The Flow Softening Behavior and Deformation Mechanism of AA7050 Aluminum Alloy

Abstract

The flow softening behavior and deformation mechanism of AA7050 aluminium alloy are investigated though hot compressive tests using a Gleebe-1500 thermal simulator at strain rates of 0.01³10 s ¹1 and temperatures of 300³450°C. The results show that the maximal relative softening transforms from 350°C to 450°C with increasing strain rate. Based on the processing maps and microstructure characterizations, dynamic recovery, dynamic precipitation and coarsening may be responsible for the softening behavior of AA7050 aluminium alloy at 350°C and 0.01 s ¹1. With increasing strain rate and temperature, high level of the flow softening is associated with deformation heating, dynamic recovery and dynamic recrystallization. The superimposed processing map with various strains is established, indicating that the optimum hot workability domain is the temperature range of 390³450°C and strain rate range of 0.1³0.01 s ¹1 .

Effect of Deformation Heating on the Flow Behavior and Processing Maps of Al–Zn–Mg–Cu Alloy

“…1(e)), the flow curves display a rapid decrease after the peak strain, which is attributed to DRV, DRX as well as deformation heating. 14) The deformation temperature analysis confirms the occurrence of deformation heating at a strain rate of 10 s ¹1 , as shown in Fig. 2.…”

Hot Deformation Behavior of 7085 Aluminum Alloy Based on Deformation Heating and Friction

“…This phenomenon indicates the occurrence of thermal softening due to deformation heating. 14) According to the literature 4), the increment of temperature between the actual temperature and the set temperature of AA7085 aluminum alloy during isothermal compression reaches to nearly 35°C at 450°C with strain rate of 10 s ¹1 , indicating the presence of deformation heating.…”

“…The presence of deformation heating or cracking have resulted in a continuous flow softening behavior at high strain rate. 14,15) Therefore, the experimental flow stress can't describe the hot deformation behavior at high strain rate. Multiple approaches are available to correct the flow stress due to deformation heating and friction.…”

High-Temperature Mechanical Behavior of an As-Extruded Al-5Zn-2Mg-0.3Cu (in wt.%) Alloy

“…Compared with other Al alloys, the Al-Zn-Mg-Cu (7xxx) series alloys have a relatively high specific strength, good workability and corrosion resistance, and are often used as part of an aircraft's skin and wing frame [11][12][13]. In addition, the high-temperature mechanical properties of the 7xxx series Al alloys are good [14][15][16]. In the research regarding the mechanical behavior of 7015 and 6061 Al alloys at temperatures ranging from room temperature to 500 • C, Oñoro et al reported that the tensile strength of the 7015 Al alloy was significantly higher than that of the 6061 Al alloy, but that the tensile strength of the 7015 Al alloy at 400 • C was still lower than 100 MPa [14].…”

“…In the research regarding the mechanical behavior of 7015 and 6061 Al alloys at temperatures ranging from room temperature to 500 • C, Oñoro et al reported that the tensile strength of the 7015 Al alloy was significantly higher than that of the 6061 Al alloy, but that the tensile strength of the 7015 Al alloy at 400 • C was still lower than 100 MPa [14]. Yang et al reported that the main softening mechanisms of the 7050 Al alloy at 350 • C/0.01 s −1 were dynamic recovery, dynamic precipitation, and coarsening of precipitates, while the main softening mechanisms at 450 • C/10 s −1 were dynamic recovery, dynamic recrystallization, and deformation heating [15]. Due to these reasons, the tensile strength of the as-extruded 7075 Al alloy at 550 • C was only 20 MPa [16].…”