Process for improving toughness of exported American standard SS steel rail
By optimizing the addition of Si and Mn alloying elements and using specific rolling and cooling processes, the problem of inconsistent hardness and elongation of rails under the AREMA standard was solved, achieving high strength and toughness of rails and improving production efficiency and economic benefits.
Patent Information
- Application Number
- CN202511011557.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-11-14
AI Technical Summary
The current AREMA standard has issues with the production process of rails, such as inconsistencies in hardness and elongation, leading to wasted production resources and increased costs, making it difficult to meet the high strength and toughness requirements of rails in railway transportation.
By optimizing the chemical composition design of the rails, especially the addition of Si and Mn alloying elements, and combining it with specific rolling and cooling processes, including heating time, final rolling temperature, cooling bed cooling and low-temperature tempering, the strength, elongation and hardness of the rails are ensured to meet the standard requirements.
It achieves high strength, excellent toughness, and good service performance of steel rails, improves production efficiency, reduces costs, and is suitable for large-scale industrial production.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of metallurgical materials technology, and in particular to a process for improving the toughness of exported American standard SS steel rails. Background Technology
[0002] Currently, the AREMA standard is an important technical standard for the procurement of steel rails in countries and regions in the Americas, Southeast Asia, and Africa. Based on this standard, the material composition of the rails must be C-Si-Mn, with strict limitations on microalloying strengthening elements such as V and Ni. However, the standard has stringent requirements for the strength and toughness of the rails, leading to inconsistencies in hardness and elongation during the rolling process, resulting in wasted production resources and increased costs.
[0003] With the economic development of overseas countries and the continuous increase in transportation routes, the demand for the quality and performance of railway rails is also constantly increasing. Rails used for railway transportation must possess good strength, toughness, and other mechanical properties, as well as excellent service performance. Therefore, based on the chemical composition and mechanical properties required by the AREMA material standard for SS rails, a reasonable chemical composition is designed to fully utilize the characteristics of the rolling process, steadily improving the strength and toughness of SS rails while enhancing their internal metallurgical quality. This is of great significance for increasing production efficiency and reducing costs. Summary of the Invention
[0004] The purpose of this invention is to provide a process for improving the toughness of exported American standard SS rails. By rationally designing the composition and adding optimal Si and Mn alloying elements to the rails, the strength, elongation, tread hardness, and other properties of the rails produced under this process meet the standards. The rails produced have excellent cleanliness and toughness. The process is unique, with high production efficiency, energy saving and environmental protection, and good economic benefits. It is suitable for large-scale production and has good promotional value.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] This invention discloses a process for improving the toughness of exported American standard SS steel rails. The production process is as follows: smelting → rolling → cooling bed → processing. The feature is that the rail rolling process is as follows: heating time 2.5-3.0 hours, initial rolling temperature ≥1030℃, and final rolling temperature 870~930℃.
[0007] Rail cooling bed cooling process: Rail spacing ≥550mm, rails are naturally cooled, starting at 840℃~880℃, and after cooling to ≤60℃, the rails are straightened, and after straightening, samples are processed and taken for mechanical property testing.
[0008] Furthermore, after the tensile test, the material undergoes low-temperature tempering, which involves holding it at 150-200℃ for 3 hours, followed by natural temperature control and testing at room temperature.
[0009] Furthermore, the chemical composition of the rail by mass percentage is as follows: C 0.74–0.86%; Si 0.35–0.60%; Mn 0.70–1.25%; P ≤ 0.025%; S ≤ 0.025%; Cr ≤ 0.30%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
[0010] Furthermore, the hot-rolled rails must meet the following requirements: tensile strength ≥ 980 MPa, yield strength ≥ 510 MPa, elongation ≥ 10%, and rail tread hardness ≥ 310 HB.
[0011] Furthermore, the chemical composition of the rail by mass percentage is as follows: C 0.82%; Si 0.51%; Mn 1.17%; P 0.012%; S 0.0050%; Cr 0.22%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
[0012] Furthermore, the chemical composition of the rail by mass percentage is as follows: C 0.84%; Si 0.52%; Mn 1.21%; P 0.013%; S 0.0030%; Cr 0.21%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
[0013] Furthermore, the chemical composition of the rail by mass percentage is as follows: C 0.81%; Si 0.50%; Mn 1.22%; P 0.014%; S 0.0020%; Cr 0.23%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
[0014] Compared with the prior art, the beneficial technical effects of the present invention are as follows:
[0015] This invention utilizes a post-rolling cooling process to optimize and improve the strength and hardness of the rails, and employs a low-temperature tempering process to control the heating temperature and holding time, ensuring that the material's toughness meets technical requirements. The composition design and process of this invention feature a unique production process, making it suitable for industrial pilot production and possessing significant potential for widespread application. Detailed Implementation
[0016] A process for improving the toughness of exported US standard SS steel rails, wherein the steel production process is: smelting → rolling → cooling on a cooling bed → processing. The chemical composition of each embodiment is shown in Table 1.
[0017] Table 1. Components of each embodiment (mass percentage / %)
[0018]
[0019] The material rolling process is as follows:
[0020] Table 2 Rolling process of each embodiment
[0021]
[0022] The rolled rails were inspected according to AREMA standards, and the tensile properties were tested by holding the rails at 200℃ for 3 hours.
[0023] Table 3 Mechanical properties of each embodiment
[0024]
[0025]
[0026] As can be seen from the table above, this method produces SS rails with an elongation of over 12% and excellent toughness.
[0027] 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 process for improving the toughness of exported American standard SS steel rails, the production process being: smelting → rolling → cooling on a cooling bed → processing, characterized in that: The rail rolling process is as follows: heating time 2.5-3.0 hours, initial rolling temperature ≥1030℃, and final rolling temperature 870~930℃; Rail cooling bed cooling process: Rail spacing ≥550mm, rails are naturally cooled, starting at 840℃~880℃, and after cooling to ≤60℃, the rails are straightened, and after straightening, samples are processed and taken for mechanical property testing.
2. The process for improving the toughness of exported American standard SS rails according to claim 1, characterized in that: The tensile test involves low-temperature tempering after processing, holding at 150-200℃ for 3 hours, and then testing at room temperature under natural control.
3. The process for improving the toughness of exported American standard SS steel rails according to claim 1, characterized in that: The chemical composition of the rail by mass percentage is as follows: C 0.74-0.86%; Si 0.35-0.60%; Mn 0.70-1.25%; P≤0.025%; S≤0.025%; Cr≤0.30%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
4. The process for improving the toughness of exported American standard SS rails according to claim 3, characterized in that: After hot rolling, the rails must meet the following requirements: tensile strength ≥ 980 MPa, yield strength ≥ 510 MPa, elongation ≥ 10%, and rail tread hardness ≥ 310 HB.
5. The process for improving the toughness of exported American standard SS rails according to claim 3, characterized in that: The chemical composition of the rail by mass percentage is as follows: C 0.82%; Si 0.51%; Mn 1.17%; P 0.012%; S 0.0050%; Cr 0.22%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
6. The process for improving the toughness of exported American standard SS steel rails according to claim 3, characterized in that: The chemical composition of the rail by mass percentage is as follows: C 0.84%; Si 0.52%; Mn 1.21%; P 0.013%; S 0.0030%; Cr 0.21%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.
7. The process for improving the toughness of exported American standard SS rails according to claim 3, characterized in that: The chemical composition of the rail by mass percentage is: C 0.81%; Si 0.50%; Mn 1.22%; P 0.014%; S 0.0020%; Cr 0.23%, the remainder being Fe and unavoidable impurities, with a total mass fraction of 100%.