controlling the ferrite and pearlite banded of 20CrMnTi hot rolled bar

The sampling of ferritic-pearlite banded of 20CrMnTi bar at different positions in the rolling line, the result shows that the closer the rolling end, the more serious the banded is, and the banded structure of steel is gradually aggravated from the surface to the core. By comparing the banded of different final rolling temperature and cooling rate after rolling, when the final rolling temperature is over 905℃, the banded structure of the bar can be less of 2.5 level. When the final rolling temperature is over 915℃, the banded structure can less of 2.0 level, and the banded grade gradually decreases with the increase of the final rolling temperature. Increasing the final rolling temperature can promote the transformation of austenite in situ and reduce the plastic deformation of ferrite, which is conducive to the reduction of band grade. Increasing the cooling rate after rolling can effectively inhibit the diffusion of C. Mn and Cr elements from the depleted zone to the enriched zone, which is conducive to the reduction of the strip. The scanning analysis of the samples of 20CrMnTi bars in hot rolled and annealed states shows that the annealing treatment of hot rolled bars will aggravate the zonal structure, which makes the distribution of C, Mn and Cr elements uneven, but has no obvious effect on the distribution uniformity of Si and Ti elements.