EFFECT OF WELD THERMAL CYCLE ON HELIUM BUBBLE FORMATION IN STAINLESS-STEEL

Helium bubble structure was examined on a helium-implanted stainless s teel after applying two kinds of heat input. Helium ions were implante d on Type 304 stainless steel at 573 K from 2 to 200 appm to a peak de pth of 0.5 mu m from the surface. After that, weld thermal history was applied by an electron beam. The cooling rates were selected to be 37 0 and 680 K/s from 1023 to 773 K. TEM observation revealed that nuclea tion and growth of helium bubbles were strongly dependent on the cooli ng rate after welding and the helium concentration. (C) 1998 Elsevier Science B.V. All rights reserved.