Effect of Zn and Mg Content on Crashworthiness of Al-Zn-Mg Alloy Thin-Walled Square Extrusions

Abstract

The effects of Zn and Mg content in thin-walled square extrusions of Al-Zn-Mg alloys on its crashworthiness were investigated, and the correlation between the crushing properties, mechanical properties, and microstructures of the profiles were investigated. The results showed that the strength and the compression properties were gradually increased with a decrease in the Zn/Mg ratios (from 12.48 to 4.57). When the Zn/Mg ratio is lower (less than 6.29), an increase in the Mg content simultaneously improves the alloy strength and the compression properties. An increase in Zn content (from 5.07 to 6.77) can improve the strength of the alloy however, it does not affect the compression properties. However, the higher Zn contents (6.77%) would lead to cracking in advance during the compressing, which reduces the compression energy absorption capacities of the product. Therefore, in order to obtain higher strength and excellent compression properties, the Zn/Mg ratio should be reduced. For the upper limit, the Zn content should not be too high (less than 6.77), as this may lead to early cracking and failure. For the lower limit, the Mg content should be higher (more than 0.91) to make sure that the alloy has excellent compression properties and higher strength.

Sustainability through Optimal Compositional and Thermomechanical Design for the Al-7XXX Alloys: An ANOVA Case Study

“…The chemical compositions were optimized based on the existing literature, aiming for grain refinement and enhanced performance. Alloy 1, the base, contained 6% Zn, 0.98% Mg, and 0.8% Cu, following a favorable Zn/Mg ratio of 6 (supported by [67][68][69]) and an optimal Cu content for Al7xxx series alloys (as indicated by [70][71][72]). Alloys 2, 3, and 4 were derived by introducing 0.2%, 0.4%, and 0.6% Hf, respectively, to investigate their impact on the microstructure and behavior of thermomechanical treated alloys.…”