PURPOSE: To form a σ-phase of Fe-Cr-Ni intermetallic compound on the surface of an austenitic stainless steel and to improve hardness and corrosion resistance by filling a vessel with austenitic stainless steel together with chromizing agent and allowing hydrogen gas to flow under the prescribed conditions.
CONSTITUTION: An austenitic stainless steel having a composition consisting of, by weight, 0.02-0.12% C, 17-25% Cr, 8-14% Ni, small amounts of several additive elements, and the balance Fe is prepared. This steel is filled together with chromizing agent into a vessel. Then, hydrogen gas is allowed to flow at a rate of 100-250cc/min (per kg of the above chromizing agent) in the course of temp. rise from 1000°C to 1150°C and at a rate of 25-50cc/min in the course of holding and cooling after the temp. rise, by which a σ-phase of Fe-Cr-Ni intermetallic compound can be formed on the steel surface.
SHINOHARA MASATOMO
SAGI KUNIO
KANEKO TOKI
NISHIO TOSHIAKI
NISHI AKIRA
TSUJI YUTAKA
SHINTOU KOUGIYOU KK
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