Aluminum Alloys, Processing and Characterization: Mechanical Properties, Applications, and Fitness for Service Testing
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Dimitry Sediako, University of British Columbia

Tuesday 2:00 PM
March 16, 2021
Room: RM 27
Location: TMS2021 Virtual

Session Chair: Nima Shamsaei,  Auburn University


2:00 PM  
The Effect of Rare Earth Mischmetal on the High Temperature Tensile Properties of an A356 Aluminum Alloy: Joshua Stroh1; Dimitry Sediako1; David Weiss2; 1University of British Columbia Okanagan; 2Eck Industries
    Aluminum-silicon (Al-Si) based alloys are prominently used in the transportation industry, due to their impressive wear resistance, castability and lightweight properties. Small additions of magnesium (Mg) can improve the mechanical properties through precipitation of strengthening intermetallics such as Mg2Si. However, the poor thermal stability of Mg2Si restricts the use of Al-Si-Mg alloys, such as A356, to only lower temperature applications (i.e. less than ~150 °C). With the growing demand for increasing fuel efficiency amongst the transportation industry (achieved through elevating the operating pressure and temperature of engines), it is necessary to investigate methods of improving the thermal stability and mechanical properties of the well-established A356 alloy. Addition of rare earths (RE) to Al alloys can improve the thermal stability through precipitation of fine Al-RE intermetallics. Thus, this paper aims at characterizing the effects that RE mischmetal has on the elevated temperature strength, ductility, and creep resistance of an A356 alloy.

2:20 PM  
Effects of Ultrasonic Melt Processing on Microstructure, Mechanical Properties and Electrical Conductivity of Hypereutectic Al-Si, Al-Fe and Al-Ni Alloys with Zr Additions: Suwaree Chankitmunkong1; Dmitry Eskin2; Chaowalit limmaneevichitr1; 1King Mongkut's University of Technology Thonburi; 2Brunel University London
    Ultrasonic melt processing (USP) was applied to hypereutectic alloys of three different systems (Al-Si-Zr, Al-Fe-Zr and Al-Ni-Zr) in search for an alternative to Al-Si alloys for high-temperature applications. Mechanical properties of these alloys were controlled through both structure refinement by USP and also Al3Zr nano-precipitation hardening. Significant refinement of primary intermetallics was achieved under USP during the Al3Zr formation in solidification process. The residual Zr in the aluminium solid solution enabled precipitation hardening at 450 °C. As a result, the tensile properties, especially ductility, were considerably improved at room and elevated temepratures. The mechanical properties were analysed with respect to the volume fraction of intermetallic phases. Electrical conductivity was measured to better explore the potential applications of these hypereutectic alloys.

2:40 PM  
The Corrosion Behavior of 5xxx and 6xxx Aluminum Alloys with Trace Calcium: Saugat Singh1; Kumar Sundaram2; B. Pesic1; 1University of Idaho; 2Novelis Molten Metal Processing, Novelis Corporation
    The aluminum alloys containing magnesium and silicon as main alloying elements have found to be recycle friendly. During the recycling process, calcium is found as a trace element or through deliberate addition. The addition of calcium may influence the corrosion properties of the alloy via changes like microstructure and compositional chemistry. This study investigates the potential effects of added calcium and fabrication process on the corrosion behavior of 5xxx and 6xxx alloys using standard corrosion evaluation techniques, like Tafel, linear and cyclic polarization. The results show addition of trace calcium does not show significant changes to corrosion behavior and repassivation behavior of the alloys. The breakdown potential of the alloys shown to decrease linearly with increase in the chloride concentration. The 5xxx alloy shows decrease in corrosion potential with increase in sensitization time. The mechanism for the observed corrosion behavior in presence of calcium and microstructural changes will be discussed.

3:00 PM  
Review of Retrogression Forming and Reaging for AA7075-T6 Sheet: Katherine Rader1; Jon Carter2; Louis Hector2; Eric Taleff1; 1University of Texas at Austin; 2General Motors
    Retrogression forming and reaging (RFRA) is a new warm-forming process designed to produce automotive structural components from high-strength aluminum alloys. A scientific approach is described to determine appropriate RFRA conditions for AA7075-T6 and is applied to laboratory-scale forming experiments. The concept of reduced time is used with the activation energy of retrogression measured for AA7075-T6 to predict appropriate times and temperatures for retrogression forming. Conditions recommended for AA7075-T6 are retrogression at 200°C for 3 to 12 min and forming with strain rates of up to 10-1 s-1. The recommended reaging heat treatment to fully restore strength to the T6 condition after retrogression forming is 120°C for 24 h. These RFRA conditions are successfully applied in laboratory-scale experiments to form AA7075-T6 Alclad sheet and produce a final strength equivalent to the T6 condition. Data from tensile tests provide flow stresses and tensile ductilities across the range of conditions appropriate for RFRA.

3:20 PM  
Fatigue and Failure Analysis of an Additively Manufactured Contemporary Aluminum Alloy: Pooriya Nezhadfar1; Spencer Thompson2; Ankit Saharan2; Nam Phan3; Nima Shamsaei1; 1Auburn University; 2EOS North America; 3Structures Division, Naval Air Systems Command (NAVAIR)
    Aluminum alloys have become prominent materials for additive manufacturing (AM) owing to their high specific strength and the opportunities provided by AM for fabricating parts with complex geometries. Many efforts have been devoted recently to developing novel high-strength aluminum alloys compatible with AM processes. However, the fatigue performance of these alloys needs to be thoroughly understood before being deployed in critical load-bearing applications. It is well known that build orientation affects the microstructure and defects of the AM parts, which then dictates their fatigue performance. Accordingly, this study investigates the fatigue behavior of Scalmalloy (Al-Sc-Zr) in different build orientations fabricated via laser beam powder bed fusion (LB-PBF) AM process. The anisotropy in fatigue behavior and failure mechanisms associated with the variation in micro-/defect-structure of LB-PBF Scalmalloy are addressed and discussed.

3:40 PM  
Investigation of Weld Quality for Friction Stir Welding of Extrued 6XXX Series Aluminium Alloys: Mehmet Bugra Guner1; Murat Konar; Arif Fatih Yiğit1; Görkem Özçelik1; Tolga Demirkıran1; 1Asas Aluminium
    Friction stir welding process is a solid-state welding process which uses nonconsumable, rotating tool to regionally soften the material through developed heat as a result of plastic deformation and friction, also FSW tool is allowed to stir the surfaces of the joint. In this study, the main aim is to examine the behavior of 6000 series aluminum alloys in both similar and dissimilar welding to FSW process; for this purpose, AA 6005-T6 and AA 6082-T6 extruded aluminum plates were utilized. Two of the main parameters were analyzed with emphasis: Rotational speed and welding speed. According to test results showing the quality of the weld joint, the best optimum parameters for the decided sets of parameters are tried to be found; moreover, effect of the parameters on the mechanical and microstructural properties were tried to be understood.

4:00 PM  
The Effect of Al3Er Particles on the Structure and Mechanical Properties of an Al-Mg Alloy: Anton Khrustalev1; Ilya Zhukov1; Vladimir Platov1; Alexander Vorozhtsov1; 1Tomsk State University
    The work presents a study on alloys of the Al-Mg system (5-6 wt.%) strengthened with Al3Er particles. The introduction of Al3Er particles into the Al-Mg melt was carried out using master-alloys, a mechanical mixer. In addition, when casting into the chill mold, the melt was subjected to vibration treatment before solidification. The structure of the alloys obtained in the cast state of both initial (without particles) and containing particles was studied using metallography methods, i.e. optical and scanning electron microscopy. Analysis of the mechanical properties of the alloys under loading was carried out. Vickers microhardness and Brinell hardness were also studied.

4:20 PM Question and Answer Period