method. The lower UTS and total elongations found for the U328 alloy could be addressed with a higher TSR and solution treatment temperature. Based on the U328 alloy cooling curve analysis shown in Table 2, the nucleation temperature for Cu based phase(s) reactions are closer to 529C (984.2 F), up from the 505C (941F) for the W319 alloy, used in production. It is expected that at that tem-
perature incipient melting may not occur due to the hys- teresis effect.20, 28
The main aim of this research was to improve fatigue du- rability of the engine block casting, and the control of po- rosity is the principle strategy for achieving this. Thus, as the magnitude of porosity and fatigue differences become
Figure 19. The largest pore diameter measurement for both the wedge & cast components.
300 250 200 150 100 50 0 U328 Alloy W319 Alloy W319 Alloy = Sr U328 Alloy W319 Alloy W319 Alloy = Sr
Figure 20. The monotonic properties (yield and tensile stress) from the component casting bulkhead section in the residual Sr conditions for W319 and U328 alloy, and in the 70 ppm Sr concentration for W319.
46 International Journal of Metalcasting/Fall 10
1.6 1.4 1.2 1
0.8 0.6 0.4 0.2 0
Yield & Tensile Stress Largest Pore Diameter (µm)
Total Elongation (%)
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