A New Method for Eliminating Peripheral Coarse Grain Structure Formed in the Solution Treatment of 7136 Aluminum Alloy: Strain Solution
ZHAO Fan, HE Ying, ZHANG Zhihao*
Key Laboratory for Advanced Materials Processing (MOE), Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
Abstract: The peripheral coarse grain (PCG) structure is a kind of typical defect in the extruded high strength aluminum alloys. A new method which called strain solution, is capable of eliminating the PCG structure formed in the solution treatment of 7136 aluminum alloy. Before two-stage solution (450 ℃/2 h + 470 ℃/4 h), the alloy samples were deformed to introduce various tensile strains at 420 ℃ and then kept at the same temperature for 2 h. It can be found in the two-stage solution-treated sample that the depth of PCG structure varied inversely with tensile strain introduced during strain solution, and that PGG could be eliminated when the strain introduced reached 4.6%. The strain solution consumes and releases the stored deformation energy at a relatively low temperature, and consequently, suppresses the coarsening of particles at the edge of extrusion during the two-stage solution treatment. As a result, the recrystallization behavior is regulated. This mechanism was supported by TEM and EBSD measurements of the sample which experienced strain-solution (4.6% strain) treatment prior to two-stage solution treatment, and the sample which was directly two-stage solution-treated: the former had a recrystallization volume fraction at the edge of 49.5%, fairly lower than that of the latter (76.4%), and also was spared from the generation of PGG structure for the growth of the recrystallized grains which formed fine equiaxial grains. In addition, the introduction of strain-solution treatment led to a slight reduction of material hardness, while a substantial amount of the [111]-oriented (i.e. parallel to the extrusion direction) grains were retained at the center of the sample.
赵帆, 何颖, 张志豪. 消除7136铝合金固溶热处理粗晶环的新方法:应变固溶[J]. 材料导报, 2021, 35(14): 14079-14083.
ZHAO Fan, HE Ying, ZHANG Zhihao. A New Method for Eliminating Peripheral Coarse Grain Structure Formed in the Solution Treatment of 7136 Aluminum Alloy: Strain Solution. Materials Reports, 2021, 35(14): 14079-14083.
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