Probability characterization of tensile strength of an aluminum casting

Abstract

The paper statistically studies fracture properties of an aluminum low-pressure die casting component on basis of 32 tensile tests on round bar specimens. It reveals that the probability distribution of both ultimate tensile strength and fracture strain can be described using either the Weibull or the Gaussian function. Goodness-of-fit tests based on the Anderson–Darling statistic fail to reject either of them. However, the extrapolation of the distribution of the fracture strain to a probability level of 0.01% gives an unrealistic low or even negative lower-bound value. This suggests that a pass of the goodness-of-fit tests is not sufficient for identifying a physically reasonable probability distribution. At the same time, three different methods for determining the tensile fracture strain are compared: the area reduction of the fracture surface, the critical elongation of the gauge section, and the combined experimental–numerical analysis. The first one gives the most reasonable estimate. It is also found that the ultimate tensile strength linearly correlates with the projected area of pores.