The phase transformation points of a medium carbon V - Ti - N microalloyed steel were determined, as were the continuous cooling transformation curves of austenite heated at 1100 ° C without deformation and heated at 1200 ° C with two pass deformation. The data have been further used to analyse the real production scheme of N80 grade hot rolled non-quenched/tempered seamless tubes. The results have showed clearly that the commonly used 'in line normalisation' is not always necessary in the non-quenched/tempered production process of N80 grade hot rolled seamless oil well tubes. The above viewpoint has been further demonstrated by the microstructural examination of specimens sampled from industrial production.