Abstract
The effect of asymmetric rolling with cone-shaped rolls on ultra-fine grain evolution was investigated. To do this, low-carbon steel containing 0.15 % C (mass fraction) billet (h|b|l = 10|45|100 mm3) with the initial average grain size of 60 μm was deformed up to the thickness of 5mm in cone-shaped rolls with diameters ratio of 1.5, as well as in cylindrical rolls. Rolling was conducted at three different temperatures: 900 °C, 1000 °C and 1100 °C. Four passes of asymmetric rolling in cone-shaped rolls were given to gain thickness of 5 mm with total reduction of 61,7 %. It has been shown that during asymmetric rolling in cone-shaped rolls at low temperature of 900 °C grain size is smaller (0.092 μm – at the surface layer and 0.112 μm – at the middle layer) than that of 1000 °C and 1100 °C. Tensile properties of asymmetrically rolled specimen were much higher (580 MPa) in comparison to symmetrically rolled one (486 MPa).