The helium embrittlement response of Ti and P modified and thermomecha
nically treated Fe-25% Ni-15% Cr type austenitic alloys was studied th
rough post helium implantation creep testing. Helium was introduced in
to the specimen at 923 K with a concentration of about 60 appm by heli
um-3 ion irradiation with a cyclotron. Subsequent creep tests were car
ried out at the same temperature. In terms of creep rupture time, no s
ignificant degradation by helium was appreciated in the Ti added alloy
, although the P modified one suffered from about a 40% reduction. On
the other hand, a helium-related decrease in the rupture elongation wa
s perceived in both alloys to a considerable extent. The beneficial re
sult obtained from the Ti modified alloy suggests that the mechanical
property deterioration induced by helium could be suppressed by proper
Ti addition and/or microstructure controlling even in alloys with int
ermediate nickel contents (20-25%), like in Type 316 stainless steels
of less nickel content. (C) 1998 Elsevier Science S.A. All rights rese
rved.