The influence of hardening BH-treatment on the mechanical properties of hot-rolled steel 48Г2БМ has been studied. The variation of BH-treatment parameters (degree of plastic before-deformation e and temperature of after-heating t) led to different-amount strain ageing in metal. An estimation method of the strain ageing effect, based on changing the yield stress and the tensile toughness at the uniform stage was proposed. The correlation between these values was determined.