Hot compression and industrial extrusion characteristics of an as-cast Al-10Sr master alloy
Hot compression and industrial extrusion characteristics of an as-cast Al-10Sr master alloy
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DOI：
10.1016/j.jmapro.2020.11.042
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发表时间：
2021
影响因子：
6.2
通讯作者：
Zhen Zhang;Jiamin Hu;J. Teng;Jianchun Chen;Guodong Zhao;Fulin Jiang;Dingfa Fu;Hui Zhang
中科院分区：
文献类型：
--
作者：
Zhen Zhang;Jiamin Hu;J. Teng;Jianchun Chen;Guodong Zhao;Fulin Jiang;Dingfa Fu;Hui Zhang
添加Al-Sr中间合金可以改善共晶硅的结构和形貌，显著提高Al-Si基合金的力学性能和铸造性能。研究发现，在Sr变质过程中，Al-Sr中间合金中Al_4Sr相的尺寸是影响变质效果的关键。为了获得最佳的工艺参数和了解Al 4Sr相在塑性变形过程中的细化机理，系统研究了铸态Al-10 Sr中间合金的热压缩和工业挤压特性。结果表明，Al-10 Sr中间合金的流变行为可用本构方程描述，其热变形激活能为222.23 kJ/mol。从建立的加工图中得到的最佳加工区域位于温度为460-530 °C和应变速率为0.2-1 s-1。在热压缩过程中，塑性变形主要发生在软质Al基体中，Al 4Sr相轻微破碎。在工业挤压过程中，采用上述最佳工艺条件，有效地细化了Al 4Sr相。与常规挤压工艺相比，重复Conform挤压工艺具有更好的细化Al 4Sr相的能力。经过3道次连续变形后，Al 4Sr相的长度从80 μm减小到11μm，宽度从25.6 μm减小到8.3μm，且分布均匀。通过显微组织观察和有限元分析，探讨了Al 4 Sr相在塑性成形过程中的深度细化机制。
The mechanical properties and castability of Al-Si-based alloys can be remarkably improved by adding Al-Sr master alloy, which modifies the structure and morphology of eutectic silicon. The size of Al4Sr phases in Al-Sr master alloy has been found to take key effect in Sr-modification. To obtain optimized processing parameters and understand the refinement mechanisms of Al4Sr phases during plastic deformation, the hot compression and industrial extrusion characteristics of an as-cast Al-10Sr master alloy were systematically investigated in this work. The results showed that the flow behavior of the Al-10Sr master alloy can be well described by a constitutive equation with the hot deformation activation energy of 222.23 kJ/mol. The obtained optimum processing region was located at temperature of 460–530 °C and strain rate of 0.2–1 s−1from the established processing maps. During hot compression testing, plastic deformation mainly occurred in soft Al matrix and the Al4Sr phases were slightly broken. During industrial extrusion process, the Al4Sr phases were refined effectively based on the above optimum processing conditions. Comparing to conventional extrusion process, repetitive Conform process showed better ability in refining Al4Sr phases. After three repetitive Conform passes, the length of Al4Sr phases decreased from 80 to 11μm and the width decreased from 25.6 to 8.3μm, and the Al4Sr phases were also distributed homogeneously. The in-depth refinement mechanisms of Al4Sr phases during plastic forming were also discussed based on microstructural examinations and finite element analysis.