The effects of deformation temperature and strain on bainite transformation of low carbon steel and boroncontaining steel were investigated under continuous cooling conditions by means of dilatometric measurement and microstructure observation.The results show that with decreasing the deformation temperature from 1 000to 800 ℃and increasing strains,bainite start temperature for boron-containing low carbon steel increases,whereas it decreases for low carbon steel under the same condition.The bainite microstructures are easily obtained for boron-containing steel deformed at different temperatures and different strains compared with plain low carbon steel.With increasing the continuous cooling rate,the bainite start temperature under deformed condition is about 20 ℃ higher than that under undeformed condition for boron-containing steel,but it changes slightly when the cooling rate is 20℃/s or more. The effects of deformation temperature and strain on bainite transformation of low carbon steel and boroncontaining steel were investigated under continuous cooling conditions by means of dilatometric measurement and microstructure observation.The results show that with decreasing the deformation temperature from 1 000 to 800 ° C and increasing- bainite start temperature for boron-containing low carbon steel increases, where it decreases for low carbon steel under the same condition. bainite microstructures are easily obtained for boron-containing steel deformed at different temperatures and different strains compared with plain low carbon steel. increasing the continuous cooling rate, the bainite start temperature under deformed condition is about 20 ° C higher than that under undeformed condition for boron-containing steel, but it changes slightly when the cooling rate is 20 ° C / s or more.