Investigation on the metallurgical and welding characteristics of AA7075/Fly ash composites

Abstract

This study reinforces aluminium alloy AA7075 with industrial byproduct fly ash (FA) to improve the material's metallurgical and tribological qualities. Variable amounts of fly ash were included into a high-temperature vacuum stir casting process to create metal matrix composites (viz. 0, 6, and 12 wt%). From 60 BHN (AA7075) to 80 BHN (for 12 wt% FA), the hardness of the reinforced Al alloy was pointedly increased. Although there was only a little shift in values from 263 to 251 J for impact strength, this was in direct contrast to the upward trend shown in hardness. Different process factors, including FA concentration, sliding velocity, and applied load, were examined to see how the composites worn against an EN31 hardened steel disc. Extreme abrasive grooves and brittle fracture were observed at low levels of FA (between 0 and 6 wt%), whereas mild abrasive tracked by crumbling of the protective tribo-layer was observed at higher levels of fly ash (12 wt%). Taguchi design of trials was used to find the sweet spot between the several process parameters that would result in the least amount of sliding wear. Sliding at 1 m/s with an applied load of 20 N yielded the lowest wear rate for a composite with 12 % fly ash reinforcement.