高速干硬切削表面白层相变元胞自动机模拟
2019-02-18
作者：段春争，寇文能，张方圆
单位：大连理工大学
摘要：高速干硬切削已加工表面白层形成过程中伴随着奥氏体相变与马氏体相变，而奥氏体和马氏体微观组织结构决定了已加工表面宏观上的机械性能。为了可视化地描述白层形成过程中奥氏体相变与马氏体相变演化过程，根据TEM暗场照片测得已加工表面白层晶粒尺寸，并通过晶粒尺寸计算得到奥氏体形核数量，同时结合白层形成过程中奥氏体相变与马氏体相变特征定义了元胞自动机演化规则，建立了二维元胞自动机奥氏体相变与马氏体相变组织演化模型。模拟了已加工表面白层形成过程中的奥氏体相变与马氏体相变，得到了不同后刀面磨损量的白层马氏体形核密度。模拟得到的马氏体形核密度变化规律表明，减小后刀面磨损量有助于提高已加工表面白层内马氏体强度，从而提升已加工表面抗疲劳破坏性能。
关键词：高速干硬切削；白层；TEM；元胞自动机；相变
中图分类号：TG142.41；TH162文献标志码：ADOI：10.3969/j.issn.1000-7008.2019.02.005
Cellular Automata Simulation for Phase Transition of Surface
White Layer in Highspeed Dry Cutting
Duan Chunzheng，Kou Wenneng，Zhang Fangyuan
Abstract:Highspeed dry cutting has austenite transformation and martensitic transformation occurring in the surface white layer.The microstructure of austenite and martensite determines the macroscopic mechanical properties of the machined surface.In order to visualize the process of austenite transformation and martensitic transformation during the formation of the white layer，the TEM dark field images of the white layer on machined surface are obtained by TEM experiments，then the grain sizes are measured according to the images.The number of austenite nucleation is calculated by the grain size.Combining the mechanism of phase transition，a phase evolution model of cellular automata for white layer formation is established.The austenite transformation and martensitic transformation about the evolutionary process of white layer are simulated，and the martensitic nucleation density of white layer with different flank wear is obtained.The simulation result shows that reducing the flank wear can improve the strength of martensite in white layer on machined surface to improve the fatigue resistance of machined surface.
Keywords:highspeed dry cutting；white layer；TEM；cellular automata；phase transition