Microstructural evolution and anisotropic tensile properties of a bimodal 6A02 Al semi-solid billet
Microstructural evolution and anisotropic tensile properties of a bimodal 6A02 Al semi-solid billet
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双峰 6A02 Al 半固态坯料的微观结构演变和各向异性拉伸性能
DOI：
10.1016/j.jallcom.2022.164937
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发表时间：
2022-04
影响因子：
6.2
通讯作者：
Minjie Huang
中科院分区：
文献类型：
--
作者：
Ying Zhang;Jufu Jiang;Ying Wang;Yingze Liu;Minjie Huang
研究了等温温度和等温时间对双峰6A02 Al半固态坯料显微组织和各向异性力学性能的影响。这些半固态坯料是通过热挤压铝合金半固态等温处理（SSITHEAA）方法制造的。具有不同位错密度的细长晶粒和等轴晶粒在 610–650 °C 共存 5–30 分钟。随着温度的升高，显微织构和晶内位错的强度降低。横向的平均施密德因子仍然大于沿挤压方向的平均施密德因子，初步从晶粒取向的角度预测了各向异性特征。双峰半固态显微组织的各向异性特征首先通过0°、45°和90°方向的单轴拉伸试验得到验证，其中610°C/20 min的0°试样表现出最高的拉伸强度和延展性（屈服强度σy为103.8 MPa，最大拉伸强度σmax为286.9 MPa，伸长率δ为22.0%）。与固态温度下的显微组织不同，一旦晶界被液相浸泡，再结晶会在一定程度上降低半固态显微组织的机械强度。变形晶粒内部的位错强化和固溶强化是两种主要的强化机制。此外，拉长的晶粒通过晶粒内部的位错堆积、“桥接”效应、“颈缩”效应以及减少缺陷和液相含量来改善机械性能。面内各向异性（IPA）因子表明伸长率各向异性最为严重。总体而言，650℃/20min钢坯的各向同性最好，对应的σy、σmax和δIPA值分别为21.9%、26.2%和47.0%。对于 0° 试样，韧性断裂占主导地位，但对于 45° 和 90° 试样，脆性特征越来越显着。
The effects of isothermal temperature and duration on the microstructures and anisotropic mechanical properties of bimodal 6A02 Al semi-solid billets were studied. These semi-solid billets were fabricated by semi-solid isothermal treatment of hot extruded aluminum alloy (SSITHEAA) method. Elongated and equiaxed grains owning different dislocation densities coexisted at 610–650 °C for 5–30 min. With the increase of temperature, the intensities of micro-textures and intragranular dislocation decreased. The average Schmid factors in transverse directions were still larger than those along extruding directions, preliminarily predicting anisotropic features from the perspective of grain orientation. The anisotropic features of bimodal semi-solid microstructures were verified firstly by uniaxial tensile tests in 0°, 45°, and 90° directions, among which 0 ° specimen at 610 °C/ 20 min exhibited the highest tensile strength and ductility (yield strength σyof 103.8 MPa, maximum tensile strength σmaxof 286.9 MPa, and elongation δ of 22.0%). Different from microstructures at solid temperatures, recrystallization degraded mechanical strength of semisolid microstructures to some degree once the grain boundaries were soaked with liquid phase. The dislocation strengthening inside the deformed grains and solid solution strengthening were two dominant strengthening mechanisms. Besides, the elongated grains improved the mechanical properties through dislocation pileup inside the grains, “bridging” effect, “necking” effect and decreasing the content of both flaws and liquid phase. The in-plane anisotropy (IPA) factor indicated that the elongation bore the most serious anisotropy. On the whole, the isotropy of 650 °C/20 min billet was the best, and the corresponding IPA values of σy, σmaxand δ were 21.9%, 26.2%, and 47.0%, respectively. For 0° specimens, ductile fracture was dominant, but brittle characteristic was increasingly significant for 45° and 90° specimens.
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DOI：
10.1016/j.jmrt.2021.03.061
发表时间：
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期刊：
Journal of Materials Research and Technology
影响因子：
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影响因子：
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作者：
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DOI：
10.1016/j.msea.2020.140387
发表时间：
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影响因子：
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