Warm forging of a vanadium microalloyed steel

An experimental study of the warm forging applied to a vanadium microalloyed steel has been performed by plane strain compression tests in the 720-870 degrees C range, followed by air cooling and accelerated cooling (4 degrees C/s). The microstructures obtained are ferrite-pearlite-bainite with very fine ferrite grain sizes. The distribution of vanadium precipitate sizes has been measured and related to the deformation temperature. The microstructures have good strength levels with improved UTS values in the accelerated cooling samples. For deformation temperatures lower that 830 degrees C the material exhibits a complete ductile behaviour at room temperature and at 0 degrees C. On the contrary, samples deformed at 870 degrees C are in the brittle-ductile transition regime. This different behaviour has been related to the microstructural parameters.