Porosity quantification for ductility prediction in high pressure die casting AM60 alloy using 3D X-ray tomography
Porosity quantification for ductility prediction in high pressure die casting AM60 alloy using 3D X-ray tomography
复制标题
使用 3D X 射线断层扫描对高压压铸 AM60 合金的延展性进行量化预测
DOI：
10.1016/j.msea.2019.138781
复制
发表时间：
2020-01-20
期刊：
影响因子：
6.4
通讯作者：
Liu, Qing
中科院分区：
文献类型：
--
作者：
Zhang, Yongfa;Zheng, Jiang;Liu, Qing
孔隙率在决定镁合金高压压铸件的延展性方面起着重要作用。在这项工作中，采用 X 射线断层扫描 (XRT)、断口分析和数字图像相关 (DIC) 来了解薄壁 AM60 合金高压压铸件中各种孔隙特征（特别是孔隙率空间分布和形态）与延展性之间的相互关系。结果表明，在 20 个研究样品中检测到大量孔隙。孔径遵循三参数对数正态分布。在检测到的孔隙中，小孔隙（等效直径425μm）占孔隙总体的比例很低，约为1%，仅占孔隙体积的5%左右。对于孔隙率的厚度方向分布，观察到由集中孔隙率组成的两个缺陷带。皮层和岩心内均存在大量随机分布的孔隙，岩心内也存在一些较大的孔隙（当量直径>425μm）。此外，沿拉伸轴，以局部孔隙率和孔径大小显示不均匀孔隙率分布。利用XRT数据对20个样品进行了拉伸试验和DIC测量，分析了局部孔隙率、孔隙尺寸和位置等孔隙各种参数对延展性的影响。可以看出，虽然孔隙的位置和大小会影响变形的不均匀性，从而影响延性，但断裂段的局部孔隙度在决定延性方面起主要作用。因此，延展性可以被认为是断裂段局部孔隙率的函数。此外，虽然在拉伸试验前很难获得断裂段的局部孔隙率，并且不能据此预测延展性，但伸长率与规格中最高局部孔隙率之间存在明显的相关性，可以在拉伸试验前获得，从而可以据此估计延展性。
Porosity plays an important role in determining the ductility in magnesium alloy high pressure die castings. In this work, X-ray Tomography (XRT), fractographic analysis and Digital Image Correlation(DIC) have been implemented to understand the inter-relation between various pore characteristics, specifically porosity spatial distribution and morphology, and the ductility in thin-wall AM60 alloy high pressure die casting. The results show that a great amount of porosity was detected in the 20 studied samples. The pore size follows the three-parameter lognormal distribution. Among the detected porosity, small porosity (equivalent diameter 425 pm) accounts for a very low percent of the porosity population, namely similar to 1%, and only occupies similar to 5% of the volume of porosity. For through-thickness distribution of porosity, two defect bands were observed consisting of concentrated porosity. A great amount of pores randomly distributed pores in the skin and core, and some large pores (equivalent diameter >425 pm) are presented in the core. In addition, along tensile axis, heterogeneous porosity distribution is displayed in terms of local porosity and pore size. Tensile test coupled with DIC measurement has been conducted for the twenty samples with XRT data and the influences of various parameters of pore, including local porosity, size and position of pore, on the ductility have been analyzed. It can be seen that the local porosity in the fracture segment plays the primary role in determining the ductility, although the location and size of pore have effect on deformation heterogeneity and thereby affect the ductility. Therefore, the ductility can be considered as a function of the local porosity in the fracture segment. Moreover, though it's difficult to obtain the local porosity in the fracture segment prior to tensile test and the ductility can't be predicted based on it, there is a clear correlation between the elongation and the highest local porosity in the gauge, which can be got before tensile test, and thus ductility can be estimated accordingly.