纯铝在步进式连续挤轧变形中的变形及晶粒细化的研究(ECAP法超细晶制备纯铝)-应用文.docVIP

纯铝在步进式连续挤轧变形中的 变形及晶粒细化的研究 单位名称：材料物理与化学研究所 专业名称：材料物理 东 北 大 学 摘要 细晶强化能够在提高材料强度的同时提高材料的塑性。在传统的细化晶粒方法中，大塑性变形方法以其可制备大块、致密的材料的同时兼有工艺简单、成本低廉等诸多优点而被广泛研究，但这些方法大多是由于一些缺陷而无法满足大规模的工业化生产。本文改进了实现材料大变形的实验装置，在有限元模拟（FEM）指导的情况下，探索了纯铝在步进式挤轧变形中的变形及晶粒细化规律。 本文首先是通过有限元模拟，发现挤轧变形时样品的推进长度、推进速度等因素对挤轧变形过程有很大的影响，模拟后得出最佳的实验条件，然后根据模拟结果改进实验装置以及实验条件。最后本文所采用装置推进长度为20mm，推进速度为5mm/s时，可以使纯铝试样顺利地发生挤轧变形,使得材料晶粒发生明显细化。模拟结果表明，在推进压力一定的条件下，样品挤轧变形速率仅和样品与轧辊间的摩擦系数有关，与轧辊的转速无关。挤轧变形及热处理实验结果表明，当挤轧道次为4道次，退火温度为200℃，退火时间为10min时，所获得的晶粒尺寸细小均匀，晶粒细化效果最好。 关键词：大塑性变形；晶粒细化；有限元分析；微观组织；纯铝。 Abstract Fine-grain strengthening can improve the plasticity and toughness of materials at the same time. In traditional method of fine grains, large plastic deformation methods are widely praised highly, for its preparation that can make large, compact material with simple process, low cost, and many other advantages. But most of these methods cannot be applied for large-scale industrial production because of some defects at last. This article improves the material experiment device of large plastic deformation, and explores deformation behavior and grain refinement of the pure aluminum in step-by-step continuous extrusion-rolling process under the condition of the finite element method guidance. This article founds some factors of extrusion-rolling deformation such as the length of pushing sample, and the velocity of pushing that has a big impact on extrusion-rolling process by finite element method. The best experimental conditions can be obtained after finite element method, This article improves the material experiment device and experiment condition according to the results of the finite element method. This article shows it can make extrusion-rolling deformation of pure aluminum sample smoothly with the equipment with 20mm-long of pushing sample and 5mm/s advancing speed; meanwhile the internal grain of material has been refined. Simulation results show that extrusion-rolling deformation rate of samples is only related with the