Seminar - Overcome the strength-ductility trade-off in steels by a novel short-range ordering strengthening concept by Dr. Wenwen Song
日期：2018 年 07 月 11 日 ( 星期三)
Time：11:00 am – 12:00 pm
The enhancement of mechanical properties is of great importance for the modern steels design. By adopting the conventional strengthening mechanisms, strength can increase substantially, albeit at the expense of formability. In the present work, we propose a new pathway to overcome the strength-ductility trade-off by employing a novel short-range ordering (SRO) strengthening concept. The formation of the SRO in an Al-alloyed high-Mn steel was investigated by means of a combined method of ab initio calculations and various experimental approaches, e.g. in-situ high-energy synchrotron X-ray diffraction (SYXRD) and small angle neutron scattering (SANS). The results for the first time prove the presence of SRO in Fe-Mn-Al-C lightweight steels experimentally. The quantum mechanics based ab initio calculations provide an explanation of the SRO formation mechanism in Fe-Mn-Al-C steels. By an appropriate SRO formation control, the strength and ductility are enhanced either individually or simultaneously, which distinguishes the SRO strengthening concept from other conventional strengthening mechanisms. This SRO strengthening concept seems a promising strategy to overcome the strength- ductility trade-off and be further adopted in the current available continuous annealing production lines in the industry.
Dr.-Ing. Wenwen Song is the group leader of Nano Structured Materials Group at Steel Institute of RWTH Aachen University. Dr Song received her Ph.D. with summa cum laude in 2014 from RWTH Aachen University, Germany. From 2014 to 2016, she worked as postdoctoral researcher in the Steel Institute of RWTH Aachen University. During September 2015 to March 2016, she stayed at the University of Cambridge as a guest researcher. In 2016, Dr.-Ing. Song built up her own research group “Nano Structured Materials” at Steel Institute of RWTH Aachen University. In 2018, she stayed at the University of Oxford as a “Theodore von Kármán-Fellowship” holder. On June13, 2018, she received the “Steel Innovation Prize 2018” in Berlin, Germany. Currently, she is the project leader of sub-project A5 – “Microstructure and Mechanism Maps” and scientific leader of Cloud III – “Hydrogen Management” within Collaborative Research Centre (SFB) 761 – “Steel ab initio: Quantum mechanics guided design of new Fe-based materials”, funded by German Research Foundation (DFG). She is the reviewer of many important journals in her research field, such as Metallurgical and Materials Transactions A, Materials & Design, Acta Metallurgica Sinica and Materials Research Letters. The current research interests of Dr.-Ing. Song’s group focus on developing new concepts of alloy and microstructure design for enhanced material performance by applying a combined experimental and simulation tools. Advanced characterization approaches, like atom probe tomography (APT), in situ high energy synchrotron X-ray diffraction (SYXRD) and small angle neutron scattering (SANS) are employed to analyze the nano structures in the materials. The mechanisms of the phase transformations and deformation behaviors in materials are the main target to explore by means of nano-scale characterization combined with various simulation tools, e.g. ab initio theoretical calculation, CALPHAD method, phase field simulations, etc. The understanding of these mechanisms in the materials is up-scaled to micro- and macro- level.