Effect of Final Thermomechanical Treatment on the Mechanical Properties and Microstructure of T Phase Hardened Al-5.8Mg-4.5Zn-0.5Cu Alloy

Abstract

The effect of final thermomechanical treatment (FTMT) on the mechanical properties and microstructure of a T-Mg32(Al Zn)49 phase precipitation hardened Al-5.8Mg-4.5Zn-0.5Cu alloy was studied. The as-cold rolled aluminum alloy samples were subjected sequentially to solid solution treatment, pre-deformation, and two-stage aging treatment. Vickers hardness was measured during the aging process under various parameters. Tensile tests were conducted on the representative samples based on the hardness results. Microstructural characteristics were analyzed via transmission electron microscopy and high-resolution transmission electron microscopy. The conventional T6 process was also carried out for comparison. The hardness and tensile strength are increased evidently by the FTMT process for the Al-Mg-Zn-Cu alloy, while the ductility is adversely affected to a small extent. The precipitation at the T6 state consists of a coherent Guinier–Preston zone and T″ phase in the form of intragranular, fine, and spherical particles, while a semi-coherent T′ phase appears after the FTMT process as a new constituent. The distribution of dislocation tangles and isolated dislocations is another feature of FTMT samples. Enhanced precipitation hardening and dislocation strengthening account for the improved mechanical performance of FTMT samples.

Effect of Artificial Aging Treatment on the Mechanical Properties and Regulation of Precipitated Phase Particles of High-Pressure Die-Cast Thin-Wall AlSi10MnMg Longitudinal Carrier

“…Age-hardening, a heat treatment process, enhances an alloy’s strength by exploiting precipitation or dissolution behavior within an oversaturated solid solution obtained after solution treatment [ 15 , 16 ]. Artificial age-hardening techniques substantially enhance the strength of aluminum alloys after the solution treatment, with the T6 aging process manifesting the maximum mechanical strength of the alloy [ 17 , 18 , 19 ]. Lumley et al reported significant fortification of A360 to die castings, even when the solution treatment phase was executed at 450 °C for merely 15 min [ 20 ].…”