Mechanical characterisation and quality index of A356-type aluminium castings heat treated using fluidised bed quenching

Abstract

The current study aimed at investigating the effect of fluidised sand bed quenching on the mechanical performance and quality index of A356·2 aluminium cast alloys. Traditional water and conventional hot air quenching media were used to establish a relevant comparison with fluidised sand bed quenching. Quality charts were generated using two models of quality indices to support the selection of material conditions on the basis of the proposed quality indices. The use of a fluidised sand bed for the direct quenching aging treatment of A356·2 casting alloys yields greater UTS and YS values compared to conventional furnace quenched alloys. For the same aging conditions (170°C/4 h), the fluidised bed quenched aged 356 alloys show nearly the same or better strength values than those quenched in water and then aged in a CF or an FB. Based on the quality charts developed for alloys subjected to different quenching media, higher quality index values are obtained by water quenched T6-tempered A356 alloys. Using hot sand as a quenching medium at different temperatures, namely 170, 190 and 210°C, reduces both the strength and the quality with increase in quenching temperature for the alloys investigated. The regression models indicate that the eutectic silicon modification factor has the most significant effect on the quality results of the alloys investigated, for all heat treatment cycles, as compared to other metallurgical parameters.