intermediate rolling mill for large deformation rolling, so that the micro-deformation rate within 0-2 mm thickness of the rail product surface reaches more than 35%, and the rollers of the universal intermediate rolling mill are previously roughened; descaling the rail product after the universal intermediate rolling with 30-35 MPa high-pressure water; performing universal finishing rolling on the rail product after high-pressure water descaling; and performing online heat treatment, blackening treatment, sealing treatment, and straightening on the rail product after the universal finishing rolling to obtain the corrosion-resistant rail. The corrosion-resistant rail provided by the present invention has excellent corrosion resistance and fully meets the corrosion resistance requirements of the rail during long-term service.

Description

Technical Field

[0001] The invention belongs to the field of rail manufacturing, and in particular relates to a corrosion-resistant rail and a manufacturing method thereof. Background Art

[0002] Rails are transported, stored, and used in open-air environments for the most part, making corrosion inevitable. Corrosion not only affects the rail's appearance but, in severe cases, shortens its lifespan and even affects the safe operation of trains, severely impacting the product's market competitiveness and brand image. Currently, there are two main methods for preventing rail corrosion: one is to improve the corrosion resistance of the rail matrix by adding alloying elements such as Cr, Ni, and Cu; the other is to spray protective coatings such as zinc, aluminum alloys, polymer coatings, grease, and ointments on the rail surface to improve the rail's corrosion resistance. Limited by factors such as cost, efficiency, and environmental protection, there are currently no mature, large-scale corrosion-resistant rails in use, either domestically or internationally.

[0003] Patent document CN104060187B discloses a corrosion-resistant microalloyed rail. The alloying elements, by weight, are as follows: C: 0.73% to 0.85%, Si: 0.30% to 0.90%, Mn: 0.80% to 1.20%, Cr: 0.20% to 0.40%, Cu: 0.30% to 0.50%, Ni: 1 / 2 to 2 / 3 of the Cu content, P: 0.03% to 0.05%, S: ≤ 0.025%, and at least one of the following three elements: V: 0.04% to 0.12%, Nb: 0.02% to 0.06%, Re: 0.005% to 0.05%, with the balance being Fe and unavoidable impurities. This patent adds corrosion-resistant alloying elements such as Cr, Cu, and Ni to a carbon rail, improving the corrosion resistance of the rail substrate by adjusting the proportions of P, Ni, and Cu. Domestic and foreign studies have found that at an alloying level below 5%, the addition of Cr, Cu, and Ni elements generally does not improve the corrosion resistance of rails by more than 60%. In harsh corrosive environments or during long-term service, the corrosion resistance is still lacking.

[0004] Patent document CN111719083A discloses a steel rail resistant to chloride ion corrosion and its preparation method. The rail's alloying elements, by weight, are as follows: C: 0.66%-0.76%, Si: 0.53%-0.73%, Mn: 0.9%-1.7%, P ≤ 0.012%, S ≤ 0.005%, Nb: 0.020%-0.030%, Als ≤ 0.003%, Cr: 1.2%-2.2%, Cu: 2%-4%, Co: 0.40%-0.65%, with the remainder being Fe and impurities. The preparation method inhibits chloride ion corrosion by controlling the shape of inclusions and forming a dense barrier layer on the rail surface. While the addition of high levels of Cr, Cu, and Co improves the rail's corrosion resistance, it significantly reduces its weldability. The original barrier layer on the surface of the rail is actually an oxide film, which inevitably contains gaps and is inevitably prone to breakage or cracking during the rail straightening process. The patent does not propose a method for dealing with the gaps in the surface barrier layer. During long-term service, the gaps and cracks in the barrier layer will still serve as channels for oxygen and corrosive media, and the rail will corrode. Summary of the Invention

[0005] In response to at least one of the problems of existing corrosion-resistant rails, such as high preparation cost, low efficiency, and inability to achieve long-term corrosion protection, the present invention provides a corrosion-resistant rail and a manufacturing method thereof, which has low preparation cost, high efficiency, and can achieve long-term corrosion protection.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] According to a first aspect of the present invention, a method for manufacturing a corrosion-resistant rail is provided, comprising the following steps:

[0008] (1) After converter smelting, LF refining, RH vacuum degassing, and continuous casting, corrosion-resistant rail castings are obtained;

[0009] (2) heating the corrosion-resistant rail ingot until it is easy to deform, placing it on a billet opening machine for rolling to obtain a rail rolled piece;

[0010] (3) After the rail is roughly rolled by the universal rolling mill, it is placed in the universal medium rolling mill for large deformation rolling, so that the micro-deformation rate within the thickness of 0-2mm on the surface of the rail reaches more than 35%. The rollers of the universal medium rolling mill are roughened in advance;

[0011] (4) Descaling the rails after universal intermediate rolling with 30-35 MPa high pressure water;

[0012] (5) Performing universal finishing rolling on the rail rolled piece after high-pressure water descaling;

[0013] (6) The rail rolled pieces after universal finishing are subjected to online heat treatment, blackening treatment, sealing treatment and straightening to produce corrosion-resistant rails.

[0014] According to one embodiment of the present invention, the chemical composition of the corrosion-resistant rail ingot obtained in step (1) includes, by weight percentage, at least one of: C: 0.50-0.65%, Si: 0.40-1.20%, Mn: 0.40-0.90%, Cr: 0.30-0.90%, Cu: 0.15-0.45%, Ni: 0.15-0.35%, V: 0.02-0.15%, Ti: 0.001-0.030%, and Nb: 0.01-0.08%, with the remainder being Fe and unavoidable impurities.

[0015] According to one embodiment of the present invention, in the chemical composition of the corrosion-resistant rail ingot obtained in step (1), the sum of Si and Cr contents is 1.20-1.85%, and the sum of Cu and Ni contents is 0.35-0.60%.

[0016] According to one embodiment of the present invention, in step (2), the corrosion-resistant rail casting is heated to a temperature of 1150-1200°C for a heating time of 3.0-3.5 hours, and the casting is rolled through two casting mills, with the first casting mill performing 7 passes and the second casting mill performing 3 passes.

[0017] According to one embodiment of the present invention, in step (3), the rolling elongation coefficient of the large deformation rolling is 1.13-1.20, and the rolling speed is 4.5-6.0 m / s.

[0018] According to one embodiment of the present invention, in step (5), the universal finishing elongation coefficient is 1.06-1.10.

[0019] According to one embodiment of the present invention, the rollers of the universal rolling mill are roughened by laser quenching and plasma quenching, so that the surface hardness of the rollers reaches 70HRC, the surface indentation width reaches 4-6mm, and the indentation depth reaches 2-3mm.

[0020] According to one embodiment of the present invention, in step (6), the rail rolled piece after universal finishing is accelerated cooled to 540°C to 570°C at a rate of 3.5 to 5°C / s, kept warm for more than 50 minutes, and then naturally cooled. When it is naturally cooled to 125-170°C, it is subjected to blackening treatment and sealing treatment, and then straightening with a small deformation amount is performed, and the total reduction of the upper roller of the horizontal straightening machine is ≤40mm.

[0021] According to one embodiment of the present invention, the blackening treatment time is 30 minutes to 40 minutes, and the sealing treatment time is 10 minutes to 15 minutes.

[0022] According to one embodiment of the present invention, in small deformation straightening, the reduction of the second roller of the horizontal straightening machine is 12 to 14 mm, and the total reduction of the four upper rollers is 30 to 38 mm.

[0023] According to a second aspect of the present invention, there is provided a corrosion-resistant rail obtained by using the above-mentioned method for manufacturing the corrosion-resistant rail.

[0024] By adopting the above technical solution, the present invention has the following beneficial effects:

[0025] The manufacturing method of the present invention fully removes secondary and tertiary scales of the rail rolled piece through the coordinated regulation of roller texturing, shallow surface large deformation rolling, and high-pressure water descaling. After rolling, an online heat treatment is performed to obtain an oxide film with an Fe3O4 ratio of more than 95%. The oxide film is then subjected to blackening and sealing treatment to form a dense surface protective layer with strong bonding strength and excellent corrosion resistance on the rail surface, thereby achieving protection of the rail under harsh corrosive conditions and effective protection during long-term service.

[0026] The corrosion-resistant rail provided by the present invention has excellent corrosion resistance and fully meets the corrosion resistance requirements of the rail during long-term service. In addition, the rail has excellent toughness and weldability and can be applied to plateau and mountainous railways, high-speed railways, mixed passenger and freight railways, subways and other lines to increase the service life of the rail. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] As required, specific embodiments of the present invention are disclosed in this specification; however, it should be understood that the disclosed embodiments are merely illustrative of the invention, which may be implemented in various alternative forms. In the following description, various operating parameters and components are described in connection with various contemplated embodiments. These specific parameters and components are provided herein as examples only and are not intended to be limiting.

[0029] According to a first aspect of the present invention, a method for manufacturing a corrosion-resistant rail is provided, which comprises the following steps: (1) obtaining a corrosion-resistant rail ingot through converter smelting, LF refining, RH vacuum degassing, and continuous casting; (2) heating the corrosion-resistant rail ingot until the ingot is easy to deform, placing it on a slab opening machine for rolling and forming, and obtaining a rail rolled piece; (3) after the rail rolled piece is rough-rolled by a universal rolling mill, placing it on a universal medium rolling mill for large deformation rolling, so that the micro-deformation rate within a thickness of 0-2 mm on the surface of the rail rolled piece reaches more than 35%, and the rolling rollers of the universal medium rolling mill are roughened in advance; (4) descaling the rail rolled piece after the universal medium rolling is performed with high-pressure water, and the pressure of the high-pressure water is 30-35 MPa; (5) performing universal finishing rolling on the rail rolled piece after the high-pressure water descaling; (6) performing online heat treatment, blackening treatment, sealing treatment, and straightening on the rail rolled piece after the universal finishing rolling to obtain a corrosion-resistant rail.

[0030] The converter smelting, LF refining, RH vacuum degassing, and continuous casting mentioned in step (1) of the present invention are all conventional operations in the art. The corrosion-resistant rail casting of the present invention is not limited to being obtained by the above-mentioned methods, but can also be obtained by other conventional methods in the art.

[0031] Preferably, the chemical composition of the corrosion-resistant rail ingot obtained in step (1) of the present invention comprises, by weight percentage, at least one of C: 0.50-0.65%, Si: 0.40-1.20%, Mn: 0.40-0.90%, Cr: 0.30-0.90%, Cu: 0.15-0.45%, Ni: 0.15-0.35%, V: 0.02-0.15, Ti: 0.001-0.030, and Nb: 0.01-0.08, with the remainder being Fe and unavoidable impurities. More preferably, in the chemical composition of the corrosion-resistant rail ingot obtained in step (1) of the present invention, the sum of Si and Cr contents is 1.20-1.85, and the sum of Cu and Ni contents is 0.35-0.60. Si and Cr are elements that can simultaneously improve the strength and corrosion resistance of the rail in the present invention, and Si and Cr elements can increase the pearlite transformation equilibrium temperature. Higher Si and Cr content increases the pearlite transformation equilibrium temperature, increasing the degree of undercooling during the accelerated cooling phase transformation process, reducing the pearlite interlamellar spacing, and improving rail strength, toughness, and corrosion resistance. However, excessive Si and Cr content can affect rail weldability. Cu and Ni are the primary corrosion-resistant elements in the rails of this invention. Higher Cu and Ni content increases corrosion resistance, but excessively high levels can lead to poor weldability.

[0032] In step (2) of the present invention, the heating temperature of the corrosion-resistant rail casting is 1150-1200°C, and the heating time is 3.0-3.5h. Specifically, the heating temperature of the corrosion-resistant rail casting can be 1150°C, 1160°C, 1170°C, 1180°C, 1190°C, 1200°C, and the heating time can be 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h. In some embodiments, in step (2) of the present invention, the slab is opened and rolled using two slab mills, the first slab mill rolls 7 passes, and the second slab mill rolls 3 passes.

[0033] In step (3) of the present invention, the universal medium rolling adopts a large deformation rolling process to achieve a micro-deformation rate of 35% or more within a thickness of 0-2 mm on the surface of the rail rolled piece, so as to fully break up the secondary iron oxide scale during the rolling process. The secondary iron oxide scale is formed on the surface of the steel billet due to contact with water and air during the rough rolling process. The rolling elongation coefficient of the large deformation rolling is 1.13-1.20, and the rolling speed is 4.5-6.0 m / s. Specifically, the rolling elongation coefficient of large deformation rolling can be 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, and the rolling speed can be 4.5m / s, 4.6m / s, 4.7m / s, 4.8m / s, 4.9m / s, 5.0m / s, 5.1m / s, 5.2m / s, 5.3m / s, 5.4m / s, 5.5m / s, 5.6m / s, 5.7m / s, 5.8m / s, 5.9m / s, 6.0m / s. In some embodiments, the intermediate rolling mill rolls one pass. In step (3) of the present invention, the rolls of the universal intermediate rolling mill are roughened in advance so that the secondary iron oxide scale on the surface of the rolled piece is fully cracked and broken during large deformation. The texturing treatment of the intermediate rolling mill rolls is to strengthen and roughen the surface of the intermediate rolling mill rolls through laser quenching, plasma quenching and other methods. After texturing, the surface hardness of the rolls reaches 70HRC, the surface indentation width reaches 4-6mm, and the indentation depth reaches 2-3mm, so as to improve the hardness of the roll surface and thus increase the service life.

[0034] In step (4) of the present invention, high-pressure water descaling is performed before universal finishing rolling to fully remove tertiary iron scale. Tertiary iron scale is formed on the surface of the steel billet due to contact between the steel billet surface and water and air during the intermediate rolling process. The high-pressure water descaling is performed by spraying high-pressure water from a nozzle to remove surface iron scale from the rolled piece before finishing. The pressure of the high-pressure water is 30-35 MPa, so that the surface iron scale removal rate of the rolled piece reaches more than 99%.

[0035] In step (5) of the present invention, the universal finishing elongation coefficient is 1.06-1.10. Specifically, the universal finishing elongation coefficient can be 1.06, 1.07, 1.08, 1.09, or 1.10.

[0036] In step (6) of the present invention, the rail rolled piece after universal finishing is accelerated cooled to 540°C to 570°C at a rate of 3.5-5°C / s, then kept warm for more than 50 minutes, and then naturally cooled. When naturally cooled to 125-170°C, it is subjected to a blackening treatment and a sealing treatment, and then straightened with a small deformation amount, with the total reduction of the upper roller of the horizontal straightening machine being ≤40mm. Since the temperature at which FeO in the oxide film transforms into Fe3O4 is approximately 540-570°C, the final cooling temperature of the accelerated cooling is controlled at 540-570°C. In order to convert as much FeO as possible into Fe3O4, the rail surface temperature is maintained at 540-570°C for as long as possible. In addition, in order to ensure that the surface protective layer has good corrosion resistance, the thickness needs to be at least 20 microns, and it also needs to be kept warm within the temperature range of 540-570°C. Therefore, when the rail surface is cooled to 540-570°C, it needs to be kept warm for more than 50 minutes to make the Fe3O4 ratio in the iron oxide scale on the rail surface greater than 95%. Preferably, the holding time is 50-70 minutes. Specifically, the accelerated cooling rate can be 3.5°C / s, 3.6°C / s, 3.7°C / s, 3.8°C / s, 3.9°C / s, 4.0°C / s, 4.1°C / s, 4.2°C / s, 4.3°C / s, 4.4°C / s, 4.5°C / s, 4.6°C / s, 4.7°C / s, 4.8°C / s, 4.9°C / s, 5.0°C / s, the accelerated cooling temperature can be 540°C, 545°C, 550°C, 555°C, 560°C, 565°C, 570°C, and the holding time can be 50 minutes, 55 minutes, 60 minutes, 65 minutes, or 70 minutes.

[0037] In step (6) of the present invention, when the rail is cooled to 125-170°C, a blackening treatment and a sealing treatment are performed to make the porosity of the iron oxide scale on the rail surface less than 3%. The blackening treatment is performed at a position 5 meters away from the outlet of the 100-meter cooling bed. When the surface temperature of the rail drops to 125-170°C, the rail is hoisted into a blackening tank for 30-40 minutes, and then placed in a water tank for a sealing treatment for 10-15 minutes. The starting temperature of the blackening treatment can be 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, or 170°C. The blackening treatment time can be 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, or 40 minutes. The sealing treatment time can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, or 15 minutes.

[0038] In step (6) of the present invention, a small deformation straightening is adopted, and the total reduction of the upper rollers of the horizontal straightening machine is ≤40mm, so that the oxide film on the surface of the rail will basically not crack or peel off while ensuring the straightness of the rail. In some embodiments, the reduction of the second roller of the horizontal straightening machine is 12 to 14 mm, and the total reduction of the four upper rollers is 30 to 38 mm. Specifically, the reduction of the second roller of the horizontal straightening machine can be 12 mm, 13 mm, or 14 mm, and the total reduction of the four upper rollers can be 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, 36 mm, 37 mm, 38 mm, 39 mm, or 40 mm. The smaller the deformation of the rail during the straightening process, the less likely the oxide film on the surface of the rail will crack or peel off. However, the important purpose of rail straightening is to make the rail straight, and too small a deformation cannot ensure the straightness of the rail. Therefore, when the second straightening roller of the horizontal roller straightening of the rail is pressed down by 12 to 14 mm and the total pressure of the four upper rollers is 30 to 38 mm, the oxide film on the surface of the rail will basically not crack or peel off, and the straightness of the rail can meet the standard requirements.

[0039] In some embodiments of the present invention, after straightening, some conventional operations in the art may be optionally included, such as finishing and quality inspection.

[0040] The manufacturing method of the present invention fully removes secondary and tertiary scale from the rail workpiece through the coordinated regulation of roller texturing, shallow surface large deformation rolling, and high-pressure water descaling. After rolling, an online heat treatment is performed to obtain an oxide film with an Fe3O4 ratio greater than 95%. The film is then blackened and sealed, forming a dense, highly bonded, and corrosion-resistant surface protective layer on the rail surface. Simultaneously, the rail substrate is alloyed with corrosion-resistant alloying elements to obtain a corrosion-resistant rail substrate. In conjunction with online heat treatment technology, the elements synergize to enhance the rail's corrosion and wear resistance, thereby reducing the alloying element content and ensuring the rail's weldability. The inherent corrosion resistance of the rail substrate and the surface protective layer, which exhibits excellent corrosion resistance, provide effective protection in harsh corrosive environments and during long-term service.

[0041] According to a second aspect of the present invention, a corrosion-resistant rail obtained using the above-mentioned method for manufacturing a corrosion-resistant rail is provided. The corrosion-resistant rail comprises a corrosion-resistant rail substrate and a corrosion-resistant rail surface protective layer. The chemical composition of the corrosion-resistant rail substrate comprises, by weight percentage, at least one of: C: 0.50-0.65%, Si: 0.40-1.20%, Mn: 0.40-0.90%, Cr: 0.30-0.90%, Cu: 0.15-0.45%, Ni: 0.15-0.35%, V: 0.02-0.15%, Ti: 0.001-0.030%, and Nb: 0.01-0.08%, with the remainder being Fe and unavoidable impurities. To ensure the corrosion resistance of the substrate, preferably, the sum of the Si and Cr contents is 1.20-1.85, and the sum of the Cu and Ni contents is 0.35-0.60. The surface protective layer of the corrosion-resistant rail is composed of Fe3O4, FeO, Fe2O3, and fillers (oils and greases) in the pores of the iron oxide scale. The Fe3O4 ratio is greater than 95%, the protective layer is 30 to 50 microns thick, and the porosity of the surface iron oxide scale is less than 3%. The oxide film has a compact structure, stable crystal form, and strong adhesion, providing excellent corrosion resistance. Testing has shown that the corrosion-resistant rail has a tensile strength of greater than 1000 MPa and an elongation of ≥14%.

[0042] The corrosion-resistant rail provided by the present invention has excellent corrosion resistance and fully meets the corrosion resistance requirements of the rail during long-term service. In addition, the rail has excellent toughness and weldability and can be applied to plateau and mountainous railways, high-speed railways, mixed passenger and freight railways, subways and other lines to increase the service life of the rail.

[0043] The present invention will be described in detail below through specific examples.

[0044] Example 1

[0045] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.60%, Si 0.55%, Mn 0.78%, Cr 0.45%, Cu 0.25%, Ni 0.12%, V 0.07%, and the balance is Fe and other inevitable impurities.

[0046] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0047] After cleaning, the steel slab is loaded into a heating furnace and heated to 1180°C for a total heating time of 3.2 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.20 and a rolling speed of 4.5 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 5 mm and a depth of 3 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 35 MPa is applied, achieving a surface oxide scale removal rate of over 99%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are cooled at an accelerated rate of 3.8°C / s starting at 783°C using compressed air. After cooling to 550°C, the rails are held in a heat-insulating condition for 60 minutes before naturally cooling on a cooling bed. The rails are cooled to 150°C and then blackened for 35 minutes. After blackening, they are sealed by soaking in anti-rust oil for 15 minutes. Once the rails have cooled to room temperature, they are straightened using a horizontal and vertical composite roller straightening process using a small deformation process. The second straightening roller in the horizontal roller straightening process has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0048] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and machining to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1151 MPa and an elongation of 15.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 35 μm. Image tool analysis of the cross-section revealed an average Fe₃O₄ area of ​​96%, and a porosity of less than 2.5%. After 300 hours of exposure to a 5% NaCl neutral salt spray test, corrosion on all surfaces, excluding the rail head and tread (where the wheel and rail meet), accounted for 3.5% of the total rail surface area.

[0049] Example 2

[0050] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.53%, Si 0.98%, Mn 0.89%, Cr 0.52%, Cu 0.34%, Ni 0.19%, V 0.09%, and the balance is Fe and other inevitable impurities.

[0051] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0052] After cleaning, the steel slab is loaded into a heating furnace and heated to 1165°C for a total heating time of 3.0 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.10 and a rolling speed of 6.0 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 4 mm and a depth of 2.5 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 32 MPa is applied, achieving a surface oxide scale removal rate of over 98%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are accelerated from 792°C using compressed air at a rate of 4.2°C / s. After cooling to 558°C, accelerated cooling is stopped and the rails are held in place for 60 minutes before naturally cooling on a rail cooling bed. The rails are cooled to 150°C and then blackened for 40 minutes. After blackening, they are sealed by soaking in anti-rust oil for 12 minutes. Once the rails have cooled to room temperature, they are straightened using a small deformation process using a horizontal composite roller system. The second straightening roller in the horizontal roller system has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0053] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and processing to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1140 MPa and an elongation of 16.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 31 μm. Image tool analysis of the cross-section of the oxide film revealed an average Fe₃O₄ area of ​​95%, and a porosity of less than 3.0%. After 300 hours of 5% NaCl neutral salt spray testing, the corrosion area on the rail surface, excluding the rail head and tread (where the wheel and rail meet), accounted for 2.5% of the total area.

[0054] Example 3

[0055] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.64%, Si 0.47%, Mn 0.56%, Cr 0.75%, Cu 0.41%, Ni 0.19%, V 0.07%, and the balance is Fe and other inevitable impurities.

[0056] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0057] After cleaning, the steel slab is loaded into a heating furnace and heated to 1180°C for a total heating time of 3.2 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.20 and a rolling speed of 6.0 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 5 mm and a depth of 3 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 35 MPa is applied, achieving a surface oxide scale removal rate of over 98%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are cooled from 783°C using compressed air at a rate of 3.6°C / s. After cooling to 560°C, accelerated cooling is stopped and the rails are held in place for 55 minutes before naturally cooling on a cooling bed. The rails are cooled to 165°C and then blackened for 40 minutes. After blackening, they are sealed by soaking in anti-rust oil for 12 minutes. Once the rails have cooled to room temperature, they are straightened using a small deformation process using a horizontal composite roller system. The second straightening roller in the horizontal roller system has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0058] After straightening, the surface oxide scale remained intact, with only some flaking on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and machining to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1176 MPa and an elongation of 15.0%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 43 μm. Image tool analysis of the cross-section revealed an average Fe₃O₄ area of ​​93%, and a porosity of less than 3.0%. After 300 hours of exposure to a 5% NaCl neutral salt spray test, corrosion on all surfaces, excluding the rail head and tread (where the wheel and rail meet), accounted for 3.5% of the total rail surface area.

[0059] Example 4

[0060] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.50%, Si 0.40%, Mn 0.90%, Cr 0.90%, Cu 0.15%, Ni 0.35%, Nb 0.08%, and the balance is Fe and other inevitable impurities.

[0061] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0062] After cleaning, the steel slab is loaded into a heating furnace and heated to 1180°C for a total heating time of 3.2 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.20 and a rolling speed of 6.0 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 5 mm and a depth of 3 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 35 MPa is applied, achieving a surface oxide scale removal rate of over 98%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are cooled from 783°C using compressed air at a rate of 3.6°C / s. After cooling to 560°C, accelerated cooling is stopped and the rails are held in place for 55 minutes before naturally cooling on a cooling bed. The rails are cooled to 165°C and then blackened for 40 minutes. After blackening, they are sealed by soaking in anti-rust oil for 12 minutes. Once the rails have cooled to room temperature, they are straightened using a small deformation process using a horizontal composite roller system. The second straightening roller in the horizontal roller system has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0063] After straightening, the surface oxide scale remained intact, with only some flaking on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and machining to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1176 MPa and an elongation of 15.0%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 43 μm. Image tool analysis of the cross-section revealed an average Fe₃O₄ area of ​​93%, and a porosity of less than 3.0%. After 300 hours of exposure to a 5% NaCl neutral salt spray test, corrosion on all surfaces, excluding the rail head and tread (where the wheel and rail meet), accounted for 3.5% of the total rail surface area.

[0064] Example 5

[0065] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.65%, Si 1.20%, Mn 0.40%, Cr 0.30%, Cu 0.30%, Ni 0.15%, Ti 0.030%, and the balance is Fe and other inevitable impurities.

[0066] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0067] After cleaning, the slab is loaded into a heating furnace and heated to 1165°C for a total heating time of 3.0 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the slab is then subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.15 and a rolling speed of 6.0 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 4 mm and a depth of 2.5 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 32 MPa is applied, achieving a surface oxide scale removal rate of over 98%. The product is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are accelerated from 792°C using compressed air at a rate of 4.2°C / s. After cooling to 558°C, accelerated cooling is stopped and the rails are held in place for 60 minutes before naturally cooling on a rail cooling bed. The rails are cooled to 150°C and then blackened for 40 minutes. After blackening, they are sealed by soaking in anti-rust oil for 12 minutes. Once the rails have cooled to room temperature, they are straightened using a small deformation process using a horizontal composite roller system. The second straightening roller in the horizontal roller system has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0068] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and processing to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1140 MPa and an elongation of 16.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 31 μm. Image tool analysis of the cross-section of the oxide film revealed an average Fe₃O₄ area of ​​95%, and a porosity of less than 3.0%. After 300 hours of 5% NaCl neutral salt spray testing, the corrosion area on the rail surface, excluding the rail head and tread (where the wheel and rail meet), accounted for 2.5% of the total area.

[0069] Example 6

[0070] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.60%, Si 0.80%, Mn 0.65%, Cr 0.60%, Cu 0.22%, Ni 0.25%, V 0.02%, Nb 0.01%, and the balance is Fe and other inevitable impurities.

[0071] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0072] After cleaning, the steel slab is loaded into a heating furnace and heated to 1180°C for a total heating time of 3.2 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.20 and a rolling speed of 4.5 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 5 mm and a depth of 3 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 35 MPa is applied, achieving a surface oxide scale removal rate of over 99%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are cooled at an accelerated rate of 3.8°C / s starting at 783°C using compressed air. After cooling to 550°C, the rails are held in a heat-insulating condition for 60 minutes before naturally cooling on a cooling bed. The rails are cooled to 150°C and then blackened for 35 minutes. After blackening, they are sealed by soaking in anti-rust oil for 15 minutes. Once the rails have cooled to room temperature, they are straightened using a horizontal and vertical composite roller straightening process using a small deformation process. The second straightening roller in the horizontal roller straightening process has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0073] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and machining to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1151 MPa and an elongation of 15.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 35 μm. Image tool analysis of the cross-section revealed an average Fe₃O₄ area of ​​96%, and a porosity of less than 2.5%. After 300 hours of exposure to a 5% NaCl neutral salt spray test, corrosion on all surfaces, excluding the rail head and tread (where the wheel and rail meet), accounted for 3.5% of the total rail surface area.

[0074] Example 7

[0075] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.60%, Si 0.80%, Mn 0.65%, Cr 0.40%, Cu 0.20%, Ni 0.15%, V 0.15%, Nb 0.01%, Ti 0.001%, and the balance is Fe and other inevitable impurities.

[0076] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0077] After cleaning, the steel slab is loaded into a heating furnace and heated to 1180°C for a total heating time of 3.2 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.20 and a rolling speed of 4.5 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 5 mm and a depth of 3 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 35 MPa is applied, achieving a surface oxide scale removal rate of over 99%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are cooled at an accelerated rate of 3.8°C / s starting at 783°C using compressed air. After cooling to 550°C, the rails are held in a heat-insulating condition for 60 minutes before naturally cooling on a cooling bed. The rails are cooled to 150°C and then blackened for 35 minutes. After blackening, they are sealed by soaking in anti-rust oil for 15 minutes. Once the rails have cooled to room temperature, they are straightened using a horizontal and vertical composite roller straightening process using a small deformation process. The second straightening roller in the horizontal roller straightening process has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0078] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and machining to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1151 MPa and an elongation of 15.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 35 μm. Image tool analysis of the cross-section revealed an average Fe₃O₄ area of ​​96%, and a porosity of less than 2.5%. After 300 hours of exposure to a 5% NaCl neutral salt spray test, corrosion on all surfaces, excluding the rail head and tread (where the wheel and rail meet), accounted for 3.5% of the total rail surface area.

[0079] Example 8

[0080] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.53%, Si 0.98%, Mn 0.89%, Cr 0.87%, Cu 0.30%, Ni 0.30%, Nb 0.04%, Ti 0.015%, and the balance is Fe and other inevitable impurities.

[0081] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0082] After cleaning, the steel slab is loaded into a heating furnace and heated to 1165°C for a total heating time of 3.0 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.10 and a rolling speed of 6.0 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 4 mm and a depth of 2.5 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 32 MPa is applied, achieving a surface oxide scale removal rate of over 98%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are accelerated from 792°C using compressed air at a rate of 4.2°C / s. After cooling to 558°C, accelerated cooling is stopped and the rails are held in place for 60 minutes before naturally cooling on a rail cooling bed. The rails are cooled to 150°C and then blackened for 40 minutes. After blackening, they are sealed by soaking in anti-rust oil for 12 minutes. Once the rails have cooled to room temperature, they are straightened using a small deformation process using a horizontal composite roller system. The second straightening roller in the horizontal roller system has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0083] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and processing to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1140 MPa and an elongation of 16.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 31 μm. Image tool analysis of the cross-section of the oxide film revealed an average Fe₃O₄ area of ​​95%, and a porosity of less than 3.0%. After 300 hours of 5% NaCl neutral salt spray testing, the corrosion area on the rail surface, excluding the rail head and tread (where the wheel and rail meet), accounted for 2.5% of the total area.

[0084] Example 9

[0085] The chemical composition of the rail matrix in this embodiment consists of the following elements in weight percentage: C 0.60%, Si 0.55%, Mn 0.78%, Cr 0.65%, Cu 0.45%, Ni 0.19%, V 0.10%, Ti 0.020%, and the balance is Fe and other inevitable impurities.

[0086] In this embodiment, the chemical composition of the steel billet is consistent with that of the rail substrate.

[0087] After cleaning, the steel slab is loaded into a heating furnace and heated to 1165°C for a total heating time of 3.0 hours. High-pressure water descaling is then applied to the slab mill, with seven passes in the first slab mill and three passes in the second slab mill. After rough rolling on a universal rolling mill, the steel slab is subjected to high-deformation rolling on a universal intermediate rolling mill, achieving a rolling elongation coefficient of 1.10 and a rolling speed of 6.0 m / s. To increase the deformation of the shallow surface of the rail product and ensure sufficient cracking of the secondary oxide scale on the surface during high deformation, the surface of the intermediate rolling mill rolls is roughened using laser quenching to increase the hardness and service life. This results in a rough surface with a surface indentation width of 4 mm and a depth of 2.5 mm. After the universal intermediate rolling and before finishing rolling, high-pressure water descaling at 32 MPa is applied, achieving a surface oxide scale removal rate of over 98%. The steel slab is then rolled on a universal finishing mill, achieving a finishing elongation coefficient of 1.08. After universal finishing, the rails are accelerated from 792°C using compressed air at a rate of 4.2°C / s. After cooling to 558°C, accelerated cooling is stopped and the rails are held in place for 60 minutes before naturally cooling on a rail cooling bed. The rails are cooled to 150°C and then blackened for 40 minutes. After blackening, they are sealed by soaking in anti-rust oil for 12 minutes. Once the rails have cooled to room temperature, they are straightened using a small deformation process using a horizontal composite roller system. The second straightening roller in the horizontal roller system has a reduction of 13mm, and the total reduction of the four upper straightening rollers is 32mm.

[0088] After straightening, the surface oxide scale remained intact, with only some peeling on the rail head and tread, and no noticeable cracks were observed. The rails were then subjected to online automatic inspection, internal ultrasonic testing, eddy current testing for surface defects, and processing to obtain the finished rails. Tensile testing according to GB / T 228 revealed a tensile strength of 1140 MPa and an elongation of 16.5%. Metallographic analysis of the cross-section of the rail surface oxide film revealed an average thickness of 31 μm. Image tool analysis of the cross-section of the oxide film revealed an average Fe₃O₄ area of ​​95%, and a porosity of less than 3.0%. After 300 hours of 5% NaCl neutral salt spray testing, the corrosion area on the rail surface, excluding the rail head and tread (where the wheel and rail meet), accounted for 2.5% of the total area.

[0089] Comparative Example 1

[0090] The chemical composition of the rail matrix in this comparative example consists of the following elements in weight percentage: C 0.67%, Si 0.75%, Mn 0.88%, Cr 0.32%, Cu 0.42%, Ni 0.23%, and the balance is Fe and other inevitable impurities.

[0091] In this comparative example 1, the chemical composition of the steel billet and the rail substrate are consistent.

[0092] The rail production method in Comparative Example 1 is essentially the same as the existing production process. After cleaning, the steel slab is loaded into a heating furnace and heated to 1230°C for a total heating time of 2.5 hours. High-pressure water is used for descaling, followed by slab rolling. The first slab mill performs five passes, the second slab mill performs three passes, and the rail is rough-rolled on a universal mill before being rolled on a universal intermediate mill. The rolling elongation coefficient is 1.12, and the rolling speed is 6.0 m / s. After universal finish rolling, the rail is accelerated cooled from 783°C using compressed air at a cooling rate of 3.6°C / s. After cooling to 560°C, the rail is then naturally cooled to room temperature. The rail is roller-leveled. The horizontal roller straightening method uses a second straightening roll with a reduction of 23 mm and a fourth straightening roll with a reduction of 18.5 mm, for a total reduction of 56 mm for the four upper straightening rolls.

[0093] After rail straightening, the iron oxide on the rail head tread, the head-waist joint, and the waist-leg joint began to flake, and dense cracks appeared on the rail waist oxide scale. Tensile testing according to GB / T 228 revealed a tensile strength of 1133 MPa and an elongation of 13.5%. Metallographic analysis of the rail surface oxide film revealed a maximum thickness of 72 μm, a minimum of 27 μm, and an average thickness of 43 μm. Image tool analysis of the oxide film revealed an average Fe₃O₄ area of ​​48%, and a porosity of 24.8%. After 300 hours of exposure to a 5% NaCl neutral salt spray test, the corrosion area on the rail surface accounted for 52% of the total area.

[0094] Comparative Example 2

[0095] The chemical composition of the rail matrix in this comparative example consists of the following elements in weight percentage: C 0.78%, Si 0.32%, Mn 1.06%, Cr 0.14%, V 0.04%, and the balance is Fe and other inevitable impurities.

[0096] In this actual comparison, the chemical composition of the steel billet and the rail substrate are consistent.

[0097] After cleaning, the steel slabs are loaded into a heating furnace and heated to 1180°C for a total heating time of 3.2 hours. High-pressure water descaling is then used. The steel slabs are then rolled using the first slab mill for seven passes and the second slab mill for three passes. After rough rolling on a universal rolling mill, the steel slabs are then subjected to large deformation rolling on a universal intermediate rolling mill with a rolling elongation coefficient of 1.20 and a rolling speed of 6.0 m / s. The steel slabs are then rolled on a universal finishing mill with a finishing elongation coefficient of 1.08. After universal finishing rolling, the rails are accelerated cooled starting at 783°C using compressed air at a cooling rate of 3.6°C / s. After cooling to 535°C, the accelerated cooling is stopped and the rails are held in the heat for 50 minutes. The rails are then naturally cooled on a cooling bed. The rails are cooled to 155°C and then blackened for 50 minutes. After blackening, they are sealed by soaking in anti-rust oil for 15 minutes. After the rails are cooled to room temperature, they are straightened by horizontal and vertical composite rollers using a small deformation process. The second straightening roller of the horizontal roller straightening of the rails has a reduction of 13 mm, and the total reduction of the four upper straightening rollers is 32 mm.

[0098] After rail straightening, the iron oxide on the rail head tread, the head-waist joint, and the waist-leg joint began to flake, and dense cracks appeared on the rail waist oxide scale. Tensile testing according to GB / T 228 revealed a tensile strength of 1167 MPa and an elongation of 13.0%. Metallographic analysis of the rail surface oxide film revealed a maximum thickness of 112 μm, a minimum of 38 μm, and an average thickness of 61 μm. Image tool analysis of the oxide film revealed an average Fe₃O₄ area of ​​42% and a porosity of 35.4% for the surface protective layer. After 300 hours of exposure to a 5% NaCl neutral salt spray test, the corrosion area on the rail surface accounted for 67% of the total area.

Claims

1. A method for manufacturing a corrosion-resistant rail, characterized in that: The following steps are involved: (1) After converter smelting, LF refining, RH vacuum degassing, and continuous casting, a corrosion-resistant rail ingot is obtained, wherein the chemical composition of the corrosion-resistant rail ingot comprises, by weight percentage, at least one of: C: 0.50-0.65%, Si: 0.40-1.20%, Mn: 0.40-0.90%, Cr: 0.30-0.90%, Cu: 0.15-0.45%, Ni: 0.15-0.35%, V: 0.02-0.15%, Ti: 0.001-0.030%, and Nb: 0.01-0.08%, and the remainder is Fe and unavoidable impurities; (2) Heating the corrosion-resistant rail ingot until it is easy to deform, placing it on a billet opening machine for rolling to obtain a rail rolled piece; (3) After rough rolling, the rail is placed in a universal medium rolling mill for large deformation rolling, so that the micro deformation rate within the thickness of 0-2mm on the surface of the rail reaches more than 35%. The rollers of the universal medium rolling mill are roughened in advance; (4) Descaling the rails after universal intermediate rolling with 30-35 MPa high pressure water; (5) Performing universal finishing rolling on the rail rolled pieces after descaling with high-pressure water; (6) The rail rolled pieces after universal finishing are subjected to online heat treatment, blackening treatment, sealing treatment and straightening to produce corrosion-resistant rails. In step (6), the rail rolled piece after universal finishing is cooled at a speed of 3.5-5°C / s to 540-570°C, kept warm for more than 50 minutes, and then cooled naturally. When cooled naturally to 125-170°C, it is subjected to blackening treatment and sealing treatment, and then straightened with a small deformation amount. The total reduction of the upper roller of the horizontal straightening machine is ≤40mm.

2. The method for manufacturing a corrosion-resistant rail according to claim 1, wherein: The chemical composition of the corrosion-resistant rail ingot obtained in step (1) comprises a sum of Si and Cr contents of 1.20-1.85%, and a sum of Cu and Ni contents of 0.35-0.60%.

3. The method for manufacturing a corrosion-resistant rail according to claim 1, wherein: In step (2), the corrosion-resistant rail casting billet is heated to a temperature of 1150-1200°C for a heating time of 3.0-3.5 hours, and the billet is rolled through two billet mills, with the first billet mill rolling 7 passes and the second billet mill rolling 3 passes.

4. The method for manufacturing a corrosion-resistant rail according to claim 1, wherein: In step (3), the rolling elongation coefficient of large deformation rolling is 1.13-1.20, and the rolling speed is 4.5-6.0 m / s; in step (5), the universal finishing rolling elongation coefficient is 1.06-1.

10.

5. The method for manufacturing a corrosion-resistant rail according to claim 1, wherein: The rollers of the universal rolling mill are roughened by laser quenching and plasma quenching, so that the surface hardness of the rollers reaches 70HRC, the surface indentation width reaches 4~6mm, and the indentation depth reaches 2~3mm.

6. The method for manufacturing a corrosion-resistant rail according to claim 1, wherein: The blackening treatment time is 30min~40min, and the sealing treatment time is 10~15min.

7. The method for manufacturing a corrosion-resistant rail according to claim 1, wherein: In small deformation straightening, the reduction of the second roller of the horizontal straightening machine is 12~14mm, and the total reduction of the four upper rollers is 30~38mm.

8. A corrosion-resistant steel rail obtained by the method for manufacturing a corrosion-resistant steel rail according to any one of claims 1 to 7.