Heat treatment method for improving structural homogenity of rolled steel integral wheel for large-size railway vehicle

Abstract

The invention provides a heat treatment technique for steel of a rolled steel integral wheel for large-size railway, which is characterized by comprising the following steps: heating a wheel, which is rolled by a conventional technique and subjected to slow cooling treatment, to 860-880 DEG C along with the furnace, keeping the temperature for 3-3.5 hours, discharging, cooling in air to room temperature, heating the wheel to 840-860 DEG C along with the furnace, keeping the temperature for 3.5-4 hours, discharging, immediately cooling until the rim internal metal is quickly cooled to 550 DEG C below at the cooling rate of 2-5 DEG C / s, cooling in air to room temperature, putting the cooled wheel in a 480-500 furnace, keeping the temperature for 4.5-5 hours, discharging, and cooling in air. The structure grain fineness of the wheel rim subjected to heat treatment is Grade 8.5, the structure state tends to conformity, and the structure is uniform and fine; and compared with the wheel subjected to conventional heat treatment, the invention obviously improves the uniformity of the as-rolled structure and obviously refines the structure.

Description

technical field [0001] The invention belongs to the field of manufacturing rolling steel wheels for railway vehicles, and is suitable for heat treatment of large-size steel rolling integral wheels for railways, and particularly relates to a heat treatment method for railway wheels with an outer diameter of 1250 mm. Background technique [0002] Railway wheels have the functions of loading, guiding, transmitting traction and braking force, and the working conditions are very harsh, which has an important impact on traffic safety. With the development of high-speed and heavy-duty railway transportation in my country, the requirements for the quality of railway wheels continue to increase. Therefore, the requirements for the production and preparation methods of wheel steel are getting higher and higher. [0003] The TB / T2708-1996 Technical Conditions for Steel Rolled Integral Wheels for Railway Express Passenger Cars currently in use in my country, the Technical Conditions fo...

AI Technical Summary

Problems solved by technology

However, for a large wheel with an outer diameter of 1250mm, the metal flow displacement is relatively large during the thermoforming process, the cooling rate of each part is greatly different, and the microstructure of different parts after thermal processing is greatly different, with poor uniformity and severe grains. Inhomogeneity, the conventional heat treatment process can not effectively improve the bad structure inheritance, eliminate the uneven structure produced by rolling, resulting in the mechanical properties of large-size wheels with an outer diameter of 1250mm have not been able to stably meet the requirements of relevant technical conditions, especially the increasingly important toughness requirements

[0006] In the relevant technical conditions of large-sized wheels, the fracture toughness and low-temperature impact performance of the rim have been explicitly required. In the development process of large-sized locomotive wheels, there has always been a problem that the single value of the low-temperature impact toughness and fracture toughness of the same wheel fluctuates greatly and cannot meet the requirements stably. , which seriously affects the qualification rate and safety performance of large-size wheel products

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