Examination of the High Tensile Ductility Improvement in an As-Solutionized AA7075 Alloy with the Aid of a Friction Stir Process

Abstract

The ductility enhancement of an AA7075 aluminum alloy aided by a friction stir process (FSP) and various heat treatments was investigated and compared in terms of outcome with full annealing (O). The results indicate that a big improvement in the tensile ductility was achieved by freezing the sample at temperatures below 0 °C after the solution treatment and water quenching (W treatment), and further improvement could be acquired via a friction stir process due to grain refinement (<6 μm). Thus, the observed improvement in tensile ductility can be explained by the fact that the W treatment and friction stir processing scheme had an increased strain-hardening effect and decreased the presence of intermetallic particles that are harmful to uniform tensile deformation, consequently causing strain localization in the early stage of tensile deformation, which suggests that these treatment are a potential solution for insufficient formability. In general, the elongation to failure values for the W and FSP-treated specimens (>40%) were at least 1.5-fold greater than that of the annealed alloy. In addition, serrated flow could be observed in the tensile flow curves, and both the Piobert–Lüders effect and the Portevin–LeChatelier (PL) effect could be observed. The enhancement in the tensile ductility was examined in terms of the existence of intermetallic particles and the supersaturated concentration of the solid solution.

A New Infrared Heat Treatment on Hot Forging 7075 Aluminum Alloy: Microstructure and Mechanical Properties

“…Even after heat treatment at 200 °C for 240 min, the IR-heated specimen showed a better Young's modulus than that of the RH-heated specimen. In the XRD patterns (shown in Figure 13), according to our previous research [11], MgZn2 and Al-Cu(Cr)Fe compounds could be observed. Comparing RA60-120-12H_200-4H and IA60-120-12H_200-4H specimens, RA60-120-12H_200-4H has a more obvious MgZn2 peak compared to that for IA60-120-12H_200-4H.…”

“…The heating rate of the IR heating furnace has been published in our previous research [7]. Conventional artificial aging parameters [10,11] were utilized to establish baseline information (i.e., solution heat treatment conditions: RH/480 • C_60 min, aging conditions: RH/120 • C_24 h). The heat treatment conditions are shown in Tables 2 and 3.…”

Al/Niobium Diboride Nanocomposite’s Effect on the Portevin-Le Chatelier Phenomenon in Al-Mg Alloys

“…In closing, the present research provides an alternative means to control the PLC phenomenon via the addition of a nanocomposite material to an Al-Mg alloy while concurrently offering a means to analyze and quantify the serrated flow. With the increasing application of new joining technologies for aluminum, including friction stir processing [29,30] and alternative welding materials [31], the manifestation of PLC in the base metal, the heat affected zone, or the weld requires control. In this context, the present work proposes an appealing approach to counteract DSA upon such fabrication processes using an Al/NbB 2 nanocomposite.…”