Ferritic-Pearlitic Steel with Deformation Induced Spheroidized Cementite

The study of medium-carbon steel (0.35% C) with a deformation induced globular cementite produced by a heavy warm deformation (HWD) was carried out as a potential substitution of a conventional quenching and tempering (QT) or soft annealing (SA). Specimens for all three treatments were re-heated into the austenite range and hot deformed at the same temperature and with the same strain to get an optimum conditioning of the initial austenite structure. The HWD samples were cooled with cooling rates - 7-8K/s and heavily deformed (*e#~0.6) at the temperatures below the *g-*a transformation (600 - 710DGC), with a subsequent simulated coiling at the deformation temperatures. The QT samples were tempered at temperatures 600 - 670DGC. The SA samples were annealed at 710DGC for 16 h. The HWD allows to accelerate essentially the spheroidisation of lamellar pearlite. The subsequent soaking at the suitable coiling temperature leads to a rather homogeneous distribution of a fine dispersed cementite in a recrystallized fine grained ferritic micro structure. As a result, the mechanical properties of the HWD samples proved to be well comparable to those after QT.