Effect of Hot Deformation and Heat Treatment on the Microstructure and Properties of Spray-Formed Al-Zn-Mg-Cu Alloys

Abstract

Spray forming is a manufacturing process that enables the production of high-performance metallic materials with exceptional properties. Due to its rapid solidification nature, spray forming can produce materials that exhibit fine, uniform, and equiaxed microstructures, with low micro-segregation, high solubility, and excellent workability. Al-Zn-Mg-Cu alloys have been widely used in the aerospace field due to their excellent properties, i.e., high strength, low density, and outstanding machinability. The alloy manufactured by spray forming has a combination of better impact properties and higher specific strength, due to its higher cooling rate, higher solute concentration, and lower segregation. In this manuscript, the recent development of spray-formed Al-Zn-Mg-Cu alloys is briefly reviewed. The influence of hot working, i.e., hot extrusion, hot forging, and hot rolling, as well as different heat treatments on the property and microstructure of spray-formed Al-Zn-Mg-Cu alloys is introduced. The second phases and their influence on the microstructure and mechanical properties are summarized. Finally, the potential in high-temperature applications and future prospects of spray-formed aluminum alloys are discussed.

Research on Alloy Design and Process Optimization of Al–Mg–Zn-Cu-Based Aluminum Alloy Sheets for Automobiles with Secured Formability and Bake-Hardenability

“…were performed under conditions of 470 °C/2 h of solution temperature and 120 °C of artificial aging, and, in order to learn more about the formation tendency of the GP zone, which is the nucleation site of the η' phase, the region between 0 and 1 h was enlarged and is shown in Figure 1. The heat treatment conditions used in the calculation were the commonly performed T6 heat treatment conditions for Al-Mg-Zn-Cu-based aluminum alloys [14][15][16]. It was confirmed that the GP zone was formed rapidly at a temperature of 120 °C, peaked within about 30 min of aging, and then transformed to η' and decreased.…”

“…Therefore, currently, Al-Mg-Si alloys are mainly used, which have high formability and relatively low yield strength, even after natural aging, and excellent bakehardening characteristics after paint bake treatment. On the other hand, in the case of Al-Mg-Zn-Cu alloys, it is generally known that maximum strength is obtained through artificial aging at a temperature of around 120 • C [14][15][16], and excellent mechanical properties of over 500 MPa can be secured [17,18]. But, despite their high-strength characteristics, they are not preferred due to increased yield strength due to natural aging, increased sheet-forming pressure, and reduced mechanical properties due to grain coarsening at bake-hardening temperatures [7,[19][20][21].…”