PURPOSE: To obtain Fe base heat resisting alloy superior in smooth creep strength, etc., by hot forging ingot of Fe base heat resisting alloy having a prescribed component compsn., then applying solid soln. heat treatment by homogenization holding, next the first step ageing treatment, then the second step ageing treatment from temp. higher than previously described temp.
CONSTITUTION: Steel ingot of Fe base heat resisting alloy composed of, by weight % 0.002W0.12 C, ≤1.0 Si, ≤2 Mn, 12W18 Cr, 20W35 Ni, 1W2 Mo, 1.2W3.0 Ti, ≤1 Al, 0.001W0.015 B, 0.1W1 V and the balance Fe with inevitable impurity is hot forged. Next, the steel is soaked at 890W1,100°C and solid soln. heat treated, then soaked at 650W720°C for 5W35hr. Next, the steel is subjected to the second step ageing treatment in which it is heated to temp. higher than the soaking temp. by 20°C, soaked for 5W35hr, then cooled, to obtain Fe base heat resisting forging alloy having previously described characteristics and superior in notch creep strength and rupture elongation.
HONJO TAKEMITSU
KINOSHITA SHUJI