PROCEDE DE FABRICATION D'UN ALLIAGE FERRITIQUE - MARTENSITIQUE RENFORCE PAR DISPERSION D'OXYDES

Oxide dispersion strengthened ferritic or martensitic chromium steel production comprises austenitization of a martensitic structure and then slow cooling to transform austenite into ferrite. An oxide dispersion strengthened ferritic chromium steel is produced by subjecting a martensitic preform to austenitization at the Ac3 point or above and then slow cooling at a rate equal to or less than the critical austenite to ferrite transformation cooling rate which is determined from a continuous cooling phase transformation diagram. Independent claims are also included for the following: (i) production of an oxide dispersion strengthened martensitic chromium steel by subjecting the above produced steel to martensitic transformation and tempering; (ii) manufacture of a nuclear fuel cladding from an oxide dispersion strengthened ferritic chromium steel produced as described above; (iii) an oxide dispersion strengthened ferritic or martensitic chromium steel having an average grain size of greater than 1 mu m; (iv) a nuclear fuel cladding comprising the above steel; (v) a nuclear power reactor element which is resistant to neutron radiation and to temperatures of 400-700 degrees C and which comprises the above steel; and (vi) an element which is resistant to temperatures above 400 degrees C and which comprises the above steel.