J. Phys. IV France 123 (2005) 111-115
A study of the high temperature tensile properties of an Fe-Ni alloyG. Saindrenan1, M.T. Simonetta-Perrot1, R. Le Gall1 and R. Louahdi2
1 École Polytechnique de l'Université de Nantes, Rue Christian Pauc-La Chantrerie, BP. 50609, 44306 Nantes Cedex 3, France
2 Département d'Optique et de Mécanique de Précision, Faculté des Sciences de l'Ingénieur, Université Ferhat Abbas, Sétif 19000, Algérie
Tensile tests carried out at different temperatures on Fe-Ni alloys with different sulphur contents revealed a marked drop in ductility in the temperature range 600C to 1000C. The presence of manganese was found to reduce the loss of ductility. The morphology of the fracture surface revealed smooth intergranular failure in the most severe cases and failures showing local indications of ductility (dimples) for the less severe cases. The behaviour is explained in terms of sulphur segregation to the grain boundaries and the action of Mn is related to the formation of MnS precipitates which hinder segregation of free sulphur. The presence of nitride formers such as Boron and aluminium was found to have a detrimental effect if these elements are in their combined form (i.e., nitrides) and a beneficial effect if they are in their free atomic form. This behaviour is related to the formation and dissolution of BN and AlN precipitates.
© EDP Sciences 2005