EFFETTI DEI TRATTAMENTI DI FINITURA SULLE PROPRIETÀ MECCANICHE DI GETTI STRUTTURALI PER APPLICAZIONI IN CAMPO AUTOMOTIVE

Aim of this work is to investigate the effect of adhesive bonding and painting operations performed on B356 T6 aluminum alloy castings. Some parts were produced by gravity casting in steel permanent mold, and were thus treated using three different aging time-temperature combinations according to industrial practice. The castings were then submitted to some thermal cycles to simulate the finishing stages of the production (bonding and painting): such operations are usually performed at temperatures which, in some steps, are close or above to those used during the aging heat treatment and may therefore somehow modify the properties of the castings. In order to validate this hypothesis, the mechanical properties before and after the finishing steps were evaluated both on specimens machined from the castings and on separately cast tensile samples. Time and temperature test parameters were selected through the analysis of the industrial cycle. The results of the experimental tests are showing that the mechanical properties can be influenced by the exposure to those times and temperatures. The analysis of the collected data, moreover, shows as the difference of mechanical properties between the three levels of elongation is reduced with the progress of the finishing process, up almost to zero once reached the end of the production cycle.