Effect of simulated thermomechanical processing on transformation behavior and microstructure of 82B steel
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The effects of loop-laying temperature and austenite deformation on the phase transformation behavior during continuous cooling, microstructure, and pearlite interlaminar spacing in 82B steels were investigated. Static and dynamic continuous cooling transformation (CCT) diagrams were measured with a Gleeble-3500 thermal simulator, and the mechanisms governing changes in the initial temperature, initial time, and duration of the phase transformation zone were also analyzed and discussed. The results show that CCT diagram shifted to the bottom right, the initial temperature of the phase transition decreased, the initial time of the phase transition increased, the duration of the phase transition increased, and the lamellar spacing of pearlite was finer as the loop-laying temperature increased. The initial phase transition time decreased, and the phase transition duration first reduced, then increased, and finally decreased in the static condition and in the dynamic condition at 850 °C as the cooling rate increased. Meanwhile, the phase transition duration continuously decreased in the dynamic condition at 900 °C. At a given loop-laying temperature, the lamellar spacing in pearlite was finer due to austenite deformation compared with the undeformed case. Compared with the results shown in the dynamic CCT diagram, the corresponding phase diagrams of the static CCT diagram slightly shifted to the bottom right. Moreover, there was a clear linear relationship between the reciprocal of the lamellar spacing in pearlite and the average undercooling degree in the phase transformation zone.
Keywords82B steel Phase transformation Loop-laying temperature Austenite deformation Microstructure
This work was financially supported by the National Key R&D Program of China (2016YFB0301302).
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