Quality Index Charts of Al-Si-Mg Semi Solid Alloys Subjected to Multiple Temperatures Aging Treatments and Different Quenching Media.

Khaled Ahmed Ragab,X.-Grant Chen,Mohamed Bouazara

doi:10.3390/ma12111834

Abstract

The use of quality index charts is considered as an effective mean for evaluating the mechanical performance of Aluminum alloys for industrial engineering applications. The current study was carried out to investigate the influences of multiple-interrupted temperatures aging and quenching media (water versus air) on the quality index performance and precipitations evolution of A357 Aluminum semi solid alloys. Regarding the lack of similar investigations applied on such alloys, the quality index charts were generated for Al-Si-Mg semi solid castings based on its tensile properties. These charts are used to determine the quality index, in MPa, as a simple mean for compromising the strength and ductility together in one value using the Drouzy model. The multiple temperatures aging cycles were applied to improve the quality index values of Al-Si-Mg semi solid alloys for enhancing its characteristic and performance to resist the mechanical failures relating to automotive dynamic parts. The evolution of Mg2Si hardening precipitates, formed for specific thermal aging cycles, was investigated using transmission electron microscopy (TEM). The results obtained in this work revealed that the optimum quality index values were obtained by the application of T6-thermal under-aging treatment cycles. The regression models, using a statistical design of experiments, indicated that the optimum strength and high-quality index values were obtained by the application of interrupted thermal aging cycles, mainly C2,3-T6/T4/T7 conditions.

Highlights

The excellent combination of the strength and ductility of A357 (Al-Si-Mg) semi solid alloys is considered to be a key factor in selecting such castings for automotive engineering applications, e.g., suspension control arms
The semi solid casting using Swirled Equilibrium Enthalpy Device (SEED) technique and the unconventional thermal aging cycles were applied to enhance the quality of A357 alloys [1,2,3,4,5]
The quality index of aluminum castings is considered as one useful tool in the selection of thermal aging parameters of the A357 semi solid alloys used for automotive dynamic parts as suspension control arm

Summary

Introduction

The excellent combination of the strength and ductility of A357 (Al-Si-Mg) semi solid alloys is considered to be a key factor in selecting such castings for automotive engineering applications, e.g., suspension control arms. The quality of aluminum alloys is affected by several metallurgical parameters. The semi solid casting using Swirled Equilibrium Enthalpy Device (SEED) technique and the unconventional thermal aging cycles were applied to enhance the quality of A357 alloys [1,2,3,4,5]. The SEED casting technique induces optimum microstructure with globular Si particles and fragmentation of brittle Fe-rich intermetallics, e.g., β-Fe and π-Fe iron phases. Such microstructural changes positively affect enhancing the ductility of aluminum alloys, which in turn improve the quality of such materials

Methods

Results

Conclusion