【作者】 王裕；

【导师】 梁伟；

【作者基本信息】 太原理工大学 ， 材料学， 2006， 硕士

【摘要】 为进一步探索纯铜和纯铝在等通道转角挤压(ECAE)过程中的变形行，弄清这两种面心立方金属等通道转角挤压时的应力、应变及应变速率的大小和分布，本文借助有限元软件DEFORM-3D对其变形过程进行了有限元数值模拟。模拟结果表明：1．摩擦对试样在ECAE时的变形行为有很大的影响，当无摩擦时，棒料不能完全填充模具的内腔，在通道的外拐角处产生一未填充的“死角”；当有摩擦存在时，棒料可以紧贴着模腔内壁流动，同时在棒料的头部和尾部有“毛刺”出现。2．等效应力曲线的变化趋势是先迅速上升到最大值，接着有个瞬间的快速下降，然后又快速上升到最大值，保持一段时间后又逐渐下降，试样中大部分区域的应力状态为压应力，而在试样转角后的上表面，应力状态为拉应力，因而断裂很容易从此处发生。3．试样内部等效应变的变化过程主要可以分三个阶段：①缓慢增长阶段，②迅速增长阶段，③平缓阶段。4．在相同的摩擦条件下，挤压速度越大，变形越均匀；5．在主要剪切变形区，外转角附近的变形量最大，流动速度最慢；而在内转角处的等效应变速率最大。6．ECAE的挤压力很大一部分是用来克服摩擦力的。7．纯铜的应变分布比纯铝更均匀，且纯铜的塑性流动比纯铝更一致。 为了和模拟结果形成对照，本文采用与模拟相同的参数对纯铜和纯更多还原

【Abstract】 In this dissertation, finite element modeling of Equal Channel Angular Extrusion (ECAE) was conducted using the DEFORM-3D code to obtain a better understanding of the plastic deformation behavior of T2-copper and pure aluminum during ECAE in terms of the values and distributions of stress, strain and strain rate. The results are as follows: 1. Friction conditions deeply affect the deformation behavior of the billet during ECAE. Low friction conditions carry out a partial filling, creating a "dead zone" in the outside corner of the die. On the other hand, high friction conditions assure a complete filling of the outside corner, but the "flash" is appeared at the head and the rear of the billet. 2. The variation tendency of effective stress is complied with the following laws: the effective stress curve rapidly reaches a peak point followed by a sudden drop. Afterwards, it rises to the maximum again and keeps for a time, and then falls down gradually. The stress state is compressive in the most part of the deformation zone, but the tensile stress is predicted on the top surface of the billet adjacent to the exit channel of the die,更多还原