| The precipitation/recrystallization interaction in HSLA steels were investigated using computer modelling based on the classical nucleation and growth theory. Using the computer model developed, the RPTT(recrystallization-precipitation-temperature-time) diagram was constructed to analyze the interaction between precipitation and recrystallization in hot rolled Nb steels. The three region interaction behavior was confirmed in the RPTT diagram, which was in agreement with the reported interaction of precipitation and recrystallization. It was found that the kinetics of precipitation after recrystallization was faster than that of strain-free precipitation. it has been generally known that the nose of the precipitation curve was shifted to a shorter time and a higher temperature with increasing strain, diffusivity, C and Nb contents and decreasing interfacial energy. However, with regard to the strain effect, the nose temperature was shifted to a longer time and a lower temperature with increasing strain greater than a critical value. It was found that the average size of precipitate before completing precipitation were less than 5OA. Comparison of the reported data with the predicted behavior appeared to be satisfactory, which indicates that the present precipitation model can be used to describe the interaction of precipitation and recrystallization in Nb microalloyed steels. |
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