Abstract
Void swelling in 0.045%Ti-modified 316 stainless steel was investigated by 200-keV C+ ion bombardment. Three metallurgical conditions, i.e. solution treated, 20% cold-worked and 20% cold-worked+ aged at 898 K for 1, 000 h, were compared. Solution treated materials showed considerably low swelling, while the other two conditioned materials showed much higher swelling. The swelling for 20% cold-worked+ aged materials was the highest. In solution treated condition, a number of fine-scale TiC precipitates appeared uniformly in the irradiated matrix. The precipitates and also solute Ti and C are considered to sup- press void nucleation by vacancy trapping mechanism. In 20% cold-worked condition, high density dislocation networks were observed being heavily decorated dy TiC precipitates, leading to void swelling increase as a consequence of reduced dislocation sink strength and of depletion of solute Ti and C in matrix. In 20% cold-worked+ aged condition, as a result of solute depletion by precipitation of various type precipitates and partial recovery of cold-worked dislocation structure, an enhancement of void swelling occurred. The 0.045% Ti-modified 316 steel was found to be more swelling resistant than type 316 steel.
