The Effect of Environment

Abstract

Fatigue is initiated at the surface where local imperfections are present and a location where environment acts on the material, and its influence is thus more pronounced. Whatever the environment might be, liquid or gaseous, its effect generally is a reduction in fatigue life. The liquid environments are: water, seawater, liquid metals; those of gases are: hydrogen, water vapor (steam), helium, oxygen and air. Vacuum should also be considered as environment. Some of these environments were applied in the experimental investigations of alumina, yttria stabilized zirconia, SiC and Si3N4. In particular comparison of the mechanical properties in water and air should be emphasized, although tests were investigated in vacuum also.