Preparation and microstructure characteristics of low-temperature bainite in surface layer of low carbon gear steel

► An approach is proposed for the development of ultrafine low-temperature bainitic microstructure in the surface layer of a low-carbon gear steel. ► Phase transformation within different depth of the carburized layer, which has different carbon content, is investigated. ► This type of material which has low-temperature bainite in the surface layer and low-carbon martensite in the center is potentially of use in the manufacture of heavy-duty gears if the process is further optimized.