Efecto de los parámetros de deformación y de la temperatura de precalentamiento sobre la temperatura de no recristalización en aceros microaleados con Nb y Nb-Ti

Abstract

The main objective of the present work has been to determinate the no-recrystallisation temperature ( T nr ) of two Nb-bearing steels and two Nb-Ti microalloyed steels. The T nr has been obtained performing multipass torsion tests under continuous cooling conditions. The influence of deformation parameters: interpass time, t ep , pass strain, e, and strain rate, έ and reheating temperature, T , on the non-recrystallisation temperature has been investigated. In the range of short interpass time ( t ep T nr decreases as interpass time increases. For intermediate interpass time, precipitation takes place leading to an increase in the T nr . However, in the range of long interpass time ( t ep > 60 s), precipitated particles coarse loosing its effectiveness as recrystallisation retarding agents, which leads again to a decrease in the no-recrystallisation temperature. The T nr decreases with increasing pass strain following this type of relationship: T nr = β∙e -α . Moreover, an increase in the strain rate leads to a decrease in the non-recrystallisation temperature. By increasing the reheating temperature, the amount of dissolved elements that can precipitate at lower temperatures rises, which results in an increase of the T nr . 18 Leaching of vanadium from sulphuric acid manufacture spent catalysts Lixiviacion de vanadio de catalizadores agotados procedentes de la fabricacion del acido sulfurico