600MPa-grade high-wear-resistance corrosion-resistant steel for railway vehicle and manufacturing method thereof

Abstract

The corrosion-resistant steel comprises the following chemical components: 0.068 to 0.088 percent of C, 0.58 to 0.75 percent of Si, 1.03 to 1.23 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.006 percent of S, 0.86 to 1.07 percent of Cr, 0.14 to 0.29 percent of Cu, 0.074 to 0.089 percent of Mo, 0.054 to 0.074 percent of Al, 0.0087 to 0.0107 percent of RE, 0.021 to 0.032 percent of V, 0.033 to 0.048 percent of Ti, 0.084 to 0.104 percent of W, 0.038 to 0.057 percent of Sn, 0.0028 to 0.0058 percent of B, more than 0.16 percent of Mo and less than 0.20 percent of W, more than 9.6 percent of Si and less than 11.6 percent of Al. The manufacturing method comprises the steps of pre-desulfurization, converter steelmaking, external refining, slab continuous casting heating, hot continuous rolling, laminar cooling and coiling. The thickness of the steel plate is 4.5-9.5 mm, ReL is larger than 600 MPa, Rm is larger than 750 MPa, A is larger than 25%, KV2 at-40 DEG C is larger than or equal to 97 J, and the acid environment corrosion rate is smaller than 0.72 g / m < 2 >. H. The high-strength steel has high strength, high wear resistance and corrosion resistance, greatly prolongs the service life of the rail wagon, and has obvious advantages in the field of high-strength steel for the rail wagon.

Description

Technical Field

[0001] The present invention belongs to the field of corrosion-resistant steel for railway vehicles, and relates to a 600 MPa grade high-wear-resistant corrosion-resistant steel for railway vehicles and a manufacturing method thereof. Background Art

[0002] With the rapid development of China's railway transportation industry, heavy haul has become an important direction for the development of China's railway vehicles. In order to meet the development needs of heavy haul and lightweight of railway freight cars, higher performance requirements are also put forward for the steel used in railway freight cars. At present, the steel used for manufacturing railway freight cars is mainly weathering steel of 345 MPa and 450 MPa grades. In order to meet the development needs of lightweight steel for Chinese railway vehicles, it is urgent to develop a weathering steel for railway freight cars with higher strength. In addition, for railway coal-carrying freight cars, during the coal loading and unloading process, coal solid particles continuously cause wear and corrosion to the car body, and a large amount of SO4 2- , Cl - acidic ions are contained in the coal water acidic medium formed inside the car body, which is likely to cause acidic corrosion to the inside of the car body. Therefore, in order to solve the above-mentioned many deficiencies of the steel used in current railway vehicles, it is urgent to develop a high-strength, high-wear-resistant and corrosion-resistant steel for railway vehicles to meet the technical requirements of lightweight, high-wear resistance and corrosion resistance of the steel used in railway vehicles.

[0003] Before the present invention, the patents related to the present invention mainly include the following several items:

[0004] (1) "Coal water wear and corrosion resistant steel plate for railway coal-carrying vehicles and its manufacturing method" with the publication number of CN 107653423 B, the composition is C: 0.01 - 0.15%, Si: 0.10 - 0.50%, Mn: 0.20 - 1.0%, P≤0.020%, S≤0.010%, Cu: 0.20 - 0.60%, Ni: 0.50 - 1.5%, Cr: 0.20 - 2.0%, Sb: 0.030 - 0.10%, Mo: 0 - 0.25%, Nb: 0 - 0.05%, V: 0 - 0.05%, Ti: 0 - 0.10%, B: 0 - 0.005%, and the rest is Fe and impurities. In this invention, the contents of noble metal elements such as Cu, Ni, Mo, Cr, and Nb are relatively high. At the same time, it is necessary to control that C, Cr, and Ni need to meet 1.6%≤12C + Cr / Ni≤2.8%, and this invention does not elaborate on the corrosion resistance of the invented steel.

[0005] (2) The invention patent of "A weathering steel for railway vehicles and its manufacturing method" with the publication number of CN 117265382 A has a composition of C: 0.04 - 0.09%, Si: 0.12 - 0.24%, Mn: 0.6 - 0.9%, P ≤ 0.015%, S ≤ 0.006%, Al: 0.02 - 0.04%, Cu: 0.15 - 0.35%, Cr: 0.60 - 0.95%, Ni: 0.05 - 0.12%, Mo: 0.03 - 0.12%, Ti: 0.01 - 0.02%, Nb: 0.01 - 0.02%, N ≤ 0.006%, 5 ≤ Cr / Mo ≤ 25, and the balance is Fe and impurity elements. The content of precious metals Cu, Ni, and Mo in this patent is relatively high, resulting in a high cost. Its weathering level is equivalent to that of traditional weathering steels, that is, the relative corrosion rate ≤ 55%, and the steel of this invention does not consider the impact of coal on the wear of steel plates during the loading and unloading process.

[0006] (3) The "A low-alloy wear-resistant and corrosion-resistant steel and its manufacturing method" with the publication number of CN 101423916A has a composition of C: 0.10 - 0.16%, Si: 1.0 - 1.6%, Mn: 0.8 - 1.6%, Cr: 1.0 - 1.6%, Mo: 0.3 - 0.4%, Ni: 0.30 - 0.40%, Al: 0.6 - 1.0%, rare earth + Nb ≤ 0.1%, and the balance is Fe and impurities. This patent obtains a low-alloy wear-resistant and corrosion-resistant steel suitable for use in marine sediment wear and corrosion environments by forming a Mn - Si - Cr - Mo - Al series carbide-free bainitic steel. It mainly adopts a composition design with high Si and high Al to inhibit the formation of carbides, and adds elements such as Cr, Ni, and Mo to improve corrosion resistance. However, it pays more attention to wear resistance and atmospheric corrosion resistance, which is different from the service environment of coal-water wear and corrosion.

[0007] (4) The invention patent of "A 450MPa grade wear-resistant and corrosion-resistant steel and its manufacturing method" with the publication number of CN 114574782 A has a composition of C: 0.061 - 0.082%, Si: 0.51 - 0.79%, Mn: 0.45 - 0.89%, P ≤ 0.018%, S ≤ 0.006%, Cr: 0.81 - 1.31%, Cu: 0.14 - 0.24%, Sb: 0.041 - 0.075%, W: 0.15 - 0.35%, Ti: 0.051 - 0.072%, Als: 0.015 - 0.045%, N ≤ 0.004%, and the balance is Fe and inevitable impurities. This invention improves the anti-wear performance of the material through the synergistic effect of Si, Mn, Cr, and W elements and the formation of a certain amount of FeMnCrC, TiC, and WC. However, it focuses on the wear resistance and corrosion resistance of containers, which is different from the service environment of weather resistance and wear-resistant and corrosion-resistant of railway freight cars. Summary of the Invention

[0008] The object of the present invention is to provide a corrosion-resistant steel for 600 MPa grade high-wear-resistant railway vehicles and its manufacturing method. By strictly controlling the chemical composition in the steel and the rolling production process, the produced steel plate has high strength, corrosion resistance and high wear resistance at the same time, can greatly extend the service life of railway freight cars, and has obvious competitive advantages in the application field of high-strength steel for railway freight cars.

[0009] The present invention provides a corrosion-resistant steel for 600 MPa grade high-wear-resistant railway vehicles. The chemical composition by weight percentage is as follows: C: 0.068% - 0.088%, Si: 0.58% - 0.75%, Mn: 1.03% - 1.23%, P: ≤0.015%, S: ≤0.006%, Cr: 0.86% - 1.07%, Cu: 0.14% - 0.29%, Mo: 0.074% - 0.089%, Al: 0.054% - 0.074%, RE: 0.0087% - 0.0107%, V: 0.021% - 0.032%, Ti: 0.033% - 0.048%, W: 0.084% - 0.104%, Sn: 0.038% - 0.057%, B: 0.0028% - 0.0058%, wherein 0.16% < Mo + W < 0.20%, 9.6 < Si / Al < 11.6, and the balance is Fe and unavoidable impurities.

[0010] The reason for selecting the above alloy element types and their contents in the present invention is as follows:

[0011] C: One of the effective elements for increasing the strength in steel. When dissolved in steel, it ensures the strength of the material in the form of solid solution strengthening. It can combine with other alloy elements in the steel to exist in the form of carbides, and further improve the strength of the material through precipitation strengthening and grain refinement strengthening during rolling and cooling. However, a relatively high C content will not only deteriorate the plasticity of the material, but also reduce the corrosion resistance of the material due to the formation of more pearlite structures. In the present invention, the content of C is limited to 0.068% - 0.088%.

[0012] Si: The deoxidizing element in the steelmaking process, which is a key element to improve the strength, hardness and corrosion resistance of the steel plate. The specific functions of Si in this invention are as follows: (1) Deoxidization, reducing the O content in the molten steel, thereby increasing the solid solubility rate of rare earth elements in the steel; (2) As a solid solution element to improve the strength of the material; (3) Interacting with C in the steel can form a kind of SiC hard particles, which can increase the wear resistance of the material. When added in combination with Cr, it can promote the formation of stable hydroxy oxide α-FeOOH in the inner rust layer and the enrichment of corrosion-resistant elements, thus improving the corrosion resistance of the material. The content of Si in this invention is 0.58% - 0.75%. Due to the relatively high content of Si in this invention, "red scale" Fe2SiO4 that is difficult to remove is likely to be generated on the surface of the steel plate. Therefore, in this invention, Si and Al are added in combination, which can not only enhance the antioxidant ability of the matrix, but also make the thickness of Fe2SiO4 thinner, the descaling is easy to fall off, and significantly improve the surface quality of the steel plate. In this invention, it is defined that 9.6 < Si / Al < 11.6.

[0013] Mn: One of the main strengthening elements in the steel, which can improve the strength of the steel plate through solid solution strengthening. At the same time, Mn in this invention, as an important austenitizing stabilizing element, can expand the austenite phase region, has the effect of improving the stability of retained austenite in the steel, and can improve the plasticity of the material. Therefore, to ensure the strength and plasticity of the material, the content of Mn in this invention is set to be 1.03% - 1.23%.

[0014] P: When the content of this element is relatively high, it is easy to have an adverse impact on the mechanical properties of the steel plate, especially the impact toughness and formability of the steel plate. In theory, the lower the better, but considering the operability of steelmaking and the steelmaking cost, P in the steel of this invention is controlled below 0.015%.

[0015] S: S is a harmful impurity element, which is easy to form segregation, inclusions and other defects, and when the content is too high, it will cause cracking of the steel during hot working. Therefore, the content of S in this invention should be controlled below 0.006%.

[0016] Cr: As an active cathode in the steel, it promotes the passivation of the steel as an anode and promotes the formation of an oxide rust layer with high density and strong adhesion on the surface of the steel. When acting in combination with Si and Cu elements, it can refine the stable phase α-FeOOH in the rust layer and effectively improve the cation selective permeability of the rust layer to the corrosive medium. In addition, the addition of Cr is easy to combine with Fe in the steel to form compounds such as CrFe3C and CrFe7C3. When these compounds are distributed at the grain boundaries, they can strengthen the grain boundaries, thereby improving the strength and impact toughness of the material. Therefore, the content of Cr in this invention should be controlled at 0.86% - 1.07%.

[0017] Cu: As an effective element to improve the strength and corrosion resistance of materials. Cu can play a role in solid solution strengthening in steel. When co-added with rare earth element Ce, by controlling the rolling temperature, Cu4Ce precipitates can be formed, achieving the effect of secondary precipitation strengthening. The addition of Cu can promote the formation and enrichment of protective CuO in the inner rust layer, improving the corrosion resistance of materials. However, when the Cu content is too high, it will not only increase the alloy cost but also increase the generation of "copper brittleness" defects. Therefore, in the present invention, the Cu content should be controlled within 0.14% - 0.29%.

[0018] Mo: Adding Mo can form a hard Mo2O3 oxide film on the substrate surface, increasing the wear resistance of the substrate surface. At the same time, it can form stable and insoluble alloy cementite (Fe,MO)3C and carbide MoC with C in steel, significantly improving the wear resistance of materials; Mo can partially replace Fe to form molybdenum iron hydroxy oxide, and finally a dense and stable protective phase α-(Fe,Mo)OOH can be formed in the atmosphere and enriched in the inner rust layer, thereby improving the atmospheric corrosion resistance of materials. In addition, when Mo is added in combination with Ti, through the control of the rolling process, nano-sized (Ti,Mo)C is easily precipitated between phases. The size of this carbide is finer than that of TiC formed by adding Ti alone, and the precipitation strengthening effect is more obvious. However, a high content of Mo will increase the production cost. Therefore, in the present invention, the Mo content should be controlled within 0.074% - 0.089%.

[0019] Al: An important deoxidizing element, which can avoid the generation of excessive rare earth oxides and at the same time improve the surface quality problem of "red scale" caused by Si element. As an important nucleating agent, the addition of Al can increase the number of crystal nuclei in steel to achieve the effect of refining grains, improving the strength and toughness of materials; Al can shift the corrosion potential of steel to the positive, and mainly exists as Al2FeO4 in spinel-type oxides, promoting the transformation of spinel to a finer and denser structure, refining the grains of the inner rust layer, and increasing the compactness of the inner rust layer; accelerating the formation of the protective phase α-FeOOH in the inner rust layer. However, excessive Al is not only not conducive to casting billets during continuous casting but also increases the number of inclusions in steel. Therefore, in the present invention, its range is limited to 0.054% - 0.074%.

[0020] RE: The main functions of RE in the steel of the present invention are: (1) Modifying inclusions, reducing the number of inclusions and the tendency of pitting corrosion. Rare earth ions (La 3+ 、Ce 3+(1) As a cathodic inhibitor, it often precipitates in the cathodic area, can inhibit the electrochemical reaction occurring at the cathode, and effectively slow down the further progress of corrosion; (2) In the present invention, due to the presence of easily segregating element Sn, the addition of rare earth elements can effectively improve the segregation problem caused by Sn, and thus significantly improve the plasticity and toughness of the material; (3) When added together with Cu, it can not only disperse Cu in the steel and inhibit the generation of "copper brittleness", but also act synergistically with Cu. By controlling the rolling temperature, nano-scale Cu4Ce precipitation phases can be formed, and the strength of the material can be further improved through precipitation strengthening; (4) The addition of rare earth elements helps to inhibit the decomposition of retained austenite and the precipitation of carbides, and can significantly improve the plasticity of the steel plate. The present invention limits its range to 0.0087% - 0.0107%.

[0021] V: This element reacts with C and N in the steel to form insoluble V(C,N). These compounds precipitate during and after the γ / α phase transformation. By controlling the rolling and coiling temperatures, the purpose of refining the precipitation phases can be achieved, and the precipitation strengthening effect can be used to improve the strength of the steel plate. In addition, V combines with N in the steel, fixing the dissolved N in the steel, which helps to improve the low-temperature impact toughness of the steel plate. However, excessive V also increases the manufacturing cost and reduces the welding performance of the steel plate. Therefore, the present invention limits the range of V to 0.021% - 0.032%.

[0022] Ti: One of the alloying elements that play a strengthening role. Ti in the steel mainly exists in the forms of TiC and Ti(C,N). The Ti(C,N) formed during the heating of the continuous casting billet can effectively inhibit the growth of austenite grains, playing a fine-grain strengthening role. During the rolling and cooling processes, nano-sized (Ti,Mo)C precipitates between phases to play a precipitation strengthening role. However, when the Ti content is too high, it will deteriorate the plasticity and toughness of the material. The present invention limits its range to 0.033% - 0.048%.

[0023] B: The addition of this element can significantly improve the hardenability of the steel plate, promote the formation of bainite, a low-temperature phase transformation product, and improve the strength of the steel plate through transformation strengthening. In addition, B dissolved in the matrix reacts with other elements to form stable borides. This compound not only has extremely high hardness and can significantly improve the wear resistance of the steel plate, but also can segregate at the grain boundaries of the steel, hindering grain growth, achieving the purpose of fine-grain strengthening, and reducing the amount of strengthening precious metals to a certain extent. The present invention limits the range of B to 0.0028% - 0.0058%.

[0024] W: Due to its strong binding force with C in steel, W dissolved in steel can form the hard phase (Fe, W)7C3 through substitution, which can improve the wear resistance of the steel plate. Especially when co-added with Mo, the dissolved W can form a stable and hardly soluble nanoscale hard phase (Fe, W, Mo)7C3 with Mo in the steel, and the wear resistance effect produced by this hard phase on the steel plate is more significant. However, when the W content is too high, it will not only increase the cost but also deteriorate the impact performance of the steel plate. Therefore, the scope of the present invention is limited to 0.084% - 0.104%. At the same time, to avoid the precipitation and agglomeration of the hard phase (Fe, W, Mo)7C3 and control its precipitation size, in the present invention, it is limited that 0.16% < Mo + W < 0.20%.

[0025] Sn: The addition of Sn is beneficial to form a dense and well-adhesive amorphous oxide (hydroxy oxide) protective layer on the surface of the steel, which can prevent the infiltration of SO4 2- , Cl - in the acidic medium, and the acid corrosion resistance effect is obvious. However, Sn belongs to the elements prone to segregation. When the Sn content is on the high side, it is easy to segregate at the grain boundaries, which will not only reduce the plasticity and toughness of the material but also deteriorate the corrosion resistance of the material. Therefore, the Sn content in the present invention should be controlled within 0.038% - 0.057%.

[0026] The structure of the steel of the present invention is composed of ferrite + bainite + pearlite, in which the proportion of the ferrite phase is 28% - 33%, and the proportion of the bainite phase is 51% - 55%. Fine strengthening phases (Ti, Mo)C and hard phases (Fe, W, Mo)7C3 are precipitated in the structure. Among them, the area proportion of (Ti, Mo)C with a size range of 10 - 40 nm reaches 63.1% - 65.8%, and the area proportion of (Fe, W, Mo)7C3 with a size range of 30 - 60 nm reaches 61.2% - 64.3%. The precipitation phases of this level are beneficial to improving the strength and wear resistance of the invented steel.

[0027] The present invention also provides a manufacturing method for a corrosion-resistant steel for 600 MPa grade high-wear-resistant railway vehicles. This method manufactures a high-corrosion-resistant and wear-resistant steel containing the above chemical components through hot metal pre-desulfurization, converter steelmaking, secondary refining (LF furnace + RH furnace refining), slab continuous casting, slab heating, hot strip rolling, laminar flow cooling, and coiling. Among them:

[0028] Slab heating: To ensure the full solution of alloying elements such as Si, P, Sn, and W, and considering that a relatively high content of Si is added to the steel, in order to avoid the formation of hard-to-remove Fe2SiO4 / FeO "red scale" during the heating process of the slab, the tapping temperature of the slab in this invention is controlled at 1198 - 1231 °C, the atmosphere in the heating furnace is a reducing atmosphere, and the air-fuel ratio is controlled at 1.3 - 1.5, which helps to reduce the liquefaction of Fe2SiO4, make the scale thinner, and facilitate descaling; when the heating temperature is below 1156 °C, slow heating is required, and the heating rate is controlled at 7.2 - 9.2 °C / min to ensure uniform temperature inside and outside the billet and full solution of the alloy; when it is above 1156 °C, rapid heating is required, and the heating rate is controlled at 19.2 - 20.6 °C / min, and the slab stays in the furnace for 161 - 181 min to reduce the adhesion of liquid Fe2SiO4 to the steel plate and achieve an easy descaling effect.

[0029] Hot tandem rolling: Two-stage controlled rolling is adopted in rough rolling and finish rolling. In rough rolling, a high-temperature and large reduction method is used. The rough rolling exit temperature is 1141 - 1161 °C, and the cumulative reduction rate in the rough rolling stage is 76.2% - 79.2%. In this stage, the purpose of refining grains and breaking the oxide scale on the steel plate surface is achieved by increasing the reduction amount. The finish rolling starting temperature is 1059 - 1083 °C. To reduce the formation of viscous scale Fe2SiO4 and at the same time ensure the full precipitation of Cu4Ce and (Ti, Mo)C strengthening phases without excessive growth of the precipitation phases, the finish rolling ending temperature is controlled at 908 - 928 °C.

[0030] Laminar cooling and coiling: After finish rolling, two-stage cooling is adopted for laminar cooling. In the first stage, it is cooled at a cooling rate of 10 - 17 °C / s to 721 - 741 °C (this temperature range belongs to the ferrite transformation region), and air-cooled for 21 - 25 s (to ensure the full formation of ferrite and hard phases). In this stage, soft-phase ferrite tissue can be formed and the precipitation of hard phases (Fe, W)7C3, (Fe, W, Mo)7C3, and Cu3(PO4)2 can be ensured, thereby obtaining the required plasticity and wear resistance of the steel plate; then, it is cooled in the second stage at a cooling rate of 35 - 40 °C / s and coiled after cooling to 597 - 617 °C. In this stage, a sufficient amount of hard-phase bainite can be formed by rapid cooling, and the formation of pearlite in the matrix can be reduced to ensure the strength of the steel plate and improve the corrosion resistance of the steel. In addition, this coiling temperature has a good control effect on refining grains and inhibiting the coarsening of precipitation phase (Ti, Mo)C.

[0031] Furthermore, the addition amount of the hot metal pre-desulfurization desulfurizer ≥ 3.9 kg / t to ensure that the desulfurized S ≤ 0.017%; the converter adopts a top-bottom combined blowing process, the converter tapping temperature ≥ 1659 °C, and ferro-aluminum alloy is added during tapping to deoxidize the molten steel.

[0032] Furthermore, secondary refining includes LF refining and RH refining. LF refining mainly focuses on deoxidation and desulfurization, and temperature increase and minor composition adjustment are carried out at this stage. All compositions are controlled within the target range as much as possible before the LF refining ladle is tapped, and S in the molten steel is controlled to be ≤0.007%. During the RH refining of the molten steel, the vacuum degree in the vacuum chamber is maintained at less than 3.3 kPa. Rare earth alloys are added to the molten steel in the RH refining furnace. After adding the rare earth alloys, RH pure circulation is carried out on the molten steel for 2.2 - 4.4 min. After the RH refining furnace breaks the vacuum, weak blowing is carried out on the molten steel for 28 - 31 min to ensure that inclusions float up sufficiently.

[0033] Furthermore, the rare earth alloy is La, Ce alloy.

[0034] Preferably, the flow rate of the weak blowing argon is 74 - 86 NL / min, and the pressure is 0.25 - 0.36 MPa.

[0035] Furthermore, during slab continuous casting, a protective slag is used throughout the process to protect the molten steel and prevent it from being exposed to the air. The thickness specification of the continuous casting slab is 210 - 230 mm. Since the rare earth elements (La, Ce) in the invented steel have a strong affinity and are prone to forming a large amount of rare earth inclusions with O and S elements in the steel, which affects the fluidity of the molten steel, the casting speed is controlled at 1.46 - 1.61 m / min during casting. To reduce the "segregation" problem of the continuous casting slab caused by P and Sn in the steel, the superheat is controlled between 18 - 25 °C during casting, and at the same time, electromagnetic stirring technology is adopted, with the electromagnetic stirring current being 351 - 357 A and the frequency being 4.4 - 6.4 HZ.

[0036] The steel for railway freight cars with a thickness of 4.5 - 9.5 mm produced by applying the above chemical compositions and processes has high strength, high wear resistance, and corrosion resistance. Through precise control of the composition and tissue ratio, the yield strength ReL of the invented steel is >600 MPa, the tensile strength Rm is >750 MPa, the elongation after fracture A is >25%, and the cold bending performance is qualified.

[0037] KV2 at -40 °C ≥97 J, the wear rate relative to the currently mainstream used steel Q450NQR1 is 38.4% - 40.7%, the corrosion rate of the steel plate in the simulated acidic medium corrosion environment of a coal - transporting freight car is <0.72 g / m 2 ·h, and the corrosion rate relative to Q345B in the industrial atmospheric environment is <48.6%. While having high strength and corrosion resistance, the invented steel also has high wear resistance, meeting the requirements of railway coal - transporting freight cars for high strength, high wear resistance, and corrosion resistance of the steel plate. Specific embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. The following embodiments are only some of the optimal implementation solutions of the present invention, and do not impose any restrictions on the scope of the foregoing invention and technical means. Among them, the composition of the steel in the embodiments of the present invention is shown in Table 1, the main process parameters for the smelting and continuous casting of the steel in the embodiments of the present invention are shown in Table 2, the heating process parameters of the steel in the embodiments of the present invention are shown in Table 3, the rolling and coiling process parameters of the steel in the embodiments of the present invention are shown in Table 4, the various properties of the steel in the embodiments of the present invention are shown in Table 5, the microscopic structure of the steel in the embodiments of the present invention is shown in Table 6, and the results of the cyclic immersion corrosion test of the steel in the embodiments of the present invention are shown in Table 7.

[0040] Table 1 Composition of the steel in the embodiments of the present invention (wt%)

[0041]

[0042]

[0043] Table 2 Main process parameters for the smelting and continuous casting of the steel in the embodiments of the present invention

[0044]

[0045] Table 3 Heating process of the steel in the embodiments of the present invention

[0046]

[0047] Table 4 Main process parameters for the rolling and cooling of the steel in the embodiments of the present invention

[0048]

[0049] It can be seen from Table 5 that the yield strength of the steel in the embodiments of the present invention is between 628 and 649 MPa, all reaching above the designed strength of 600 MPa, the tensile strength is between 756 and 786 MPa, the elongation is greater than 25%, the cold bending performance is qualified, and the average value of the impact energy at -40°C is 97 - 114 J, indicating that the strength of the steel in each embodiment not only meets the design requirements, but also has high plasticity and impact toughness.

[0050] The wear resistance test in Table 5 was carried out on a wet rubber wheel abrasive wear testing machine. Specimens with a processed size of 57.0 mm × 25.0 mm × 6.0 mm were used for the abrasive wear test, and the wear test was carried out in accordance with "JB / T7705 - 1995 Loose Abrasive Wear Test Method - Rubber Wheel Method". The results of the wear resistance test were as follows: the wear rate of the steel in the embodiments relative to Q450NQR1 steel was 38.4% - 40.7%, indicating that the steel in the embodiments has excellent wear resistance.

[0051] Table 5 Test Results of Performance Indicators of Each Example

[0052]

[0053] Table 6 Microstructure of Steel in the Embodiment of the Present Invention

[0054]

[0055] To simulate the corrosion situation in an industrial atmospheric environment, a 72-hour cyclic immersion rapid corrosion evaluation test was carried out on the invented steel according to the test method specified in TB / T 2375-1993; meanwhile, to simulate the corrosion situation of the invented steel in an acid corrosion environment, a full immersion corrosion experiment was carried out according to the implementation method of JB / T 7901 (the temperature was 23±2°C, and it was immersed in a 10% H2SO4 + 3.5% NaCl solution medium for 24 h). Table 7 shows the comparison results of the corrosion resistance performance between the steel in the embodiment of the present invention and the comparative steel. It can be seen from Table 7 that the steel in the embodiment of the present invention has high atmospheric corrosion resistance and acid corrosion resistance, and its corrosion resistance indicators all meet the requirements of the technical objectives.

[0056] Table 7 Comparison Results of the Cyclic Immersion Corrosion Test between the Steel in the Embodiment of the Present Invention and the Comparative Steel

[0057]

[0058] It is hereby specified that the above embodiments are only for illustrating the technical concept and characteristics of the present invention, and are not a limitation to the present invention. Any equivalent replacement or modification improvement made without departing from the essence of the present invention falls within the protection scope of the present invention.

Claims

1. A corrosion-resistant steel for 600 MPa grade high-wear-resistant railway vehicles, characterized in that, The chemical composition of the steel plate by weight percentage is as follows: C: 0.068% - 0.088%, Si: 0.58% - 0.75%, Mn: 1.03% - 1.23%, P: ≤0.015%, S: ≤0.006%, Cr: 0.86% - 1.07%, Cu: 0.14% - 0.29%, Mo: 0.074% - 0.089%, Al: 0.054% - 0.074%, RE: 0.0087% - 0.0107%, V: 0.021% - 0.032%, Ti: 0.033% - 0.048%, W: 0.084% - 0.104%, Sn: 0.038% - 0.057%, B: 0.0028% - 0.0058%, where 0.16% < Mo + W < 0.20%, 9.6 < Si / Al < 11.6, and the balance is Fe and inevitable impurities.

2. The corrosion-resistant steel for 600MPa high-wear railway vehicles according to claim 1, characterized in that, The thickness of the produced steel plate is 4.5 - 9.5 mm.

3. The corrosion-resistant steel for 600 MPa high-wear-resistant railway vehicles according to claim 1, characterized in that, The microstructure of the steel consists of ferrite + bainite + pearlite. Among them, the proportion of the ferrite phase is 28% - 33%, and the proportion of the bainite phase is 51% - 55%. Fine strengthening phases TiC / MoC and hard phases Fe7C3 / W7C3 / Mo7C3 are precipitated in the microstructure. The area proportion of TiC / MoC with a size range of 10 - 40 nm reaches 63.1% - 65.8%, and the area proportion of Fe7C3 / W7C3 / Mo7C3 with a size range of 30 - 60 nm reaches 61.2% - 64.3%.

4. The corrosion-resistant steel for 600 MPa high-wear railway vehicles according to claim 1, characterized in that The yield strength ReL of the steel > 600 MPa, the tensile strength Rm > 750 MPa, the elongation after fracture A > 25%, the cold bending performance is qualified, -40°C KV2 ≥ 97 J, and the wear rate relative to the current mainstream steel Q450NQR1 is 38.4% - 40.7%.

5. The corrosion-resistant steel for 600 MPa high-wear-resistant railway vehicles according to claim 1, characterized in that The corrosion rate of the steel plate under the acidic medium corrosion environment of the simulated coal-carrying truck is < 0.72 g / m 2 ·h, and the corrosion rate relative to Q345B in the industrial atmospheric environment is < 48.6%.

6. A manufacturing method of a corrosion-resistant steel for 600 MPa grade high wear-resistant railway vehicles according to any one of claims 1 to 5, comprising hot metal pre-desulfurization, converter steelmaking, secondary refining, slab continuous casting, billet heating, hot continuous rolling, laminar flow cooling and coiling, characterized in that, The tapping temperature of the continuous casting billet is 1198 - 1231°C, the air-fuel ratio is 1.3 - 1.

5. When the heating temperature is below 1156°C, it needs to be heated slowly with a heating rate of 7.2 - 9.2°C / min. When it is above 1156°C, it needs to be heated quickly with a heating rate controlled at 19.2 - 20.6°C / min. The residence time of the continuous casting billet in the furnace is 161 - 181 min; in the hot continuous rolling process, temperature-controlled rolling is adopted in two stages of rough rolling and finish rolling, the outlet temperature is 1141 - 1161°C, and the cumulative reduction ratio is 76.2% - 79.2%; the start rolling temperature of finish rolling is 1059 - 1083°C, and the finish rolling temperature is controlled at 908 - 928°C; after finish rolling, laminar cooling is carried out in a two-stage cooling method. In the first stage, it is cooled at a cooling rate of 10 - 17°C / s to 721 - 741°C and air-cooled for 21 - 25 s; then, it is cooled in the second stage at a cooling rate of 35 - 40°C / s and coiled when cooled to 597 - 617°C.

7. The manufacturing method of the corrosion-resistant steel for 600MPa grade high-wear-resistant railway vehicles according to claim 6, characterized in that, During the pretreatment of hot metal desulfurization and converter steelmaking, the addition amount of desulfurizer ≥ 3.9 kg / t, and the tapping temperature of the converter ≥ 1659°C.

8. The manufacturing method of the corrosion-resistant steel for 600 MPa high wear-resistant railway vehicles according to claim 6, characterized in that, The LF refining is used for heating up and fine-tuning the composition. During the RH refining process, the vacuum degree in the vacuum tank is maintained at less than 3.3 kPa. After adding the rare earth alloy, the molten steel is subjected to 2.2 - 4.4 min of pure RH circulation, and after breaking the vacuum, the molten steel is weakly blown for 28 - 31 min.

9. The manufacturing method of the corrosion-resistant steel for 600 MPa grade high-wear-resistant railway vehicles according to claim 8, characterized in that, The rare earth alloy is La and Ce alloy; the flow rate of the weak argon blowing is 74 - 86 NL / min, and the pressure is 0.25 - 0.36 MPa.

10. The manufacturing method of the corrosion-resistant steel for 600 MPa grade high-wear-resistant railway vehicles according to claim 6, characterized in that, The thickness of the continuous casting billet is 210 - 230 mm. During casting, the casting speed is controlled at 1.46 - 1.61 m / min, the casting superheat is 18 - 25 °C, and at the same time, the electromagnetic stirring technology is adopted, with the electromagnetic stirring current being 351 - 357 A and the frequency being 4.4 - 6.4 HZ.

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