Advanced Heat Treatment of Pearlitic Rail Steel

Abstract

The aim of this research is a systematic investigation of heat treatments of 60E1 profile rails made of steel R350HT, which would ensure the properties required by the standard EN 16273. Additionally, it presents a concept of cooling rails on a semi-industrial station, which will make it possible to obtain the desired properties. The dilatometric tests have demonstrated that the optimal cooling rate is within the scope of 3 °C/s to 6 °C/s, when both the EN 16273 standard’s hardness distribution and microstructure requirements are fulfilled. The tests on the designed and built station showed that the optimal pressure with respect to the microstructure and properties of the rail equals 6.5 bar. For these parameters, measurements of the interlamellar distance were also performed—the cooling rate obtained at the surface was 3.68 °C/s, with an interlamellar distance of about 80 nm, whereas inside the rail the rate was 2.63 °C/s and the distance 110 nm. The achieved results confirm that the designed station can be used for controlled cooling of rail steels from R350HT steel.