奥氏体钢降水NbC的模型.pdfVIP

Acta Materialia 50 (2002) 735–747 /locate/actamat Precipitation of NbC in a model austenitic steel W.M. Rainforth a,*, M.P. Black a, R.L. Higginson a, E.J. Palmiere a, C.M. Sellars a, I. Prabst b, P. Warbichler b, F. Hofer b a IMMPETUS (Institute for Microstructural and Mechanical Process Engineering: The University of Sheffield), Department of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK b Forschungsinstitut fur Electronmikroskopie, Technische Universitat Graz, Steyrergasse 17, 8010 Graz, Austria ¨ ¨ Received 27 October 2000; received in revised form 16 October 2001; accepted 17 October 2001 Abstract A model Fe–30 wt% Ni, 0.1 C, 1.61 Mn, 0.1 Nb microalloyed steel, that simulates conventional microalloyed C– Mn steels, but does not transform from the austenite phase on cooling, is reported. Plane strain compression testing was undertaken at 950°C at a constant true strain rate of 10 s1. Samples were deformed in a two stage process. An initial true strain of 0.25–0.45 was followed by unloading, a hold of 1–1000 s and a final deformation to a total true strain of 0.5–0.9. A single deformation was undertaken under identical conditions, but to the total true strain of the double deformation tests. Electron spectroscopic imaging (ESI) in the TEM was used to determine precipitate size and distribution. A 1 s hold time between equal strains of 0.25 was sufficient for appreciable strain induced precipitation, although 40% static recrystallisation occurred during the hold time. Precipitation occurred entirely on dislocatio