INVESTIGATION OF THE AUSTENITE DECAY KINETICS DURING CONTINUOUS COOLING OF STEEL WITH 0.84 % С, 0.44 % Si, 0.95 % Mn, 0.01 % B, 0.0006 % Са FOR RAILWAY RAILS OF THE NEW GENERATION

Purpose. Investigation of the supercooled austenite decay kinetics during continuous cooling steel with 0.84 % C, 0.44 Si, 0.95 Mn, 0.01 B, 0.0006 Ca for railway rails a new generation increased operational properties to develop parameters differential cooling. Method. The investigation was carried out using thermal analysis. Samples were cooled at different rates, temperature control performed chromel-aluminum thermocouples installed in center sample. Microstructural investigations are optical (AxioVert 200M mat) and electronic (SEM-106) microscopes. interplate distance pearlite is determined by linear method, diagonals located perpendicular plate packages. Vickers hardness load 10 kg. number structural components recognized on microstructural images imageJ software complex. Results. TKD analysis showed that rates 0,06...5,96 °C/s, structure investigated consists pearlite. As rate increases, morphology changes dispersion increases: from medium sorbitol-like. It should be noted range 0,06...0,07°С/s, tertiary cementite formed ferrite. diagram shows 5.96 °С/s 468 НВ (432 НВ), does not contain bainite. At 1.47 °С/s, 356 НV (345 НВ). This slightly below minimum allowable value (370 HV), but interpolation it can must least 2.5 °C/s achieve 393 HV HV). That is, when rolling surface rail central volumes head high-strength following categories manufactured: higher (DSTU (National Standard Ukraine) 4344:2004) R400HT (EN 13674-1:2011) С, Ca. Scientific novelty. Constructed thermokinetic Са. Practical value. established use experimental possible above 400NV without formation needle-like structures, therefore this recommended chemical composition manufacture R400NT category according EN 13674-1-2011.