Instrumented impact strength tests have been carried out on KV sub-size Charpy samples drawn from A356 aluminium alloy 17-inch wheels, produced by a low pressure die casting process (LPDC). The wheels show different geometry and thermal treatment. In this paper, the effects of microstructure and defects on the impact properties are studied. In order to evaluate the amount and distribution of defects around the notch, the specimens have been analysed by means of density measurements, according to Archimedes’s principle, and X-ray investigations. Through an optical microscope, the microstructural features, such as secondary dendrite arm spacing (SDAS) and eutectic silicon particles, have been examined. A dedicated image-analysis software has been used for SDAS measurements. By means of optical and scanning electron microscopes, the fracture profile and surface of Charpy specimens have been investigated in order to identify the crack paths and to describe the characteristic morphological features of the fracture surface. Numerical simulations have been performed to study the filling and solidification behaviour of the alloy of the wheels analysed, in order to predict the final microstructure and shrinkage formation.
Impact behaviour of A356 alloy for low pressure die casting automotive wheels
MERLIN, Mattia;GARAGNANI, Gian Luca
2008
Abstract
Instrumented impact strength tests have been carried out on KV sub-size Charpy samples drawn from A356 aluminium alloy 17-inch wheels, produced by a low pressure die casting process (LPDC). The wheels show different geometry and thermal treatment. In this paper, the effects of microstructure and defects on the impact properties are studied. In order to evaluate the amount and distribution of defects around the notch, the specimens have been analysed by means of density measurements, according to Archimedes’s principle, and X-ray investigations. Through an optical microscope, the microstructural features, such as secondary dendrite arm spacing (SDAS) and eutectic silicon particles, have been examined. A dedicated image-analysis software has been used for SDAS measurements. By means of optical and scanning electron microscopes, the fracture profile and surface of Charpy specimens have been investigated in order to identify the crack paths and to describe the characteristic morphological features of the fracture surface. Numerical simulations have been performed to study the filling and solidification behaviour of the alloy of the wheels analysed, in order to predict the final microstructure and shrinkage formation.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
