Multi-scale strain measurements vs. grain size in aluminium
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Now days, aluminum usage is increasing in industry. This metal has good formability and mechanical properties, but combination of mechanical strength and elongation could be improved in order to enhance competition.One of the important properties of aluminum which should be increase is aluminum strength; this property is related to aluminum Strain. The objective of the current experimental trials was to investigate the influence of the different grain size on strain of Al-5.3% Mg.This project proposes a method that allows a strain ﬁeld on plane samples to be determined using the digital image correlation method. The displacement ﬁeld is approximated by an iterative process attempting to optimize the correlation between two pictures, the ﬁrst one before strain and the second one after strain. This method could be used, nowadays, for all application which need the knowledge of displacement and strain field for a plane surface. In order to have different grain sizes, it was needed to have rolling process and different heat treatments. 3 steps of rolling process 30%, 20%, 50% reduction in thickness have been done in order to have different grain sizes. Besides heat treatment have been done at several different temperatures for different times. 2 methods had been studied in this project; strain from extensometer and strain measured by digital image correlation (DIC) method. Results from the extensometer and DIC method shows that DIC method is a trust-able method to measure the strain of the sample. Another result from DIC method of samples with different grain sizes shows different stress-strain curve for samples with 10 and 70µm grain sizes.