Evolution of microstructure and hardness in aluminum processed by High Pressure Torsion Extrusion
Evolution of microstructure and hardness in aluminum processed by High Pressure Torsion Extrusion
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DOI：
10.1016/j.msea.2019.138074
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发表时间：
2019-08-05
期刊：
影响因子：
6.4
通讯作者：
Gubicza, Jeno
中科院分区：
文献类型：
--
作者：
Omranpour, Babak;Ivanisenko, Yulia;Gubicza, Jeno
以AA1050铝合金为研究对象，研究了高压扭转挤压过程中铝合金的显微组织和硬度的变化规律。一次HPTE后样品中累积的等效应变在0.9和65.5之间的宽范围内变化，这取决于加工参数。HPTE导致形成梯度显微组织，其中晶粒尺寸通过增加距坯料中心轴的距离而减小。通过增加旋转速度与挤出速度的比率，该梯度显著减小。大部分的晶粒细化和硬度增加发生在接近5的等效应变下，但在接近20的应变下达到饱和水平。晶粒尺寸和硬度的饱和度分别与0.7 μ m和67 HV相似。HPTE技术可以提供与HPT获得的相似的显微组织和硬度饱和度，但在更大的样品中。因此，HPTE可以被命名为一个合适的候选人，用于实际应用，以生产块体超细晶材料与硬度显着提高。
An investigation was conducted on aluminum samples (AA1050) to study the microstructure and hardness evolution during processing by High Pressure Torsion Extrusion (HPTE). The equivalent strain accumulated in the samples after one pass of HPTE varied in a wide range between 0.9 and 65.5, depending on the processing parameters. HPTE led to the formation of a gradient microstructure in which the grain size decreased by increasing the distance from the central axis of the billets. This gradient decreased significantly by increasing the ratio of rotational speed to extrusion speed. Most of the grain refinement and hardness-increase occurred up to the equivalent strain of similar to 5 but saturation level was achieved at the strain of similar to 20. Saturation levels in grain size and hardness were similar to 0.7 mu m and similar to 67 HV, respectively. HPTE technique can provide similar saturation in microstructure and hardness as those obtained by HPT but in much larger samples. Therefore, HPTE can be a named as a suitable candidate for practical applications to produce bulk ultrafine-grained materials with considerable enhancement in hardness.