报告题目：Expanded austenite; from fundamental understanding to predicting composition- and stress-depth profiles
主 讲 人：Marcel A.J. Somers
The case developing during low temperature surface hardening of austenitic stainless steel by nitriding, carburizing or nitrocarburizing consists of a supersaturated interstitial solid solution of nitrogen and/or carbon in austenite. The favorable properties of this so-called expanded austenite depend on the profiles of interstitial concentration and associated composition-induced residual stress over the case. The prediction of composition and stress profiles for a certain steel grade from the process parameters gas composition, temperature and treatment time would enable targeted surface engineering of stainless steels. Furthermore, such a numerical model would enable the design of new stainless steel grades that are tailored for optimal performance during low temperature surface hardening, equivalent to the well-known nitriding steels. Preferably, such a numerical model departs from the state of knowledge of microstructure evolution in order to arrive at accurate predictions. For this purpose the availability of fundamental parameters as determined experimentally on homogeneous powders and foils under well-defined conditions is essential.
Marcel A.J. Somers (1960) received his M.Sc. degree in physical metallurgy (1985) and his Doctor’s degree (1989) from Delft University of Technology (NL). In 89/90 he was with Philips Center for Materials, Technology and Innovation as section leader in advanced materials characterization. He returned to Delft University of Technology as assistant professor in physical chemistry of the solid state in 1990 and was appointed full professor of physical metallurgy at the Technical University of Denmark in 1997. A red thread through Dr. Somers’ scientific work is gas-metal interactions in surface engineering and gaseous corrosion along with microstructure characterization with microscopy, diffraction and spectroscopy. Furthermore, his interests involve martensitic transformations at cryogenic temperatures. His work is of fundamental character with a technological importance and spin-off for industrial application. Since 2000 Marcel Somers has led a university group in Materials and Surface Engineering with strong expertise in atmospheric, aqueous and microbial corrosion, (electro) chemical deposition of metals and alloys and the stability of high temperature materials in coal and biomass fired power plants. Marcel Somers has co-authored more than 280 papers in international scientific and technological journals and conference proceedings and, together with Prof. E.J. Mittemeijer he is co-editor of Thermochamical Surface Engineering of Steels. He is co-inventor of 10 patents, all of which have been implemented in industrial applications, and co-founder of the industrial spin-outs Expanite and TRD Surfaces. He was awarded the Brandsma prize (1989); ASM European Lecturer (1999); Reinholdt W. Jorck prize (2001); DTU's innovation prize (2007); Alex Foss gold medal for rewarding contributions to engineering sciences (2014) and Fellow of ASM International (2016). The latter appointment is an international recognition for the contribution of his team to research, innovation and teaching in Materials Science and Engineering, in particular Thermochemical Surface Engineering. He is an elected member of the Danish Society for Technical Sciences (ATV) since 1999 and was chairman of the Danish Research Council for Technology and Production Sciences (FTP) from 2007 to 2009.