Atom probe tomography characterization of heavily cold drawn pearlitic steel wire

Institut für Materialphysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
Ultramicroscopy (Impact Factor: 2.44). 11/2010; 111(6):628-32. DOI: 10.1016/j.ultramic.2010.11.010
Source: PubMed


Atom Probe Tomography (APT) was used to analyze the carbon distribution in a heavily cold drawn pearlitic steel wire with a true strain of 6.02. The carbon concentrations in cementite and ferrite were separately measured by a sub-volume method and compared with the literature data. It is found that the carbon concentration in ferrite saturates with strain. The carbon concentration in cementite decreases with the lamellar thickness, while the carbon atoms segregate at dislocations or cell/grain boundaries in ferrite. The mechanism of cementite decomposition is discussed in terms of the evolution of dislocation structure during severe plastic deformation.

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    • "APT data were visualized and analyzed through the program IVAS3.6.2 (Cameca). The assignment of peaks in the mass spectra of pearlitic steels was addressed according to reports [15] [16]. "
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    ABSTRACT: Atom-probe tomography (APT) and first-principle calculations are employed to investigate the role of Si on the partitioning behavior of Mn in pearlitic steel. Mn is experimentally observed to partition preferentially to cementite, while Si prefers to bcc α-Fe by APT. The partitioning ratio of Mn in SWRS87BM steel (i.e., 8.17±1.57) is more pronounced than that in SWRS82B steel (i.e., 3.66±0.44), which is attributed to the higher content of Si in the former than in the latter. First-principle calculations illustrate that Si atoms, which strongly partition to bcc α-Fe phase, repulse Mn atoms into cementite phase and increase the Mn partitioning ratio.
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