Manufacturing method of high-corrosion-resistance steel for railway vehicle

Abstract

The invention discloses a manufacturing method of steel with high corrosion resistance for railway vehicles. The steel comprises the following chemical components in percentage by mass: 0.048 to 0.052 percent of C, 0.18 to 0.20 percent of Si, 0.52 to 0.56 percent of Mn, less than or equal to 0.006 percent of P, less than or equal to 0.0012 percent of S, 0.26 to 0.30 percent of Cu, 0.25 to 0.29 percent of Ni, 3.5 to 4.0 percent of Cr, 0.028 to 0.032 percent of Ti and the balance of Fe and impurities. A controlled rolling and controlled cooling process: heating the casting blank to 1150 + / -10 DEG C, and keeping the temperature; the initial rolling temperature is stabilized at 1150 + / -10 DEG C, the final rolling temperature is 850 + / -10 DEG C, water cooling is conducted immediately after rolling, the steel is cooled to 650 + / -10 DEG C, and then the steel is naturally cooled to the room temperature in air. By optimizing the components and the process, the manufactured steel has excellent corrosion resistance and good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of steel manufacturing technology, and in particular relates to a method for manufacturing steel with high corrosion resistance for railway vehicles. Background Technology

[0002] With the rapid development of the railway transportation industry, railway vehicles are constantly moving towards higher speeds, heavier loads, and longer service lives. In this process, railway vehicle steel faces enormous challenges. On the one hand, vehicles are exposed to various complex environments for extended periods, such as alternating wet and dry conditions, large temperature variations, and industrial pollution areas, making the steel highly susceptible to corrosion and shortening the vehicle's corrosion life. On the other hand, railway vehicles bear significant loads during operation, placing high demands on the strength and ductility of the steel. Currently, existing railway vehicle steels are insufficient to fully meet these requirements in terms of corrosion resistance and mechanical properties, necessitating the development of a new manufacturing method to improve the overall performance of the steel. Summary of the Invention

[0003] The purpose of this invention is to provide a method for manufacturing high corrosion-resistant steel for railway vehicles. By optimizing the composition and process, the manufactured steel has excellent corrosion resistance and good mechanical properties, effectively solving the corrosion problem of steel for railway vehicles, improving the safety and reliability of vehicles, and extending the service life of vehicles.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] This invention discloses a method for manufacturing high corrosion-resistant railway vehicle steel, the chemical composition of which is as follows: C 0.048-0.052%, Si 0.18-0.20%, Mn 0.52-0.56%, P≤0.006%, S≤0.0012%, Cu0.26-0.30%, Ni 0.25-0.29%, Cr 3.5-4.0%, Ti 0.028-0.032%, with the remainder being Fe and unavoidable impurities. High-purity cast billet raw materials meeting the composition requirements are selected, and each batch of raw materials undergoes rigorous quality testing to ensure that its chemical composition conforms to the design standards.

[0006] Controlled rolling and cooling process: The prepared billet raw material is fed into the rolling mill; it is first heated to 1150±10℃ and held at that temperature for a period of time to ensure that the steel is heated fully and evenly; during the rolling process, the temperature change is closely monitored to ensure that the initial rolling temperature is stable at 1150±10℃, and multiple rolling passes are performed according to the preset rolling procedure to gradually deform the steel to the target size; near the final rolling stage, the final rolling temperature is strictly controlled at 850±10℃, and water cooling is performed immediately after rolling to cool the steel to 650±10℃, and then the steel is allowed to cool naturally to room temperature in the air.

[0007] Furthermore, its chemical composition by mass fraction is as follows: C 0.05%, Si 0.19%, Mn 0.54%, P 0.005%, S 0.001%, Cu 0.28%, Ni 0.27%, Cr 3.56%, Ti 0.03%, with the remainder being Fe and unavoidable impurities.

[0008] Furthermore, the rolling mill is Experimental rolling mill.

[0009] Furthermore, heat to 1150℃ and keep warm for 0.5-3 hours.

[0010] Furthermore, ensure that the rolling temperature is stable at 1150℃.

[0011] Furthermore, the final rolling temperature is 850℃.

[0012] Furthermore, the steel is immediately water-cooled after rolling to 650°C.

[0013] Furthermore, the mechanical properties of the manufactured railway vehicle steel are: yield strength of 475 MPa, tensile strength of 685 MPa, and elongation of 25%.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0015] (1) High corrosion resistance: The steel produced can have a relative corrosion rate as low as 27% in a simulated industrial atmospheric environment. Compared with the steel used in traditional railway vehicles, the corrosion resistance is significantly improved, which effectively reduces the corrosion loss of vehicles during operation, greatly extends the service life of vehicles, and reduces maintenance costs.

[0016] (2) Good mechanical properties: The microstructure of the steel is mainly ferrite + bainite, which endows the steel with excellent comprehensive mechanical properties. The yield strength reaches more than 460MPa, the tensile strength is 678MPa, and the elongation is 24%, which can withstand various stresses generated by railway vehicles during high-speed and heavy-load operation, ensuring the safe and reliable operation of the vehicles.

[0017] (3) High process feasibility: The composition design and controlled rolling and cooling process adopted in this invention can be realized on existing steel production equipment without large-scale equipment upgrades. It has high process feasibility and operability, and is easy to promote and apply in steel production enterprises. Detailed Implementation

[0018] The following is a detailed description of a method for manufacturing a high corrosion-resistant steel for railway vehicles according to the present invention.

[0019] Example: This example is a preferred embodiment of the various embodiments of the present invention.

[0020] The manufacturing method of a high corrosion-resistant railway vehicle steel in this embodiment is as follows: chemical composition design and controlled rolling and cooling process.

[0021] The chemical composition of the steel is designed and controlled to have the following mass fractions: C 0.05%, Si 0.19%, Mn 0.54%, P 0.005%, S≤0.001%, Cu 0.28%, Ni 0.27%, Cr 3.56%, Ti 0.03%, with the remainder being Fe and unavoidable impurities. High-purity raw materials meeting the composition requirements are selected, and each batch of raw materials undergoes rigorous quality testing to ensure that its chemical composition conforms to the design standards and that the impurity content is controlled within the specified range. Each raw material is precisely weighed according to the composition ratio to ensure accuracy.

[0022] The controlled rolling and controlled cooling process involves feeding the prepared raw materials into... The experimental rolling mill initially heated the steel to 1150℃ and held it at that temperature for a period of time to ensure thorough and uniform heating. During the rolling process, temperature changes were closely monitored to ensure the initial rolling temperature remained stable at 1150℃. Multiple rolling passes were performed according to the pre-set rolling schedule, gradually deforming the steel to the target dimensions. Near the final rolling stage, the final rolling temperature was strictly controlled at 850℃. Immediately after rolling, the steel was water-cooled to 650℃, and then allowed to cool naturally to room temperature in air. Throughout the entire rolling process, the dimensional accuracy and surface quality of the steel were monitored in real time to ensure stable steel quality.

[0023] Performance Testing: Comprehensive performance testing was conducted on the rolled steel. Scanning electron microscopy was used to observe its microstructure, confirming it to be primarily ferrite + bainite. Tensile tests were performed to determine mechanical properties, showing a yield strength of 475 MPa, a tensile strength of 685 MPa, and an elongation of 25%, meeting the expected mechanical property indicators. A cyclic immersion corrosion test was used to evaluate its corrosion resistance. The experiment simulated an industrial atmospheric environment. After a specified period of corrosion testing, the relative corrosion rate of the steel was calculated to be 25%, indicating its excellent corrosion resistance.

[0024] Comparative Example 1:

[0025] The Cr content was reduced to 2.0%, while other components and processes remained the same as in the previous example. Testing revealed that the steel's microstructure was still predominantly ferrite and bainite, but the relative corrosion rate increased significantly to 40%, the yield strength decreased to 430 MPa, the tensile strength decreased to 640 MPa, and the elongation was 22%. This indicates that reducing the Cr content significantly weakened the steel's corrosion resistance and strength, fully demonstrating the importance of the Cr content design in this invention.

[0026] Comparative Example 2:

[0027] The controlled rolling and cooling process was modified by increasing the initial rolling temperature to 1200℃ and decreasing the final rolling temperature to 800℃, while keeping other components the same as in the previous example. Test results showed that the steel's microstructure exhibited partially coarse grains, a relative corrosion rate of 35%, a yield strength of 440 MPa, a tensile strength of 650 MPa, and an elongation of 23%. This indicates that the change in the controlled rolling and cooling process parameters adversely affected the steel's microstructure and properties, demonstrating the rationality of the process parameter selection in this invention.

[0028] A comparison of the embodiments and comparative examples clearly demonstrates that the present invention, through precise composition design and a reasonable controlled rolling and cooling process, can stably manufacture railway vehicle steel with high corrosion resistance and good mechanical properties. In actual production, the process parameters of the present invention can be fine-tuned within a reasonable range according to specific needs to meet the special requirements of different application scenarios for steel performance.

[0029] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for manufacturing high corrosion-resistant steel for railway vehicles, characterized in that, Its chemical composition by mass fraction is as follows: C 0.048-0.052%, Si 0.18-0.20%, Mn 0.52-0.56%, P≤0.006%, S≤0.0012%, Cu0.26-0.30%, Ni 0.25-0.29%, Cr 3.5-4.0%, Ti 0.028-0.032%, with the remainder being Fe and unavoidable impurities. High-purity casting billet raw materials that meet the composition requirements are selected, and each batch of raw materials undergoes strict quality testing to ensure that its chemical composition meets the design standards. Controlled rolling and cooling process: The prepared billet raw material is fed into the rolling mill; it is first heated to 1150±10℃ and held at that temperature for a period of time to ensure that the steel is heated fully and evenly; during the rolling process, the temperature change is closely monitored to ensure that the initial rolling temperature is stable at 1150±10℃, and multiple rolling passes are performed according to the preset rolling procedure to gradually deform the steel to the target size; near the final rolling stage, the final rolling temperature is strictly controlled at 850±10℃, and water cooling is performed immediately after rolling to cool the steel to 650±10℃, and then the steel is allowed to cool naturally to room temperature in the air.

2. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 1, characterized in that, Its chemical composition by mass fraction is as follows: C 0.05%, Si 0.19%, Mn 0.54%, P 0.005%, S 0.001%, Cu 0.28%, Ni 0.27%, Cr 3.56%, Ti 0.03%, with the remainder being Fe and unavoidable impurities.

3. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 1 or 2, characterized in that, The rolling mill is Experimental rolling mill.

4. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 2, characterized in that, Heat to 1150℃ and keep warm for 0.5-3 hours.

5. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 1, characterized in that, Ensure that the rolling temperature is stable at 1150℃.

6. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 5, characterized in that, The final rolling temperature is 850℃.

7. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 6, characterized in that, Immediately after rolling, the steel is water-cooled to 650°C.

8. The method for manufacturing high corrosion-resistant railway vehicle steel according to claim 7, characterized in that, The mechanical properties of the steel used in the manufactured railway vehicles are: yield strength of 475 MPa, tensile strength of 685 MPa, and elongation of 25%.

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