Loading patent…
AssigneeCommissariat a l'Energie Atomique
InventorsVeronique Lambard, Ana Alamo, Jean-Louis Seran
Estimating the term…
This invention relates to a method of manufacturing an improved ferritic or martensitic alloy based on iron and chromium strengthened by a dispersion of oxides, commonly called an Oxide Dispersion Strengthened or ODS alloy, and, more particularly to a method of manufacturing a ferritic or martensitic ODS alloy with large grains based on iron and chromium which has a single phase ferritic or martensitic matrix having an isotropic microstructure and a grain size that is sufficient to guarantee mechanical strength compatible with a use of this alloy at high temperature and/or under neutron irradiation. According to the invention, the method comprises slow cooling of an austenite at a cooling rate less than or equal to the critical cooling rate for transformation of this austenite into ferrite.
A method of manufacturing an alloy with a ferritic ODS structure that includes chromium, said method comprising preparation of a martensitic ODS blank that includes chromium and a step consisting of subjecting the martensitic ODS blank to at least one thermal cycle, said, at least one thermal cycle comprising an austenitization of the martensitic ODS blank at a temperature greater than or equal to the AC3 point of this alloy in such a way as to obtain an austenite, followed by cooling of this austenite at a slow cooling rate that is less than or equal to the critical cooling rate for transformation of this austenite into ferrite in such a way as to obtain an alloy with a ferritic ODS structure, said slow critical cooling rate being determined from a phase transformation diagram for this austenite under continuous cooling.
A method according to any one of the preceding claims, in which the austenitization is carried out at a temperature of about 1000° C. for a period of about 30 minutes.
A method according to any one of the preceding claims, in which the preparation of the martensitic ODS blank that includes chromium is carried out by mechanical alloying of a pre-alloyed powder obtained by atomization under argon of an ingot, that has a composition corresponding to that of the manufactured alloy and adding oxides.
An alloy with a ferritic ODS structure including chromium, said alloy having a mean grain size greater than 1 μm.
An alloy with a martensitic ODS structure including chromium, said alloy having a mean grain size greater than 1 μm.
Dependencies are inferred from the claim text.