The Effect of Corrosive Environment due to High Temperature on the Stress-Rupture Strength and the Fatigue Strength of Heat Resisting Alloy Inconel 700

Abstract

Hereunder is reported an experimental study made of the effect that the corrosive environment due to high temperature gives on the stress-rupture strength and the fatigue strength of Inconel 700 which is heat resisting Ni-base alloy.The experiments were carried out in such environments as residual fuel combustion gas, vanadium ash, mixture of vanadium ash and nickel sulfide and their combination at 700° and 750°C. The results are summarized as follows:(1) The strength of the alloy showed a remarkable declining tendency in sulfur-bearing environment.(2) The corrosive effect was found larger on the whole in the fatigue test than in the stress-rupture test. This is presumably due to the fact that the alloy is more sensitive to intergranular corrosion and notches under repeated stress than under static stress.(3) The estimation of the stress-rupture life of this alloy under gradually increasing stress caused by corrosion was investigated by using linear damage rule. The estimated life showed critical value when the corrosive environment is due to sulfur content.