Microstructural evolution of indirectly extruded seamless 6xxx aluminum tubes with axial variable wall thickness
Microstructural evolution of indirectly extruded seamless 6xxx aluminum tubes with axial variable wall thickness
复制标题
轴向可变壁厚间接挤压无缝 6xxx 铝管的微观结构演变
DOI：
10.1016/j.jmatprotec.2015.11.024
复制
发表时间：
2016
影响因子：
6.3
通讯作者：
W. Reimers
中科院分区：
文献类型：
--
作者：
M. Negendank;U. A. Taparli;S. Gall;S. Müller;W. Reimers
在这项研究中，铝合金EN AW-6060和EN AW-6082的无缝方管挤压轴向可变壁厚，通过施加轴向可移动的阶梯心轴。研究了这些管材厚壁和薄壁截面的微观组织，并与挤压条件进行了关联。EN AW-6060的结果显示在低冲压速度（vram= 0.8 mm/s）下的纤维状颗粒，因此具有低应变速率。在这些情况下，在管表面上也观察到周边粗晶粒。应用更高的vram = 3.3 mm/s导致完全再结晶的显微组织。对于EN AW-6082，纤维微观结构占主导地位。这归因于该合金的Mn含量，其充当再结晶的抑制剂。只有在最高值的应变，应变速率和温度的再结晶组织观察到该合金。EBSD分析的边界取向差角表明，几何动态再结晶似乎是在低应变速率的主要机制。低角度晶界的数量显着减少的亚晶被删除和大角度晶界的数量增加的事实表明，再结晶发生在较高的应变速率和应变。此外，对壁厚逐渐减小的过渡区进行了研究。由于应变增加，从而增加应变速率，薄壁管段显示出比厚壁部分更低的晶粒尺寸。还揭示了PCG层厚度随着应变的增加而保持大致恒定，但是由于管壁厚度减小，再结晶分数对于更高的应变而增加。
For this study, seamless square tubes of aluminum alloys EN AW-6060 and EN AW-6082 were extruded with axial variable wall thickness by applying an axial moveable stepped mandrel. The microstructures in thick-walled and thin-walled sections of these tubes were investigated and correlated to the extrusion conditions. The results for EN AW-6060 revealed fibrous grains at low ram velocity (vram= 0.8 mm/s) and thus low strain rate. In these cases, peripheral coarse grains were also observed on the tube surfaces. Applying a highervram= 3.3 mm/s lead to a fully recrystallized microstructure. For EN AW-6082 the fibrous microstructure was predominant. This was attributed to the Mn-content of this alloy, which acts as an inhibitor for recrystallization. Only at the highest values of strain, strain rate and temperature a recrystallized microstructure was observed for this alloy. EBSD analyzes of boundary misorientation angles indicate that geometric dynamic recrystallization seems to be the predominant mechanism at low strain rates. The facts that the amount of low angle boundaries significantly decreased as subgrains were removed and the amount of high angle grain boundaries is increased revealed that recrystallization occurred at higher strain rates and strains. Furthermore, the transition areas, where the wall thickness was gradually reduced were investigated. Due to increasing strain and thus increasing strain rate, thin-walled tube segments show lower grain size than thick-walled sections. It was also revealed that the PCG layer thickness remained about constant with increased strain, but since the tube wall thickness was reduced, the recrystallized fraction increased for higher strains.
材料流动的有限元分析和间接挤压定制铝管的管尺寸表征
DOI：
10.4028/www.scientific.net/amr.922.531
发表时间：
2014
期刊：
Advanced Materials Research
影响因子：
--
作者：
M. Negendank;S. Müller;W. Reimers
通讯作者：
W. Reimers