Effects of cryogenic temperature and pre-stretching on mechanical properties and deformation characteristics of a peak-aged AA6082 extrusion

Abstract

Plastic deformation and surface characteristics of a peak-aged AA6082 alloy have been studied by means of tensile tests, Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), Transmission Electron Microscopy (TEM) and Atom force Microscopy (AFM). The results showed that a simultaneous enhancement in ductility and strength of the alloy was obtained at 77K in comparison with that at 295K. The enhanced properties at 77K are attributed to higher work hardening accompanied by a more homogeneous slip mode.Moreover, in order to clarify the effect of temperature-induced microstructural changes on mechanical properties, a further investigation, i.e., pre-stretching at 77K and 295K with or without subsequent annealing treatment, followed by tension to fracture at 295K, was conducted. It was found that pre-stretching at both temperatures produce a yield point and followed by different yield drop zones, while pre-stretching and annealing lead to reduced stress levels, much less pronounced yield point behavior and improved ductility compared to their predecessors. Especially, pre-straining at 77K with subsequent annealing demonstrated the highest ductility and work hardening ability among the four cases. It is thought the obtained results are associated with variety of microstructure such as strain localization, β ' /β '' ratio and dislocation densities under different conditions.

Effect of Pretreatment and Cryogenic Temperatures on Mechanical Properties and Microstructure of Al-Cu-Li Alloy

“…However, the relatively low formability at room temperature, easy wrinkle and rupture during the forming process, and easy corrosion after hot forming significantly limit their further development [5,6]. The excellent mechanical properties of the alloy not only depend on the microstructure but are also closely related to temperature [7]. The microstructure can be well regulated through an appropriate heat treatment process, thereby improving its mechanical properties [8][9][10].…”

Development of High Performance of Al Alloys via Cryo‐Forming: A Review

“…Elongation to fracture of typical Al alloys at room and below zero temperatures (data from refs. [17,39,41,43–50]).…”

“…Hussain et al [ 102 ] observed a similar trend on cryorolled and RTRed AA6061 plates that when the aging treatment was at 423 K for 68 h, the UTS and elongation increased at the same time due to the nanosized precipitates in the ultrafine grains. In addition, Yogesha et al [ 76 ] reported that the elongation and fracture toughness of the cryo‐deformed AA5052 were improved after annealing for 1 h at the temperatures between 453 and 573 K. Xu et al [ 47 ] demonstrated that prestretching at 77 K and subsequent annealing at 433 K for 5 h promoted the strength and ductility of AA6082. Joshi et al [ 34 ] found that annealing at 373 K for 45 min resulted in an improvement of the high cycle fatigue strength of cryorolled AA2014.…”

Influence of artificial aging on the electrochemical properties of the aluminium AA 6063 alloy

“…where EW is the equivalent weight of the sample in g, A is the sample area in cm 2 , d is its density in g/cm 3 , and C is a conversion constant that is dependent upon the required units. The steeper linear polarization curves means lower polarisation resistance (R p ) which is directly linked to higher corrosion currents (I corr ).…”

“…These alloys find application in the artificial aging condition, which makes it possible to obtain excellent mechanical properties. [1][2][3][4][5][6][7][8][9][10][11][12] The physical properties exhibited by aluminium alloys are significantly influenced by the treatment of the sample. In all the above-mentioned applications, alloys are prone to corrode, while also exposed to severe atmospheric environments.…”