Effect of deformation on the evolution of spheroidization for the ultra high carbon steel

The hot compression tests were performed on the ultra high carbon steel to investigate the spheroidization mechanism. Several processing routes were designed for this purpose. The experiment results showed that when the samples were austenitized at 1150 °C for 1 min, cooled to 700 °C (above Arcm) with rate of 20 °C/s, deformed with reduction of 60%, cooled with rate of 0.2 °C/s to 550 °C, the excellent spheroidized structure was obtained. The formation of spheroidized cementite is related with the energy stored in the form of dislocations, the breakup or bended cementite and pearlite directly formed during deformation. The lower the deformation temperature (above Arcm) and the longer the cooling time is, the more and better the spheroidized structure can be obtained.