Cooling of rails: how to avoid a "hot core" for precise fixation in the summer

The subject of the research is the problem of "hot core" occurrence during intensive cooling of railway rails, which is critically important when preparing rails for fastening in the summer period. The aim of the work is to scientifically substantiate and propose methods for minimizing this phenomenon to ensure a uniform temperature field across the rail section. The research methodology includes an analysis of the influence of the limited thermal conductivity of steel on the formation of a temperature gradient and its negative impact on rail geometry, internal stresses, and fastening accuracy. The work proposes and substantiates methods for reducing the "hot core" effect, including cooling mode management (cascaded and phased intensity reduction), expanding active heat dissipation zones through multi-sided cooling, and applying comprehensive numerical modeling. The research results show that cascaded cooling with pauses effectively redistributes heat from the core to the surface, significantly reducing temperature gradients across the rail section, which is confirmed by numerical simulation results. Phased cooling intensity reduction prevents excessive gradients in later stages. Comprehensive numerical modeling allows not only to predict deformations and stresses but also to visualize optimal temperature fields, optimizing cooling parameters to achieve a uniform fastening temperature. The proposed methods ensure the stability and durability of continuous welded tracks. Effective external heat exchange management is key to solving the "hot core" problem. The implementation of the proposed strategies minimizes temperature gradients, reduces the risk of internal defects, and improves the accuracy of rail fastening, which directly affects their operational strength and safety.