HW #7 7.23 (a) From the plot of yield strength versus (grain diameter)–1/2 for a 70 Cu–30 Zn cartridge brass, Figure 7.15, determine values for the constants σ 0 and k y in Equation 7.7. (b) Now predict the yield strength of this alloy when the average grain diameter is 1.0 10-3 mm. Solution (a) Perhaps the easiest way to solve for 0 and k y Shortcut key for date and time together in excel