MechE Colloquium: On the best compromise between strength, ductility and fracture toughness in metallic alloys

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Date 19.12.2022 12:3013:30  
Speaker Prof. Thomas Pardoen, Institute of Mechanics, Materials and Civil Engineering, UCLouvain
Location Online
Category Conferences - Seminars
Event Language English
Abstract: The race for ultra-high strength in metallic alloys has turned into an even more complex quest for high strength/high ductility balance over the last two decades. Depending on the list of requirements of the applications, a minimum ductility is always needed at least for formability. More recently, it has been recognized that a high strength / high ductility compromise does not necessarily translate into high fracture toughness, involving the remnant confusion between the concepts of toughness and fracture toughness. A vast number of structural applications calls for an optimum trade-off between fracture toughness, strength and ductility with a weight that depends on the type of loading conditions and constraints. This has brought back to the front scene the old question of the link between fracture toughness and the two other properties.

In the simplest paradigm, fracture resistance expressed in terms of critical J integral JIc or critical energy release rate GIc is a product of strength, true fracture strain under the appropriate triaxiality and a microstructure length scale. The last aspect is often neglected as well as other contributors, such as a possible change of failure mechanism at crack tip compared to tensile bars, the resistance to void nucleation, the strain hardening capacity and the thickness dependent dissipation by crack tip necking in plates and sheets. Recent results on DP steels with elongated martensite second phases, Cantor type high entropy alloy, Ti-12wt.% Mo alloy, friction stir modified Al alloys and stainless steel, will highlight several important messages on how to raise or to keep high fracture toughness in strong and ductile systems. 

Biography: Thomas Pardoen is full professor at the Ecole Polytechnique de Louvain and at the Institute of Mechanics, Materials and Civil Engineering of UCLouvain. He is the Senior Advisor to the President of UCLouvain for corporate relations. Outside UCLouvain, he is the Chair of the Scientific Council of the Belgian Nuclear Research Center SCK•CEN, vice chair of the Board of the Von Karman Institute (VKi) and of the Board of the Centre Terre et Pierre (CTP). He represents Belgium at the Euratom Science and Technical Committee and at the Global Nuclear Forum (NEA/OECD). After graduating as engineer (1994), receiving a master in philosophy (1996) and a PhD (1998) at UCLouvain, and being a postdoctoral researcher at Harvard University, he became faculty member in 2000. His research interests span the area of the nano-, micro- and macro- mechanics of materials and systems, with an emphasis on multiscale experimental investigations and modelling of deformation and fracture phenomena, as well as coupled functional-mechanical properties and irradiation effects, from both fundamental and applied perspectives. His research activity is articulated around the mechanics of (i) composites, hybrids, multimaterials, and adhesives, (ii) thin films, coatings and mems, (iii) high performance metallic alloys. He has supervised >50 Ph. D. students and > 25 post docs. He is a member of the editorial advisory board of J. Mech. Phys. Solids, Engng. Fract. Mech and Int. J. Damage Mech. He has published over 230 papers in peer reviewed international journals, with current h factor = 66 (Google), and 4 patents. He received the Grand Prix Alcan of the French academy of sciences in 2011 and a Francqui Chair from Université de Liège in 2015. He has been nominated Euromech Fellow in 2015.

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MechE Colloquium: On the best compromise between strength ductility and fracture toughness in metallic alloys

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