Influence of temperature rise during finishing rolling on the mechanical properties of T8 cord steel

Different temperature rises during finishing rolling of T8 cord steel were obtained through normal procedure (process 1) and controlled cooling procedure (process 2), and its effects on the microstructure and the mechanical properties were studied. The microstructure of T8 cord steel obtained by process I consisted of clusters of coarser and inhomogeneity sorbite colonies, and that obtained by process 2 consisted of equiaxed and finer sorbite colonies, with the similar interlamellar spaces of sorbite cementite in the two microstructures. The results of tensile tests showed that the tensile strength of T8 cord steel obtained by process 2 was higher than that obtained by process 1 by 20MPa, with higher reduction of area and tensile elongation. In addition, the tensile fracture of T8 cord steel obtained by process 1 consisted of a lot of lotus cleavage plane, while that of T8 cord steel obtained by process 2 mainly consisted of finer dimples. That indicated that the smaller temperature rise of process 2 during finishing rolling can improve the mechanical properties of T8 cord steel.