کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10620184 988603 2013 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The dynamic transformation of deformed austenite at temperatures above the Ae3
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
The dynamic transformation of deformed austenite at temperatures above the Ae3
چکیده انگلیسی
Recent observations regarding the dynamic transformation of deformed austenite at temperatures above the Ae3 are reviewed. Experimental results obtained on four different steels over the temperature range from 743 to 917 °C and at strains up to ε = 5 are described. It is shown that there is a critical strain for the formation of superequilibrium ferrite and that the volume fraction of transformed ferrite increases with the strain. The structures observed are Widmanstätten in form and appear to have nucleated displacively. The effect of deformation on the Gibbs energy of austenite is estimated by assuming that the austenite continues to work-harden after initiation of the transformation and that its flow stress and dislocation density can be derived from the experimental flow curve by making suitable assumptions about two-phase flow. By further taking into account the inhomogeneity of the dislocation density, Gibbs energy contributions (driving forces) are derived that are sufficient to promote transformation as much as 100 °C above the Ae3. The C diffusion times required for the dynamic formation of the cementite particles observed are estimated. These range from ∼25 to 100 μs and are therefore consistent with the times available during rolling. The Gibbs energy calculations suggest that growth of the Widmanstätten ferrite is followed by C diffusion at the lower carbon contents, while it is accompanied by C diffusion at the higher carbon levels.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Acta Materialia - Volume 61, Issue 7, April 2013, Pages 2348-2362
نویسندگان
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