Linking spectrograph to mechanical and physical properties of X7475 experimental alloys produced from recycling beverage cans for bumper beam applications

Abstract

The automobile industry intends to consume more aluminium alloys in an effort to reduce the greenhouse emissions through the cut in the weight of the passenger cars. Experimental X7475 aluminium alloy is a good candidate to achieve this mission. Past efforts targeted at exploring the aluminium for bumper beam applications and even the recovery of aluminium from recycled beverage can (RBC) were not with the aim of upgrading the 3xxx to a novel 7xxx alloy. The wt.% of Zn was 5.0, 4.5 and 4.0, while Mg was left at 1.50, 1.25 and 1.00 wt.% with Mn at a peak of 0.075, 0.050 average and a least wt.% of 0.025. Alloys were homogenized and taken through annealing (O), natural aging (T4) and artificial aging (T6). The effect of hardening phases such as MgZn2 (ICDD 034-0457) due to heat treatments on the physical and mechanical properties of the new X7475 alloys was investigated. Formation of precipitates affected the density and hardness of the alloys produced via stir casting route. A least hardness of 63.40 Hv was observed in alloy H with a density of 2.7264 g/cm3 while the maximum of 113.06 Hv was recorded against alloy C in as-cast (AC). The result has contributed to the database of experimental alloys with the possibilities of producing a new material from RBCs for bumper beam applications. Future investigation should employ design of experiment (DOE) in optimization of the heat treatment for better mechanical properties.