The effect of the addition of alloying elements on carbide precipitation and mechanical properties in 5% chromium martensitic steels

Pierre Michaud (1, 2, 3) , Denis Delagnes (1, 4) , Pascal Lamesle (1) , M. H. Mathon (5) , Christophe Levaillant (1)

1 CROMeP - Centre de Recherche Outillages, Matériaux et Procédés
2 Aubert & Duval
3 IP - Institut Pascal
4 CEMES - Centre d'élaboration de matériaux et d'études structurales
5 LLB - UMR 12 - Laboratoire Léon Brillouin

Carbide-forming elements (W, Mo, Nb, V), as well as elements that influence only the tempering kinetics (Co, Ni), were added to a 5% Cr tempered martensitic steel in order to modify its precipitation. The main goal was to shift the secondary hardening peak towards higher tempering temperatures. Small angle neutron scattering and X-ray diffraction experiments, as well as transmission electron microscopy, were performed to characterize the precipitation of nanometric carbides. A significant modification of the volume fraction and/or chemistry of the very fine secondary precipitation was observed only for Mo, V and Ni additions. Moreover, the mechanical properties showed that the volume fraction of small precipitates (VC, Fe(3)MO(3)C) directly influences the mechanical resistance at high temperature but has a detrimental effect on Charpy impact energy.

Mots clés: Martensitic steels; Precipitation; Secondary carbides; Yield strength; Impact test

Domaines: Matériaux

Pierre Michaud, Denis Delagnes, Pascal Lamesle, M. H. Mathon, Christophe Levaillant. The effect of the addition of alloying elements on carbide precipitation and mechanical properties in 5% chromium martensitic steels. Acta Materialia, 2007, 55 (14), pp.4877-4889. ⟨10.1016/j.actamat.2007.05.004⟩. ⟨hal-01715082⟩