|
|||||
|
|
Static and dynamical ageing processes at room temperature in a Fe25Ni0.4C virgin martensite: effect of C redistribution at the nanoscale |
|
| Authors: | Sébastien Allain Frédéric Danoix Mohamed Goune Khalid Hoummada Dominique Mangelinck |
| Affiliation: | 1. Arcelormittal Maizières Research SA , Voie Romaine, BP 30302, F-57283 Maizières les Metz , France sebastien.allain@arcelormitta.com;3. Faculté des Sciences, GPM, UMR CNRS 6634 , Université de Rouen, Avenue de l’Université , F-76801 Saint Etienne du Rouvray, Cedex , France;4. Department of Physical Metallurgy and Materials Testing , Montanuniversit?t Leoben , Leoben , Austria;5. ICMCB, UPR CNRS 9048I, Université de Bordeaux , 87 Avenue du Docteur Schweitzer, 33608 Pessac , France;6. Faculté Saintt-Jér?me, IM2NP, UMR CNRS 6242 , Aix-Marseille Université, Domaine Universitaire de Saint Jér?me , Case 142, Avenue Escadrille Normandie Niemen, F-13397 Marseille Cedex 20 , France |
| Abstract: | The work-hardening behaviour of virgin martensitic steel has been investigated in a strictly un-aged state and after various ageing conditions. At room temperature (RT), the un-aged alloy shows astonishing tensile performances (ultimate tensile stress?=?1600?MPa/uniform elongation?=?15%) but unexpected serrations. These serrations can be suppressed by static ageing (at RT or higher) while maintaining the initial work-hardening rate (ageing at RT). Parallel investigations using atom probe tomography reveal that the distribution of carbon at the atomic scale evolves from purely homogeneous for virgin martensite to partly segregated at a very fine scale (5–10?nm) after static ageing. This particular mechanical behaviour can therefore be associated with a very local decrease in available carbon in solid solution due to redistribution and segregations on defects (nanotwins) that occurs rapidly, even after few days at RT. |
| Keywords: | martensite ageing carbon steel tensile strength atom probe tomography |