The dynamic recrystallization behavior of austenite was studied using an 0.11C-1.0Mn steel (B) and two Nb steels containing 0.02Nb-0.10C-1.0Mn (K8) and 0.02Nb-0.01C-1.0Mn (K12) by analyzing stress-strain (σ/ε) curves obtained by hot tensile deformation at temperatures (
T) of 8501 100°C and at strain rates (ε) of 10
-410
-1 s
-1. The peak stress (σ
p) in the σ/ε curve, observed under the dynamic recrystallization, was larger in the order of the steels K8, K12 and B. In the steels B and K12, σ
pwas correlated with T and ε by the following equation; ε=A σ
npexp(-
Q/
RT). The value of
Q was 59.3 and 69.3 kcal/mol for the steel B and K12, respectively and that of n was about 5.0 for both steels. In the steel K8, the Arrhenius plot had two slopes, in which larger one in the lower temperature range gave
Q=85.6 kcal/mol. These phenomena can be explained by the precipitation behavior of Nb(C, N). Strain to peak stress (ε
p), which is usually taken to be the strain for the dynamic recrystallization, increased by Nb addition. In the steel K8, the recrystallization of the specimen deformed after solution treatment was remarkably retarded at a specific strain rate for a given deformation temperature, e.g. 10
-3_??_ε_??_10
-1 s
-1 at 900°C. This can be explained by the precipitation of fine Nb(C, N) particles during deformation. It was observed that the retardation was much smaller in the case of the steel K12. This was ascribed mainly to solid solution of niobium.
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