Analysis of variability in tensile ductility of a semi-solid metal cast A356 Al-alloy
Analysis of variability in tensile ductility of a semi-solid metal cast A356 Al-alloy
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DOI：
10.1016/j.msea.2004.09.051
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发表时间：
2005-02-15
期刊：
影响因子：
6.4
通讯作者：
Patel, GR
中科院分区：
文献类型：
--
作者：
Gokhale, AM;Patel, GR
研究了半固态铸造A356铝合金(Al-7wt.%Si-0.5wt.%镁基合金)拉伸试件的延性变异性。塑性的变异性与三维组织中的树枝晶尺寸、硅颗粒尺寸和孔隙率等全球平均组织参数无关。拉伸断口表面含有微缺陷，本质上是变质剂、助熔剂、细粒剂和脱模剂的残留物：能量色散分析表明，这些缺陷中存在0、Na、K、C、Cl、Ca、Fe、Ti和S等元素。断裂路径优先穿过包含缺陷的区域。采用扫描电子显微镜、定量断口分析等方法，估算拉伸试件断口中此类缺陷的总面积分数。拉伸延性百分数e与相应断口缺陷的面积分数f有很强的定量相关性，可以用以下简单的公式表示：e=e(0)[1-f](N)在这个方程式中，Eo和n是经验常数。对于本数据集，EO等于11.5%，n等于41.66。因此，可以通过更好的工艺控制来减少加工缺陷的数量，从而降低延展性的可变性。(C)2004爱思唯尔B.V.保留所有权利。
Variability in the ductility of tensile test specimens of semi solid process cast A356 Al-alloy (Al-7 wt.% Si-0.5 wt.% Mg-base alloy) is examined. The variability in the ductility does not correlate to the global average microstructural parameters such as dendrite cell size, Si particle size, and amount of porosity in the three-dimensional microstructure. Tensile fracture surfaces contain micro-defects that are essentially residues of modifiers, fluxes, grain refiners, and mold release agents: the energy dispersive analysis shows presence of elements such as 0, Na, K, C, Cl, Ca, Fe, Ti, and S in these defects. The fracture path preferentially goes through the regions containing the defects. Scanning electron microscopy, quantitative fractography was used to estimate the total area fraction of such defects in the fracture surfaces of the tensile test specimens. The percent tensile ductility e shows strong quantitative correlation with the area fraction of the defects f in the corresponding fracture surfaces, which can be represented by the following simple equation.e = e(0)[1 - f](n)In this equation, eo and n are empirical constants. For the present data set, eo is equal to 11.5% and n is equal to 41.66. Thus, the variability in the ductility can be decreased through a reduction in the amount of processing defects via better process control. (C) 2004 Elsevier B.V. All rights reserved.