The significance of microstructure heterogeneities on the fatigue thresholds of aluminum castings
The significance of microstructure heterogeneities on the fatigue thresholds of aluminum castings
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微观结构不均匀性对铝铸件疲劳阈值的意义
DOI：
10.1051/matecconf/201816514005
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Michels
中科院分区：
文献类型：
--
作者：
Knorre;Michels
工业串联铝铸件含有广泛的微观结构异质性，例如二次枝晶臂间距 (SDAS) 的差异、共晶硅和不同形态的金属间析出物以及不同形状和大小的孔隙率。由于技术和经济的限制，完全消除它们很难实现，这需要保守的设计，即增加壁厚以适应失效容限。为了提高铸铝产品在安全和疲劳性能方面的性能，目前的工作涉及此类结构在裂纹扩展阈值 ΔKI、雷电纯弯曲以及高周疲劳和极高周疲劳状态（HCF 和 VHCF）中的疲劳行为方面的重要性。因此，使用了取自发动机缸体 (AlSi8Cu3) 和气缸盖 (AlSi7Cu0.5Mg) 的两种汽车铸造合金以及经过 T6 调节或额外热等静压 (HIP) 的重力压铸套件 (AlSi7Mg0.3)。对于串联铸件，提取冷却速率和各自显微组织差异最大的两个位置。通过这组样本，显示了 SDAS 与 (i) 共晶硅区域、(ii) 不同出现的金属间析出物、(iii) 晶体取向以及 (iv) 与疲劳阈值相关的孔隙率相互作用的重要性，并与准无孔材料疲劳损伤机制的初步结果进行了比较。
Industrial in-series aluminum castings contain a wide range of microstructural heterogeneities like differences in secondary dendrite arm spacing (SDAS), eutectic silicon and intermetallic precipitates of varying morphologies and diverse-shaped and-sized porosity. Regarding to technical and economic limitations, the complete elimination of them is hard to achieve, which requires conservative design, i.e., increased wall thicknesses to accommodate the failure tolerance. To improve the performance of cast aluminum products concerning safety and fatigue properties, the present work deals with the significance of such structures with respect to the threshold for crack propagation ΔKI,thunder pure bending and the fatigue behaviour in the high-and very-high-cycle-fatigue regime (HCF and VHCF). Therefore, two automotive cast alloys taken from engine blocks (AlSi8Cu3) and cylinder heads (AlSi7Cu0.5Mg) and a gravity die cast set (AlSi7Mg0.3), either T6 conditioned or additionally hot isostatic pressed (HIP), were used. For in-series castings, two positions of maximal difference in cooling rate and respective microstructure were extracted. With this set of specimens, the significance of SDAS in interaction with (i) eutectic silicon regions, (ii) intermetallic precipitates in varying occurrence, (iii) the crystallographic orientation, and (iv) the porosity in correlation with the fatigue threshold is shown and compared with first results of fatigue damaging mechanisms in quasi pore-free material.
DOI：
10.1007/s00170-017-0192-6
发表时间：
2017-09-01
影响因子：
3.4
作者：
Ben Ahmed, A.;Nasr, A.;Fathallah, R.
通讯作者：
Fathallah, R.
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
D. Gross;Tom Seelig
通讯作者：
Tom Seelig