Development of new Al-Si9Cu3 alloys for HPDC components with tailored properties

Aluminium high pressure die casting (HPDC) is the most common process in order to produce aluminium castings, due to the excellent balance of cost and properties for high series production volumes. The AlSi9Cu3 is the most common used aluminium alloy, representing approximately the 70% of the HPDC produced parts. AlSi9Cu3 alloys Nevertheless, conventional AlSiCu3 alloys present certain limitations in terms of mechanical properties attainable due to the intrinsic porosity of HPDC castings as well as the alloy composition. New process variants and alloys have been developed in recent years trying to improve these aspects. AlSi9Cu3 standards have a wide range for alloying elements, that can vary for example in the AlSi9Cu3(Fe) EN-AC 46000 from 8-11% in the Silicon alloying element. For HPDC the standard properties are Elongation (E) < 1%, Yield strength (Y.E.) 140 MPa, Tensile Strength (T.S.) 240 Mpa and Hardness <80 HB. The present work approaches the development of new alloys similar to the AlSi9Cu3 alloys, but with tailored properties in function of the desired requirements. Specific ranges of compositions provide improvements in the elongation, yield strength, ultimate tensile strength and hardness and also combinations of them. As cast properties shows an alloy with E > 1%, Y.S. >200 MPa, T. S. >320 Mpa and Hardness >135 HB.