Automotive Extrusions with Improved Strength and Ductility
Plenary Speaker: Nick Parson – Senior Scientist, Rio Tinto Aluminium
The trend for increased light-weighting in the automotive market represents a growth opportunity for aluminum sheet, castings, forgings and extrusions. The latter are particularly suitable for applications such as crash structures including bumpers, crash rails and side sills along with structural body components. The successful performance of an extruded product relies on the combination of the profile shape and the underlying material properties. Thin wall multi void profiles are widely used to provide stiffness and increase energy absorption in axial or lateral crush through the formation of multiple plastic hinges which impose large strains on the material. In addition, many profiles are cold formed prior to final assembly by bending or hydroforming. Joining techniques such as self-piercing rivets also require a minimum level of ductility to avoid cracking. Therefore, from a material perspective, extruded profiles have to exhibit good ductility combined with high strength to permit down-gauging and structure weight reduction while at the same time maintaining sufficient extrudability to allow the profiles to be produced at economical rates. In order to assist extrusion billet customers in meeting these challenges, Rio Tinto Aluminium initiated a research and development program in collaboration with external partners including the Universities of British Columbia and Waterloo and the Canadian National Research Council. This presentation, based on the results of that work, will discuss the metallurgical factors contributing towards improved performance of common extrusion alloys in automotive applications.
Role: Plenary Speaker
Rio Tinto Aluminium
Nick Parson –Nick obtained his PhD in Mechanical Metallurgy at Imperial College, University of London UK. He started his career at Alcan’s R&D facility at Banbury in the UK, before moving to Canada in the mid 90s to provide production and customer technical support for Alcan’s expanding extrusion ingot business. He has a worked on a wide range of extrusion related subjects including soft and hard alloy metallurgy, extrusion process development and heat exchanger products. Nick is a regular contributor at industry conferences and has been granted a number of patents on improved extrusion alloys. He is currently Principal Scientist for ingot products at the Rio Tinto Aluminium research center in Saguenay, Quebec and is adjunct professor at the University of Quebec at Chicoutimi.
Sandwich Distribution of Metastable Precipitates in an Al-Cu-Au Alloy
Invited Speaker: Jian-Feng Nie – Professor, Monash University
Precipitation process in binary Al-Cu alloys involves the formation of GP zones, theta” and theta’ metastable phases and the equilibrium theta phase, depending on the ageing temperature. Additions of trace elements may change the precipitation process or lead to the formation of other precipitate phases. While the effects of trace additions of Sn, Cd, In, Mg/Ag, or Mg/Si on the precipitation process are well established, the effect of Au addition has been less well studied and therefore remains to be fully established. In this work, the precipitation process and the distribution of precipitates in an Al-1.7Cu-0.02Au (at.%) have been studied using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS)-STEM. It is found that GP zones and metastable precipitates theta” and theta’ are often distributed in a sandwich manner. This unique distribution of precipitates is analysed using first-principles calculations.
Role: Invited Speaker
Jian-Feng Nie received his PhD degree from Monash University in 1993. He is a professor of Monash University. His current research interests cover physical metallurgy of light alloys, applications of scanning transmission electron microscopy in materials characterization, and processing-microstructure-property relationships in light alloys. He edited proceedings of several major international conferences. He was awarded the Marcus Grossmann Young Authors Award of ASM International in 2006 and AIME Champion Mathewson Medal Award of TMS in 2015. He is editor of Metallurgical and Materials Transactions, and chair of the National Events Committee of Materials Australia.
Characterization of Cu, Ag Segregations at the Interfaces of the Metastable Phases in Al-Mg-Si-(Cu, Ag) Alloys at Atomic Scale
Invited Speaker: Zhihong Jia – Professor, Chongqing University
Addition of Cu or Ag in Al-Mg-Si alloy has been found to improve the precipitation kinetics and the precipitation strengthening capability in a positive way. This two microalloying elements may modify the composition, morphology and structure of the precipitates from an initial stage and through subsequent structural formation and evolution. In this work, we will introduce segregation of adding Cu or Ag at the interfaces of different metastable phase and its influence on precipitate structures as well, studied by atomic resolution electron microscopies and first principle calculations. In the Al-Mg-Si-Cu alloy, Cu atoms segregate selectively at some dedicated atomic positions of the precipitate habit plane, and occupation of segregated Cu atom also varies with type of metastable phases. In the Al-Mg-Si-Ag alloy, the added Ag is found to segregate at the interface between the precipitate and the Al materix, and with changable heat treatments, Ag enters the βˊ phase composition, substituting the Si-network to create its own local symmetries and changing its hexagonal unit cell parameter from a = 0.715nm to a = 0.690nm. Both added microalloying elements shows evident influence on natural gaing and bake hardening properties.
Role: Invited Speaker
Zhihong Jia, professor (since 2010.10) in College of Materials Science and Engineering, Chongqing University (CQU) in Chongqing, China. He got his PhD from Philipps University of Marburg, Germany in 2005, and subsequently worked as postdoc/researcher at Department of Materials and Engineering, Norwegian University of Science and Technology (NTNU) in the period of 2005-2010. His research interests are focused on aluminum materials; materials microstructure and the relationship to properties; advanced electron microscopy. He has worked on more than 20 projects from China, Germany and Norway in the past years. Jia has 70 publications with 60 SCI indexed and more than 20 invited presentations in international and national conferences. He, as a key person, had organized the 15th International Conference on Aluminum Alloys (ICAA15, 2016), and the First East-Asian Electron Microscopy (EAMC1, 2013). He is a member of Focus Ion Beam (FIB) Committee of China, a member of Chongqing new material expert committee, a member of Chinese Electron Microscopy Society, and the reviewer for many scientific journals.
Memory Effects in Models for Forming Simulations
Invited Speaker: Bjørn Holmedal – Professor, Norwegian University of Science and Technology
During non-monotonic loading the formability of aluminium alloys may be severely reduced due to a built-in material memory of its previous loading history. For example a 12% cold rolled AA1xxx sheet will have nearly no uniform elongation in the transverse direction, as compared to 20% uniform strain in the rolling direction. Memory effects have been included in crystal and continuum plasticity models. In this paper recent progress in model formulations, behavior and predictability is reviewed.
Role: Invited Speaker
Bjørn Holmedal, DrScient
Department of Materials Science and Engineering, NTNU
Professor Bjørn Holmedal, Norwegian University of Science and Technology (NTNU) email@example.com Professional interests: Hardening mechanisms in metals, primarily Aluminium alloys. Dislocations, microstructure evolution, influence of solute, particles & precipitates. Crystal plasticilty (CPFEM, Taylor type models), continuum mehanics. Transients related to strain-path changes. Accumulated roll bonding. Enhanced strength. Metal composites. Mathematical modelling.
Effect of Cu Additions upon the Strengthening Mechanisms and Recrystallization Behavior in Al-Mn-Fe-Si Heat Exchanger Fin Stock
Invited Speaker: Kenta Suzuki – Senior Researcher, Nippon Light Metal Co., Ltd.
Previous work has shown that the strengthening Al-Mn alloys with copper, while increasing the strength of the material leads, to the formation of an undesirable smaller recrystallized grain structure. In this study the mechanisms of strengthening and recrystallization behavior with a 0.3%Cu addition, after a brazing heat treatment, were investigated in Al-1.1%Mn-0.5%Fe-0.3%Si, using a simulated continuously cast starting stock. Metallurgical analysis revealed that the strengthening by Cu was dominated by the formation of dispersoid particles, while solid solution strengthening decreased with the Cu addition; this result is attributed to the decrease in the amount of Mn solid solution. The recrystallized grain size after brazing heat treatment with Cu addition was reduced compared to that without Cu. It is believed the decrease in Mn solid solution with Cu addition leads to a finer grain size due to Mn in the aluminum matrix inhibiting some boundary migration but allowing other grains to grow during heat treatment. These results are consistent with particle stimulated nucleation (PSN), wherein dispersoid particles are more likely to become active recrystallization nuclei during the heat treatment. The increase in the number of active dispersoid particles with Cu addition is correlated to the recrystallized grain structure.
Role: Invited Speaker
Kenta Suzuki, Dr
Nippon Light Metal Co., Ltd.
Kenta Suzuki is senior researcher in Nippon Light Metal Co., Ltd. in Japan. Kenta Suzuki received a doctor degree of engineering from Tokyo institute of Technology in 2003. After serving as post-doctral resercher in Tokyo Institute of Technology, Kenta Suzuki has been serving as resercher to develop manily automotive heat exchanger Aluminum alloys in Nippon Light Metal Co., Ltd. since 2006.
Four Regions in Low-Temperature Creep of Ultrafine-Grained Aluminum
Invited Speaker: Eiichi Sato – Professor, Institute of Space and Astronautical Science
The present study investigated the low-temperature creep mechanisms in ultrafine-grained (UFG) aluminum manufactured by accumulative roll bonding. UFG aluminum with grain size 0.39 μm showedε-ε plot. The low-temperature behavior was divided into four regions by three distinctive stresses, σI, σII and σIII: σI (=45 MPa) is denoted as the micro-yielding stress with which dislocations start movement, σII (=85 MPa) the dislocation multiplication stress above which dislocations multiply with creep deformation, and σIII (=171 MPa) the conventional yield stress above which macroscopic plastic strain is generated. During low-temperature creep, below σI, negligible plastic strain is generated. Between σI and σII, creep deformation with stress exponent 2.5 occurred, which is accommodated by dislocation absorption into grain boundary and by grain boundary sliding, similarly to the low-temperature creep of h.c.p. metals. Between σII and σIII, creep deformation with stress exponent 7.0 occurred, whose mechanism is similar to the low-temperature creep of coarse-grained aluminum. Above σIII, power-law breakdown occurred..
Role: Invited Speaker
Eiichi Sato, PhD
Institute of Space and Astronautical Science, JAXA
An overview understanding of the precipitation hardening behaviour in naturally-aged AA6xxx alloys
Shahrzad Esmaeili, Li Hua Liao, David J. Lloyd
The effect of natural aging on the precipitation hardening behaviour of AA6xxx alloys has been the subject of numerous studies in the past decades. It has been well established that natural aging generally plays an adverse role on the precipitation hardening behaviour of these alloys for commercially-relevant aging processes. More recent studies, however, have provided evidence for the reversal of this effect if the natural aging time is significantly extended or artificial aging temperature is increased beyond the current practical levels. It is postulated that understanding the fundamental aspects of such behaviour reversal in relation with alloy composition and processing history may open new design avenues to enhance the hardening responses of these alloys during processing operations. An overview of the most recent investigations on the precipitation hardening behaviour of naturally-aged AA6xxx alloys will be presented. The results will be used to propose practical schemes towards enhancing the precipitation hardening efficiency in AA6xxx alloys.
Role: Featured Speaker
Professor, Mechanical and Mechatronics Engineering
University of Waterloo