High-toughness low-hydrogen embrittlement sensitivity bainite railway steel and production method

Abstract

The application discloses a kind of high tough low hydrogen embrittlement sensitivity bainite railway steel and production method, comprising: after smelting casting, using predetermined temperature holding within predetermined time;After dephosphorization, universal rolling is carried out, and cooling to room temperature after rolling;Carry out up and down and left and right bending deformation treatment;Tempering treatment.The application controls heat treatment and tempering process after casting, combines reasonable component design, while ensuring the existing online heat treatment bainite railway steel toughness, reduces the hydrogen embrittlement sensitivity of railway steel, improves the running safety of railway steel, meets heavy load railway steel or switch railway steel.

Description

Technical Field

[0001] This invention relates to the field of railway steel production technology, and in particular to a high-strength, high-toughness, low-hydrogen-embrittlement-sensitive bainitic railway steel and its production method. Background Technology

[0002] The performance of railway steel directly affects railway transportation efficiency and traffic safety. Bainitic steel, as a newly emerging type of railway track steel, is gradually being used in railway applications due to its superior performance and longer service life. However, in the research and application of bainitic railway steel, hydrogen directly affects its mechanical properties and service performance.

[0003] Hydrogen in steel is mainly introduced during the smelting process and has very low solubility. When the hydrogen content in steel reaches a certain level, it will cause changes in the material's mechanical properties; this phenomenon is called hydrogen damage. Hydrogen damage exists in most metallic materials, and the most prominent form of hydrogen damage is hydrogen embrittlement, which means that the presence of hydrogen leads to a decrease in the material's plasticity and toughness, and may even cause brittle cracking and fracture.

[0004] Hydrogen has a significant impact on the mechanical properties of steel, including its plasticity, strength, fracture toughness, and impact toughness, with plasticity being the most sensitive. Simultaneously, hydrogen also greatly affects the physical properties of steel.

[0005] (1) Effect of hydrogen on steel plasticity: Hydrogen can significantly reduce the plasticity of steel, and hydrogen in steel will cause its plasticity index to drop sharply. In order to reduce the harmful effect of hydrogen on steel plasticity, the main measures are to strictly control the hydrogen content in steel, and at the same time reduce hydrogen embrittlement sensitivity through composition and process to ensure the normal use of materials.

[0006] (2) Effect of hydrogen on steel strength: Hydrogen has little effect on the tensile strength and yield strength of steel, but its fracture strength is very sensitive to hydrogen. The higher the hydrogen content, the lower the fracture strength.

[0007] (3) Effect of hydrogen on the physical properties of steel: Hydrogen entering the metal will cause distortion of the metal lattice, thereby causing changes in its physical properties. When the metal contains a certain amount of hydrogen, its coercivity will increase, its permeability will decrease, and its resistivity will show a trend of first increasing and then decreasing.

[0008] Hydrogen embrittlement sensitivity characterizes the degree to which hydrogen causes embrittlement in steel, and is generally expressed by the embrittlement index, i.e., hydrogen-induced relative plasticity loss. It is usually measured by the rate of change in reduction of area before and after hydrogen embrittlement, or by the rate of change in elongation after fracture. However, hydrogen has a more significant effect on reduction of area than elongation after fracture. Different steels exhibit different sensitivities to hydrogen due to variations in their composition and microstructure.

[0009] In recent years, bainite has attracted worldwide attention from researchers due to its excellent strength-ductility balance, high wear resistance, and fatigue resistance, and has been applied to railway steel with good results. However, during service, it has been found that bainitic railway steel suffers from insufficient ductility and toughness, making it prone to brittle fracture and spalling failures. These phenomena are caused by hydrogen in the steel.

[0010] my country has the richest reserves of vanadium and titanium resources. Fully leveraging the technical characteristics of V and Ti microalloying to develop high-performance V / Ti microalloyed steel has significant economic and strategic importance.

[0011] Therefore, existing technologies still need improvement. Summary of the Invention

[0012] To address the aforementioned technical problems, this invention proposes a high-strength, high-toughness, low-hydrogen-embrittlement-sensitive bainitic railway steel and its production method.

[0013] To address the aforementioned technical problems, some embodiments of the present invention disclose a method for producing high-strength, high-toughness, low-hydrogen-embrittlement-susceptibility bainitic railway steel, comprising:

[0014] S1. After smelting and casting, the material is kept at a predetermined temperature for a predetermined time.

[0015] S2. After dephosphorization, universal rolling is performed, followed by cooling to room temperature.

[0016] S3. Perform bending and deformation treatment in all directions;

[0017] S4. Tempering treatment.

[0018] In some embodiments, in S1, the predetermined high-temperature heat preservation time is: 40-300 min at 1230-1280℃.

[0019] In some embodiments, in S2, the rolling compression ratio of universal rolling is not less than 11:1.

[0020] In some embodiments, in S2, the final rolling temperature of the universal rolling is 850-950°C.

[0021] In some embodiments, in S2, the cooling rate after rolling is 5-10°C / min.

[0022] In some embodiments, in S3, the bending deformation process in the up, down, left, and right directions is performed by bending deformation in the up, down, left, and right directions at a rate of 15-25 mm / mm.

[0023] In some embodiments, the composition is designed using a carbon content of 0.10-0.40% and a composite microalloy of 0.03% ≤ V + Ti + Al ≤ 1.20% by weight.

[0024] On the other hand, embodiments of the present invention also disclose a high-strength, high-toughness, low-hydrogen-embrittlement-sensitivity bainitic railway steel, which is produced by the aforementioned production method of high-strength, high-toughness, low-hydrogen-embrittlement-sensitivity bainitic railway steel.

[0025] In some embodiments, the chemical composition, by weight percentage, includes:

[0026] 0.10%-0.40% carbon, 0.03%≤V+Ti+Al≤1.20%, 4.0≤Si+Mn+Cr+Mo+Ni≤6.0.

[0027] In some embodiments, the tensile strength is 1280-1510 MPa, the elongation is 12%-17%, the reduction of area is 45%-60%, and the hydrogen embrittlement susceptibility is 12.5-14.0.

[0028] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0029] This invention provides a high-strength, high-toughness, low-hydrogen-embrittlement-sensitivity bainitic railway steel and its production method. By controlling the heat treatment and tempering process after casting and combining it with reasonable composition design, this invention reduces the hydrogen embrittlement sensitivity of railway steel while ensuring the strength and toughness of existing online heat-treated bainitic railway steel, thereby improving the operational safety of railway steel and meeting the requirements for heavy-haul railway steel or turnout railway steel. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 Metallographic and tensile specimen inspection locations for a production method of high-strength, tough, low-hydrogen-embrittlement-sensitive bainitic railway steel disclosed in some embodiments of the present invention.

[0032] Figure 2 Metallographic photographs of bainitic railway steel produced according to a method for producing high-strength, high-toughness, low-hydrogen-embrittlement-susceptibility bainitic railway steel as disclosed in some embodiments of the present invention. Detailed Implementation

[0033] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0034] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0035] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0036] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0037] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0038] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0039] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0040] This invention, through control of steel composition and specific adjustment of process parameters, fully considers the influence of alloying elements, steel microstructure, strength, hydrogen trapping, and external factors on hydrogen embrittlement sensitivity. By adding V element to bainitic steel, it achieves ultra-high precipitation strengthening effect and good comprehensive performance.

[0041] Among the various factors affecting hydrogen embrittlement sensitivity, the types and contents of alloying elements in steel can influence the solubility and diffusion coefficient of hydrogen, thus having a strong impact on the hydrogen embrittlement sensitivity of steel. Carbon, as the main alloying component of steel, has the greatest impact on its hydrogen embrittlement sensitivity. The hydrogen embrittlement sensitivity of steel increases with increasing carbon content. Furthermore, adding V, Ti, and Al to high-strength bainitic steel can significantly reduce its hydrogen embrittlement sensitivity.

[0042] Regarding the influence of steel microstructure on its hydrogen embrittlement susceptibility, numerous experimental studies have shown that austenitic microstructures are less sensitive to hydrogen, followed by pearlitic and bainitic microstructures, while martensitic microstructures are more sensitive to hydrogen.

[0043] Regarding the effect of steel strength on hydrogen embrittlement sensitivity, the degree of hydrogen embrittlement in steel increases significantly with increasing strength. For high-strength steel, due to the increase in steel strength, the hydrogen embrittlement sensitivity is greater, and the damage caused by hydrogen is also more severe.

[0044] Regarding the impact of hydrogen traps on hydrogen embrittlement sensitivity, engineering steels typically contain a certain amount of crystal defects. These defects bind hydrogen atoms and form hydrogen-rich regions, known as hydrogen traps. Hydrogen traps in materials include grain boundaries, dislocations, and second-phase particles. Hydrogen traps have a significant impact on hydrogen adsorption, diffusion, and distribution. Currently, there are two theories regarding the effect of hydrogen traps on hydrogen embrittlement sensitivity. One theory suggests that hydrogen traps significantly reduce the diffusion capacity of hydrogen atoms by binding them, thus significantly reducing hydrogen embrittlement sensitivity. However, the other theory argues that the localized hydrogen enrichment caused by hydrogen traps increases the hydrogen embrittlement sensitivity of steel.

[0045] Of the external factors influencing hydrogen embrittlement sensitivity, temperature has the most significant effect on hydrogen diffusion. Low temperatures can reduce hydrogen diffusion and decrease the occurrence of hydrogen embrittlement. Strain rate also has a significant impact on hydrogen embrittlement; the higher the strain rate, the less hydrogen atoms can diffuse in time and thus accumulate locally, making hydrogen embrittlement less likely to occur. As the strain rate decreases, the sensitivity to hydrogen embrittlement gradually increases and eventually tends to stabilize.

[0046] Composite titanium microalloying refers to the technical measure of adding other strong carbide-forming elements (such as vanadium and aluminum) to titanium microalloying to significantly improve the comprehensive performance of steel. Composite microalloying is an important development direction of microalloying technology. From a thermodynamic point of view, microalloyed nitrides are more stable than carbides. Through strict control of chemical composition and production process, the beneficial effects of different microalloying elements can be fully utilized. Like other microalloying elements, vanadium mainly affects the microstructure and properties of steel by forming carbonitrides. Vanadium has a high solid solubility in austenite, and the formation temperature of VN is slightly higher than the Ac3 temperature of low-carbon steel, resulting in a smaller hindering effect on the recrystallization process of deformed austenite. Therefore, the grain-refining effect of vanadium is relatively weak. The precipitation temperature of V(C,N) is low. After rapid cooling through the output roller, under typical coiling processes, V(C,N) will precipitate in large quantities in the transformed ferrite, resulting in significant precipitation strengthening. Sole vanadium alloying in microalloyed steels is relatively rare.

[0047] In titanium-vanadium composite microalloyed steel, titanium inhibits grain growth to improve toughness, while vanadium mainly acts as a precipitation strengthening agent. Combining titanium and vanadium, leveraging the individual roles of different microalloying elements, yields an optimal balance of strength and toughness.

[0048] The recrystallization controlled rolling process is ideal for V-Ti-N series steels. Because TiN precipitates at very high temperatures, it reduces the nitrogen content in austenite, inhibiting VN precipitation. Furthermore, VN is less prone to precipitation during low-temperature rolling. Therefore, V-Ti-N series steels exhibit high grain coarsening temperature, low grain coarsening rate, and low recrystallization temperature. Finally, the vanadium remaining in the austenite can form precipitates during ferrite transformation, thereby improving the strength of the finished steel.

[0049] Experiments revealed that, at a given homogenization temperature, V-Ti-N steel exhibited lower yield strength and dispersion strengthening compared to VN steel. The two main factors influencing dispersion strengthening were the volume fraction and average size of the precipitated particles. In V-Ti-N steel, V-Ti nitrides precipitate in the austenite at higher temperatures, limiting austenite grain growth during and after rolling. However, due to their large size, they did not significantly contribute to the strip's strength. Conversely, the presence of these particles reduced the content of vanadium and nitrogen dissolved in the steel before the γ→α phase transformation, thus decreasing the amount of VN precipitates in the ferrite and reducing dispersion strengthening. Dispersion strengthening decreased with increasing final cooling temperature; at the same final cooling temperature, V-Ti-N steel showed significantly lower dispersion strengthening than VN steel. While the addition of titanium to vanadium-containing steel reduced the yield strength, it slightly refined the grains and improved the steel's impact toughness. V-Ti-N strip has a finer grain size than VN steel; however, the number of fine particles in the ferrite matrix of V-Ti-N steel is less than that in VN steel.

[0050] The main role of vanadium in steel is:

[0051] (1) Refine the structure and grains of steel, increase the grain coarsening temperature, thereby reducing the overheating sensitivity and improving the strength and toughness of steel.

[0052] (2) When austenite is dissolved at high temperature, the hardenability of steel is increased; conversely, when it exists as carbides, the hardenability of steel is reduced.

[0053] (3) Increase the hardenability and tempering stability of quenched steel, refine the grains, and produce a secondary hardening effect.

[0054] (4) Vanadium carbide and vanadium nitride have high solid solubility products in austenite. Therefore, they are less likely to develop cracks due to precipitation at high temperatures, and the billet is less prone to cracking during solidification.

[0055] (5) Vanadium carbonitride has a low precipitation temperature and is dissolved in austenite, resulting in low drag force for grain boundary migration. This is beneficial for austenite recrystallization, making controlled recrystallization rolling easier and resulting in a uniform microstructure along the steel cross-section. Uniform recrystallized grains can be obtained over a wide temperature range, and the final rolling temperature has little effect on mechanical properties. Compared to other microalloyed steels and alloy steels, vanadium-containing steel has lower rolling resistance, comparable to carbon-manganese steel.

[0056] (6) Vanadium precipitates in ferrite or martensite, resulting in precipitation strengthening. The precipitation strengthening increment in ferrite is generally 50 MPa to 100 MPa. Increasing the nitrogen content in steel can promote vanadium precipitation and achieve a greater precipitation strengthening effect. This is a good technology in the production of high-strength hot-rolled ribbed steel bars, achieving the effect of saving vanadium usage and increasing precipitation strengthening.

[0057] (7) Vanadium has a strong affinity for nitrogen and can form vanadium nitride, which is beneficial to reduce the strain aging of steel. This characteristic is very important for steel bars that have undergone cold deformation during service.

[0058] (8) Adding vanadium to martensitic steel can increase the steel’s resistance to tempering softening, allowing the steel to maintain the martensitic lath morphology during tempering, or precipitate vanadium carbide during tempering, resulting in a secondary hardening effect.

[0059] Adding vanadium to steel serves two purposes: deoxidation and denitrogenation, and improvement of steel properties, ultimately reducing production costs or the amount of steel used. Currently, vanadium is primarily used as an additive in steel production, for manufacturing high-strength low-alloy steel, high-speed steel, tool steel, stainless steel, spring steel, and bearing steel. Vanadium steel is characterized by high strength, good toughness, wear resistance, and corrosion resistance. It is widely used in machinery manufacturing, automotive, aerospace, railway transportation, and bridge construction industries.

[0060] Furthermore, the earliest addition of Al to steel was to accelerate the bainitic transformation. Al is insoluble in cementite, which reduces the activity coefficient of carbon in ferrite, increases its solid solubility, and inhibits carbide precipitation. Al can raise the onset temperature of cementite, increasing the transformation driving force through its influence on the magnetic and non-magnetic components, thereby accelerating the bainitic transformation. Simultaneously, Al can significantly increase the Ms temperature. Adding Al to carbide-free bainitic steel shifts the curve to the right towards the high-temperature region. Bainitic steel with added Al exhibits greater undercooling, meaning that adding Al increases the bainite nucleation driving force, thereby increasing the bainite nucleation density and refining the bainite laths. Appropriate addition of Al can significantly reduce the hydrogen embrittlement susceptibility of bainitic steel.

[0061] Current research on bainitic railway steel mainly focuses on the effects of a single element, such as V, Ti, or Al. These three elements exhibit different characteristics in terms of precipitation, microstructure, and service life. Based on this, this invention employs a composite microalloying method using V, Ti, and Al. It was found that the three elements have a synergistic effect, maximizing the strength and toughness of bainitic railway steel while reducing hydrogen embrittlement sensitivity. Significant interaction occurs between hydrogen and the precipitated phases; the precipitated phases can capture hydrogen at a mass fraction of 5 ppm, which is sufficient to suppress delayed fracture in high-strength steel.

[0062] Some embodiments of the present invention disclose a method for producing high-strength, high-toughness, low-hydrogen-embrittlement-susceptibility bainitic railway steel, comprising:

[0063] S1. After smelting and casting, the temperature is kept at a predetermined temperature for a predetermined time. The predetermined temperature and time for high-temperature holding is 40-300 minutes at 1230-1280℃.

[0064] S2. After dephosphorization, universal rolling is performed. After rolling, the temperature is cooled to room temperature. The rolling compression ratio of universal rolling is not less than 11:1. The final rolling temperature of universal rolling is 850-950℃. The cooling rate after rolling is 5-10℃ / min.

[0065] S3. Perform bending deformation treatment in all directions at a rate of 15-25mm / mm.

[0066] S4. Tempering treatment.

[0067] In the above embodiments, the composition design is based on a carbon content of 0.10-0.40% and a composite microalloy of 0.03%≤V+Ti+Al≤1.20% by weight during smelting and casting.

[0068] The high-strength, high-toughness, low-hydrogen-embrittlement-susceptibility bainitic railway steel prepared by the above method has the following chemical composition by weight percentage: 0.10%-0.40% carbon, 0.03%≤V+Ti+Al≤1.20%, 4.0≤Si+Mn+Cr+Mo+Ni≤6.0. Testing shows a tensile strength of 1280-1510 MPa, elongation of 12%-17%, reduction of area of ​​45%-60%, and a hydrogen embrittlement sensitivity of 12.5-14.0.

[0069] The above embodiments of the present invention, by employing composite microalloying of V, Ti and Al, and in conjunction with corresponding process parameters, can reduce the hydrogen embrittlement sensitivity of railway steel while ensuring the strength and toughness of existing online heat-treated bainitic railway steel, thereby improving the operational safety of railway steel and meeting the requirements for railway steel used in heavy-haul railways or turnout railways.

[0070] Some embodiments of this invention also disclose a low-hydrogen-embrittlement-sensitive bainitic railway steel and its production method, relating to a V, Ti, Al composite microalloyed low-hydrogen-embrittlement-sensitive bainitic railway steel and its production method. The steel is designed with a carbon content of 0.10-0.40% and a composite microalloying composition of 0.03%≤V+Ti+Al≤1.20%. After smelting and casting, the steel billet is held at a high temperature of 1230-1280℃ for 40-300 min for an extended period. After descaling, the billet is subjected to universal rolling with a compression ratio ≥11:1, and a final rolling temperature between 850-950℃. After rolling, it is cooled to room temperature at a cooling rate of 5-10℃ / min, and then bent at a bending deformation of approximately 15-25mm / 1600mm. Finally, it is tempered at 200-400℃ for 5-12 hours. The bainitic railway steel produced using this method has a tensile strength ≥1280MPa, an elongation ≥12%, and a hydrogen embrittlement index (EH) <15%, exhibiting low hydrogen embrittlement sensitivity. It is particularly suitable for railway steel used in heavy-haul railways or turnout railways.

[0071] This invention compares the process and performance of the low-hydrogen-embrittlement-sensitive bainitic railway steel and its production method using Examples 1-5 and Comparative Examples 1 and 2. Based on the Si-Mn-Cr bainitic rail composition system, the steel billet is designed using V, Ti, and Al microalloying. After smelting and casting, the billet is cooled to room temperature. Then, it is held at a high temperature of 1230-1280℃ for 40-300 minutes. After descaling, the billet is rolled using universal rolling with a compression ratio ≥11:1, and the final rolling temperature is between 850-950℃. After rolling, it is cooled to room temperature at a cooling rate of 5-10℃ / min, and then bent at a bending deformation of approximately 15-25mm / 1600mm. Finally, it is tempered at 200-400℃ for 5-12 hours. The bainitic railway steel produced using this method has a tensile strength ≥1280MPa, an elongation ≥12%, and a hydrogen embrittlement index (EH) <15%, exhibiting low hydrogen embrittlement sensitivity. Its chemical composition is shown in Table 1 and Table 5, and the heating process, rolling process relaxation time, and heat treatment process conditions are shown in Table 2.

[0072] Table 1 Chemical composition and gas content of railway steel in the examples and comparative examples

[0073]

[0074] Table 5 Chemical composition of railway steel in the examples and comparative examples

[0075]

[0076] Table 2. Heating, rolling, and heat treatment processes for the examples and comparative examples.

[0077]

[0078] The examples and comparative examples were prepared in accordance with the requirements of TB / T 2344 "Technical Conditions for Ordering 43kg / m~75kg / m Rails", as per the appendix. Figure 1 Tensile specimens are machined and inspected at the sampling locations. Simultaneously, according to the attached... Figure 1 As shown, metallographic microstructure was examined at the locations indicated on the metallographic specimens. Metallographic photographs are attached. Figure 2 As shown in the figure. The tensile and metallographic data statistics are shown in Table 3.

[0079] Table 3 Tensile properties of railway steel in examples and comparative examples

[0080]

[0081] The electrolytic hydrogen charging experiment employed a single electrolytic cell structure. A 1000 ml beaker served as the electrolytic cell, with an plexiglass frame inside. Six graphite electrodes were symmetrically placed near the beaker wall. The sample was placed in the center of the beaker and connected to the negative terminal of a digital display DC regulated power supply, serving as the cathode. The graphite electrodes were connected to the positive terminal of the power supply, serving as the anode. The electrolyte solution was a 0.2 mol / L NaOH aqueous solution with 2 mL of saturated Na₂S solution added as a poisoning agent. The hydrogen charging current was 15 mA, and the charging time was 72 h. Nickel plating was performed immediately after hydrogen charging to prevent hydrogen atom escape.

[0082] The slow tensile test was conducted on a testing machine, and the effect of hydrogen on the experimental results was studied using a tensile rate of 0.01 mm / min.

[0083] Hydrogen charging significantly reduces the plasticity of materials, which is generally characterized by the embrittlement index (EH). The expression for the embrittlement index is:

[0084]

[0085] Among them, Z0, Z H These represent the reduction of area after tensile testing of the uncharged and hydrogen-charged samples, respectively. Based on general experience, the embrittlement index E... H When the concentration is less than 15%, it indicates that the material has a low sensitivity to hydrogen embrittlement, as shown in Table 4.

[0086] Table 4 Hydrogen embrittlement sensitivity of railway steel in examples and comparative cases

[0087]

[0088] It can be seen that the low-hydrogen-embrittlement-sensitive bainitic railway steel and its production method disclosed in the embodiments of the present invention exhibit the best performance in terms of both mechanical properties and hydrogen embrittlement sensitivity when, by weight percentage, the chemical composition is 0.35% carbon, 0.15% vanadium, 0.12% titanium, 0.63% aluminum (V+Ti+Al=0.9%), Si+Mn+Cr+Mo+Ni=5.5%, the heating soaking temperature is 1270℃, the heating time is 240min, the rolling compression ratio is 16:1, the final cooling temperature is 920℃, the cooling rate is 9℃ / s, the cold deformation within 1600mm is 22mm, the tempering temperature is 350℃, and the holding time is 40h.

[0089] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0090] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A method for producing a high-toughness low-hydrogen embrittlement sensitivity bainite railway steel, characterized by, The application relates to a method for producing a tough low-hydrogen embrittlement sensitive bainite railway steel. S1, after smelting and casting, the steel is kept at a predetermined temperature for a predetermined time; S2, after dephosphorization, the steel is subjected to universal rolling, and then cooled to room temperature; S3, the steel is subjected to up-down and left-right bending deformation treatment; S4, the steel is subjected to tempering treatment; In S1, the predetermined temperature keeping for a predetermined time is high-temperature keeping at 1230-1280 DEG C for 40-300 min; In S2, the rolling compression ratio of the universal rolling is not less than 11:1, the final rolling temperature of the universal rolling is 850-950 DEG C, and the cooling rate after rolling is 5-10 DEG C / min; In S3, the up-down and left-right bending deformation treatment is carried out by 15-25 mm / mm; The component design is carried out by using 0.10-0.40% carbon content and 0.03%<=V+Ti+Al<=1.20% composite micro-alloy.

2. A high tough and low hydrogen embrittlement sensitivity bainite railway steel, characterized in that, The tough low-hydrogen embrittlement sensitive bainite railway steel is produced by the method.

3. The high tough and low hydrogen embrittlement sensitivity bainite railway steel according to claim 2, characterized in that, The chemical components include, in percentage by weight: 0.10%-0.40% carbon, 0.03%<=V+Ti+Al<=1.20%, and 4.0<=Si+Mn+Cr+Mo+Ni<=6.

0.

4. The high tough and low hydrogen embrittlement sensitivity bainite railway steel according to claim 2, characterized in that, The tensile strength is 1280-1510 MPa, the elongation is 12%-17%, the section shrinkage is 45%-60%, and the hydrogen embrittlement sensitivity is 12.5-14.0.

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