Effects of natural aging and low strain-rate on mechanical properties of aluminium alloy sheets used in automotive industry

Abstract

These days, lightweight materials such as aluminum alloy sheets, especiallythose in the AA6xxx series, are in high demand for use inthe automotive industry. During natural aging, the properties of aluminummay undergo significant changes due to the diffusion of atomswithin the crystal structure, impacting the strength and formabilityof aluminum sheets. This phenomenon prompts suppliers to carefullyassess the appropriate duration of storage concerning the minimal rateof change and stability in mechanical properties. This study aims toinvestigate the effects of natural aging at room temperature on themechanical properties of two aluminum alloys AA6014 and AA6016,over predefined 10, 100, and 1000 hours. The Digital Image Correlationmethod and MATLAB employed alongside uniaxial tensile teststo estimate changes in Young’s modulus, yield strength, ultimate tensilestrength, and localized necking strain across three material anglesand three tensile load speeds during these specific time periods.Thisstudy aims to investigate the impact of natural aging on the mechanicalproperties of aluminum alloys, specifically AA6014 and AA6016with the goal of identifying the ideal storage duration that minimallyaffects their mechanical characteristics. Subsequently, it suggests therecommended strain rate for optimal time periods. To achieve thisgoal, over two hundred and sixty experiments have been conducted.How ever,the results indicated that,despite the two aluminum alloyshaving similar specifications, distinct behaviors were observed duringthe process of natural aging.Keywords: Aluminium Alloys 6014 and 6016, Mechanical properties,Strain rates, Natural aging