The distribution and diffusion of carbon atoms during deformation of undercooled austenite in medium carbon steel
北京科技大学
Cite this article:
. The distribution and diffusion of carbon atoms during deformation of undercooled austenite in medium carbon steel. Acta Metall Sin, 2007, 43(8): 785-790 .
Abstract The distribution and diffusion of carbon atoms during deformation of undercooled austenite in the medium carbon steel were investigated by means of uniaxial hot compression simulation experiment and SEM, XRD, thermomagnetic methods. The experimental results showed that the effective diffusion coefficient of the carbon atoms during dynamic transformation of undercooled austenite increased significantly compared with that during the isothermal transformation at the same temperature, as a result the completion of ferrite and pearlite transformation was shortened. During the subsequent spheroidization process of lamellae pearlite, high density dislocations and vacanies introduced during hot deformation promoted the diffusion of the carbon atoms, therefore the cementite spheroidization kinetics was accelerated dramatically as compared to isothermal annealing treatment. The dissolution, re-precipitation of cementite and supersaturated carbon inside the ferrite grains were confirmed. The supersaturated carbon atoms were not located at interstitial sites within the iron lattices homogeneously, but highly segregated in ferrite grain boundaries and dislocation cores.
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