Prediction of Ferrite Grain Size after Warm Deformation of Low Carbon Steel

Abstract

When deformation is carried out near the A₁ temperature in low carbon steel, ferrite recrystallisation appears to be the dominant mechanism in controlling the grain size. The present investigation has shown the dominance of ferrite recrystallisation at low temperature between 665-690°C by the application of an austenite recrystallisation power law on experimentally measured grain sizes in 0.05%C steel. Comparison has also been made between predictions using this power law and the experimentally measured grain size after deformation in the two phase (α+γ) region. The results show that the ferrite grain size is influenced significantly by the relative proportions of γ and α phases within the structure just prior to deformation. In addition the good correlation found between predicted and measured grain sizes indicates that ferrite recrystallisation dominates between 850-690°C. Despite this, the possibility still exists for the occurrence of a transformation induced mechanism within this temperature region.