INVESTIGATION OF DECARBURIZATION PROCESSES E90HAF RAIL STEEL WHEN HEATED FOR ROLLING

Abstract

The results of laboratory studies of decarburization processes of E90HAF grade rail steel when heated to temperatures of 800 – 1250 °C. are presented. The depth of the visible decarbonized steel layer was determined by metallographic method. During laboratory experiments, samples with a size of 10-10 (2 ÷ 26) mm were used. The samples were heated in an electric furnace of resistance SUOL-0.25.1/12.5-I1 with silicon carbide heaters in an air atmosphere. Heating was carried out to temperatures of 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200 and 1250 °C and kept at a constant temperature for 10, 30 and 50 minutes. Temperature ranges have been established and scientifically substantiated, for which different dynamics of the formation of a decarbonized layer are characteristic. In the temperature range of 800 – (1000 ÷ 1050) °C, an increase in the depth of the visible carbonized layer is observed from 0 to 0.15 – 0.24 mm. At temperatures (1000 ÷ 1050) – 1200 ° C and a holding time of 30 and 50 minutes. A decarbonized layer is formed with a depth of up to 0.57 and 0.72 mm, an increase in temperatures of more than 1200 – 1250 °C is accompanied by its decrease to 0.4 and 0.52 mm. For a holding time of 10 minutes at temperatures of 1200 – 1250 °C, the depth of the decarbonized layer is stabilized at 0.27 mm. The obtained data are recommended for the development of metal-saving temperature regimes for heating continuously cast blanks in methodical furnaces in the production of rail products with a regulated depth of the visible decarbonized layer.