Helium effects on the creep and fatigue resistance of austenitic stainless steels at high temperatures

The effects of helium on the high temperature mechanical properties of austenitic stainless steel, also known as high temperature helium embrittlement, are reviewed. Special emphasis is given to such experimental data which simulate a fusion reactor environment best, i.e., to creep and low frequency fatigue experiments at high helium levels (≥ 100 appm He). Correlations between mechanical properties data and microstructural data are presented and compared to recently developed models for helium embrittlement. The presented data are critically assessed in the light of fusion reactor materials needs and some suggestions for future work are made.