The Influence of Two Different Casting Moulds on the Fatigue Properties of the Al–Si–Cu Cast Alloy

Abstract

The most widely used technologies for founding Al castings are sand casting and die casting (gravity casting; high pressure die casting; low pressure die casting; vacuum die casting; squeeze casting or squeeze forming). The lower cooling rate setting used for casting into a sand mould (sand casting) causes a coarse granular structure and lower values of mechanical properties. Higher cooling rate settings used for casting into a metallic mould (chill casting) causes fine-grained structures and higher values of mechanical properties. The present study provides information about the effect of casting into two different moulds on the fatigue properties of the heat treated AlSi9Cu3 cast alloy. Fatigue fracture surfaces were observed using a scanning electron microscope (SEM) after the fatigue test. The results show that the existence of casting defects and different morphologies of structural parameters (especially eutectic Si particles and Fe-rich intermetallic phases) has considerable influence on fatigue properties in both types of experimental materials. The results show that the fatigue lifetime is longer for samples casted into a metallic mould (chill casting) (average fatigue lifetime for 107 of cycles = 68 MPa) compared to casting the same materials into a sand mould (sand casting) (average fatigue lifetime for 107 cycles = 39 MPa).