Recrystallisation kinetics and yield-strength adjustment after annealing of cold-rolled microalloyed steel

Abstract

After continuous annealing process (CAP) at 790°C, 85% of the coils of 50% cold-rolled low carbon microalloyed (LCM) steel did not exhibit yield-strength (YS) on the target range, while the 70% cold-reduced LCM coils did. In this context, the non-isothermal recrystallisation kinetics of ferrite for the above two full-hard LCM steel were investigated using differential scanning calorimetry and the Friedman differential isoconversional method. The recrystallisation kinetics of ferrite for the two deformed states showed different behaviour. Regarding a fixed degree of cold-rolling deformation, the soaking temperature was found as the manageable parameter to control YS during CAP. Consequently, a suitable YS of the 50% cold-rolled LCM steel was achieved by setting the soaking temperature at 773°C.