(1. 廣西科技大學 職業(yè)技術教育學院，柳州 545006；
2. 廣西科技大學 機械工程學院，柳州 545006；
3. 廣西大學 機械工程學院，南寧 530004；
4. 廣西大學 土木建筑工程學院，南寧 530004)
摘 要: 為了揭示鎂合金晶體微結構與孿生變形之間的關聯(lián)性，采用偽滑移模式描述孿生變形，建立包含滑移與孿生變形機制的晶體塑性本構關系，推導以剪切應變率作為自變量的本構方程牛頓-拉普森迭代式。采用基于體素方法建立的多晶三維微結構有限元模型，對擠壓鎂合金材料沿擠壓方向加載的單軸拉伸和壓縮變形行為進行模擬。模擬結果表明，單軸加載下模擬與試驗的材料宏觀硬化行為基本吻合，及壓縮變形的模擬織構演化與試驗織構演化也基本趨同。對多晶體內基本物理量的統(tǒng)計分析表明，該模型能夠展現(xiàn)多晶內的應力應變、孿晶體分數在空間的不均勻分布特性，而孿晶體分數分布與晶粒尺寸、晶界位向角及晶界傾角等微結構之間缺乏確切的關聯(lián)性，表明非均勻微結構所導致的獨特應力非均勻狀態(tài)并不是出現(xiàn)孿生變形與微結構強關聯(lián)性的原因。
關鍵字: 鎂合金；孿生變形；微結構；塑性本構模型；織構
（1. School of Vocational and Technical Education, Guangxi University of Science and Technology, Liuzhou 545006, China;
2. School of Mechanical Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China;
3. School of Mechanical Engineering, Guangxi University, Nanning 530004, China;
4. College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China）
Abstract:In order to discover the relationship between the twinning deformation and microstructure in Mg alloy, describing twinning by pseudo-slip mode, the crystal plastic constitutive relation including slipping and twinning was established. And the Newton-Raphson iteration method was developed with the shear strain rate directly as the basic variables of iteration. The deformation behaviors of extruded Mg alloy loaded by uniaxial tension and compression along the extrusion direction were simulated using the finite element model of polycrystal based on voxel algorithm. The simulation results show that the macroscopic hardening behaviors predicted using the proposed model are in good agreement with the experimental results, and there are the same evolutions of polycrystalline texture during testing and simulating for Mg alloy. The statistical analyses of principal physical variables show that the proposed constitutive model is available to demonstrate the inhomogeneous characteristic of spatial distribution of stress-strain, the fraction of twinning in polycrystal, but there is a short age of the explicit relatedness of the volume fraction of twinning with respect to grain size, the misorientation between grain boundary plane normal and loading direction, the grain boundary misorientation angles in polycrystal, respectively. It is shown that the inhomogeneous state of unique stress resulted from the inhomogeneity of microstructure is not the reason for the strong relatedness between twinning deformation and microstructure.
Key words: magnesium alloy; twinning deformation; microstructure; plastic constitutive model; texture
