Experimental Techniques to Characterize Large Plastic Deformations in Unlubricated Hot Aluminum Extrusion
Experimental Techniques to Characterize Large Plastic Deformations in Unlubricated Hot Aluminum Extrusion
复制标题
表征无润滑热铝挤压中大塑性变形的实验技术
DOI：
10.4028/www.scientific.net/kem.367.17
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
H. Valberg
中科院分区：
文献类型：
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作者：
H. Valberg
回顾了作者所在大学近二十年来为研究铝挤压过程中的金属流动所做的实验工作。在移除操作期间，如果不对内部图案进行后变形，则很难从容器中移除具有内部网格图案的部分挤压坯料。因此开发了一种技术，通过该技术可以在不造成任何损害的情况下将这种坯料从容器中移除。除此之外，还开发了一种特殊的栅格图案技术。该技术将对比材料条纹应用于坯料的对称面，并且是有利的，因为即使在变形非常严重的剪切区，获得的图案在挤压后仍保持清晰可见。传统的划痕图案在这些区域变得不可见，并且不能提供剪切带中的金属流动信息。当两种技术，即新去除技术和新网格技术同时使用时，进行了“完美”式的金属流动实验。还开发了一种三维网格图形技术。它非常适合在没有对称平面进行传统网格图形分析的复杂形状挤压过程中的金属流动特性。报道了金属流动研究的新技术在各种挤压情况下的应用。结果表明，在计算机模拟中，准确的金属流动信息确实是正确计算金属流动的必要条件。
A review is given of experimental work done at the author’s university during the last two decades, to investigate metal flow in aluminum extrusion. Partially extruded billets with internal grid patterns are difficult to remove from the container without post-deforming the internal pattern during the removal operation. A technique was therefore developed by which such billets can be removed from the container without any damage. In addition to this, a special grid pattern technique was developed. This technique applies contrast material stripes in the symmetry plane of the billet, and is advantageous because the pattern obtained remains clearly visible after extrusion, even in shear zones subjected to very heavy deformations. Traditional scratched patterns become invisible in such regions, and do not provide metal flow information in shear zones. When the two techniques, i.e. the new removal technique and the new grid pattern technique, were used concurrently, “perfect” type of metal flow experiments were conducted. A three-dimensional grid pattern technique was also developed. It is well suited for characterization of metal flow in complex shape extrusion, when there is no symmetry plane in which to conduct traditional grid pattern analysis. Applications of the new techniques for metal flow studies in various cases of extrusion are reported. It is shown that precise metal flow information indeed is a necessary requirement to get metal flow correct in computer simulation.