The main objective of this study was to evaluate the performance of 354-type Al-Si-Cu-Mg cast alloys at both ambient (25 °C) and elevated temperatures (250 °C) through the addition of zirconium (Zr), nickel (Ni) and manganese (Mn). The motive behind these additions was to develop thermally stable alloys capable of resisting softening instigated by prolonged exposure at elevated temperatures and hence preserve acceptable mechanical properties. Another parameter affecting performance is geometry. Four different notch geometries were employed: two hole-type geometries and two types of V-notches (symmetric and asymmetric for each). The results reveal that the presence of asymmetric notches in the tensile test bars proved to be more deleterious than symmetric notches to the notch tensile strength and percentage elongation to fracture at both 25 °C and at 250 °C. The softening that took place during tensile testing at 250 °C rendered the alloys some ductility (in particular, the M1S (354 + 0.3 wt.% Zr), M2S (354 + 0.3 wt.% Zr + 2 wt.% Ni) and M3S alloys (354 + 0.3 wt.% Zr +0.75 wt.% Mn)), as a result, the notched tensile bars with asymmetric holes exhibited high strength values for these alloys compared to the tensile strength of unnotched bars subjected to similar heat treatment conditions owing to the presence of notches. The notch sensitivity ratios vary between 0.78 and 0.95 for asymmetric holes versus 0.7 and 0.85 for asymmetric V-notches at room temperature and 0.9 and 1.07 for asymmetric holes versus 0.7 and 0.92 for asymmetric V-notches at 250 °C.

这项研究的主要目的是评价354型铝的表现-通过添加锆（Zr），镍（Ni）和锰（Mn）在环境温度（25°C）和高温（250°C）下生产Si-Cu-Mg合金。这些添加物的动机是开发能够抵抗因在高温下长时间暴露而引起的软化的热稳定合金，并因此保持可接受的机械性能。影响性能的另一个参数是几何形状。使用了四种不同的槽口几何形状：两种孔型几何形状和两种类型的V型槽孔（每种对称和不对称）。结果表明，在25°C和250°C下，拉伸测试棒中不对称缺口的存在对缺口拉伸强度和断裂伸长率的影响比对称缺口更为有害。在250°C的拉伸试验过程中发生的软化使合金具有一定的延展性（特别是M1S（354 + 0.3 wt。％Zr），M2S（354 + 0.3 wt。％Zr + 2 wt。％Ni）和因此，M3S合金（354 + 0.3 wt。％Zr + 0.75 wt。％Mn））与经过类似热处理的无缺口钢筋的抗拉强度相比，具有不对称孔的缺口抗拉钢筋显示出较高的强度值由于存在缺口而导致的情况。在室温下，不对称孔的陷波灵敏度比在0.78和0.95之间，而在室温下，不对称V形切口在0.7和0.85之间变化，在250°C下，不对称孔的凹形灵敏度比在0.7和0.92之间，而不对称孔在0.7和0.92之间变化。结果，与由于缺口的存在而经受类似热处理条件的未缺口的钢筋的拉伸强度相比，具有不对称孔的缺口的拉伸钢筋对这些合金表现出高强度值。在室温下，不对称孔的陷波灵敏度比在0.78和0.95之间，而在室温下，不对称V形切口在0.7和0.85之间变化，在250°C下，不对称孔的凹形灵敏度比在0.7和0.92之间，而不对称孔在0.7和0.92之间变化。结果，与由于缺口的存在而经受类似热处理条件的未缺口的钢筋的拉伸强度相比，具有不对称孔的缺口的拉伸钢筋对这些合金表现出高强度值。在室温下，不对称孔的陷波灵敏度比在0.78和0.95之间，而在室温下，不对称V形切口在0.7和0.85之间变化，在250°C下，不对称孔的凹形灵敏度比在0.7和0.92之间，而不对称孔在0.7和0.92之间变化。