Interaction between Recrystallization and Precipitation during Multipass Rolling in a Low Carbon Niobium Microalloyed Steel

抄録

The interaction between recrystallization and precipitation processes during multipass deformation has been analysed in terms of the non recrystallization temperature ( T_nr). Multipass torsion tests performed at continuous cooling conditions have been used for thermomechanical simulation. The effect of the passstrain and the initial austenite microstructure on the T_nr value have been investigated. Conventionally reheated austenite ( T_soak=1200–1250°C) and as-cast austenite, the latter simulated in the laboratory by reheating at very high temperatures (T_soak=1400°C), have been considered. It was observed that at low pass-strains the retardation on recrystallization was mainly due to solute drag effects, while increasing the strain, precipitation induced by deformation was allowed to occur during the interpass interval leading to a drastic reduction of the softening reached between passes at temperatures below the T_nr. The increment of the reheating temperature led to higher T_nr values, being this effect related to higher austenite supersaturation levels prior to deformation.