Mean stress and notch effect in HCF experiments on alloy 617 between 600 and 950 degree C

The heat exchanger tubing in a high temperature gas cooled reactor is subjected both to static loading and to a high frequency loading; superimposed on this. High cycle fatigue experiments at various mean stresses and stress rupture tests were carried out on smooth, on notched and on welded samples of Alloy 617 (NiCr 23 Co 12 Mo) at elevated temperatures.