Bainite steel rail with low hydrogen embrittlement sensitivity and preparation method thereof

Abstract

The invention discloses a bainite steel rail with low hydrogen embrittlement sensitivity and a preparation method thereof, and belongs to the technical field of steel rail preparation. The steel rail comprises the following chemical components in percentage by weight: 0.25%-0.30% of C, 1.10%-1.40% of Si, 1.20%-1.50% of Mn, 0.3%-0.7% of Cr, 0.4%-0.9% of Mo, 0.03%-0.06% of Nb, less than or equal to 0.010% of P, less than or equal to 0.010% of S and the balance of Fe and inevitable impurities. According to the bainite steel rail, the stability of a steel rail structure and retained austenite is regulated and controlled through component design and a controlled cooling technology, and the bainite steel rail has high strength and low hydrogen embrittlement sensitivity; compared with an existing high-strength bainite steel rail, the heat preservation time is shortened, the alloy cost is reduced, long-time tempering of the bainite steel rail after straightening is omitted, the production cost is reduced, the use safety of the steel rail is improved, and the high-strength bainite steel rail is suitable for heavy-load freight railway steel rails and turnouts.

Description

Technical Field

[0001] This invention belongs to the field of rail manufacturing technology, specifically relating to a low-hydrogen-embrittlement-sensitive bainitic rail for heavy-haul freight railways and turnouts, and its manufacturing method. Background Technology

[0002] With the increasing demands for rail strength in heavy-haul railways and turnouts, bainitic rails with a strength of 1380 MPa and above have attracted significant attention due to their superior strength and toughness. However, hydrogen embrittlement fracture of rails often occurs suddenly and without obvious warning, posing a far greater threat than other types of fracture and seriously endangering railway safety. Compared with pearlitic rails, high-strength bainitic rails have significant advantages in strength and toughness, but their complex microstructure (mainly composed of bainite, martensite, and retained austenite) makes them more susceptible to hydrogen embrittlement during production and use, exhibiting higher hydrogen embrittlement susceptibility. Experiments show that the notched tensile strength of bainitic steel under hydrogen-filled conditions is significantly lower than that of pearlitic steel, and its hydrogen embrittlement susceptibility is much higher. Hydrogen embrittlement can lead to microcracks in bainitic rails during production, and even fracture before tempering. During use, hydrogen in the rail may accumulate at inclusions, inducing hydrogen-induced cracks and further forming core damage, seriously affecting the reliability and service life of the rail. Therefore, reducing the hydrogen embrittlement sensitivity of bainitic rails is of great significance for improving rail performance, ensuring production quality, and ensuring safe use.

[0003] Patent publication number CN107779759A discloses a boron-containing bainitic steel rail with excellent resistance to delayed fracture and its production method. The composition of the steel rail, by weight percentage, is as follows: C: 0.18%-0.26%; Si: 1.30%-1.70%; Mn: 1.75%-2.15%; Cr: 0.30%-0.70%; Mo: 0.15%-0.40%; P≤0.020%; S≤0.010%; B: 0.0006%-0.0015%; Ti: 0.01%-0.03%; H≤0.00017%, with the remainder being iron and unavoidable impurity elements. The production method includes steelmaking, continuous casting, billet heating, hot rolling, and heat treatment. The heat treatment process involves air cooling the hot-rolled rail to 700℃±60℃ or 600℃±60℃, followed by cooling at a rate of 0.5℃ / s-4℃ / s to 300℃±40℃, and finally air cooling to room temperature. This patent improves the delayed fracture resistance of bainitic rails by precisely controlling the boron content; however, the control range of boron content is only 0.0006%-0.0015%, increasing the difficulty of smelting. Furthermore, the patent does not explicitly address the hydrogen embrittlement sensitivity of the rails.

[0004] In summary, the research and development of a low-cost, low-hydrogen-embrittlement-sensitive bainitic rail has become an important research topic that urgently needs to be addressed. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a low-cost, low-hydrogen-embrittlement-sensitivity bainitic rail and its preparation method. This invention regulates the microstructure and mechanical stability of the rail and retained austenite through composition design and controlled cooling technology. The bainitic rail of this invention exhibits high strength and low hydrogen embrittlement sensitivity. Simultaneously, the rail provided by this invention reduces the heat treatment time and alloy cost compared to existing high-strength bainitic rails, eliminates the long tempering process after straightening, lowers production costs, and improves the safety of rail use. It is suitable for use in heavy-haul freight railway rails and turnouts.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a low-hydrogen-embrittlement-sensitive bainitic steel rail, the chemical composition and weight percentage of which are: C: 0.25%~0.30%, Si: 1.10%~1.40%, Mn: 1.20%~1.50%, Cr: 0.3%~0.7%, Mo: 0.4%~0.9%, Nb: 0.03%~0.06%, P: ≤0.010%, S: ≤0.010%, with the balance being Fe and unavoidable impurities.

[0007] The reasons for the specific composition design of the bainitic steel rail in this application are as follows: Carbon (C) is the cheapest element used to improve the strength and hardness of the matrix. For the bainitic rail of this invention, a C content greater than 0.25% is beneficial to improving the strength and hardness of bainite. At the same time, during the bainitic phase transformation, C atoms diffuse into the adjacent untransformed austenite, improving the stability of the retained austenite. However, a high C content will cause excessive martensite structure in the steel, reducing the toughness of the bainitic rail. Therefore, this invention selects a C content of 0.25% to 0.30%.

[0008] Si is a solid-solution strengthening element that mainly dissolves in bainitic ferrite. In this invention, the main role of Si is to dissolve in bainitic ferrite and inhibit the precipitation of cementite during phase transformation. Excessive Si content will reduce the reduction of area of ​​the material and worsen its plasticity. Therefore, this invention selects a Si content of 1.10% to 1.40%.

[0009] Mn can improve the stability of supercooled austenite, refine bainite laths, and enhance the strength and toughness of rails. However, excessively high Mn content can easily lead to local segregation in the rail, affecting the weldability of bainitic rails and disrupting the uniformity of the microstructure, thus deteriorating the rail's impact performance. Therefore, this invention selects an Mn content of 1.20%~1.50%.

[0010] Cr can improve hardenability, ensure that the rail obtains bainitic structure at a lower cooling rate, delay bainite transformation, and refine the width of bainite laths. Excessive Cr content will increase the proportion of martensite in the structure. Therefore, the Cr content selected in this invention is 0.3%~0.7%.

[0011] During the rolling process, Nb dissolves in austenite, which can effectively refine the austenite grains. During the subsequent cooling process, nano-sized Nb (C, N) precipitates are formed, which have a strong binding ability with hydrogen and effectively reduce the diffusion ability of hydrogen in steel. Therefore, the present invention selects an Nb content of 0.03%~0.06%.

[0012] Mo can effectively delay the transformation of pearlite and improve the stability of retained austenite. At the same time, the carbides formed by Mo and Nb are strong hydrogen traps. However, excessive addition of Mo will significantly increase the cost of rails and increase the martensite content. Therefore, this invention selects a Mo content of 0.4% to 0.9%.

[0013] P is a harmful element in steel rails and is very prone to segregation at grain boundaries. Under the premise of ensuring steelmaking conditions and costs, this invention requires that the P content be ≤0.010%.

[0014] S is a harmful element in the rails of this invention. Excessive S content can easily form large-sized Class A non-metallic inclusions, causing quality defects in the weld heat-affected zone. Therefore, the lower the content, the better, without increasing unnecessary costs. This invention requires S ≤ 0.010%.

[0015] Based on the above technical solution, the rail microstructure mainly consists of bainitic ferrite with an average slab thickness of 170-200 nm and thin-film retained austenite with a thickness of 20-40 nm. The retained austenite content is 3%-7%, the bainitic ferrite content is 80%-90%, and the remainder is martensite and trace amounts of nanoscale carbide phases. The original austenite grain size is 8-10 μm. The rail yield strength (Rp) 0.2 ≥1350MPa, tensile strength (Rm) ≥1420MPa, elongation (A) ≥13%, rail head tread hardness ≥430HBW.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned low hydrogen embrittlement sensitive bainitic rail, including continuous casting billet heating, rail rolling, controlled cooling, and heat treatment. After the rails are rolled, they are cooled to 790~830℃. First, forced cooling is applied to the rail head tread and both sides at a cooling rate of 5~8℃ / s. When the surface temperature of the rail head drops to 350~380℃, forced cooling is applied to the rail head tread and both sides at a cooling rate of 1~3℃ / s. When the surface temperature of the rail head drops to 290~320℃, forced cooling is stopped. Then, the rails are held at 330~360℃ for 30~50 minutes and then air-cooled after being taken out of the furnace.

[0017] Based on the above technical solution, the rail is further cooled to 800~820℃ after rolling, and the cooling method is air cooling.

[0018] Based on the above technical solution, the forced cooling method is further described as forced cooling by air jets.

[0019] Based on the above technical solution, the continuous casting billet is further defined as a cross-sectional continuous casting billet with a diameter of 280~320mm × 380~410mm.

[0020] Based on the above technical solution, further, the homogenization temperature of the continuously cast billet during the heating process is 1270~1290℃, and the holding time is 2.5~3.5 hours.

[0021] Based on the above technical solution, the continuously cast billet is further descaled by high-pressure water after heating.

[0022] Based on the above technical solution, the rail rolling process further adopts the universal method or the die rolling method to roll rails with a cross section of 50~75kg / m, the rail rolling compression ratio is greater than 11, the BD1 initial rolling temperature is 1155~1185℃, and the final rolling temperature is 1020~1050℃.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention prepares a low-cost, low-hydrogen-embrittlement-sensitive bainitic rail by combining alloy composition design with controlled cooling process. First, the original austenite grains are effectively refined by Nb microalloying. The original austenite grain size of the rail is 8~10μm. In the subsequent cooling process, nano-sized dispersed Nb carbonitrides rich in Mo will also be formed. Second, the two-stage controlled cooling process is fully utilized to control the morphology and proportion of bainite, martensite and retained austenite in the rail. The microstructure is bainitic ferrite with a lath thickness of 170~200nm and thin film-like retained austenite with a thickness of 20~40nm. The retained austenite content is 3%~7%, the bainitic ferrite content is 80%~90%, and the rest is martensite and trace amounts of nano-sized carbide phases. Third, the continuous casting billet heat preservation and slow cooling process is eliminated, which reduces the rail production cost and improves the rail production efficiency.

[0024] (2) The rail of this invention adopts a two-stage controlled cooling. In the first stage, a larger cooling rate is used to reduce the overall temperature of the rail to below the phase transformation initiation temperature, increasing the degree of undercooling. This allows the undercooled austenite to begin bainitic phase transformation in a lower temperature range, refining the bainitic structure and reducing the content of blocky retained austenite in the bainitic rail structure. The retained austenite exists in a uniformly dispersed, fine film. At the same time, the higher cooling rate is conducive to the precipitation of nano-sized Nb and Mo carbonitrides, which are uniformly dispersed in the bainitic structure. The uniformly dispersed retained austenite and carbonitrides are both strong hydrogen traps, causing hydrogen in the rail to accumulate at the phase interface and in the internal vacancies. This helps to suppress the accumulation of hydrogen at the newly formed martensite interface caused by the transformation of retained austenite during subsequent straightening and use, thereby increasing the local hydrogen concentration and forming hydrogen-induced cracks under stress. In the second stage, a lower cooling rate is used to reduce the content of martensite in the rail. Martensite is hydrogen embrittlement sensitive. The martensite content is higher than that of bainitic structures. The rails of this invention do not undergo prolonged tempering heat treatment after straightening. Excessive untempered martensite content significantly reduces the limiting hydrogen content of high-strength bainitic rails. After forced cooling is stopped, the rails are placed in a holding furnace for a certain period. This holding process primarily stabilizes the retained austenite, distributes carbon, improves the stability of thin-film retained austenite, and further decomposes blocky retained austenite. Due to the controlled cooling method, bainitic phase transformation occurs at a lower temperature, resulting in a higher dislocation density in the microstructure. Short-term holding at a specific temperature helps reduce the dislocation density in the rail, lowering its yield strength and reducing excessive load on the straightening equipment during the straightening process. After straightening, only a small amount of retained austenite phase transformation occurs in the rail, forming a more uniformly distributed and smaller martensite phase, reducing localized stress concentration and hydrogen accumulation during rail straightening.

[0025] (3) The yield strength (Rp) of the rail prepared by this invention 0.2 With a strength of ≥1350MPa, tensile strength (Rm) ≥1420MPa, elongation (A) ≥13%, and rail head tread hardness ≥430HBW, this design significantly reduces the hydrogen embrittlement sensitivity of bainitic rails while ensuring their strength and toughness, thereby reducing production costs and improving the safety of rail use. Attached Figure Description

[0026] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0027] Figure 1 This is a microstructure diagram of the bainitic rail prepared in Example 3 of the present invention.

[0028] Figure 2 This is a phase diagram of carbonitride precipitation in the bainitic steel rail prepared in Example 3 of the present invention. Detailed Implementation

[0029] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0030] This invention provides a low-hydrogen-embrittlement-sensitive bainitic steel rail, the chemical composition and weight percentage of which are: C: 0.25%~0.30%, Si: 1.10%~1.40%, Mn: 1.20%~1.50%, Cr: 0.3%~0.7%, Mo: 0.4%~0.9%, Nb: 0.03%~0.06%, P: ≤0.010%, S: ≤0.010%, with the balance being Fe and unavoidable impurities.

[0031] Based on the above technical solution, the rail microstructure mainly consists of bainitic ferrite with an average slab thickness of 170-200 nm and thin-film retained austenite with a thickness of 20-40 nm. The retained austenite content is 3%-7%, the bainitic ferrite content is 80%-90%, and the remainder is martensite and trace amounts of nanoscale carbide phases. The original austenite grain size is 8-10 μm. The rail yield strength (Rp) 0.2 ≥1350MPa, tensile strength (Rm) ≥1420MPa, elongation (A) ≥13%, rail head tread hardness ≥430HBW.

[0032] The present invention also provides a method for preparing the above-mentioned low hydrogen embrittlement sensitive bainitic rail, including continuous casting billet heating, rail rolling, controlled cooling, and heat treatment; After the rails are rolled, they are cooled to 790~830℃. First, forced cooling is applied to the rail head tread and both sides at a cooling rate of 5~8℃ / s. When the surface temperature of the rail head drops to 350~380℃, forced cooling is applied to the rail head tread and both sides at a cooling rate of 1~3℃ / s. When the surface temperature of the rail head drops to 290~320℃, forced cooling is stopped. Then, the rails are held at 330~360℃ for 30~50 minutes and then air-cooled after being taken out of the furnace.

[0033] Based on the above technical solution, the rail is further cooled to 800~820℃ after rolling, and the cooling method is air cooling.

[0034] Based on the above technical solution, the forced cooling method is further described as forced cooling by air jets.

[0035] Based on the above technical solution, the continuous casting billet is further defined as a cross-sectional continuous casting billet with a diameter of 280~320mm × 380~410mm.

[0036] Based on the above technical solution, further, the homogenization temperature of the continuously cast billet during the heating process is 1270~1290℃, and the holding time is 2.5~3.5 hours.

[0037] Based on the above technical solution, the continuously cast billet is further descaled by high-pressure water after heating.

[0038] Based on the above technical solution, the rail rolling process further adopts the universal method or the die rolling method to roll rails with a cross section of 50~75kg / m, the rail rolling compression ratio is greater than 11, the BD1 initial rolling temperature is 1155~1185℃, and the final rolling temperature is 1020~1050℃.

[0039] Examples 1-5 This embodiment provides a method for preparing a low-hydrogen-embrittlement-sensitive bainitic rail. The chemical composition and weight percentage of the rail are shown in Table 1. Table 1. Chemical composition and weight percentage (wt%) of the rails in Examples 1-5

[0040] This includes continuous casting billet heating, rail rolling, controlled cooling, and online heat treatment; The continuous casting billet adopts a cross-section of 280×380mm. The hot-soaking temperature of the continuous casting billet is 1270~1290℃, and the holding time is 2.5~3.5 hours. After high-pressure water descaling, it is rolled into the required cross-section rails of 60~75kg / m using the universal method, ensuring that the rail rolling compression ratio is greater than 11. The initial rolling temperature of BD1 is 1155~1185℃, and the final rolling temperature of the universal rolling mill is 1020~1050℃. After final rolling, the rails are air-cooled to 800-820℃. First, forced cooling with air jets at a cooling rate of 5-8℃ / s is applied to the rail head tread and both sides. When the surface temperature of the rail head drops to 350-380℃, forced cooling with a cooling rate of 1-3℃ / s is applied to the rail head tread and both sides. When the surface temperature of the rail head drops to 290-320℃, forced cooling is stopped, and the rails are sent to a 330-360℃ holding furnace for 30-50 minutes. After being air-cooled to room temperature, the finished rails are obtained through processes such as straightening, flaw detection, and processing.

[0041] The microstructure, mechanical properties, and hydrogen embrittlement sensitivity of the rails prepared in Examples 1-5 are shown in Tables 4-5.

[0042] Table 2. Main process parameters for heating and rolling of continuously cast billets in Examples 1-5

[0043] Table 3. Controlled cooling and online heat treatment process parameters for Examples 1-5

[0044] Table 4. Microstructure of the rails prepared in Examples 1-5

[0045] Table 5. Mechanical properties and hydrogen embrittlement susceptibility of the rails prepared in Examples 1-5

[0046] Note: The hydrogen embrittlement susceptibility of the test steel was evaluated using an electrochemical hydrogen charging combined with a slow strain rate tensile test. The specific steps are as follows: using a 0.1 mol / L NaOH aqueous solution as the electrolyte, at a current density J = 1-16 mA / cm²... 2 The hydrogen charging parameters were adjusted within a certain range, and samples with different hydrogen contents were obtained by changing the current density and hydrogen charging time. The hydrogen embrittlement sensitivity was evaluated by the embrittlement index (i.e., the ratio of the reduction in elongation of the hydrogen-charged sample to the elongation of the uncharged sample).

[0047] The rail yield strength (Rp) prepared within the composition range defined by this invention and according to the controlled cooling process given by this invention. 0.2 The rail has a tensile strength (Rm) ≥1350MPa, an elongation (A) ≥13%, and a rail head tread hardness ≥430HBW. The bainite content in the rail is significantly higher, the total amount of retained austenite is significantly lower, and the percentage of stable film-like retained austenite is higher. This allows hydrogen to be fixed in the retained austenite, preventing hydrogen diffusion and reducing the hydrogen embrittlement sensitivity of the material.

[0048] Comparative Examples 1-3 Comparative Examples 1-3 provide a conventional method for preparing bainitic steel rails. The rail compositions of Comparative Examples 1 and 2 are existing bainitic steel compositions, and the rail composition of Comparative Example 3 is the same as that of the rail composition of Example 4. Bainitic steel rails are prepared using conventional processes. The chemical composition and weight percentage of the rails of Comparative Examples 1-3 are shown in Table 6. Table 6 Chemical composition and weight percentage (wt%) of rails used in Comparative Examples 1-3

[0049] This includes continuous casting billet heating, rail rolling, cooling, and tempering; The continuously cast billet adopts a cross-section of 280×380mm. The soaking temperature of the continuously cast billet is 1250~1270℃, and the holding time is 2.5~3.5 hours. After high-pressure water descaling, it is rolled into the required cross-section rails of 60~75kg / m using the universal method, ensuring that the rail rolling compression ratio is greater than 11. The initial rolling temperature of BD1 is 1135~1165℃, and the final rolling temperature of the universal rolling mill is 970~1020℃. After the final rolling, the rail is air-cooled to 690~710℃. Forced cooling with a cooling rate of 2~3℃ / s is applied to the rail head tread and both sides of the rail. When it drops to 280~320℃, it is air-cooled to room temperature, straightened, and then tempered at 290~320℃ for 10~20 hours.

[0050] Table 7. Main process parameters for heating and rolling of continuously cast billets in Comparative Examples 1-3

[0051] Table 8 Cooling and tempering process parameters for Comparative Examples 1-3

[0052] Table 9. Microstructure of rails prepared in Comparative Examples 1-3

[0053] Table 10 shows the mechanical properties and hydrogen embrittlement susceptibility of the rails prepared in Comparative Examples 1-3.

[0054] Note: The hydrogen embrittlement susceptibility of the test steel was evaluated using an electrochemical hydrogen charging combined with a slow strain rate tensile test. The specific steps are as follows: using a 0.1 mol / L NaOH aqueous solution as the electrolyte, at a current density J = 1-16 mA / cm²... 2 The hydrogen charging parameters were adjusted within a certain range, and samples with different hydrogen contents were obtained by changing the current density and hydrogen charging time. The hydrogen embrittlement sensitivity was evaluated by the embrittlement index (i.e., the ratio of the reduction in elongation of the hydrogen-charged sample to the elongation of the uncharged sample).

[0055] The bainite content in the rails of Comparative Examples 1-3 was significantly lower, while the total amount of retained austenite was significantly higher. Furthermore, the percentage of stable film-like retained austenite was low, and the blocky retained austenite was unstable and prone to decomposition, leading to the diffusion of hydrogen and significantly increasing the hydrogen embrittlement sensitivity of the material.

[0056] The above experimental results show that the rails prepared using the method of this invention exhibit improved standard position strength and elongation. Under different hydrogen content conditions, the elongation reduction rate of the samples prepared according to this invention is significantly lower than that of comparative examples 1-3, demonstrating excellent resistance to hydrogen embrittlement. In summary, within the composition range given in this invention, combined with the optimized preparation process, the hydrogen embrittlement sensitivity of bainitic rails can be effectively reduced, improving safety while reducing production costs, providing a more competitive solution for heavy-haul railway rails.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-hydrogen-embrittlement-sensitive bainitic steel rail, characterized in that, Its chemical composition and weight percentage are as follows: C: 0.25%~0.30%, Si: 1.10%~1.40%, Mn: 1.20%~1.50%, Cr: 0.3%~0.7%, Mo: 0.4%~0.9%, Nb: 0.03%~0.06%, P: ≤0.010%, S: ≤0.010%, with the balance being Fe and unavoidable impurities; The microstructure of the rail consists of bainitic ferrite with an average lath thickness of 170–200 nm and thin-film retained austenite with a thickness of 20–40 nm. The retained austenite content is 3%–7%, the bainitic ferrite content is 80%–90%, and the remainder is martensite and trace amounts of nanoscale carbide phases. The yield strength (Rp) of the rail is... 0.2 ≥1350MPa, tensile strength (Rm) ≥1420MPa, elongation (A) ≥13%, rail head tread hardness ≥430HBW; The preparation method of the low hydrogen embrittlement sensitive bainitic rail includes continuous casting billet heating, rail rolling, controlled cooling, and heat treatment; After the rails are rolled, they are cooled to 790~830℃. First, forced cooling is applied to the rail head tread and both sides of the rail at a rate of 5~8℃ / s. When the surface temperature of the rail head drops to 350~380℃, forced cooling is applied to the rail head tread and both sides of the rail at a rate of 1~3℃ / s. When the surface temperature of the rail head drops to 290~320℃, forced cooling is stopped. Then, the rails are held at 330~360℃ for 30~50 minutes and then air-cooled after being taken out of the furnace. The rail rolling process produces 50~75kg / m cross-section rails with a rail rolling compression ratio greater than 11. The initial rolling temperature of BD1 is 1155~1185℃, and the final rolling temperature is 1020~1050℃.

2. The low-hydrogen-embrittlement-sensitive bainitic rail according to claim 1, characterized in that, After the rails are rolled, they are cooled to 800~820℃ by air cooling.

3. The low-hydrogen-embrittlement-sensitive bainitic rail according to claim 1, characterized in that, The forced cooling method is forced air cooling.

4. The low-hydrogen-embrittlement-sensitive bainitic rail according to claim 1, characterized in that, The continuously cast billet is a cross-sectional continuously cast billet with a diameter of 280~320mm × 380~410mm.

5. The low-hydrogen-embrittlement-sensitive bainitic rail according to claim 1, characterized in that, During the heating process of the continuously cast billet, the homogenization temperature of the billet is 1270~1290℃, and the holding time is 2.5~3.5 hours.

6. The low-hydrogen-embrittlement-sensitive bainitic rail according to claim 1, characterized in that, After heating, the continuously cast billet is descaled by high-pressure water.

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