Influence of strain rate on recrystallisation– precipitation interaction in V,Nb, and V–Ti microalloyed steels

Abstract

A study has been made of the recrystallisation–precipitation interaction in three microalloyed steels, containing respectively V, Nb, and V–Ti, applying two different strain rates. Recrystallised fraction v.time curves were determined and used to draw recrystallisation–precipitation–time–temperature (RPTT) diagrams. The influence of strain rate has been shown to be similar in the three steels. On the basis of the results the value of }}SB0·19 has been found for the exponent of the strain rate, following Dutta and Sellars'model for the parameter t _0·05 , which differs from the value }}SB0·5 proposed by these authors. Simultaneously, the influence of strain rate on the static recrystallis ation critical temperature has been determined, it being observed that an increase in the former leads to a drop in the latter. Furthermore, strain rate is shown to have an influence on the recrystallisation–precipitation interaction, acting on those parameters that best contribute to defining RPTT diagrams In this sense, it was found that an increase in the strain rate led to a drop in the curve nose temperature T _N and a reduction in the time necessary for precipitation to finalise t _0·95 , as well as an increase in the recrystallisation rate.