Recrystallization Kinetics of Low and Ultra Low Carbon Steels during High-rate Annealing

概要

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Annealing experiments were carried out to study the effect of rapid heating rates on the recrystallization kinetics and grain size of steels with a range of carbon levels (0.003–0.05 %C). The steels were cold-rolled to 70% reduction and subsequently annealed at heating rates from 50 to 1 000°C/s to peak temperatures (Tp) in the range 600 to 800°C and held at Tp for various times and cooled to ambient temperature at a rates up to 2000°C/s. For the steels investigated, the rate of anisothermal recrystallization and the final grain size decreases with increasing heating rate. These results do not support previous work in which it was concluded that ultra-rapid softening (which was associated with an observed decrease in recrystallization temperature at high heating rate and a concomitant increase in grain size) occurs at heating rates in excess of 500°C/s. An annealing model, based on JMAK transformation kinetics, is presented, which predicts the kinetics of recrystallization for any combination of input parameters: heating rate, peak temperature, holding time and cooling rate. The model is shown to predict the strong effect of holding time and cooling rate on the rate of recrystallization at high heating rates.
社団法人日本鉄鋼協会の論文
2001-09-15