Aluminum Alloys, Processing and Characterization: Properties of Aluminum Alloys II
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Dmitry Eskin, Brunel University
Wednesday 2:00 PM
February 26, 2020
Room: 1A
Location: San Diego Convention Ctr
Session Chair: Kumar Sundaram, Novelis
2:00 PM Introductory Comments
2:05 PM Cancelled
Hemming Evolution of 6xxx Aluminum Alloys in the Course of Natural Aging Following the Continuous Annealing: Mehdi Lalpoor1; Ellen Lambrechts2; Alexis Miroux1; Christian Bollmann3; Chengchao Yu4; 1Aleris Aluminum Duffel BVBA; 2Gent University; 3Aleris Rolled Products Germany GmbH; 4RWTH Aachen University
The thermomechanical processing steps immediately following the continuous annealing in a production line were simulated in the lab to understand the evolution of hemming behavior of AA6016 and AA6005A in the course of natural aging (NA). After solution heat treatment and quench, samples received various post-treatments namely pre-straining (PS) and pre-aging (PA) followed by NA. The results show that the hemming performance of both alloys significantly drop immediately after quenching followed by a milder decrease up to 1 month of NA. The significant drop of the work hardening and dynamic recovery rate during the first hour of NA after quench may explain the degradation of hemming. PS shows a similar effect as NA on the work hardening rate without affecting the dynamic recovery rate noticeably. PA decreases the work hardening and the dynamic recovery rate considerably.
2:30 PM
The Effect of Deformation Mode and Microstructure on the IGC Susceptibility of Al Mg Si Cu Alloys for Automotive Applications: Roland Müller-Jena1; Joachim Becker2; Tobias Beyer3; Thomas Hentschel4; Marcel Rosefort3; Andreas Stieben2; Daniela Zander1; 1RWTH Aachen University; 2Otto Fuchs KG; 3TRIMET Aluminium SE; 4Hydro Aluminium Rolled Products GmbH
6000 series alloys are widely used in automotive applications due to their good formability, strength, and corrosion resistance. Nevertheless, intergranular corrosion (IGC) can occur due to the formation of corrosion-active Mg2Si-phases or copper-enriched grain boundary nanofilms. The formation of those films highly depends on the alloy composition and thermomechanical history. The present study explores the underlying mechanism of IGC of different industrially-used extruded, rolled and cast 6000 aluminum alloys with high copper contents using standardized immersion tests (DIN ISO 11846 B). A particular focus is set on the influence of processing parameters on grain size and morphology and its effect on the corrosion susceptibility. The results are correlated to the microstructure using optical light microscopy, scanning and transmission electron microscopy as well as differential scanning calorimetry. The corrosion susceptibility as well as the corrosion mechanism was found to be highly dependent on the processing route and the resulting grain structure.
2:55 PM Student
Evolution of Grain Refinement in AA5083 Sheet Metal Processed by ECAP: Christian Illgen1; Philipp Frint1; Maximilian Gruber2; Wolfram Volk2; Martin Wagner1; 1Institute of Materials Science and Engineering, Technische Universität Chemnitz; 2Chair of Metal Forming and Casting, Technische Universität München
Achieving superplasticity requires a homogeneous, fine-grained microstructure with (primarily) globular grains. Equal-Channel Angular Pressing (ECAP) is an established method that produces considerable grain refinement. While there is substantial knowledge about work hardening and grain refinement during ECAP of bulk materials, there is only little information on the effect of ECAP on sheet materials. In the present study, AA5083 aluminum sheets are deformed by single and multiple passes using a 120° die that enables processing of sheet metals following novel ECAP routes, like route D. The effect of different ECA-processing routes on microstructural evolution is characterized by EBSD and supported by additional micro-hardness measurements. Our first results presented here clearly show that microstructural evolution during sheet metal ECAP is strongly path dependent. Our study highlights the challenges of sheet metal ECAP (e.g., microstructural gradients) for producing ultrafine-grained microstructures for superplastic applications.
3:20 PM
High Strength Nanotreated Filler Material for TIG Welding of AA6061: Maximilian Sokoluk1; Gongcheng Yao1; Shuaihang Pan1; Chezheng Cao1; Xiaochun Li1; 1University of California Los Angeles
Advanced, lightweight materials are essential for improving the energy efficiency of modern day vehicles and aircraft. In order to qualify for use in large scale production lines, a material must be readily joinable by fusion welding techniques. However, many of the strongest aluminum alloys exhibit hot-cracking tendencies, if subjected to fusion welding such as arc welding, hindering the widespread application of such materials. To resolve this problem, we developed specifically tailored, nano-treated filler materials for hard to weld aluminum alloys (AA), such as AA7075 and AA2024. The chemical composition of latter filler materials is designed to match its parent alloy’s chemistry to avoid liquation cracking, while a low volume fraction of refractory nanoparticles is added to alter the alloys solidification characteristics, and therefore prevent solidification cracking. Using this technology, the resulting joints are free of cracks and show unprecedented strength in as-welded and Post Weld Heat Treatment conditions.
3:45 PM Break
4:00 PM
Optimization of Thermo-mechanical Processes for Continuous Casting Products using High Aluminum - Magnesium Alloys in Automotive Industry Applications: Ali Ulus1; Görkem Demir1; Ali Ulaş Malcıoğlu1; Sümbüle Sağdiç1; 1Asaş Aluminium
Aluminium–magnesium (Al–Mg) alloys (5XXX series) are preferred for the automotive industry due to their superior properties such as high strength to weight ratio, corrosion resistance and weldability. In this study, in order to meet high-quality expectations of the automotive industry, for an efficient and sustainable production continuous casting (twin roll caster) conditions were determined and thermo-mechanical processes, which are required for the final products, were developed. Regarding its high strength, weldability and excellent deep drawing properties the demand for 5754 aluminum alloy in the automotive industry is increasing significantly. In the scope of this project, industrial production and laboratory prototype studies were evaluated comparatively at each production stage. Microstructures of the samples and thermo-mechanical properties were examined in detail. Moreover, the surface properties were analyzed by non-destructive testing methods at each production stage to fulfil the requirements of the automotive industry.
4:25 PM
Plastic Flow of AA6013-T6 at Elevated Temperatures and Subsequent Reaging to Regain Full Strength: Katherine Rader1; Louis Hector2; Jon Carter2; Eric Taleff1; 1University of Texas at Austin; 2General Motors
Combining a retrogression heat treatment with simultaneous warm forming can increase the formability of certain high-strength aluminum alloys while allowing peak-aged strength to be recovered with a single reaging heat treatment. This new process is called retrogression-forming-and-reaging (RFRA). Elevated-temperature tensile tests of AA6013-T6 were performed over a range of temperatures and strain rates, followed by a reaging heat treatment, to investigate the potential of RFRA. The flow stresses measured at a true strain of 0.10 ranged from 230 MPa at 250°C and 3.2×10-3 s-1 to 290 MPa at 230°C and 10-1 s-1. The average elongation to rupture and reduction in area under the conditions studied were 22% and 56%, respectively, which are comparable to the room-temperature ductility of AA6013-T4. Subsequent reaging of the specimens, however, raised the hardness to 96% of the T6 hardness, which is much higher than the T4 condition. Recommendations for implementing RFRA of AA6013-T6 are presented.