ys_10674_杨智强_zy.doc.docVIP

附件2 论文中英文摘要格式 作者姓名：杨智强 论文题目：大塑性变形复合挤压有限元模拟研究 作者简介：杨智强，男，1983年09月出生，2007年09月师从于昆明理工大学大学史庆南教授，于2010年06月获硕士学位。 中 文 摘 要 超细晶材料具有优异的力学性能，在保持韧性的同时，具有较高的强度，是近年来材料科学领域研究热点之一。反复镦挤（Cyclic Channel Die Compression，CCDC）和等径角挤压（Equal-Channel Angular Pressing, ECAP）都能够在不改变材料横截面积的情况下使变形试样积累较高等效应变，从而使块体材料的微观组织得到有效细化。根据该特点，将反复镦挤和等径角挤压工艺结合，提出CCDC—ECAP复合挤压大塑性变形工艺来制备超细晶材料的新思路。 基于有限元数值模拟技术，分别对问题进行了分析， 有限元软件DEFORM-3D建立三维有限元模型，进一步探索在制备过程中的变形行为，弄清楚了在时的应力、应变、金属流动大小和分布以及它们对制备超细晶的影响。，应力集中，×2.5h均匀化退火的6061铝合金分别进行了2道次等径角挤压及复合挤压实验，测量了复合挤压两个道次的挤压力，发现计算的挤压力同测量的挤压力非常相近，说明计算过程选取的参数较为准确，为模拟摩擦系数等参数的选取提供了实验支持。 变形工艺路线 CCDC-ECAP工艺在晶粒细化效果方面好，道次有部分晶粒尺寸接近μm。同时在提高屈服强度等方面也挤压一道次后屈服强度发生了明显的增长，由86MPa增长到124MPa，增长了约1.5倍。CCDC-ECAP工艺路线在细化晶粒与提高力学性能方面为CCDC-ECAP工艺路线将是可作为后续深入研究中优先考虑的复合挤压加工工艺路线。tudy on the finite element simulation of Large plastic deformation composite extrusion Yang Zhi-qiang ABSTRACT Ultrafine-grained materials have excellent mechanical properties, while maintaining toughness with high strength, which is one of the hot field of materials science research in recent years. Cyclic Channel Die Compression（CCDC）and the Equal-Channel Angular Pressing（ECAP）are two kinds of severe plastic deformation methods to make a higher accumulation of effectively equivalent strain deformation of the specimen to obtain ultrafine-grained materials without changing the material section. According to the characteristics, Combination of the Cyclic Channel Die Compression and Equal-Channel Angular Pressing obtains the ultrafine-grained materials The finite element numerical simulation techniques were used in the paper. The stress field, strain field, metal flow velocity field, squeezing pressure have been analyzed respectively in process of equal channel angular extrusion and composite extrusion . The maximum equivalent strain of the specimen processed two passes by CCDC?ECAP is 10.1 while the maximum equivalent strain of the specimen processed two passes by the single ECAP is 7.82 . The equivalent strain distribution of CC