| 摘要 |
PROBLEM TO BE SOLVED: To impart excellent intergranular corrosion resistance, on the surface of a structure composed of an Ni base or Fe base austenitic alloy contg. a specified amt. of Cr, by forming a layer in which Cr carbides are dispersed into austenitic recrystallized grains or on the grain boundaries. SOLUTION: In a light water reaction, or the like, a work hardening layer is formed on the surface part of a structure composed of an Ni base or Fe base austenitic solid solution strengthening type alloy preferably contg. 15 to 25 wt.% Cr. Then, this surface part is locally heated to a temp. below the m.p., preferably, at >850 to 1000 deg.C at an executing rate of <=5 mm/sec by using a high density energy source of 0.5 to 2 kJ/cm as heat input. In this way, on the surface part, a surface layer composed of austenite recrystallized grains (primarily recrystallized grains), and Cr carbides precipitated and dispersed into the recrystallized grains or on the grains is formed. At this time, the region in which the austenite recrystallized grains is desirably controlled to a depth of about >=100μm from the surface is desirable.
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