The combined effects of Sr additions and heat treatment on the microstructure and mechanical properties of high pressure die cast A383 alloy

Abstract

The combined effects of heat treatment and strontium (Sr) additions on the microstructure and mechanical properties of high pressure die cast A383 alloy components were investigated. A series of high pressure die cast engine components were produced using combined Sr additions and heat treatments. The resulting micro- and nanostructures were characterized using optical and electron microscopies. The tensile behavior was measured for material taken from the bulkhead sections of the engine bock. The results showed that Sr additions increased the elongation, but not the strength, of as-cast A383 alloys due to the refinement of the Al–Si eutectic. Heat treatment combined with Sr addition improved the strength because of the formation of fine nano-precipitates with a high number density. The results suggest that the formation of these precipitates may be affected by the Sr additions. This same combination also improved the ductility by maintaining the small size and roundness of the Al–Si eutectic particles.