Method for producing dispersed oxide reinforced ferritic steel having coarse grain structure and being excellent in high temperature creep strength

摘要

A method of manufacturing an oxide dispersion strengthened ferritic steel excellent in high-temperature creep strength having a coarse grain structure. The method comprises mixing alloy powders and an Y₂O₃ powder, subjecting the mixed powder to mechanical alloying treatment, solidifying the alloyed powder by hot extrusion, and subjecting the extruded solidified material to final heat treatment involving heating to and holding at a temperature of not less than the Ac₃ transformation point and slow cooling at a rate of not more than a ferrite-forming critical rate which comprises, 0.05-0.25% C, 8.0-12.0% Cr, 0.1-4.0% W, 0.1-1.0% Ti, 0.1-0.5% Y₂O₃ by weight, with the balance being Fe. In this method, by using a TiO₂ powder as a Ti component to be mixed at the mechanical alloying treatment or by adding a Fe₂O₃ powder, the bonding of Ti with C is suppressed, and the C concentration in the matrix does not decrease.