The different dependencies of the mechanical properties and microstructures on hot extrusion and artificial aging processing in case of the alloys Al 7108 and Al 7175
The different dependencies of the mechanical properties and microstructures on hot extrusion and artificial aging processing in case of the alloys Al 7108 and Al 7175
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DOI：
10.1016/j.jmatprotec.2016.02.012
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发表时间：
2016-07-01
影响因子：
6.3
通讯作者：
Reimers, W.
中科院分区：
文献类型：
--
作者：
Paulisch, M. C.;Lentz, M.;Reimers, W.
为了优化几乎无铜合金7108和含铜合金7175的强度和塑性，研究了不同参数的挤压工艺和随后的人工峰时效工艺对其强度和塑性的影响。这项工作分为三个步骤。第一步，研究了挤压比、成形速度和坯料温度对7108和7175合金挤压性能的影响。第二步，在水淬条件下对所得钢绞线进行分析，研究形貌和织构与力学性能的关系。最后进行了峰时效，分析了挤压工艺参数对合金析出行为和力学性能的影响。采用光学显微镜、x射线衍射和电子背散射衍射相结合的方法对其形貌和织构进行了分析。用扫描电镜和透射电镜对颗粒和析出物进行了分析。此外，还通过压缩和拉伸试验测量了材料的力学性能。研究表明，7108合金在较宽的参数范围内是可挤压的，并且该合金的力学性能可以通过人工时效工艺参数来改变和优化。因此，挤压工艺与人工时效相结合，使断裂伸长率达到17.4 +/- 0.2%，强度达到426 +/- 1mpa。在含cu合金7175的情况下，挤压过程被限制在较低的产品速度，因为通过塑性变形引入的温升在这种合金中更高。因此，共晶相形成并引起型材的热裂。研究表明，挤压工艺对含cu合金7175的力学性能影响较大。结果表明，采用高坯料温度的挤压工艺，其塑性可达14.5 +/- 0.5%，强度可达636 +/- 4mpa。(C) 2016 Elsevier B.V.版权所有
In view of optimizing the strength and the ductility of the almost copper-free alloy 7108 and the copper-containing alloy 7175 the influences of extrusion processes with different parameters and subsequent artificial peak aging procedures have been studied. The work was divided into three steps. In the first step the extrusion ratios, the product speeds and the billet temperatures have been varied and their influence on the extrudability of the alloys 7108 and 7175 were examined. In the second step the resulting strands were analysed in the water quenched condition to investigate the correlation of the morphology and the texture to the mechanical properties. In the last step the strands were subjected to peak aging, to analyse the influence of the extrusion parameters on the precipitation behaviour and the mechanical properties. For the analyses of the morphology and the texture a combination of optical microscopy, X-ray diffraction and electron backs catter diffraction has been used. The particles and the precipitates were analysed by scanning and transmission electron microscopy. In addition the mechanical properties were measured by compression and tensile tests. The investigations show that the almost Cu-free alloy 7108 is extrudable within a wide parameter field and that the mechanical properties of this alloy can be varied and optimized by the parameters of artificial aging processes. So the combination of the extrusion process and the artificial aging results in an elongation at fracture up to 17.4 +/- 0.2% and in strength values up to 426 +/- 1 MPa. In case of the Cu-containing alloy 7175 the extrusion process is limited to lower product speeds, because the temperature increment, which is introduced through the plastic deformation, is higher in case of this alloy. Therefore, eutectic phases form and cause hot cracking of the profiles. The investigation shows that the mechanical properties of the Cu-containing alloy 7175 are mainly influenced by the extrusion process. It was shown that the extrusion process using high billet temperatures leads to a ductility up to 14.5 +/- 0.5% and to strength values up to 636 +/- 4 MPa. (C) 2016 Elsevier B.V. All rights reserved.