lution treated condition, to 1.1 in the T4 temper. This cor- responded to a decrease in the mean, high and low values of Ef
creased to 0.6, simultaneously to increases in the mean, high and low values recorded.
, for the T4 treated alloy. This trend continued in the T6 temper (Table 4), where the value of σ(sd)
for Ef
somewhat different for those observed for the differences in σ(sd)
The trends observed for the differences in σ(sd) for Ef = 8.1,
condition had a value of σ(sd) values of σ(sd)
Table 4), the T4 and solution treated conditions show simi- lar, higher values (σ(sd)
do show a small variability for 0.2% proof stress, the differences were not significant.
~12.2, Table 2 and 3), and the as-cast = 9 (Table 1). Although the
were
for tensile strength. Here, the T6 temper displayed the lowest spread in the data for tensile strength (σ(sd)
Weibull Analysis now de-
sponding failure probability plots are shown in Figure 3 (b) and (d). A summary of the values for Weibull modulus and position parameter for all results are provided in Table 5.
When the material was solution treated, the Weibull modu- lus decreased for both tensile strength and Ef
. This means
that in this solution treated condition, the spread of results increased and hence the flaw size distribution increased, but, as shown by the failure probability plot for elonga- tion (Figure 3[d]), for example, the position parameter (the
The tensile data were evaluated further using Weibull statis- tics. Plots showing the derivation of Weibull modulus, m for the four conditions with either tensile strength or elongation at failure, Ef
are shown in Figure 3 (a) and (c). The corre-
(a)
(c)
(b) specific levels of Ef
(d)
Figure 3. a) Values of Weibull modulus [m] for tensile strength, b) corresponding probability of failure for specific levels of tensile strength, c) values of Weibull modulus for Ef
, and d) corresponding probability of failure for . In (b) and (d), the values of position parameter, are marked with the symbols corresponding to each condition. The legend for all plots is provided in (c). International Journal of Metalcasting/Fall 2011 51
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