Peculiarities of the application of non-isothermal holding in the process of spheroidizing annealing of low-carbon steel

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🔬研究者:この研究は鋼材熱処理の省エネルギー化に関する知見を提供し、産業分野の脱炭素研究に貢献する。

For heterogeneous alloys, a significant role in ensuring the required set of technological properties is played by the structural state, in this case the morphology of the microstructure obtained after heat treatment. In the case of cold heading, the necessary technological plasticity is provided by the spherical (globular) morphology of the excess phase particles. In this regard, steel billets intended for cold heading are subjected to spheroidizing annealing, which is mainly carried out in furnaces with a duration of up to ten hours or more. In this regard, the spheroidizing annealing operation is characterized by significant energy consumption. To intensify the spheroidization process, various schemes of pretreatments have been proposed, which are based on increasing the dispersion of carbide particles and the defectivity of the matrix crystal lattice by reducing the austenite decomposition temperature in the eutectoid transformation region. In this case, the duration of the process was reduced to several hours with a practically unchanged type of annealing mode. The study of the features of intensification of spheroidizing annealing and factors that affect the speed of the spheroidization process of cementite of low-carbon steels is of great practical importance. This work investigates the use of heating the workpiece metal with an internal coolant using non-isothermal holding with increasing temperature and deep supercooling in the process of spheroidizing annealing of low-carbon steel, the influence of the listed factors on the duration of the spheroidization process. It has been established that the maximum reduction in the duration of spheroidizing annealing with a pre-prepared initial structure is achieved by implementing a regime with deep supercooling and non-isothermal holding (with an increase in temperature). In this case, the metal is heated by an internal coolant, which ensures the effect of accelerating the formation of new grains. Reducing the duration of the process during deep supercooling and non-isothermal holding is achieved by optimizing the values of thermodynamic and kinetic factors that determine the speed of the process of structural transformations.

• openalex https://doi.org/10.52150/2522-9117-2026-40-009first seen 2026-06-02 04:57:14 · last seen 2026-06-16 04:50:57